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Advanced Oxidation Processes - Science topic

Advanced Oxidation Processes
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I am exploring an analytical or computational approach that can help to calculate the kinetic/thermodynamic parameters to predict the corrosion or oxidation of superalloy.
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Joe Tylczak thanks for the reply. Could you name some of free resources.
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0.1mg/l is used to degrade 10mg/l solution(RhB) under white light irradiation at room temperature, ph 3 and contineous magnetic stirring during irradiation in doubled layered glass reactor with coooling system throughout the experiment.
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With such a limited infomation it is impossible even guess. More details.
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Mineralization of organic matter takes place either by direct or indirect oxidation in an electrochemical oxidation reactor. As per literatures both occurs at same time. How can we find which one is more dominant (direct / indirect) in a particular electrode. Can OER Potential estimation can help in determining this?
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Well it depends on the potential that we applied. Positive potential gives oxidation reaction and negative potential gives reduction potential. If working electrode is in oxidation state then counter/ auxiliary electrode get reduced. It also depends on chemical behaviour of the electrolyte and assays that you studied.
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Our research group cannot find suppliers of TiCl4 locally and our access to school laboratory is very limited due to pandemic. We are looking for ways on how to synthesize TiO2-rGO composite for our study using simple equipment only. Would you please help us in this?
For your reference, here is the original method:
SYNTHESIS OF TiO2@rGO COMPOSITES
The TiO2-rGO composite will be synthesized via the typical chemical method. Reduced graphene oxide (0.1 g) and 260 mL of 0.1 M titanium chloride (TiCl4) aqueous solution will be subjected to magnetic stirring for 0.5 hours at 80˚C. The mass ratio of TiO2 to rGO is based on the results of several studies indicating that the optimum concentration for the latter is 2 wt % 13,14. Slowly, 260 mL of 0.4M NaOH will be added under constant stirring for 3 h. The mixture will be washed with deionized water and ethanol five times; the former is for adjusting the pH to 7 while the latter is for better dispersion of the molecules. The formed product will be recovered using filter papers. Finally, it will be dried at 80˚C for 4 h.
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Hi, Magnetic stirrer and RB flask are enough to reach out TiO2-RGO composite (https://www.sciencedirect.com/science/article/abs/pii/S1004954118308759)
If you want methodology in a detail, kindly let me know.
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Which method is easier to measure PFAS in water?
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High-pressure membranes, such as nanofiltration or reverse osmosis, have been extremely effective at removing PFAS. Reverse osmosis membranes are tighter than nanofiltration membranes.
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Microplastics (MPs) pollution has become a global environmental concern because of their severe threat to biota. However, limited studies on the elimination of MPs pollution were reported. The conventional treatment methods such as coagulation, sedimentation, screening, and flotation were not suitable for MPs owing to their smaller size than plastic items. Hence many methods for MPs treatment, including AOPs (direct photodegradation, photocatalytic oxidation, and electrochemical oxidation) and biodegradation, have been examined.
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The flow diagram
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Hello,
I want to start experiments using sulfate AOPs. In many papers, there is used for example : 1 mM of potassium persulfate. Can ayone help me how to prepare this solution?
For example:
I have 100 mL of methylene blue (10 mg/L) solution. I want to add 1 mM of potassium persulfate. Should I add 27 mg of solid potassium persulfate and then fill it up to 100 mL with my methylene blue solution, or can I use 0,1 M potassium persulfate solution and add 1 ml of this solution and then fill it up to 100 mL with methylene blue solution ?
Thanks for answers
Juraj
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thanks for this information
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I'm working on an industrial wastewater mainly composed by DMF and alcohols. I'm treating samples with hydrodynamic cavitation, hydrodynamic cavitation/H2O2 or hydrodynamic cavitation/O3 but at the end of each process the COD value is slightly higher than the wastewater one. I tried to remove excess of H2O2 by heating the samples at 90°C or adjusting pH to 10-11 and then heating at 45°C because of its interference, but also other samples have same problem Hannah Instrument COD kits are used to determine COD values.
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Hi Federico Verdini,
For the said industrial wastewater, determine or (repeat) the COD by varying dilution factors
(1:10, 1:50, 1:100, 1: 200). After that you may get average range of COD.First confirm intial value of given sample. For more accuracy you can correlate with BOD value.
However you can more details about interference and its limitations in APHA Standard method 5220, SECTION 5-11)
Reg
Prashant. B.B
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According to below articles about kinetic modelling of ODH reactions by G. Che-Galicia and et al. there are some problems need your guidance and advices:
Q.A
  1. According to the nomenclature and equation 13, Kn (absorption equilibrium coefficient) should have the unit of 1 / Pa, but by referring to equation 19 Kn is unitless. why?
  2. According to Equation 18, the first statement in the exp function has the unit of mmol / (g.h), but the second statement is unitless, so we think A' must be outside the exp function. why?
  3. The quantity of Cps (solid heat capacity) and Kez (effective thermal conductivity in axial coordinate) did not reported in the main article and the references mentioned in the context of article. how can we calculate or get this property?
we emailed to authors but don't received any response !
Thank you for the time you spent reading.
Respectfully
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Amir Loghmani i do agree with the expert comments above but I only have to say about that there are many studies available and reports various kinetic modelling of ethane oxidative dehydrogenation under an oxygen free atmosphere employing a catalyst of various percentage and sometimes it might be based on the weight and can from 5-12% wt % of VOx supported on ...... and one can see these studies in the links shared
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Dear Colleagues,
I’m pleased to inform you that open access journal /Catalysts/ (ISSN 2073-4344, Impact Factor: 3.444) is planning to publish a Special Issue on the topic of "Trends in Catalytic Advanced Oxidation Processes". The submission deadline is 31 July 2020.
Detailed information regarding this issue, please follow the link below to the Special Issue website at:
This Special Issue is dedicated to novel achievements in the field of catalytic advanced oxidation processes. The contributions should be related to the listed topics:
· Catalytic processes in water and wastewater treatment
· Developments in Fenton-like AOPs
· Activation of Persulfates for AOPs
· Formation of sulfate radicals
· Catalytic cavitation-based AOPs (hydrodynamic cavitation and acoustic cavitation)
· Sonocatalysts
· Catalytic ozonation
· Photocatalysts—including visible light and UV applications
· Catalytic wet air oxidation (CWAO)
· Catalytic–electrochemical AOPs
· Carbon catalysts for AOPs
· Nanocatalysts
· Risk of by-product formation during water and wastewater treatment
· Developments in process control of catalytic AOPs (analytical methods, chromatographic, and spectroscopic techniques)
· Methods of catalysts characterization
· Post-process assessment of effluents toxicity
· Application of nanobubbles in AOPs
· Economic analysis of catalytic AOPs application and catalysts life cycle assessment (LCO)
· Industrial catalytic wastewater treatment
· Modelling and optimization of catalytic processes
· Green chemistry aspects in catalytic water and wastewater treatment
Detailed information regarding this issue, please follow the link below to the Special Issue website at:
Sincerely hope this invitation will receive your favorable consideration.
Best regards,
Guest Editor
Prof. Grzegorz Boczkaj, PhD. Sc. Eng. Assoc. Prof.
Department of Process Engineering and Chemical Technology, Faculty of
Chemistry, Gdansk University of Technology, 80-233 Gdansk, Poland
Caroline Zhan
Assistant Editor
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Dear Prof.
Looking forward to hear if any special issue under your editorship.
Thanks
Siddhartha
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It is hypothesized that the nature/energies/electron distribution of the frontier orbitals of a molecule changes under external field condition. Under applied bias, the molecule can be oxidised/reduced and this changes its electronic distribution and eventually the molecules ability to conduct current. Can we model such an hypothesis using DFT in Turbomole? Some information in this regard is very welcome.
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Almost all quantum chemistry codes support applying external electric field in calculations. My recent work about ultrastrong regulation effect of electric field on various properties of cyclo[18]carbon is a typical example: https://doi.org/10.1002/cphc.202000903.
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During electrocoagulation of biomethanated distillery spent wash, almost all of the spent wash converts into froth, leaving behind little amount of water. What could be the reasons for this and how to prevent this? 
Electrodes used - Aluminum/Iron/Graphite
Input current - DC, 24 V, 2-3 A
 
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Try using electrodes with high OER and HER overpotentials. Such materials include MMO and Pt. This will reduce the overall gas evolution, thereby reducing the froth formation.
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Dear Colleagues,
I’m pleased to inform you that open access journal /Catalysts/ (ISSN 2073-4344, Impact Factor: 3.444) is planning to publish a Special Issue on the topic of "Trends in Catalytic Advanced Oxidation Processes". The submission deadline is 30 March 2020.
This Special Issue is dedicated to novel achievements in the field of catalytic advanced oxidation processes. The contributions should be related to the listed topics:
· Catalytic processes in water and wastewater treatment
· Developments in Fenton-like AOPs
· Activation of Persulfates for AOPs
· Formation of sulfate radicals
· Catalytic cavitation-based AOPs (hydrodynamic cavitation and acoustic cavitation)
· Sonocatalysts
· Catalytic ozonation
· Photocatalysts—including visible light and UV applications
· Catalytic wet air oxidation (CWAO)
· Catalytic–electrochemical AOPs
· Carbon catalysts for AOPs
· Nanocatalysts
· Risk of by-product formation during water and wastewater treatment
· Developments in process control of catalytic AOPs (analytical methods, chromatographic, and spectroscopic techniques)
· Methods of catalysts characterization
· Post-process assessment of effluents toxicity
· Application of nanobubbles in AOPs
· Economic analysis of catalytic AOPs application and catalysts life cycle assessment (LCO)
· Industrial catalytic wastewater treatment
· Modelling and optimization of catalytic processes
· Green chemistry aspects in catalytic water and wastewater treatment
Detailed information regarding this issue, please follow the link below to the Special Issue website at: https://www.mdpi.com/journal/catalysts/special_issues/catalytic_aop
By publishing with Catalysts, you will take advantage of the following attributes:
*Fast Publication*:
First decision provided to authors approximately 13.4 days after submission; acceptance to publication is undertaken in 5.5 days (median values for papers published in this journal in the second half of 2018).
The papers will be processed immediately upon receipt. A Special Issue (SI) is not an issue of the journal. It is a collection of articles on a common topic. These articles are published in the regular issues of the journal when they are accepted (no delay) but additionally labelled with the Special Issue name (including a link). A single click on the link will organize all the articles on the Special Issue webpage.
*High Impact*:
According to Web of Science data, the impact factor for Catalysts 2018 was 3.444. The five-year impact factor was 3.808. Catalysts now ranks in Q2 of the "Chemical, Physical" category.
According to Scopus data, the CiteScore for Catalysts 2018 was 3.85, which ranks it in Q1 of the “Chemistry, Physical and Theoretical Chemistry” category, and Q2 of the “Chemical Engineering, Catalysis” category.
*Low Article Processing Fees*:
To enable the journal to make all of its content open access, Catalysts levies an article processing charge (APC) of CHF 1600 for each manuscript accepted after peer review in 2019 which compares well with other journals.
Please note that for papers submitted after 31 December 2019 an APC of 1800 CHF applies.
*Discount*:
A discount may apply if your institute has established an institutional membership with MDPI. For more information, see http://www.mdpi.com/about/memberships.
If you have helped review for MDPI journals and got a discount voucher, you can use it.
In order to plan for the whole paper project, I appreciate you could inform me within three weeks as to whether you would be willing to contribute. I also encourage you to send a short abstract to me (grzegorz.boczkaj@pg.edu.pl) or to Caroline Zhan (caroline.zhan@mdpi.com) in advance.
Sincerely hope this invitation will receive your favorable consideration.
Best regards,
Guest Editor
Prof. Grzegorz Boczkaj, PhD. Sc. Eng. Assoc. Prof.
Department of Process Engineering and Chemical Technology, Faculty of
Chemistry, Gdansk University of Technology, 80-233 Gdansk, Poland
Caroline Zhan
Assistant Editor
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Thanks for your invitation. We can contribute if publication charges are waived.
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dear friends, what is the most suitable iron complex to work with photo-Fenton without needing to stabilize the pH between 2.5 and 3?
I would like to work with the reaction at a pH between 4.5 and 6, would it be possible using some iron complex? like for example ferrioxalate?
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In the paper, "Heterogeneous photo–Fenton treatment for degradation of indigo carmine dye ". Cosme-Torres, et al., MRS Advances © 2019 Materials Research Society DOI: 10.1557/adv.2019.451 . 23 de febrero 2020. https://www.cambridge.org/core/terms,
you can read about this topics
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Actually I have faced a significant quantity of nanocatalyst loss during immobilization on glass surface. Though I have used ethanol(volatile) to spread the catalyst effectively towards the surface of a glass but somehow found significant drop of catalyst outside the glass.
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For L-B-L technique you need strong binder and pH control, maybe you try with chitosan. You can also try screen printing or dip coating method with TiO2 paste. Ref:
Fabrication of screen-printing pastes from TiO2 powders for dye-sensitised solar cells
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I am trying to understand the nature of a H2O2 neutral loss in HCD fragmentation data of cysteic acid containing peptides. The y-series showing the neutral loss is complete so we believe it must be true. Can anyone make sense out of it? Thanks!
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So sorry Stjepan!..in fact my answer was directed to the person who asked the question in the first place (@Michael Wierer)
Best regards
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As a promising electrochemical advanced oxidation processes (EAOPs), electro-Fenton (EF) process has been widely used in various environmental remediation applications. The type of cathode determines the perfromance of EF process from the following two aspects:
(1) H2O2 production through 2-electron oxygen reduction reaction (2eORR);
(2) Fe3+ electroreduction;
Currently, majority of work focus on the cabonaceous cathode materials on their catalytic performance on H2O2 production. Various factors such as degree of graphitilization, porosity, surface chemistry, and heteroatoms have all been examined to maximize the catalytic performance.
However, I am curious that few work focused on the discussion on Fe3+ electroreduction. What properties of carbon materials (porosity, surface chemistry......) determines the performance on Fe3+ reduction?
This question is also important in carbon-assisted water electrolysis process, because Fe2+/Fe3+ cycle is also used, and the effective Fe3+ reduction by carbon is the decesive factor of system performance.
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That is a really awesome question, which has troubled me for quite a long time. To be honest, we have paid too much attention to the cathodic H2O2 accumulation and unquestionably, it is crucial in the electro-Fenton process. In fact, electro-Fenton comprises two Fenton’s reagents: one is H2O2 and another is VALID Fe2+. The role of the valid Fe2+ is important as well since Fe3+/Fe2+ is the rate-limiting step in the classical Fenton reaction. We could notice as we pave our way to improve H2O2 accumulation to fabricate various cathodes, among which gas diffusion electrodes (GDEs) are regarded as one of the most efficient ones for H2O2 formation, however, hydroxyl radical generation in the GDEs-based electro-Fenton is not that promising. Because iron precipitation happened near-cathode vicinity as H+ was consumed too much by an oxygen reduction reaction (Journal of Power Sources, 2020, 466: 228342). As a result, we need to balance H2O2 formation and Fe3+ reduction to maximize the radical generation if one single cathode used for both reactions.
Regarding Fe3+ reduction, in my view, we need to consider it from two aspects.
One is about its chemical nature before it migrates to the cathode surface, I mean, iron tend to complex with various ions (like -OH) or chelating agents with function groups (-O, -N) such as humic substances polycarboxylates, etc, commonly presented in the aqueous environment. Those ligands donate a pair of electrons to the Fe atom and then redox-properties of Fe3+/Fe2+ were modified.
Another one is what you have mentioned is the nature of the cathode itself once iron approaches to the cathode. Research about it is quite limited and as far as I knew, cathode surface modified with electron-donating moieties, like phenolic -OH, quinoid -C=O, carbon-centered persistent free radicals favors Fe3+ reduction.
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Hello,
I want to know whether or not the Zeta potential can give me an idea about the stirring degree in an electrochemical reactor, since i m dealing with a petroleum refinery wastewater.
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The relation between these two parameters is what i m seeking indeed. During my research to chose the main parameters to study in the electrochemical reactor, the fact that i don't have an interesting idea about the stirring degree rang makes me wonder about finding the appropriate domain basing on the bulk proprieties to get an idea about the mass transfer in this later, and i ended up with the Zeta potential.
As you mentioned, i think the Zeta potential will be influenced by the hydrodynamic regime and so the mass transfer, thus, it will be interesting if we can express such relation.
Thank you for the clarification and your support.
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I'm looking for this material from an accessible source that I can conduct my experiences. Basing on my research, I found that it is used in the electronic devises, but I don't have a clear idea about it, so I'm asking if anyone has ever thought about it.
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Thanks for sharing, I appreciate your help.
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I have synthesized bismuth doped titania (Bi-TiO2). Now i am confused about the position of Bismuth. whether it should be above the valence band of TiO2 or below the conduction band of TiO2. Considering the energy level of Bi dopant, please discuss its position with proper reason and references.
Please check the attached image.
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Dear Noor
To understand the position of Bi in TiO2 you need to first perform Neutron scattering to get a high resolution Data, Next you should perform Rietveld refinement using the TiO2 cif file. However, you will have to perform solid state NMR to understand the coordination number of Bi in the structure.
Using these methods, you will be able to develop a model for your structure which will tell you the exact occupation of your Bi.
There is another method which is called first principle method. in this method you will be able to optimize your geometry based on your primary guess for occupation of Bi. This is an excellent method in which you can even calculate band gap energy using HUMO and LUMO difference and by density of states.
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In seedlings it is important to verify that ozone does not cause damage, because plants are more sensitive to ozone in juvenile stages (Timonen et al., 2004).
Ozone, applied diluted in water and sprinkled on seedlings of ornamental perennial species such as Salix integra, Hydrangea paniculata or Spiraea japonica, has proven to be a very effective treatment against fungal foliar diseases, ultimately causing a saving of chemical products. This fact in a world that increasingly requires more ecological treatments, and in which the demands for reducing the residues of fungicides and other pesticides are increased not only in fruits but also in foods processed with them (Edder et al., 2009 ).
Ozone is considered as a possible organic biocide because apart from not leaving chemical residues, it acts in two ways, a direct and an indirect way through the ROS species (Zotti et al., 2008). Toxic doses in sprinkler irrigation were observed from 1.5 ppm on the mentioned perennial seedlings, in applications of 7.5 minutes of irrigation / day (approx 1L per plant / day) for 6 weeks. The non-toxic dose was observed in concentrations below 1.5 ppm, such as 0.5 ppm. At these levels, an elimination of algae and biofilm is ensured, without showing phytotoxic effects (Graham et al., 2009).
In hydroponic or semi-hydroponic systems, water (30%) and fertilizer (40%) were saved by recycling leached or closed-circuit water (Runia, 1988, 1993, 1994; McDonald, 2007).
In hydroponic tomato cultivation with nutritive solution + ozone, larger tomato plants were obtained than in nutritive solution - ozone. It was demonstrated in this work that the concentration of macro and micronutrients of the nutrient solution is not modified: there is no variation in the levels of Calcium, Potassium, Magnesium, Phosphate, Ammonium, Nitrate, Copper, Molybdenum or Zinc depending on the dose increasing ozone up to 10 ppm. There is a drastic decrease in Manganese (from 0.5 ppm) and Iron (from 5 ppm). To avoid that, Terazoe (2001) proposed the ozonation of the water in a separate tank before adding the nutrients or separating the irrigation with ozone and the irrigation of nutrients. Despite this drastic decrease in the irrigation solution, there are no differences in the content of these nutrients in the leaves, which is not negatively affecting their normal development. There is a notable decrease in the incidence of root rot, typical of hydroponic cultivation (Ohashi-Kaneko et al., 2009).
Questions:
So, everything seems quite good in that way, but many questions comes to my mind:
1) Given the potential of this tool, why is ozone not an essential tool in agriculture today?
2) Are we still in a time of transition to tools such as ozone in agriculture? Or, on the other hand, do people distrust this technology due to unethical actions carried out by certain companies in the manufacturing sector of ozone generators and other innovative technologies?
3) Are there few studies in agriculture with ozone application? Or perhaps the studies show very contradictory results among them?
Feel free to discuss and propose your own questions/answers,
Thank you!
JD
References:
Edder, P., Ortelli, D., Viret, O., Cognard, E., Montmollin, A. D., & Zali, O. (2009). Control strategies against grey mould (Botrytis cinerea Pers.: Fr) and corresponding fungicide residues in grapes and wines. Food Additives and Contaminants, 26(5), 719-725.
Graham, T., Zhang, P., Zheng, Y., & Dixon, M. A. (2009). Phytotoxicity of aqueous ozone on five container-grown nursery species. HortScience, 44(3), 774-780.
Ohashi-Kaneko, K., Yoshii, M., Isobe, T., Park, J. S., Kurata, K., & Fujiwara, K. (2009). Nutrient solution prepared with ozonated water does not damage early growth of hydroponically grown tomatoes. Ozone: Science & Engineering, 31(1), 21-27.
Timonen, U., Huttunen, S., & Manninen, S. (2004). Ozone sensitivity of wild field layer plant species of northern Europe. A review. Plant Ecology, 172(1), 27-39.
Zotti, M., Porro, R., Vizzini, A., & Mariotti, M. G. (2008). Inactivation of Aspergillus spp. by ozone treatment. Ozone: Science and Engineering, 30(6), 423-430.
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Were your experiments done with ozone generated from air or from oxygen? If from air, you may find other molecules formed in the generator, are interfering with your results.
In answer to question 1, I would guess that it is the same as why ozone is not more used in Medicine i.e. there have been lo large scale trials. The reason for the lack is the same. There is no way of protecting your investment in a trial nor large money to be made.
It certainly is a cheap biocide. Even the equipment needed is cheap.
I have had saline ozone IVs and my condition did improve although it's back to where it was prior to treatment 2yrs ago.
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Does the dye degredation reaction with H2O2 over a heterogeneous catalyst can follow a zero order with respect to dye?
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It depends. It might be good because the degradation rate does not decrease in the course of reaction
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I'll be carrying a Fenton reaction and I will be taking around 5 samples in the duration of the reaction. I would like to quench the reaction in the samples until I make TOC, COD and other analyses without affecting it. Total number of samples at a time would be 15, as I will be having 3 parallel cells. What should I use as quencher?
Best regards,
Omar
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If it is homogeneous Fenton's process, two options could be used: (i) removing H2O2 by adding small quantity of sodium sulfite (Na2SO3) (conc. of around 30 mM) should be enough and (ii) precipitating the catalysts by adding strong base. The aim of both method is to remove one of the Fenton's reagents, which will immediately halt the reaction.
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A dyeing plant produces a very high concentration of wastewater, and I'm looking for a low-cost method, requiring low space and, if possible, a high-speed process.
Removing or separating colors is one of the most important parameters of this factory.
Some colors of this factory can be applied to the coagulation and flocculation process (with FeCl3 and Ca(OH)2), but for a very high concentration of black, it will be costly ...
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When your dyes are sulfur ones, the choice of activated carbon as an adsorbent is not too good. It is well known, that efficiency of sulfur dyes reduction by activated carbon is rather low. Please see for example Thai Anh Nguyen, Ruey-Shin Juang (2013): Treatment of waters and wastewaters containing sulfur dyes: A review, Chemical Engineering Journal 219:109–117:
"The effectiveness of the activated carbon adsorption process is different with various dyes [ O. Marmagne, C. Coste, Color removal from textile plant effluents, Am. Dyest. Rep. 85 (1996) 15–21. ]. High removal rates (over 90%) are achieved using activated carbon for cationic, mordant, and acid dyes. For direct, sulfur, dispersed, and reactive dyes, the efficiency is moderate (over 40%); it can be improved using massive dosages of activated carbon. For vat dyes, color removal is very low (under 20%). In the case of sulfur dyes, the COD removal is 45.5% and the color removal is 40.9%"
Best regards
Vit
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Does using porous sparger any effect on ozone bubble destruction?
I was measuring ozone yield of lab-scale ozone generator. For about 15 cm height of sample, using porous sparger decreases the amount of ozone delivered to the sample.
Assuming the fact that using sparger would increase mass transfer, what can be the reason of this result?
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Hi,
I agree with Dr. Frank ... You need to give more informations about your operating conditions (gas pressure and flow, T°, pH of your liquid, ... )
There are many factors to be considered in your experiment to optimize the O3 solubility. First at all, try to increase the height of your sample ...
Kind regards
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Suggest references.
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Chemical treatment of photocatalytic degradation (semiconductor based materials like ZnO and TiO2 ), has been used extensively due to its excellent catalytic activity, eco-friendly as well as low secondary pollution.
Unfortunately metal oxide nanomaterials have no efficient absorption in the visible light region and require activation/irradiation in the UV region.
Metal nanoparticles, on the other hand exhibit strong absorption and excellent catalytic activity in the visible range and gained much attention due to its potential application in degradation and removal of organic pollutants under irradiation of visible light.
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I’m planning to treat a highly contaminated petroleum refinery wastewater of local petroleum refinery. I would like to work on a project focused on the Combined chemical oxidation and biological treatment of highly contaminated petroleum refinery or petrochemical effluents (recalcitrant or refractory compounds). The chemical process would be used as a pre-treatment in order to enhance the biodegradability index (BOD5/COD) of wastewater. I plan on reading some literature related to my work and perhaps find a gap for novelty in my thesis
Any prospective leads and suggestions would be highly appreciated.
Thank you.
Saeed Molaei
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Keep in mind the energy consumption of AOPs (ozone generation, UV lamps, production of H2O2 etc)!
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I was wondering the future direction of new perspectives for Advanced Oxidation Processes(AOPs) treatment of industrial wastewater, especially used for treatment of highly contaminated petroleum refinery or petrochemical effluents, such as electro-Fenton, Fenton, photo-electro-Fenton and ... system.
Any prospective leads and suggestions would be highly appreciated.
Thank you.
Saeed Molaei
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In the case of hospital discharges, where the contents must be of nano grams, the use is indicated even if it costs relatively expensive but the obligation to remedy renders the technique valabale
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I’m planning to treat a highly contaminated petroleum refinery or petrochemical effluents with recalcitrant or refractory compounds.
I would like to work on a project focused on the Combined chemical oxidation and biological treatment.
The chemical process would be used as a pre-treatment in order to enhance the biodegradability index (BOD5/COD) of wastewater.
Any prospective leads and suggestions would be highly appreciated.
Thank you.
Saeed Molaei
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The choice of the most suitable treatment technique depends upon pollutant concentration. When free phase of products is present, the first step should be physical treatment followed by.............. It depends upon quality of pollutants present in the effluent.
Best regards
Vit
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I want to design a solar photo-Fenton plant but I will not design the solar collector but rather determine the size/power require for the collectors to be installed off shell.
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In general, you have to answer these questions in order:
1. What is the design capacity of your plant (m3 wastewater/day)?
2. How much energy is required to process 1 m3 of watstewater (J/m3)?
3. How much one solar cell can generate (J/cell)?
It depends on solar cell design capacity, efficiency, local solar data (solar isolation, air, temp.,...). You can take ready solar modules from industry, and weather data from RETScreen if not available locally.
4. How many solar cells are required (cells)?
Hope this helps,
Abdo,
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I'm a student in the final year of my M.Sc in Environmental Engineering. I want to work on a project focused on the feasibility of using the combined advanced oxidation and biological processes to treat highly contaminated petroleum refinery wastewater.
I want to ask you to borrow me about 10 minutes of your time and answer my question. Is anyone able to help me with this?
What topic can I use for my thesis?
Any prospective leads and suggestions would be highly appreciated.
Thank you.
Saeed Molaei
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Dear Saeed,
This is one of the main concerns for students who must determine their own research topic. So, please do not be frustrated. I know that you are looking for a new, yet efficient, way to refine one of the most complex sewage. But please note that your time is only one year, and this time is not enough to carry out the number of tests. My suggestion is to combine two of them, such as oxidation and biological methods, and then focus only on them and all the effective parameters. I can tell without any information and only on the basis of my experience that there are still thousands of experiments that can be done on their combination that nobody has done yet. So you do not have to create a new method, but just do experiments that others have not done. I'll give you a simple example. Changes in temperature, pH, flow rate and feed concentration! That is, even if another researcher has checked the parameter effect, you can change the parameter check range. This is also a new experiment. Please do not drown yourself in a world of papers and methods of purification. What I've done before.
Good Luck
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I am working on Electro-Fenton System using Air Diffusion Cathode. I am not able to produce enough amount of H2O2 in my system. My objective is to generate H2O2 at Neutral pH
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Hi Ayushi,
Our research group found that applying pulsed current could drastically enhance the H2O2 production in EF process, especially for porous cathode materials, such like graphite felt, carbon felt, carbon foam, etc.
Below are links of our recent research, hope they are helpful to you:
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Sodium thiosulfate is usally used to quench with this. However, it has an effect on the TOC of its sedimentation.
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Many options are available.
1. KI,
2. NaOH can be used.
3.We can use MnO2 but it may interfere with TOC analysis.
4. We can safely use inorganic scavengers- Catalase is the best as it will not interfere with the analysis.
5. Tert-butanol or tert-butyl alcohol can be used but may interfere in analysis.
6.Even Chelating agents like EDTA can also be used for the purpose.
7. One of my students had used Sodium Thiosulfate Na2S2O3 without pH adjustment successfully.
Answers given by Niels and Soliu are very right and recommended by me
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Can hydroxyl radicals be generated by using hydrogen peroxide alone in treating wastewater by AOPs? 
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Hydrogen peroxide and UV light from the sun together catalyzes the reaction  yielding two free hydroxyl radicals  which are potent oxidizing agents.
H2O2 + hv→ 2OH·
Presence of metal ions like Fe2+ or Cu+  in seawater may assist generation of hydroxyl radical .Iron(II) is oxidized by hydrogen peroxide to iron(III), forming a hydroxyl radical and a hydroxyl ion in the  Fenton's process
Fe2+ + H2O2 → Fe3+ + HO• + OH−
Also, additional source of hydroxyl radicals is the photo-Fenton  process  
H2O2 + hν → HO• + HO•
Fe3+ + H2O + hν → Fe2+ + HO• + H+
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I am going through a project about the removal of glyphosate and AMPA from water in a plasma reactor. I'm looking for some information about the rate constant for the reaction of hydroxyl radicals with aminomethylphosphonic acid (AMPA). Please, help with some published documents and literatures.
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Thank you very much for the answer
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Greetings,
If the wastewater contains inorganic components comparatively more than organics in its composition is it likely to oxidize the organic compounds especially (which contributes in COD, BOD, TOC, TN, etc.,). For example, if the wastewater may contain inorganics like Fe, Ni, Cu, Cl, S, etc., the target oxidation of organic compounds should interfere by the presence of inorganics, and there will be the cause for the addition of more catalyst, and the treatment efficiency will be comparatively small.
So, is it plausible to oxidize the organic compounds specifically by the available AOP's?
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Dear Pounsamy,
It is difficult to answer as long as the question is very broad. Some people define AOPs solely as processes that work through HO· reactions. In this case it is difficult to find a process that has a variable reactivity to inorganic ions. If you take the broader definition you can get more selectivity from reactions that involve sulfate radicals (UV/PS, figure 3 in Maria Antoniou paper), ClO2, ozone and possible Cl· from UV/Cl2
I think a novel and very interesting process for selective reactions is the hydrated electrons generated by UV/SO32- and gamma radiation. 
You can find very fine work on both sulfate radicals and hydrated electrons in Prof. Sayeds recent publications.
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these antioxidants are used to protect HDPE geomembrane from getting oxidized.
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pKa of BHT (Butylated hydroxytoluene) is 12.3. No ideas about pKa of phenolic group on the surface of antioxidant. BHT is an antioxidant because of the weak O-H bond. No relationship with pKa.
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Hello,
I'm looking for a feasible industrial application to treat DENIM effluent and remove dyes (indigo and black sulfur).
Biological treatment are not good for vat days removal...
Many Advanced Oxidation Processes are able to remove recalcitrant dyes but they are too much expensive...
Any idea? any experience in full-scale application? 
thanks!!
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We have several full-scale case studies where ozone was used to removed various dyes from textile plant effluent.  Ozone is not technically an AOP and is much less expensive compared to AOP's and chemical removal using coagulants and flocculants.  I agree with Mohamed that biological is best for pretreatment prior to chemical oxidation.  If you have a vat or batch process perhaps it is possible to use SBR or MBBR.
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Under UV irradiation, it is normal that free radicals occur.
Meanwhile, is there some reagent that can release H+ or OH- under UV-Vis irradiation?
Thx
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In photo Fenton process, hydrogen  ions H+ are produced through reduction of Fe3+ ions under UV light: 
Fe3+ + H2O+ hν → Fe2++ HO•+H+
Also, some organic  dyes  show changes in   pH  of their solution under UV irradiation
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one of the most strongest & advanced water treatment technology is what's called "AOP" advanced oxidation process , which depends on ultraviolet radiation in presence of either ozone gas , TiO2 , or H2O2 as strong oxidants, that produces the very active OH radical which has the ability to attack org. matter...in a certain retention time 
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Yes, I approve the answer of Patrick! time depends on many parameters. The performer needs to know about (weight) of the parameters in the experiment.
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I'm currently doing research about Fenton oxidation in CSTR. So, I should feed the wastewater, Fe(II) catalyst, and hydrogen peroxide to 1-L reactor continuously.
How is the best feeding strategy for this case? I've some idea about feeding strategy in this case, but I don't know which is the best.
1) I dissolve Fe(II) in wastewater stock solution and wastewater in the reactor, then I feed hydrogen peroxide separately.
2) I just dissolve Fe(II) in wastewater stock solution and feed hydrogen peroxide separately.
3) I dissolve Fe(II) in hydrogen peroxide and feeding this Fenton's reagent and wastewater separately.
Which is the best feeding strategy? Thanks before.
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Fenton's process should be an appropriate method for the treatment of industrial wastewaters which are characterized by a high COD content, so it it is a bit strange that only a poor COD removal is experimentally observed. In the Fenton process is recommended as a typical range for
However, in your description above, nothing was mentioned about the initial pH value of your wastewater. Remind that the Fenton process is usually inefficient when the solution under treatment has a pH value higher than 5. When the pH value of the wastewater is to high, Fe3+ ions willl tend to precipitate as iron(III)hydroxide, and hydrogen peroxide will decompose in H2O2 and O2. This will result in a significantly lower production of OH* radicals, and hence a lower process efficiency.
In the most ideal case, the pH value should be adjusted to pH = 2. You can use sulphuric for doing this pH correction. At the optimal pH value of 2, the optimal dose Fe2+ / H2O2 of is approximately 1:3.(on weight basis). When you have a very high COD concent I also would recommended you to use 5 parts of Fe2+ for one part of COD (also on weight basis).
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As part of my Advanced Oxidation Process in water purification using UV- hydrogen peroxide, I would want to filter out the nitrate ions and permit the humic acids to enter with the rest of the feed water into the UV reactor.
Is there any suitable pre-filtration method like ion-exchange or membrane seperation that would allow me to do so.
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One possibility could be to use electrodialysis and separate the nitrate ions (smaller) from the humic acids. It also depends on the feed you have and if you only want to separate nitrates, because in this case other anions could be separated too (like chlorides, for example).
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Hello everyone;
I need to use manganese oxyde in my research but I have only the manganese powder.
could you show me the appropriate process to oxidise Mn powder totally?
Thank you in advance
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Thank you again Mr Manohar Sehgal for your clear explication.
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I am working on degradation of organic contaminants present in water using advanced oxidation processes.
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If your organic contaminants are known then use UV/visible spectroscopy
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TiO2 crystallizes in rutile structure (tetragonal, space group P42/mnm) and this modification is stable under ambient conditions. Other stable under ambient conditions, however metastable thermodynamically, TiO2 polymorphs are anatase (tetragonal, I41/amd) and brookite(rhombohedral, Pbca). Moreover, it is known that transformation from anatase or brookite to rutile is irreversible.
Is there a way of conversion Rutile to Anatase?
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Yes, I converted Rutile to Anatase phase by multiple shock treatment for the first time, on subsequent shock treatment Anatase converted back to Rutile structure. I am in the process of finding the exact thermodynamic condition to convert Rutie TiO2 to Anatase TiO2 phase. However I am presenting a research paper on reversible phase transformation from Rutile to Anatase and back to Rutile (controllable ratio of mixed phase) in SAMPE 2016 symposium on 24th May 2016 at Long beach CA, USA.    
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I plan to perform the Iron-Ferrozine Chelation Assay to determine how well my thiol prevents the formation of hydroxyl radicals but I wanted to see how well they scavenged hydroxyl radicals. I've seen protocols for the p-nitrosodimethylaniline bleaching assay but they typically didn't incorporate the volumes used for the reaction mixture itself. If anyone has a protocol that includes this I would appreciate it very much.
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Dear Jonathan,
In my opinion, the volume and initial concentration of p-nitrosodimethylanyline (RNO) depend on your system. For example, if you generate hydroxyl radicals by an electrochemical system using large electrodes, you need a larger reactor. If your method has a high rate of generation of OH radicals using a low concentration of the RNO, you will see complete bleaching with little reaction time. You could start with 10 mg/L.
You only need to perform this bleaching method in the presence and absence of your thiol in the same conditions in order to compare.
See J Appl Electrochem (2011), 41: 599-607 and Journal of Photochemistry and Photobiology A: Chemistry (2010) 216:244-249.
Hope this helps.
Best regards.
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There is a brief and interesting question/answer on the oxidation of amorphous silicon here on Research Gate:
In relation to this discussion I am wondering about the doping dependence:
In crystalline silicon the oxidation rate actually depends also on the doping type and concentration. Both, boron doping (from concentrations >1e20cm-3) and phosphorus doping (from concentrations >1e19cm-3) increases the oxidation rate compared to non-doped or only moderately-doped silicon.
Has the effect of doping on the oxidation rate actually also been looked at for amorphous silicon?
  • Do the oxidation rates or limiting oxide thicknesses of a-Si:H (hydrogenated amorphous silicon) depend on the doping concentration or dopant type?
  • Does phosphorus or boron incorporation in non-hydrogenated amorphous silicon (e.g. from sputtering) also depend on doping?[...possibly despite the fact that the conductivity type may not be really affected by phosphorus or boron incorporation in non-hydrogenated silicon?] 
Thank you very much in advance if you care to share your knowledge. 
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As for the oxidation of a-Si:H HOMO plays an important role. the higher energy level of HOMO is , the faster oxidation rate is if hydrogen densies are same . So you should investigate the differene of HOMO energy between n-type and p-type a-Si:H  
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The free activated chloride is a mixture of Cl2, HOCl, and OCl- where the distribution of the three components is mainly defined by the pH. At pH 2, Cl2 is 50% and HOCl is 50%, where HOCl increases to 100% by pH 6; then decreases to 50% at pH 7.4, at which OCl- becomes 50%; and above pH 9, only OCl- is left.
[pKa (Cl2/HOCl) = 2; pKa (HOCl/OCl-) = 7.4
That is theoretical, but when experimenting electrochemical removal of micro-pollutants in the presence of chloride ions, the pH in the anode is low and can be lower than 2. 
Can we account the removal of micro-pollutants to free active chlorine? or  will this be depleted because Cl2 will escape as a gas resulting in the dominance  of OH radicals instead? Or will this be accounted for with regards to the oxidation power causing the removal of organic matter?
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Dear Ali Farhat,
How well chlorine works in water, depends on what the pH level is. At a pH of 8.0, chlorine is only 20% effective! That means green and cloudy water and dangerous bacteria. The higher the pH, the less effective chlorine is. At a pH between 7.4 – 7.6, chlorine works best.
Chlorine is a gas. It does not have a pH value. However, if the chlorine gas is dissolved in water, the following occurs: 
Cl2 + H2O → HOCl + HCl 
hypochlorous acid (HOCl) and hydrochloric acid are formed. Obviously these are acid solutions, and the pH will be below 7.00. The actual figure will depend on the concentrration.
 At pH 0, Chlorine in water is present as Chlorine gas – Cl2. With rising pH, Chlorine reacts with water to form Hypochloric acid - HOCl. In the range of pH 2-6, this is the prominent compound. At higher pH values, Hypochloric acid is neutralized to form its corresponding salt ion, the Hypochlorite ion – ClO-. At approx. pH 9, the neutralisation is complete. The disinfection activity of Hypochlorite is only 1% of that of the Hypochloric acid. As a result of its reaction with water, Chlorine remains in solution for several hours, depending on temperature, circulation etc. 
Regards,
Prem Baboo
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I prepared ZnO via thermal decomposition of zinc acetate dihydrate. I evaluated its performance for dye degradation under UV light. It exhibited 42% dye degradation in slurry system. After keeping it in the Lab (temperature of around 30 deg.) for about 2 yrs, it showed 15% performance enhancement under identical experimental conditions. In fact, I unintentionally did this and therefore have no expectation for the result. I speculated that its properties are altered and some characterizations are thus required for elucidation. But, why does its performance change ?    
*I assume the dye properties are unchanged 
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There may be several factors that contribute to the enhanced activity. First of all the ZnO may have altogether different vacancy states when it was synthesized and kept for years. It could easily come across the atmospheric oxygen, moisture and other gases to have some chemistry which can modify the properties easily. Did you check the XPS of the sample just after synthesis and after keeping it for 2  years? That may provide some fruitful information.
The bottom line is that you do not have the same structure anymore, although, you didn't do any chemistry but the nature did some chemistry with your sample. 
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Of course, colorless molecules are better choices for photocatalytic activity test, but I mean if we are still interested in using dyes because of simple, low-cost protocol for determining their concentration spectrophotometrically. As it is known, many dyes show hypo/bathochromically shifted absorption peaks after degradation test, possibly due to the presence of degradation products. 
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Dear Hanggara,
To the contrary, a study entitled " Is Methylene Blue An Appropriate Substrate for A Photocatalytic Activity Test? A Study with Visible-Light Responsive Titania" revealed the following: 
An analysis of decomposition of methylene blue (MB) in an aerated aqueous solution by its action spectrum has shown that sulfur-doped titania (S–TiO₂) has activity under visible-light irradiation and that the decomposition mechanism depends on the excitation wavelength. This suggests that photosensitive materials are not suitable as probe chemicals for photocatalytic activity tests, especially those for evaluation of activity under visible light. It is confirmed using acetic acid instead of MB that S–TiO₂, but not ordinary non-doped titania, leads to the photocatalytic reaction under visible radiation below 600 nm, which corresponds to its absorption spectrum.
4. Conclusion
The results indicate that there are two significant problems in the photocatalytic
activity test. One is the inadequacy of MB as a probe molecule for semiconductor
photocatalysis, since the photoinduced reaction by MB photoabsorption may mislead into  believing that a given semiconductor material has visible-light photocatalytic activity. Dyes other than MB [35] should also be examined for their suitability as a probe molecule. The other problem is the photoirradiation systems for the activity test. As above, action spectrum analyses enable us to discriminate the origin of photoresponse by checking the wavelength
dependence. However, when the samples are irradiated in MB solutions, for example, with a set of optical cut-off filters that transmit light of a wavelength longer than a given wavelength, as customarily employed, the results cannot be a proof of visible-light sensitizing ability, i.e., real photocatalytic activity.
In summary, the use of transparent substrates in the region of working wavelengths is strongly recommended, if at all possible, in a photocatalytic activity test for photocatalysts and for action spectrum analysis. By using the preferred test system, the present S-TiO2 has been proved really photoactive in the visible region, at least for the decomposition of AcOH into CO2. However, the present finding does not guarantee the visible-light activity for other frequently-used substrates such as acetone or toluene, which need careful individual examination.
For more details, see attached paper.
Hoping this will be helpful,
Rafik
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The most widely reported redox potentials for SO4 radicals is ranging from 2.5 to 3.1 V by Neta and Huie 1988 and for OH radicals is in the range of 1.9 - 2.85 V by Wardman 1989.
Many papers mention very different single values, and that could mainly be because they are different at different pH values, but sadly, most papers mention these redox potentials without mentioning the pH.
"Standard redox potential" is defined as redox potential at pH of 0. But even this value is argued around in literature for OH radicals; some report 2.38V and other reports 2.8 V.
Is there any graph or plot to display the variations of the radicals formation as a function of pH? I am very interested to know at what pH, the redox potential of SO4 radicals is 3.1V?????
It is widely reported that 2.4 V is standard potential of SO4 (i.e. at pH 0) thus it makes sense that as pH increases the redox potential increases (building on the fact that Neta and Huie reports the range being 2.5 - 3.1V). BUT it is also widely published that at high pH (basic pH), SO4 radicals transform into OH radicals (ALTHOUGH the redox of OH radicals is reported to be high (2.8V) at pH 0, and thus expected to be lower (1.9V) at higher pH.
I am very interested to know if there any graph or plot of redox potential variations versus pH, primarily to know at what pH, the redox potential of SO4 radicals is 3.1 V !?!
Any hints/explanations would be highly appreciated!
Thanks.
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This is a good question. Standard redox potential does not mean the potential at pH 0, BUT shout be the one as redox couple is at 1 mol/L. To answer this question, please read the original papers by Neta and Huie, or contact the authors directly..Good luck!
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wastewater treatment researchers, Supercritical water oxidation, Hydrothermal degradation 
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Hi Ammar, glucose is easily degraded and easily assayed.
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It is stabe under direct UV, but I'm not sure about this if the solution is heated up.
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Hi, we just add the powder to a beaker and heat it under continuous stirring. We have done this for all our experiments and I discussed this with other scientists at conferences in past. It goes slow, but it does dissolve. Maybe ultrasonication is dangerous as it may induce molecular changes.
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Very few references mention this information. Moreover, when it is avalaible, there are big differences between the values. 
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Ok, I will have a look on these reviews.  Thank you.
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hi
I saw some papers they use N2 to prepare the activated carbon and the other thy use the N2 then they switched it to CO2 but they did not explain about it. 
I want to know the mechanism of CO2 during activation ?
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During heating processes, N2 and CO2 are used for two different things:
  • N2 (or any other inert gas, such as Ar or He) is used to convert the carbonaceous raw material into another more stable and heat resistant compound that consists mainly of carbon (C). Oxygen and hydrogen are largely eliminated, thus leaving a carbonaceous framework with low surface area. This process is named PYROLYSIS.
  • CO2, in contrast, reacts with the carbon (is not inert) at around 800 ºC according to C+CO2 --> 2CO. As you can see, you remove some carbon from the solid, and convert it to CO that goes away in the gas. This process of 'gasification' develops porosity by removing carbon atoms. This is one of the methods to produce active carbon. It is active because it can adsorb a lot due to its great surface area (say, from 100 to 2000 m2/g). This process is named ACTIVATION. You can also do it with other oxidizing agents such as H2O or O2 too.
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I am working on Cr (VI) + H2O2 system at acidic pH, and would like to know if there is any chemical that will stop residual OH and H2O2 without increasing the pH, and also without effecting on either Cr(VI) or the org. compound any further.
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It's also guaranteed that Cr(VI) will be reduced by Na2SO3
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- looking to partially degrade, not mineralize
- reduce color
- reduce BOD (Biochemical Oxygen Demand)
- return water to watershed
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Have a look on my papers. In the course of doctorate I worked with a highly loaded wastewater, maybe these articles are usefull for you.
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I am working on plant enzymes. After getting result of hydrogen peroxide scavenging activity for example control 2.23 and treatment plant 4.42(after putting formula). How do I interpret the result?
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To correctly interpret whatever results, all details MUST be available. No detail data, no answer. 
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I am looking into calculating over-potential for my water oxidation catalysts at basic pHs. However, I do not see information on the thermodynamic potential at which water oxidation occurs at these pHs ( such as pH 11, 12.5, 13).
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Try to find Pourbaix diagram for your systems. There are lines which gives information about water redox stability in the selected pH. I hope it is what you need. Best wishes.
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When simulate UV/H2O2 AOP process, there includes three model (turbulence, radiation and kinetics), but in kinetics there are photolysis reactions, and I cannot deal with that. Any suggestions?
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Hi  Jixing Cui,
I would try to explain it in the following lines
Rate Expression
-(dM/dt) = Iphi f (1-exp(-At))
phi = quantum yield
I0 = Incident radiation flux
f = Ratio of light absorbed by the M (organic compound) and other components 
At = Total absorbance of the solution time a factor 2.3.
Which further reduces to:
rM = - ln(10) phi epsilon [M] I0            (Leifer, 1988)
Where
epsilon = Molar extinction co-efficient  (M-1 cm-1)
I would recommend you to read following research articles + books as much as you can
References
[1] Leifer A. The kinetics of environmental aquatic photochemistry: Theory and practice. ACS professional reference book (USA). 1988.
[2] Bolton J, Cater S. Homogeneous photodegradation of pollutants in contaminated water: an introduction. Aquatic and surface photochemistry. 1994:467-90.
[3] Oppenländer T. Photochemical Purification of Water and Air: Advanced Oxidation Processes (AOPs)-Principles, Reaction Mechanisms, Reactor Concepts: John Wiley & Sons; 2003.
[4] Alpert SM, Knappe DR, Ducoste JJ. Modeling the UV/hydrogen peroxide advanced oxidation process using computational fluid dynamics. Water Res. 2010;44:1797-808.
[5] Buxton GV, Greenstock CL, Helman WP, Ross AB. Critical review of rate constants for reactions of hydrated electrons, hydrogen atoms and hydroxyl radicals (⋅ OH/⋅ O− in aqueous solution. J Phys Chem Ref Data. 1988;17:513-886.
[6] Crittenden JC, Hu S, Hand DW, Green SA. A kinetic model for H2O2/UV process in a completely mixed batch reactor. Water Res. 1999;33:2315-28.
[7] Santoro D, Raisee M, Moghaddami M, Ducoste J, Sasges M, Liberti L, et al. Modeling hydroxyl radical distribution and trialkyl phosphates oxidation in UV− H2O2 photoreactors using computational fluid dynamics. Environ Sci Technol. 2010;44:6233-41.
Regards
Tipu Sultan
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My students have some troubles to collect GO from water. The size of GO is 10-100 nm. It is difficult to get its solid by centrifugation. So does membrane filtration. Could you please give some suggestions on this problem? Thanks a lot!
Regards,
wang
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Freeze drying would help. Maybe try to centrifugate first a really low temperature, in fact, if you put your glass in which there is your GO into the fridge, you will see some differences after some days.
Regards
Adrian
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I am working on Fenton's oxidation and I would like to know if there is any chemical that will stop Fenton's oxidation without increasing the pH. I have seen NaOH being used but that increases pH. Any other chemicals?
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I think the answers given are mostly pretty good, except that which reducing agent or chelating agent or scavenger is the best choice clearly depends on the objectives of the experiment. Chelators such as those mentioned are effective, but leave unreacted H2O2. The reducing agents produce new products and may glom up the reaction mixture as far as product characterization is concerned. Scavengers such as ethanol form oxidation products such as acetaldehyde or formaldehyde, which are reactive intheir own rights with many classes of compounds
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Hi,
I have an activated carbon for which I need to know the isoelectrical point. Do you know any procedure for that?
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That can be determined by measuring the zeta-potential of activated carbon as a function of the solution pH. The pH where zero zeta potential is reached is referred as isoelectrical point.
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I am working on advanced oxidation processes.
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If you repeat the experiment i suggest that you use your photometer to measure spectra of the reaction mixture at each time point you sample. You can compare the spectra that develop with reference spectra of e.g. phenol and benzoquinol. If the mixture isn't buffered do check if pH changes over the treatment. Decreasing pH will indicate the formation of phenol. 
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How do I can reduce the amount of H2S present in a liquid gas mixture made of sulfate ? so far I 'm dealing with an enzyme, but the costs are very high, thanks!
expensive, the mixture is native to process petroleum distillate
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Ted is right. Be careful...
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When i mix the prepared activated carbon with the water to wash it, it never settles down, it always floating at the top so i could not remove the ashes completely from the prepared activated carbon. How this problem can be solved?
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Water is not enough by itself, and the washing must be extensive.
Therefore, better using a solution of HCl refluxing for several days in a Soxhlet extractor. After this, water must be used in the same conditions until the pH of the rinse if neutral. A bit long, but very efficient.
Alain
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Kindly provide information regarding the usage of Spectrofluorimeter and HPLC in the estimation of MDA and AOPP
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Dear collegues!
I would like to note what there are differences between TBARS and MDA. Of course, You could be use manual methods for determination both, but... in ours laboratory for this needs use kit' s produced Cell Biolabs company or (for MDA and 4-HNE) determination kit' s FR 22 (Lubioscience, Switzerland).  the best way, I mean, use microplate reader (for ELISA method). Such plate' s need hiting (till +98C), best equipment for it  - Thermomixer (Eppendorff). If You have really interest, I can send you Cell Biolabs product catalog for 2015. there are possibility to buy  ''training and examination''  kits, and for manual and plate technology. Good luck.
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The short answer seems to be yes:
The process patent expired in 2014.
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There are big autoclaves that need tons of oxygen and the whole process needs to be well controlled. What is most important to control and how? Which is the best technology?
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In This Process you inoculate Oxygen with specific Air Pump.
For Concentrate leaching, you should be supply required Oxygen to autoclave.
Best wishes
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I'm doing OH radical probing experiments in different natural waters exposed to UV with and without H2O2.
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It should be selective for OH radicals, but I'm not sure if it will not react also with superoxide radical.
Benzoic acid is also good, but you'll get various hydroxybenzoic acids so the detection can be unclear.
I'm using terephtalic acid. It gives only one product, and the detection is with emission spectroscopy.
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I need to calculate theoretical COD for one organic dye molecule, I know the nitrogen and sulphur oxidized as ammonia and sulfur dioxide. Can it be converted to any other forms like nitrate, nitrite etc.?
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related to above: For the S compound you have to calculate it when converted to H2SO4 not SO2. If you wantto com-pare to COD measurement assume NH3 is fiormed and not HNO3
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is it possible that the COD increase and then decrease with applying AOP treatment? any explanation with reference if possible?
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Hydrogen peroxide -- as mentioned by others -- if present in solution will contribute to COD.  A mg/L of H2O2 increases COD by about 0.393 mg/L ; this value was obtained employing Milli-Q water spiked with varying concentrations of H2O2; you may do your own measurements employing distilled and deionized water or Milli-Q water, etc.
Addition of catalase also introduces error in COD measurement that has to be accounted for; this can be done by the following relation.
CODCOR = CODS+C - CODC
Where CODS+C is COD of water sample after catalase addition and CODC is COD of Milli-Q water with the same amount of catalase.
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Electrocoagulation and electro-Fenton are two well known electrolytic processes for water and wastewater treatment. In electrocoagulation, solution pH increases with increase in electrolysis time. But the change in solution pH during electro-Fenton process is insignificant. Why?
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Dear Nidheesh,
In Fenton reaction Fe(II) is oxidized to Fe(III) by H2O2 and increases pH by producing OH- as follow (classic Fenton reaction):
H2O2 + Fe(II) --> Fe(III) + OH (-) + OH (radical)
In other hand some parallel reactions (with lower constant rate) can reduce the pH . For example H2O2 electrogeneration and/or regeneration of Fe(II):
Fe(III) + H2O2 --> Fe(II) + H(+) + HO2
Therefore change in pH will insignificant.
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In my system the oxygen is used for ozone generator.
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Here is a general guide on converting concentrations:
When measuring ozone in Milligrams per Hour ( mg/hr ), the concentration cannot be determined unless the flow rate itself is known.
1 ug/ml = 1 mg/l = 1 g/m3 = 1 gamma
1 ml is = to 1 cc.
So, to determine the actual concentration if given mg/hr., one first must convert from mg/hr to mg/l. This is done by using the flow rate. If an ozone generator pumps out 250 mg/hr at a flow rate of 1 liter per minute, then:
The ozone generator produces 4.1667 mg/min ( 250 mg/hr divided by 60 ). Since we now know that we have 4.1667 milligrams of ozone each minute, and the flow rate is 1 liter each minute, we now have 4.1667 mg for each liter, or 4.1667 mg/l.
By looking at our chart, we now know that we have an ozone generator that produces 4.1667 ug/ml.
To determine the concentration, we can use the formula given by Saul Pressman:
0.5 % X 1.4 gm/l = 7 ug/ml
Only, let's convert it properly, first, by using the mathematical version with the correct units of measurement:
0.005 X 1400mg/l = 7ug/ml
X times 1400 = 4.1667
X = .00298 or 0.298%
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As a rule, UV/H2O2 gives better results in acidic medium. But I got a color removal efficiency up to 99% in Basic pH for one direct dye.
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In fact,free radicals like .OH degradate dye molecules.And these radicals may have more life time and concentration in acidic solution.