Green Chemistry Technology - Science topic

Perhaps you should read the paper included in https://www.circusol.eu/en/nieuws/67/eco-innovations-for-pv-panels.

Model-based application for adsorption of Lead (II) from aqueous solution using low-cost jute stick derived activated carbon

Article Oct 2020, Imran Rahman Chowdhury, Mohammad Abu Jafar Mazumder, Shakhawat Chowdhury, Md. Abdul Aziz

Tea waste is a low cost absorbent for removal of some heavy metals

You can have a look at these papers

Enzymatic desizing can achieve effectively all types of starches from textiles and at workable temp. range.

If you can find a way to improve the role of TiO2 in paint component, such as ratio of TiO2/solvent, then amount of TiO2 may be decreased

Regards,

K

An efficient method for detection of benzene in water using HPLC is possible.

H2O2 decomposed safely presence of enzymes catalase peroxidases.

Reduction of BF3 by sodium hydride, /lithium hydride /or lithium aluminium hydride converts B-F bond into B-H bond.

8 BF3 + 6 LiH → B2H6 + 6 LiBF4

I tend to disagree, that ionic liquids are toxic as such. There are more possible ionic liquids than there are people on this planet. And just as people, they are different. There are toxic ones, there are also completely harmless ones, just as well there are some that are corrosive and others, which serve as corrosion inhibitors.

And that is the beauty of it, you can always find one, that can suit the properties profile that you are looking for.

To remove glycerol from the reaction mixture give gentle washing of methanol, so that glycerol becomes soluble in it and dry product separates out.

The reaction of Pyrogallol with Formaldehyde being fast you have to carry the reaction at a low temperature. if necessary change the solvent.

Karakka Kal Abdul Khader I could not find this paper.

similar question has been addressed : https://www.researchgate.net/post/what_chemical_can_replace_DMAP_4-Dimethylaminopyridine?view=58987399eeae39bbb146bd16

good luck

What is the amount of carbon based material in your case?

oxizolidine

Yes, Basically silica gel has water retaining properties.The matrix is adsorbent and hence can be effectively used as an insulating material

The entire idea behind Green Chemistry is to be sustainable.  If it is called Green and it has no sustainability to the work then it is just a title and not really green..  I am a green building consultant and I see this in the green movement in building.  Every builder is now saying they are green yet they can not even define what is meant by the term.

This is unfortunate but the way of a capitalistic society.  If there is money to be made in the claim then the companies will claim what ever gets them to more profit.

We need to stop talking about how "Green" things are and start talking about how much better it is to be sustainable.  The term Green has been abused so much that most people think it is not real anymore.  I for the most part in my chemical research and in my green consulting talk about not just green but doing the right thing for our children and making a better decision today for a better tomorrow.  

I tell people that I refuse to make a decision today that in any way will jeopardize the lives of my children or make them clean up something that I have promoted.

Green is a movement to do better for the future and future generations and to stop being self centered and asses.  I am not perfect but if we all will just do what is possible we could change the world over night.

Green chemistry has to be the way we move to the future.  It must be more them just the word it must be real.

George   

@Madhukar Baburao Deshmukh and @Leena Rao: bacterial urea hydrolysis is one such reaction which produces alkaline pH. Are there any other similar reactions which will produce alkaline pH?

Thank you Prof. Bachir Achour for sharing useful links.

Do you have any proof that KOH has not reacted with the biochar?

Please let us know the procedure and characterization you do.

it seems like everyone uses carbon to adsorb pesticides so try a hexamethyl disilazane functionalization. It reacts readily with most oxide surfaces and is hydrophobic. Be warned that it is a hazardus precursor, and you will need to read up on safe handling.

Thank you Anirbid Sircar and Carlos Araújo Queiroz for the replies and information. 

Activated carbon is a versatile adsorbent, hence, it can be used for decolorization purpose. Generally, preparation of AC is inexpensive, therefore it is one of the most used adsorbent for removal of different pollutants. However, the choice of your activation source may play a major role in terms of cost effectiveness. Here, is a simple procedure for obtaining activated carbon. First dry the husk, put it in a close contained n carbonized in an muffel furnace at 800 degree Celsius for 2-3 hours (you may vary the temperature of your choice from 400-1000 as per your requirement), ground the carbon into a fine powder (you can use planetary ball mill to obtain fine uniform particle size). After, which you can activate the carbon either with oxidizing or reducing agent. For instance, if you are using Nitric acid as your activating agent, then added the fine carbon powder (10-15 g) in a beaker, and add 0.01 M Nitric acid solution into the beaker slowly until the carbon is fully submerged and stirred it for 2 hours. Filter, wash with DW to remove excess of acid and dry the product, keep it in an air container for further analysis.  

yes you can do the kinetric study of zeolites , by changing the conditions of molar ratio of Si/Al; the concentration of template , the concentration of sodium, the sources of the  reagents , the temperature , the duration , ect )  , this kinetic will be followed by XDR analysis  each time ( you have to estimate the timing , may  be  each two hours , or each day ect 

Thank you all for your valuable answers and useful links. 

yes,characterised with  GC/MS and PNMR.

We are on the same page. I ran out of red mud that had been processed so I used some that has all its elements I used some to make ceramics. Unfortunately I don't have a thermostat for my kiln. The resort was it melted. In a further twist I was looking for magnets to see if I get the iron out of red mud and dropped the magnet and it fell on the melted remains and it stuck. 

I have since today infant ground the remains and there is lots of magnetic material I am going to get it tested for quality. I think it is suitable for pig iron,  sponge iron HBI or DRI  Thanks for your input.

I have a similar question.

I extracted phytochemicals using Petroleum Ether. I have the crude extract and want to remove any lipid content present in it.

What is it procedure called and how to do it ?

YES

This is my perspective from the field of cement and concrete. Rice husk ash and silica fume are both used as additions to concrete. As with what you have said, while both have an effect, RHA is not as effective. 

The main differences are in the elemental composition and the particle morphology. RHA is more angular and likely coarser than silica. In terms of composition, silica will be almost pure while RHA will contain impurities. The silica content of RHA can range from ~70 to 90%, with traces of CaO, Al2O3, Fe2O3 and alkalis. You are also likely to have a loss on ignition with RHA from 2-5% (with the higher value coming from low-technology burning).

Hopefully this is of use to you.

Regards,

Leon

Yes, the inert atmosphere is always recommended during carbon synthesis as the presence of impurities in organic waste and deposited solid impurities which are not removable by washing steps are responsible for the generation ash when carbonized in the presence of oxygen. Additionally, the gaseous product obtained through pyrolysis in the presence of an inert atmosphere is free from gasses like CO2 and CO, thus the pure bio-oil can be obtained by condensing the volatile gasses coming out. However, if carbonized in the presence of oxygen then contamination of the product, corrosion of the reactor by scaling and choking of the process lines may take place. Hence, it is always appreciable to use inert medium during carbonization.

Thanking you

The purpose of cooking process is to decompose lignin and hemicellulose and to remain cellulose as solid. But I think you should consider the impacts on the latter stages of pulping process as well.

It can be good starting point to investigate the impact of base load and chip load on cellulose yield and purity. Kappa number is the measure of lignin content in the solid downstream of cooking process. The solid should contain maximum cellulose and minimum lignin. 

Some contidions can decompose lignin well but decompose also cellulose. Some conditions can result in high cellulose yield but also higher lignin content in the solid. Higher lignin content in solid means more load on bleaching unit. In addition, more base load means more load the chemical recovery part, i.e. caustisation.

So the objective can be determining the compromise between maximum cellulose yield and purity, and minimum base load.  

try alumina or silica.

Please check the following discussion for its possible interest concerning to your query: https://www.researchgate.net/post/optimum_concentration_of_corrosion_inhibitor

Pigments are molecules that are capable of absorbing specific wavelengths (energies) of light and reflect all others. Following are the plant pigments we are familiar with.

1. Chlorophyll a: This is the most abundant pigment in plants and for this leaves appear green to us. It absorbs light with wavelengths of 430nm (blue) and 662nm (red).It contains a hydrophobic (fat soluble) phytol chain that allow it to be embedded in a lipid membrane. The rest of the structure called a tetrapyrrolic ring rests outside of the membrane.The metal, Mg is at the center of the structure and it can have variable oxidation states.

2. Chlorophyll b:  Structurally it is similar to chlorophyll a. It absorbs light of 453nm and 642 nm maximally.

3. Carotenoids: These are accessory pigments and absorb light maximally between 460 nm and 550 nm and appear red, orange, or yellow to us.

4. Xanthophylls: They are essentially oxidized Carotenoids and contain oxygen. They are usually red and yellow and do not absorb energy as well as cartenoids. 

5.  Anthocyanins: These are water-soluble vacuolar pigments that may appear red, purple, or blue depending on the pH. 

Thanks a lots for such great help.

With regards.

Subhash

All fats from grease traps can be recycled through treatment processes to remove solids in order to leave the triglyceride and fatty acid structures free and then process them by transesterification reaction to biodiesel, it is a good alternative to waste fat disposal.

See: https://www.researchgate.net/profile/Guerrero_Fajardo; Article: Transesterification Reaction of Waste Cooking Oil and Chicken Fat by Homogeneous Catalysis

Thanks, Moez. I used SCREEN 3 many many times, but I was asking if is there a model incorporating also the contaminant production (E.g. x kg of waste--> combustion (kkeping in account the temmperature of the smokes--> etc

Yes, a wide variety of possibilities are available, including cermet materials, ceramics or carbón-based membranes. However, I wrote this question for paying attention in Pd-based membranes because we offered a predoctorate job possibility focused in this topic for young researchers .

Ethanol with sodium ethoxide reflux works too.

 Ionic liquid can be synthesized  in two steps     quaternization followed by reaction with inorganic salt containing desired anion  

(R)3N +RCl  ---NaBF4 -----(R)3NBF4

thank you Mr Michael Pach for this wonderful site

This is an excellent project and I extend my congrats to you for carrying out in your place.

with best wishes

N S Gajbhiye

Hi, 

Thanks to Hamdah for your attached files which are useful for this question

Best regards 

Dear Humayun Akhter

You can use Hydrazine hydrate. Hydrazine is a greener reducing agent and maintain pH high of the solution.

Before to discuss any question we must clearly define the meaning of the terms. I have several general questions. 

What is a photocatalyst?

What is the difference between a photocatalyst and a photosensitizer?

What is the roles of photon? It might be a driving force for a thermodynamically unfavorable reaction or just might  initiate a thermodynamically favorable process.

A photocatalytic reaction starts by a single photochemical step followed by dark reactions, which commonly do not take place without a catalyst. Any discussion on activity of a photocatalyst does not make any sense if a catalysis of followed dark reaction is not discussed. 

Concerning the posted question. Dear Abdullah, what did you want to learn asking this question? 

 Dear Mishra,

What is your actual answer for my question??

The pore size of the activated carbon you are using should match the size of the molecules you want to adsorb. Phenols will be trapped in micropores, which is OK, but some dyes will not because much too big. In this case, the adsorption performances are significantly increased by using mesoporous carbons. You also have to consider surface chemistry, wich is at least as important as porosity for adsorption processes in the liquid phase. At similar pore sizes, for instance basic activated carbons will be far more efficient for trapping acidic species (e.g. phenols in N-doped activated carbons). Similarly, organic compounds of mercury will be adsorbed in S-doped activated carbons. So you have to select the kind of activated crabon you need for trapping organic compounds from water, as not all general-purpose aactivated carbons will work.

Alain

Since you're working on nanocataysts, I would recommend the following technology for fuel production from CO2.

The technology is called "Photocatalytic reduction of CO2" into hydrocarbon fuels. It is also called photosynthesis. It is inspired by the natural photosynthesis in plants  whereby oxygen (in the air) and carbohydrates are produced from H2O and CO2 using sunlight UV radiation as an energy source. The useful product in this case would be the liquid fuel produced from this photosynthesis process.

Hope this helps answer your question.

Professor Yehia Khalil

Yale University

USA

Dissolve your IL in dimethoxyethane (monoglyme), add an excess of  NaBH4, stir for 1 -2 days, filter off the precipitate, remove DME in vacuum. Essential: NaBH4 before use must be recrystallized from dyglime or DME/NH3 (Russian J. of Applied Chemistry, 1992, v. 65 number 11) and dried in vacuum. The purity must be > 99% for active hydrogen determined volumetrically by adding acidic water solution to a sample of NaBH4. THF or dioxane for the exchange reaction are of no use, because neither NaBH4 nor KBH4 are not soluble in them. Also you can try an equivalent quantity of Ca(BH4)2  in THF. CaCl2 formed is not soluble in THF but Ca(BH4)2 is very soluble in it. So, avoid the excess of Ca(BH4)2!

But it is difficult to find an orthogonal solvent. For PCBM mostly o-dichlorobenzene, chlorobenzene or toluene are recommended as solvents. But these solvents are also good solvents for PMMA. Non-solvents for PMMA are e.g. cyclohexane, lower alcohols and acetonitrile (perhaps good choice?). If PCBM is soluble in one of these solvents you will have a good chance. You have more possibilities if you can replace PMMA be another transparent material. Polymethylpentene is transparent but insoluble in all solvents. This would be a good alternative to PMMA. Also a transparent polyamide, like Trogamid, could be a good choice because it is also insoluble in all common solvents.

Your question is too general. The answer depends on your background and equipment of your laboratory

Reducing the molar mass of the polymer 

Dear Colleague Marakatti,

1- The total number of acidic sites (sites. m-2) over each catalyst can be measured using the temperature programmed desorption of pyridine (TPD-pyridine) as the probe molecule. The details have been described in previous publication (attached).

The acidity populations over the surface of catalysts, under investigation, were measured thermogravimetrically using the adsorption of pyridine as probe molecule. Small portions (50mg) of each sample were pre-heated at 250°C for 2 h in air before the exposure to the probe molecule. 15-20 mg of pyridine–covered samples were subjected to TG analysis on heating up to 600°C (at 20°C/min heating rate) in dry N2 (flow rate = 40 ml/min). The mass loss due to desorption of pyridine from the acidic sites, was determined as a function of total surface acidity as sites.g-1cat.

2- To detect the Bronsted acidic sites, you can use 2,6-dimethylpyridine as a probe of the strength of Brønsted acid sites.

Finally if substracted the number of acidic sites from step 2 (Lewis +Bronsted) from step 1 (Bronsted only, you can get the number of lewis acidic sites

However, FTIR- Pyridine is only used to distinguish between the Lewis and Brønsted

Hope this helping

Have a very good day

Silver is an excelent absorbent. An also Cerium oxide, Manganese Oxide

It seems possible to read the question very different.

CO₂ in the indoor air might increase if many people are together in e.g. a class room and it already decreases energy levels, ability to concentrate etc. for many people at levels as low as 1000 ppm while many school classrooms get up to 2000-4000 ppm. 

CO₂ in the Earths atmosphere has increased 43% to about 400 ppm due to burning fossil fuels. Obviously we need to limit this increase before it affect the global climate too much. I believe replacing energy production based on fossil fuel with nuclear, wind, sun and bioenergy fuels should have priority over sequestering CO₂ from flue gasses or the atmosphere. 

 How will I wash off a chitosan-methacrylic acid polymer film from the surface of a silicon dioxide crystal qcm Chip ?

Dear Christian Weinberger!

Let me to remind you that adsorption of N2 at room temperature is used for separation air by using zeolites or activated carbon- PSA at room temperature.

Best regards

Hi Fuat

I will suggest you to read following articles

Hope it will be helpful for you.

Actually, I agree that carbon left behind (because of a non-complete burning of the organic template) would bring about a darkish-grey colour; whlch often can be removed by heating (at about 300 to 400 degrees) under an oxygen flow for about 1 hour.

The answer actually is yes. Carboxylic acid salts can be used as precursors for green chemistry approaches and even in pH-neutral media. For details you can see, for example, a review in J Sol-Gel Sci Technol 2013, 68, 464–470 or a detailed experimental study in Nanoscale, 2013, 5, 3330–3336.

There  are various methods for the determination of solubility of gas in ionic liquids. Here, I am attaching a review article file. I hope this will help you.

During heating processes, N₂ and CO₂ are used for two different things:

Thank you for your reply. I am trying to track down literature for stable nanoparticle synthesis. 

Assuming that, the answer you wanted is easy: follow the procedure of the cited reference...

Organic inhibitors have been the most widely used in petroleum refining processes because of their ability to form a protective layer on the metal surface in media with high hydrocarbons content. At present there are a number of organic inhibitors belonging to different chemical families i.e. fatty amides [4, 5], pyridines [6-8], imidazolines [9-12] and other 1,3-azoles [13-15] and polymers [16] have showed excellent performance as CIs (Table 1)

for details see attached article

 You must take into consideration the wavelengths at which your catalyst, reactant, and products absorb.  Many organic compounds  absorb in the UV (eg  higher energy region). Irradiating with too low a wavelength may result in unintended side reactions.  also, keep in mind that lower wavelength means more energy not more photons.

Recrystallise your product, which is most likely impure given the light beige / tan colour. The impurities will be lowering the melting point.

You'll still have the major product as expected, excess HBr may have resulted in hydrobromination of the double bond or formation of minor quantities of bromohydrin.

Excess HBr can form hydrogen tribromide in situ which may interfere with bromonium ion formation. Minor halogenation of the aromatic rings is also possible, probably in the 4-position.

However the bromination of stilbene is quite facile and should be the major observed product.

The reactions involved depend on the route used.

Physical activation is basically a controlled gasification, through the mild oxidation of carbon (formerly obtained by a preliminary carbonisation step) into CO (if CO2 is used) or into CO + H2 (when using steam as the activating agent);

Chemical activation involves both oxidation and dehydation of the biomass, therefore many complex reactions occur at the same, leading to a material enriched in carbon whose porosity was developed by removal of volatile molecules.

Alain

Iodine number is a widely used parameter for activated carbon testing for its simplicity and a rapid assessment of adsorbent quality. It gives an estimate of its surface area and porosity The iodine number is defined as the milligrams of iodine adsorbed by one gram of material when the iodine residual concentration of the filtrate is 0.02N (0.01 mol L-1) according to ASTM D4607 standard, which is based on a three-point isotherm.

The sample is treated with 10mL of 5% (V/V) HCl. The mixture is boiled for 30 s and then cooled at room temperature. 100mL of 0.1N iodine solution is immediately added to the mixture and stirred for 30 s. The solution is then filtered and 50mL of the filtrate is titrated with 0.1N (0.05 mol L-1) sodium thiosulphate solution using thyodene (or starch) as an indicator. The amount of iodine adsorbed per gram of adsorbent is plotted against the residual iodine concentration, using logarithmic axes. If the residual iodine concentration is not within the range (0.008–0.04 N), the procedure is repeated using different carbon masses for each isotherm point. A regression analysis is applied to the three points and the iodine number is calculated as the amount adsorbed at a residual iodine concentration of 0.02 N.

I hope all these information will be helpfull

Chemical activation is the best for this kind of lignocellulosic material being full of water and having intrinsicaly a very low carbon yield. In Europe, ZnCl2 is forbidden because of its polluting character. KOH may work but will be probably too agressive. I recommend H3PO4, having the advantage of not requiring inert atmosphere, and working at moderate temperature of 550°C. Just impregnate thoroughly your material with 85% H3PO4 and heat it 1H at 550°C in a muffle furnace in air. Then, wash it thoroughy with hot water in a Soxhlet. You can play with the parameters (time, impregnation ratio, temperature) to find the optimum conditions.

Alain

The recycling of CRT´s is one of the most complex tasks currently. The lead oxide is in the cone of the CRT and is collected and sent to India for the fabrication of new CRT´s. Also in Lead cast is used as silica and trap the cast impurities. I don´t now the costs but Dr. Tomas Prieto who is in this industrial field, told me that It is hope that in 10 years this lead oxide will be processed.

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

Steam activation is the opening and development of the porosity of a carbon material through its mild oxidation caused by hot steam passing on it. At 700 - 800°C, typically, H₂O reacts with carbon and produces CO + H₂. Therefore, the carbon is consumed and very narrow pores are produced (which progressively widen with time), and you get activated carbon.

It is quite easy to do it. Just bend slightly your furnace by a few degrees, and introduce water drom by drop in the flow of nitrogen at a temperature of, say, 750°C. A pump can be used for that, so that the flow of water is controlled but very very low (drop by drop). Each drop will roll towards the hot part of the furnace and transform into steam, which will react with the carbon.

You need to control the time. 15 min can be enough for getting a good burn-of (25%) and 30 min can burn everything. Sometimes, not , as it depends on temperature and carbon. Nothing else but doing trials.

Alain

Dear Nad,

There are two different standard methods for the preparation of a unit volume of powdered or granular activated carbon. The methods given in attached file are adaptations of DIN ISO 787.11 and ASTM D 2854 respectively.

Dr. Lee,

It appears that you're strictly interested in carbon "beads" rather than the more common form of granular activated carbon (GAC) as Dr. Celzard has suggested. GAC has a highly irregular particle shape that can occur in different morphologies. The term AC "beads," however, is more commonly used to refer to spherical extruded AC particles of extremely uniform size and shape. Spherical AC is a rather novel shape for carbon sorbents, and there aren't many manufacturers that produce it.

However, if you're simply looking for GAC, Dr. Celzard's suggestions above are good. FYI, "temperature" activated carbon is more commonly referred to as thermally activated carbon or steam-activated carbon (if steam is used as the activating agent). Also, even with a very pure activated carbon there will likely be a very small amount of phosphorous leaching. You'll have to determine for yourself if that amount is significant or appreciable.

Best of luck in your search, Dr. Lee.

Well, it is dif