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What factors affect the sharpening of this peak, for example, if we want to have a sharp point at a certain radius , what parameters should we manipulate in the synthesis?
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Dear Mona, thank you for your interesting technical question. For some useful information please have a look at the following article which might help you in your analysis:
Accurate characterization of full pore size distribution of tight sandstones by low-temperature nitrogen gas adsorption and high-pressure mercury intrusion combination method
This paper is freely available as public full text on RG. Also please check the answers given to the following closely related questions which have been asked earlier on RG:
How can I estimate the accurate range of pore size distribution from the BJH (Barret-Joyner-Halenda ) plot?
(9 answers)
and
What is the pore size distribution by BJH method?
(also 9 answers)
I hope you will find this information useful. Good luck with your research!
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Suggestions Would Be Appreciated!
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Dear Bochra Kouide Elouahed, the following documents may bring additional help. My Regards
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In the case of water splitting the water oxidation (OER) is the bottleneck for the process and because of the harsh conditions of the WO reaction, molecular catalysts with high TOFs are not stable in the matrix and quickly decompose. On the other hand heterogeneous catalysts are more stable but they often do not have high TOF quantities. Now what is your opinion about the future catalyst type? Will the ideal catalysts fabricated by turning the molecular catalysts to heterogeneous catalysts ( by loading the molecular catalysts on the solid surfaces ) or it will be from the single atom heterogeneous catalyst type?
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Dear Sina Safavi thank you for initiating this interesting RG discussion. Although we are inorganic chemists, I'm not an expert in this field. However, I agree with Yurii V Geletii in that there is no such thing as a true catalyst. In this context I suggest that you have a look at the following relevant article which has been published Open Access. It is stated there that future catalysts should be "low-cost and earth-abundant":
Earth-Abundant Electrocatalysts for Water Splitting: Current and Future Directions
(see attached pdf file)
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I want to modify SiO2 surface with thin porous layer in order to adsorb humidity. So, please suggest about the type of mesoporous silica and also about the modification procedure.
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Crystalline silica SiO2 may cause the gel to be blue when dry and pink when hydrated.
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When studying the adsorption of chlorate on activated carbon, it was noticed that adsorption is better at certain pH. Also noticed that the addition of activated carbon in the solution, resulted in a  change in the pH of the solution being treated.
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Video link for determination of Point of zero charge (PZC)
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I am currently carrying out some BET analysis on several fly-ash geopolymer samples. They are powdered (>500um diameter), and are dried overnight (16-18 hours) at 105C in a vacuum oven to remove any pore water. Once they are put in to the glass tubes they are degassed for a further hour in a vacuum at 105C. I have attached a sample isotherm.
Why is the desorption isotherm crossing the adsorption curve?
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Thanksnfor all the answers! If I remember correctly, we implemented a few things to stop this from happening.
1) Increased amount of sample in the tubes to increase total SA
2) Used filler rods in the tubes to reduce dead space
3) Isothermal jackets were used.
On our machine (Micromeritcs Tristar II), it also set it to measure the free space on each run, rather than use a re-calculated value. The combination of these fixed the issue, i think the first and last poiit were most effective
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Psoriasis has different types like plaque, flexural, guttate, pustular and nail psoriasis etc. having different signs like silvery scales, patches, red spots or pus filled etc, so why they are different? mean there are different triggers for each types which causes it and shows different signs? and if like this, so what are the difference in triggers that cause each types of psoriasis?
Thank you
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Thank you so much Nabodita Sinha for your help.
Actually I want to know that the triggers like IFN-γ, TNF-α, IL-1β, IL-6, IL-17/Th17 and so on. So as there any different trigger activator for each psoriasis types? because about 90% is Plaque psoriasis, so it has a different triggering cytokines for it's activation than other types? please clear me about it.
Thank you
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My oleate-capped NaCeF4:Gd,Tb NPs have been synthesized via the thermal decomposition method. 1mmol of NPs has been dispersed in 20 ml of cyclohexane.
I have tried dissolving 1 ml of NP in cyclohexane in 10 ml of 33 mg CTAB dissolved in DI water. I have washed my NPs with acetone 6 times, but I am unable to obtain a transparent and clear phase transferred solution. It is still a little cloudy after 24 hours at room temperature at 750 rmp with the first 3 hrs at 70 degrees at 1400 rpm.
However, I have carried on with the reaction and add in 150 microlitre of TEOS dropwise after adding in another 20 ml of DI water, 150 microlitre of 2M NaOH, and 3 ml of ethanol at 70 degrees 1000 rpm. The CTAB was removed via a ligand exchange method with 0.3g of NH4NO3 in ethanol on the next day.
May I seek advise on what went wrong and how I can improve?
The pictures contain before and after coating of the mesoporous shell.
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Either use IGEPAL or Brij surfactant instead of CTAB. It may form cloudy in cyclohexane.
4mL IGEPAL +40 mL cyclohexane ---> Mix and sonicate 10 min
Add required amount of NPs suspension in cyclohexane to the above emulsion.
Add TEOS and Ammonium hydroxide
sonicate and centrifuge to collect the samples
dissolve in hydrophilic solvent.
Sonication and temperature is major factor affecting your silica coating
Try this one.
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Based on the data reported in many publications mentioning the drug loading of mesoporous silica nanoparticles (MSNs) since the drug precipitate as a crystalline form and requires separation. That was so confusing, and I want to discuss if this test is an actual test or a myth.
We have here a three mentioned scenarios
1- Measuring drug loading without washing MSNs after solvent evaporation or deposition or incipient witness method. So, why we measure drug loading, actually the drug loading efficiency should be 100%, and if there is a decrease in the drug content, that means only one thing "the preparation method was messy or inadequate preparation."
2- Measuring drug loading after washing with ethanol is inaccurate because ethanol will dissolve depending on drug solubility. Also, ethanol can dissolve amorphous and crystalline drugs, so there is no preferential separation.
3- Measuring drug loading after washing with water or water containing a minimum amount of ethanol. In this method, the drug is dissolved to the limit of drug solubility in water or the water-ethanol mixture.
..........................................
-What is useful to do with crystalline form is to measure the degree of crystallinity in loaded mesoporous silica.
-If there is a washing method you can suggest to separate crystalline form efficiently out of the loaded carrier, please discuss it.
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Raman Micro-analysis is one, ()probably only one in your case(), of the best techniques to identify drug substance, as pesented in any of the input crystalline or amorphous form, or converted different polymorphic, hydrate or solvate forms, or salts and co-crystals, from local excipient carriers.
In your case, Raman response of silica is very weak, close to almost indetectable. This makes separating drug substance from its carrier easier-no cross comtanmination. However, mesoporous structure of silica would make measuring those drug substance a bit more difficult with good S/N ratio-DS inside pores, subject to the Raman response of drug substance. In summry, it is feasible to measure drug load in carriers.
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Dear all,
I have experimental data for the effect of time at different feed concentration on the permeate flux of the hybrid adsorption membrane process for the removal of dye from wastewater. I would like to get a mathematical model.
I have a question please how to calculate the concentration at the adsorbent surface?
Would please help me to understand the calculation of concentration at the adsorbent surface?
I would appreciate your reply.
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What is there to explain? In the case of a batch process, m = (Co-C)V, where V = const. In a continuous (flow) process, V increases and C changes. Therefore m=∫(0->Vf) (Cin-C (V))dV, which definite integral can be calculated graphically as the area under the Cin-C vs V curve ( V = Fvt). Unless you mean describing the change in bulk concentration? Then the mass balance in the form of a partial differential equation/s.
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I have just started to gain basic information about gas sensing materials. So here, I want to know what materials are in touch nowadays for efficient gas sensing, and what are the corresponding advantage and disadvantages?
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When it comes to the choice of materials for MOGS (Metal Oxide Gas sensors) applications, materials which exhibit high resistance variation upon exposure to the test gas is considered as most suited. Not all metal oxides can be used as a sensor material. In the last 50 years of sensors research, the choice sensing material has always been empirical. However, the thumb rule for a metal oxide to be used for MGOS application is that, the surface chemistry of the metal oxide should be in such a way that it is sensitive to oxidizing or reducing atmospheres. The details are available in plenty of review articles like this one : doi: 10.3390/s91008158 .
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Al incorporation into the SBA-15 structure can be done with limitations.
Upto what extent we can load Al into the SBA-15 structure, without creating an extra framework of alumina in the synthesized material?
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I agree with Evgeny Alexandrovich Belopukhov
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In order to calculate the TON/TOF for mesoporous material
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Both EDS and XPS are rather surface methods than methods for total metal measurements. Normally they measure a few layers of atoms in depth and covers a rather small area. I still claim that AAS and ICP are the best methods to get the total mass of metals in a sample.
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I have incorporated Fe in SBA-15. What could be possible reduction temperature when measured by Temperature program reduction (TPR).
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I think, between  600 -700 °C  temperature is needed to initiate the iron reduction
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I have obtained nitrogen adsorption desorption isotherms for a mesoporous sample. From these isotherms and BJH size distribution, I have calculated surface area, pore volume and average pore diameter. But, when I am asked "what is the pore volume fraction of meso and micropores?", what do I need to calculate and how?
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First of all, BJH is not the best model for micropores, use the DFT calculation instead. From the graphs, take total pore volume (PV), micropore volumes (<2 nm) µPV and mesopore volumes mPV (2-50 nm). Calculate the individual fractions as % or PV (µPV/PV*100, mPV/PV*100), check that you get 100% in total.
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I have mesoporous silica capsule which contains gold nanoparticles.
I have created that complex and nothing is known about it.
So I have a question about how to sterilize it.
I have tried autoclave, but the I think the complex was
aggregated and lost the original characteristics :(
Could you suggest any ideas?
or is there a special way for gold nanoparticle sterilization?
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The following article maybe useful for you....good luck
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Good afternoon,
When I have screened a bit of literature trying to find an answer of following topic, there are some papers where the size of nanoparticles is increasing with the temperature of synthesis, because thermodynamics of liquid–crystal phases of surfactants and kinetics of the hydrolysis of TEOS strongly influence on it.
Examples...
Microporous and Mesoporous Materials 128 (2010) 203–212,
However, we can find a lot of papers, where size is increasing with decreasing the temperature. The explanation that I found is: "The precipitation time at lower temperatures was much longer than that at higher temperatures. It is assumed that nucleation decreases when the synthesis temperature is lower, which presumably results in the generation of large particles."
Examples...
J. Mater. Chem., 2003, 13, 2577–2581
Nanotechnology 24 (2013) 155601 (11pp)
Nanomaterials 2018, 8(4), 230;
On the other hand, I found also a paper when temperature of synthesis does not really affect on size.
J. Mater. Chem. , 2004, 1 4 , 1579–1584 (TABLE 2)
And here is the question: Can you explain, in what situations and why the size of the particles is increasing, decreasing or being constant with increasing the temperature ?
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It seems that the effect of temperature, type of solvent and its amount on the size of the silica particles should be simultaneously investigated.
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Hi,
I am using the isotherm obtained by the BET technique to calculate the pore size of some materials; I obtained an average pore size of approximately 10 nm in all my samples (I think that means that I have mesopores in my material), but I am not sure if these results are correct since the standard pressure used in BET may won't be enough (mesopores require greater pressures (>0.3) to be calculated than micropores). Should I use a different technique?
Thanks for all your help!
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The average pore diameter is not enough to determine the porous nature of your material. I recommend that you do a pore size distribution, normally this is done using the BJH method, however if you have microporosity it is better to use a DFT method. Another thing that I can recommend is that the analysis is carried out with Ar and not with N2. When you make the measurement of microporous materials with N2 you can have erroneous readings, due to the N2's quadrupole moment, which leads to specific interactions with functional groups or exposed ions on material surfaces.
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I'm working with adsorption of organic compounds at materials that are functionalized with different concentration. It was expected that with high functionalization the higher is the adsorption capacity, however the opposite is happening. Any ideias why this happens? Note that there was insignificant surface area change.
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Dear Luana, i agree with Jose E Arevalo-Fester , functional group present on the adsorbent and adding functional groups affects adsorption capacity of the material and . However on increasing the concentration of loading available site for adsorption will decrease. Even i have found the similar pattern in my research.
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Hello,
I was thinking to use the BJH model to measure the pore size distribution of low porosity (mostly meso and macropores)-containing materials.
In this regard, I have got the following questions:
1) Which relative pressure range should I consider? P/P0 >0.35?
2) Which isotherm branch should I apply the BJH model to? Ads or Des? How does this choice relate to the Hysteresis type?
3) Would DFT model be more suitable?
Thanks,
Antonio
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DFT (NLDFT and QSDFT) methods are much more suitable than BJH for micro and mesopores.
For BJH you need the desorption branch (have a look at the original paper, I think I uploaded it in RG somewhere...).
You cannot measures macropores by adsorption (macropores behave like non-porous surface towards gas molecules)... you need something like mercury porosimetry.
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If curve of adsorption branch overlap over desorption branch, what are the type of pores in these types of materials 
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on peux savoir si un composé est micro ou meso , juste en traçant l’hystérésis. Sur l'axe des ordonnés si la courbe débute vers des volumes adsorbés de l'ordre de 50cm3/g et la courbe sera du type I d’après IUPAC.
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Recently, I try to prepare mesoporous silica film on titanium substrate by evaporation-induced self-assembly process (EISA).
I have tried two ways to prepare precursor solutions:
1. P123 (0.5 g) was dissolved in the mixture of water (5.0 g) and hydrochloric acid (0.25 g, 2 M) at room temperature. Stirring it until a homogeneous solution was obtained. Then, 1.0 g of TEOS was added and the mixture was stirred for 10 min.
2. TEOS (1.50 g) , Ethanol (15.0 g), deionized water (0.78 g), and 0.1 M Hydrogen chloride (0.15 g) were stirred at room temperature for 1 h. P123 (0.30 g), Ethanol (14.25 g) were stirred at room temperature for another 1 h. After stirring, the two different solutions were mixed and then stirred at room temperature for 1 h.
After this process, EISA was carried out. (Ti substrates were immersed in precursor solutions and put in oven under 37 ℃ for about 6 h until the solvents completely evaporated. Finally, the thin, transparent mesoporous silica films were obtained)
Considering drug loading in the future, I use a more gently method for removing of P123 by reflux with ethanol overnight (90℃) instead of calcining.
In addition, I also found a more gentle way, which was performed in an ethanol solution containing 0.1M HCl under stirring conditions for 15 min.
Unfortunately, no matter which precursor solution or which extraction method was used, the film was destroyed into small pieces and detached from the substrate.
Did I forget any details, or make something wrong?
Whats your protocol?
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  • DOI: 10.1007/s13538-014-0236-4
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As all we know, there are two conventional ways to tune MOF structures and specially pore size by altering the metal clusters or the ligands.
But the question arises when we want to have a specified pore size in an exact copled metal and ligand.
How can I adjust the pore size without changing the metal and ligand?
Which variants are involve in MOF synthesis that influence pore size?
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I am a bit confused about the answers, although they are correct.
For the question:
"How can I adjust the pore size without changing the metal and ligand?"
the answer must be simply: You basically CANNOT for a ridig linker (and most of the linkers so far used are rigid).
The size and shape of a rigid ligand together with the coordination are determining the maximum pore size, there are no synthesis parameters whatsoever than can change this.
E.g. if you use the rigid terephthalate as linker (ligand), the space between two metal atoms (ions) is rather fixed. For flexible linkers there is a lot of room for variation, see e.g.
But also for them, there is an upper limit given through the bonds and angles within the linker.
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the chosen drug size is bigger than micropores. the drug carrier is an inorganic nano-material.
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Dear Yuri
It's not a tube, It's a mesopore.
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TiO2 nanoparticles are white itself, but what is the cause of transparency after sintering?
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For the same reason that crushed glass powder is white and a bulk window is transparent. Irregularity in particle shape means that incident light is scattered in all directions and the powder appears white.. In the bulk phase the attenuation coefficient is close to zero and the material appears transparent. One also has to distinguish between primary size (if we believe this to be 18 - 20 nm as given) and the fused set of post- and sub-micron aggregates and agglomerates in the powdered form. Incidentally a set of homogeneous glass spheres (e.g. NBS 1003 c) appears transparent as the light is not scattered in all directions.
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I am using Surfactants i.e CTAB, P-123 and F-127 in meso-structured materials synthesis. After synthesis i want to remove these surfacrtants by washing the materials with boiling EtOH for 6h. Is such kind of washing will be enough to remove surfactants because in my case calcination is not suitable for the as synthesized materials. So only washing will be enough to remove CTAB, P-123, F-127? kindly share your kind suggestions.
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In my experience, it is difficult to absolutely remove ionic CTAB by hot EtOH. Because of good solubility of CTAB in water, I think hot water could be chosen. For removal of P-123 and F-127, my senior have ever used refluxing EthOH in Soxhlet extractor.
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I have a really big problem to get really good data plots for pore size distribution when doing the BET/BJH measurement. The Isotherm curve of my sample looks pertty nice. However, When I plot the pore size distribution data, I find most of the data plots are concentrated <5nm, beyond that range the data plots are so few for me to get a nice shape of peak.the pore size of my sample Is any way solve this problem? such as changing the test setup. current I am using 80 plot method.
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dearest Tianyu Li
Porous of materials are classified accordingly to International Union of Pure and Applied Chemistry IUPAC classification into 3 types of size:
1) the pores greater than 50nm in diameter are termed “macropores".
2) those with diameters between 2 and 50nm are termed “mesopores".
3) and those pores less than 2nm in diameter are termed “micropores”.
so i will explain it to you coz i got training with this equipment
Isothermal adsorption theory developed by Brunauer Emmett Teller (BET)
allows for the determination of the amount of gas to cover the solid surface with
a single layer of gas molecules. Therefore, the specific surface area and pore size
distribution of material can be determined utilizing the technique of nitrogen
adsorption desorption. The quantity of gas adsorbed is usually expressed as its
volume under standard conditions.
if you want to draw this plot the pore size distribution data
you have to take for one segment of relative pressure with the amount adsorb ....
why coz we have four type of the plots its
1) H1 well-defined cylindrical pore channels, 2) H2 disordered pores (pore blocking, percolation phenomena), 3) H3 non-rigid aggregates of plate-like particles (slit-shaped pores), 4) H4 narrow slit pores including pores in the micropore region. This standard figure was used in this work to analyse the BET measurement.
and don't forget my friend the Desorption isotherm method was adopted to calculate the pore size distributions.
all that dear will depending on types of hysteresis loops
with my hopes that you understand all that and if you need for more explanation or help for your result i am ready to help you as its possible ,,,,,
greetings
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Hi dear Scientists! :)
I was impregnating Fe or Cu over different mesoporous materials, and after TPDA analysis I concluding that when I decrease the percentage of metal over surface of material, acidity increase (more specifically, strong acidity)...
So, I thought that with increasing of percentage of metal will increase the percentage of acidity, but, this was not like I thought..
I just looking for explanation of this fact, but..... I can't found a very well explanation...
Some one could help me?
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In my experience with zeolites which reveal different Si/Al ratios, the zeolites which contain more Al can store more ammonia since there are more OH-groups available on the surface. Though NH3 is coordinated not so strong on these hydroxyl groups in comparison to the zeolites with higher Si/Al ratios.
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Here I have attached the isotherm of two samples? I have used BET multipoint for surface area (SA) calculation. For First sample SA is ~4.55 and for 2nd sample ~53.95 m2/g. Which isotherm shall I use for calculating pore size distribution? How I understand which type of pore it is?
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Is there any possibility for hysteresis in the first material (non porous) due to intra-particle porousity ?
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When preparing mesoporous materials with aluminum and comparing them with siliceous ones, the degree of organization generally decreases when increasing aluminum content. What is the explanation for this behavior?
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Some cases like; CTAB, CTAOH, TPABr, TPAOH, SDS, etc. are commonly used in laboratory scale uses, but not yet have been industrialized due to high costs. Based on the chemical structures of the long-chain alcohols (such as; pentanol, hexanol and so on) since they are amphiphilic compounds, I presumed that they can be potential cases in forming micelles to form a template structure in nano-meso-structured materials synthesis, but they often are used as co-template or intermicellar agent. Can they be used solely? or any general recommendation?
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See files
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for example Vm= 71 cm3.g-1. That's a very high number
This question continues the previous question, which so far I do not know the answer
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See my amended answer above for more than one pore. The next step is to consider when pore sizes follow a distribution in radius and length. One must integrate over the distribution function.
In review, this question now has very little to do with research. It has had far more to do with fundamentals of porous materials. The information you need is presented elsewhere in far better detail than can be provided here. By example, search for textbooks or literature resources that explain the fundamental relationships between pore volume and pore area starting from a single pore and working through systems with pore size distribution functions.
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While the BJH method is used only for mesopores.
for example:
TPV (BET): 0.474 cm3.g-1
Vp (BJH): 0.616 cm3.g-1
Naturally, the total pore volume (micropores+mesopores+macropores) should not be less than the mesopores volume.
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Younes Brahmi
, Please, Do you have an answer for this question?
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I synthesized mesoporous carbon nitride. TEM and BET approve that it is mesoporous.
also, i test low angle XRD and there is one peak at 0.85 degree.
i found that we can show that our material is mesoporous with low angle XRD, but i could not find any connection between them.
i appreciate, if you could help me about this issue
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When doing SAXS analysis be sure that the equipment is has the resolution needed for your sample. Best SAXS will be done with a synchrotron facility. The systems that are an add on to XRD instrumentation do not have the needed resolution for good SAXS data collection.
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I looking for nanoporous thin filim of mesoporous silica on SiO2 surface which can adsorb humidity. There should be uniform hexagonal pores in the thin film.
So, please suggest about the type of mesoporous silica and also about the modification procedure.
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In activated carbon samples synthesized by KOH and NaOH as activation agents, KOH activated samples have higher rate of micropore area than NaOH activated samples.
Although NaOH provides higher surface area than KOH, but the pore size distribution is wider.
My question is why KOH can produce smaller pores rather than NaOH?
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Dear All,
Thank you so much for your helps. Your suggestions made a good case for my researches, but still there is no definite reason for this behavior of KOH and NaOH on activated carbons.
There is a wide range of possibilities. To find the final answer further researches and studies are required.
I believe it can be an interesting research subject, for pore size distribution is an important factor to produce effective adsorbent materials.
Wish you best of luck in your researches,
Sahand
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Usually, the pore diameter increases with increase in surface area and pore volume. However, in my case, pore diameter is decreasing with increasing surface area and pore volume. What could be the possible case?
1. BET =11.51 m2/g, BJH pore volume = 0.013 cm3/g and BJH pore diameter =4.6 nm.
2. BET= 456 m2/g, BJH pore volume= 0.302 cm3/g and BJH pore diameter= 2.5nm.
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Hi Anam,
Indeed there is no direct correlation between pore diameter, pore volume, and surface area. However we're all talking about a general rule that could be applied for any material. If you you know the geometry of pores in your material you can actually make a correlation. For instance, if you have a well-defined cylindrical pores, the radius, r, can be correlated to the mesopore volume, V, and specific surface area, S, using the following equation: r = 2V/S. The geometrical features of your material can be assessed by low-angle XRD or SAXS if they are ordered. Such approach is not useful for disordered mesopores.
I also would like to call attention for the problem with the BJH. Although the BJH is highly applied, the method is inaccurate to determine the pore sizes of mesoporous materials. The original BJH method uses the kelvin equation to correlate the capillary condensation with pore radius. The problem is that the Kelvin equation fails in the nanoscale. This occurs because an adsorbate layer is formed prior to the capillary condensation, which is not taken into account in the BJH method. This layer is commonly known as film thickness. There are several highly cited papers showing how inaccurate the method is. I don't know why people still use the BJH method, my guess is because instrumentation have this option available. If you are interested in knowing more about it, here are two highly cited papers:
M Kruk, M Jaroniec, A Sayari, Application of large pore MCM-41 molecular sieves to improve pore size analysis using nitrogen adsorption measurements. Langmuir, 1997.
M. Jaroniec, S. Leonid A. Improvement of the Kruk-Jaroniec-Sayari method for pore size analysis of ordered silicas with cylindrical mesopores. Langmuir , 22 (16), p. 6757.
Best Regards,
Alexandre.
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Hello,
I synthesized mesoprous carbon nitride. After getting XRD test, I found that there are some impurity in my sample. After checking with different software, I found that these impurity is related to ammonium hexafluorosilicate.
I used silica nanoparticles (Ludox HS40, Aldrich) as a template and Ammonium bifluoride for removal of silica.
At the end of procedure, my sample centrifuged and washed with distilled water.
how can i remove these impurities from my sample?
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Dear, Amanj Kheradmand
In template method, some times its difficult to remove silica particles from graphitic carbon nitride g-C3N4. That's why you are observing impurities in your samples.
Try to dissolve silica template in ammonia hydrogen difluoride, no need to follow initial steps, just try to treat your present sample. I hope, it will help you wash template from g-C3N4 network.
If you want to make porous g-C3N4, then you can also use Ammonium carbonate. its very simple and one step method. It will also save your time. For this you can follow this article.
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Hello
I have mesoporous carbon nitride and I want to support cobalt on it.
The structure of final product is very important and it should be mesoporous material.
what is your idea about the precursor of cobalt?
thanks
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I think cobalt (II) nitrate will be fine for your purpose.
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I would like to fit my adsorption isotherm data with a Redlich-Peterson model, but I am confused as to how to determine the alpha values, Could someone suggested me how to prove this?
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im facing the same problems and Scidavis solve my problem..=)
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Hi, could anyone help me in finding some porous material having pore size from 100nm-500nm. I need commercially available material. Thanks for your recommendation or suggestions.
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I agree with Onyeka & Jin. Addition to CMK and AAO, some porous silica are available such as, MCM-41/48, SBA-15 etc.
Synthesis of porous silica is not very challenging. Commercial porous materials as per your requirement is available. Search online for available suppliers in your place.
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Sometimes analyzing mesoporous materials I observe appereance of phantom peak of 3.7 nm on BJH pore size distribution curves. I would like to know what is a reason for its apperance?
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Hi Andrey
The situation depends on the pore geometry and whether the pores are interconnected or not. It can get rather complex.
Making the decision to use either the adsorption or desorption branch is necessary when hysteresis is present but the reason for the hysteresis depends on the material and its pore structure.
In a cylindrical, isolated mesopore, it's thought that hysteresis is due to delayed condensation upon adsorption, rather than delayed evaporation during desorption. In that case, the desorption branch will better represent equilibrium. However, in real materials, the pores are often interconnected so there are network effects that change the situation.
There is some discussion of this in the IUPAC guidelines:
which I recommend.
For a more detailed discussion of hysteresis and the effects of pore geometry, etc, this article by Peter Monson provides a good overview:
Best regards,
Darren
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I am looking for polyurethane foam/sponge material with pore sizes up to 1000 ppi. In other words the pore size should be in the range of 20 micrometer to 100 micrometer. Thank you in advance.
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Pore size should be around the 10um. As long as the pore sizes are ok level of porosity is not very important.
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I have a platinum black of specific surface area of 31 m2/g. What will be the estimated real surface area (CO stripping)? Greatly appreciated if there is any publications on this.
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Hello , I would like to ask for your help please. I do my research on the synthesis of mesoporous materials and their application with the adsorption of pollutants (pesticides) but after several experiments carried out in the laboratory on this subject, I found that mesoporous materials do not adsorb pesticides The more polar ones such as methomyl and cymoxanil for example while all my work is based on this, someone can propose me a grouping or a precursor which can be useful for the functionalization of the mesoporous materials of the MSU family with  to these Chemical ances, please it is  urgent, thank you in advance. my greetings
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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.
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Increase in salt concentration (NaCl) in presence of block copolymer can generally increase the mesopore diameter and decrease the no of micropore. Is there any way that it can increase the surface area and no of mesopore somehow? Please reply.
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Thanks for the help Sir.
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Such as title
How to calculate the specific surface area of the inverse opal structure?
Is there any formula to calculate the specific surface area of inverse opal?
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Hi Tsai
Inverse opals are 3-dimensionally ordered macroporous (3DOM) materials, with macropore sizes typically in the range of 200-400 nm. The macropore size will have minimal impact on the specific surface area of inverse opals.
BET specific surface areas and BJH pore size distributions are typically calculated from N2 physisorption isotherms collected at 77 K. N2 physisorption measurements only probe the surface and distributions of micropores (< 2nm) and mesopores (2-50 nm) in the inverse opal (i.e. the small pores in the walls of the inverse opal, not the large ordered macropores that give the inverse opals their structural colour). We have prepared SiO2 inverse opals with macropore diameters ranging from 100-500 nm, and all displayed the same BET surface area (~800 m2/g).
To get information about the macropore size, you would typically use TEM, SEM or mercury porosimetry. From the radius of the macropores, you can calculate the geometric surface area in the inverse opal (e.g. internal area of 1 macropore = 4*pi*r2, with there being 4 macropores in the fcc unit cell which will have a side length a = 2*sqrt2*r and a volume a3). Thus, once you have the geometric internal surface area for one unit cell, you can then multiply that area by the number of units cells in a given volume of the inverse opal (e.g. 1 cm3), to get the total internal surface area (the analysis should yield a value ~11 m2/cm3 note: this analysis neglects the micropores and mesopores in the walls of the inverse opals, and assumes the macropores are spherical). Divide this value in m2/cm3 by the density of your inverse opal (g/cm3, calculated as the density of the solid material in the walls of the inverse opal times the solid volume fraction), and you can probably get some sort of specific surface area (in m2/g) to compare with the value determined by N2 physisorption. If your inverse opals do not have any micropores and large mesopores, the calculations could possibly give you a specific surface area close to that measured by N2 physisorption.
Best regards
Geoff
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I would like to synthesis the rod-shape mesoporous silica nanoparticles of sizes smaller than 100nm. Does anyone has some experiences? Also, any tips and tricks that goes along with will be extremely useful. 
Thank you much in advance.
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Ok. Thanks a lot!
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While measuring the BET area of various sorbents, I noticed that in some samples desorption curve goes slightly lower than adsorption curve. I wonder whether this is just an artifact or has some physical explanation?
Example: adsorption/desorption curves for N2 on sepiolite (degassed in vacuum at 100 °C for 24 h). BET surface area is 312.9±4.3 m2/g.
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Hey, may I make few proposals? First, I would support the Romain's suggestion and use some commercial standards, perhaps even several ones. Second, I think I have seen similar (even stronger) patterns in the data obtained by my colleague. The "rough" explanation was that the sample was not sufficiently degassed, and some impurities may remain on the sample; formally, one might suppose that impurities might be capable of demonstrating enhanced affinity as compared with a native surface becoming better exposed during desorption. The outcome would be that the initial portion of adsorption isotherm will exceed the initial portion of desorption isotherm, specifically, in the lower pressure range. Third, some tests might be elucidating: (1) a repeated cycle: sorption-desorption-sorption-desorption. Does this feature disappear in the second round? (2) longer degassing at (?) higher temperature, (3) increasing the sample mass; does it affect?
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I prepare porous silicon with conditions used before with the same properties of silicon substrate, but usually i get pore diameter lower than the one previously obtained. Could anyone tell me what is the problem?
Thanks for attention.
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If all the parameters are fixed like concentration of electrolyte, current density, silicon resistivity etc then i would suggest check the temperature of solution. Also, the thickness of the ohmic contact could have an effect. If it is n-type, then backside illumination could have an effect on the pore size. Hope this helps.
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Two micropore each having radius r will have a surface area of 2pi*r2h (if h is the depth of the pore).Instead of that one mesopore have a radius of 2r. Then its surface area will be pi(2r2)h = 4pir2h. So mesopore should have more surface area and pore volume than micropore.
Please reply.
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Hi Debarati
Micropores (pore diameter < 2 nm)
Mesopores (pore diameter between 2-50 nm)
Thus, all three of your samples should be classified as mesoporous.
As Breynaert points out, specific surface areas will generally increase with decreasing pore diameters, and indeed microporous materials such as metal organic frameworks can have extremely high specific surface areas (~5000-7000 m2/g in some cases). Surface area per pore times the number of pores per unit volume of sample is the important thing here.
I have looked at the BJH pore size distributions you posted. Your cumulative pore volumes increase quite dramatically as the pore diameter increases. Thus, it would appear in your 3 samples that the number of pores probably increases with increasing pore diameter, which would explain why the specific surface area of your samples also increases with pore diameter.
What are your samples and what is the relationship between the 3 samples? That information might be useful in explaining the trend in your data.
Best
Geoff
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Graphene was used at the initial stage, after hydrogenation we found some additional peaks at 15.5, 18.8 and 20.4, 2-theta positions in the XRD patterns. Before hydrogenation the system contains Mg, Graphene and MgO, after complete hydrogenation under hydrogen pressure of 3.5 MPa, we found MgH2, MgO and unreacted Mg, and these additional peaks. Obviously there is no graphene peak after hydrogenation.
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Dear All,
Thank you very much for your guidance. 
I found them as some polymeric materials. 
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Hello researchers!
I have prepared ZnO and Zn0.98Pd0.02O by sol-gel method. Increase in BET surface area was observed on substitution. 
What could be the probable reason for increase in SA? Can someone help me out to get some good references on same.
Thank you.
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Hi Mithil
Since you have prepared both ZnO and Zn0.98Pd0.02O by sol-gel methods, it is possible that the mean particle size of the two products are quite different. BET surface areas are inversely proportional to mean particle size. Incorporation of Pd in the sol-gel synthesis may have resulted in a smaller mean particle size, hence a higher BET surface area.
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hello, I have synthesized gold nanorod and follow standard procedure to core with mesoporous silica shell, however I can not clearly see the porous on the TEM picture, can you teach me how to use another simple way to know my sample is mesoporous or not?
Thank you
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thank you all, I will study about that
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From the characterization analyses, it was found that the addition of the new functional group to the adsorbent decreased the rigidity of the material itself. However, the modified adsorbent are still giving the best performance during the regeneration and reusability study? Could anyone elaborate the findings, giving some theoretical evidence?
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The decrease in rigidity while maintaining the performance (or higher performance) may have been due to variations in the pore structure, in particular the increase in the porosity of the adsorbent particle and increase in specific surface.
Regards,
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Concerning the surface of the zeolit, it should be composed by silanol groups and some bronsted sites - as Si-OH-Al... But I would like to know if we can find groups as Al-OH on the surface...Any reference proving that?
How to characterize?
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The Presence of OH group can be determined by FTIR spectroscopy. The OH group stretching band appears between 3200 t0 3600 cm-1. The wavelength position depends on whether the hydroxyl group is free or hydrogen bonded to nearby OH groups. Make KBr pellets and scan sample from 400 cm-1 to 4000 cm-1. If you want to quantify the OH groups, you should have a standard sample that contains OH groups in the same environment as in the sample.
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Hi 
I would like to know the reason as to why most papers report that coating of unordered silica before adding a shell of mesoporous silica over it.
Thanks
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Better bonding between ironoxide  ( crystalline )and mesoporous silica ( pseudocrystalline )
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Does anybody have a complete calculation example (like a xlsx file) showing how to go from an adsorption/desorption isotherm to BJH pore volume distribution? I am trying to implement the calculations from the original 1951 BJH paper into Python coding. I am not confident that I am using the "A*c" correction term correctly, so I would be nice to see it being used in like Excel. Thanks. 
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The file Sakthivel uploaded is the report from the Micromeritics equipment. It contains only results.
In the book "Characterization of Porous Solids and Powders: Surface Area, Pore Size and Density" (pg. 104-108) there is a fully worked example on how to calculate the BJH. It contains step-by-step explanations and is the best way to understand it and can be easily programmed.
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Siliceous zeolites or with low Si/Al are synthesized with easily, however, high Al-containing zeolite synthesis end up with mixed phases of amorphous silica-alumina with desired zeolite. Please suggest me some literature. 
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 The pH of the reaction mixture should be maintained at a value of 10 or 11 to stabilize the zeolite precursors formed and avoid going to polymerization
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Dear all,
could you please give me information about solubility of mesoporous carbon nanoparticle
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Mesoporous carbon nanoparticles in water do not dissolve. Functionalized mesoporous carbon nanoparticles were constructed by modifying the mesoporous carbon nanoparticles with polyethylenimine and folic acid for the targeted chemo-photothermal therapy of cancer cells under near-infrared irradiation.
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How to quantified the silanol number in Mesoporous material like (SBA-15, MCM-41, SBA-16, KIT-6)?
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Hi Chandran,
There are several techniques, such as TGA, XPS, FTIR and 29Si NMR. As Christian mentioned, 29Si NMR spectroscopy is one of them. See the following references:
3) DOI: 10.1021/jp971366+
Reference 1 also shows titration and XPS, while references 2 and 3 adds Near-IR, and reference 4 adds thermogravimetry and FTIR. Additionally, this paper: DOI: 10.1021/jp9008724, show studies in Mid- and Near-FTIR of silanol groups. 
A simple way, is the TGA analysis of adsorbed amines. This paper: DOI: 10.1021/acsami.6b15507, and references therein, describes well the procedure. Adsorbed amines will undergo hofmann-elimination reaction, which are proton dependent, and seems to be independent of the acid site strength. Therefore the amount of desorbed amine at certain temperature range can be correlated to amount of hydroxyl groups in the materials. The paper also discuss some considerations and possible variations.
The best technique to choose will depend on the characteristics of your material.
Best Regards,
Alexandre.
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what is the synthesis procedyre for p123 (Pluronic P123(PEG-PPG-PEG) symmetric triblock copolymer constitutes of poly(ethylene oxide)(PEO) and poly (propylene oxide) (PPO))
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Thank you very much dear Matthew P Aldred.I don't want to synthesize it. I just wanted to know the procedure and your comments was satisfactory. Thanks...
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Hi, I am trying to analyze HZSM-5 external acid sites change before and after modification. I know there are papers employing 2, 6 di-tert-butylpyridine as a probe, which  is assumed to absorb exclusively on acid sites outside of the micropore due to its large molecule size, and using FTIR to detect the molecule-relevant peak change to characterize HZSM-5 external surface acid sites change. Theoretically, there is no problem with this method. However, technically, when prepare a HZSM-5 sample for FTIR test, the pelletizing process (to make a HZSM-5 wafer) could easily crack HZSM-5 crystals into fragments (discovered by SEM, also Journal of Catalysis 1983, 80, 221-227) and expose much interal aicd sites to the 2, 6 di-tert-butylpyridine atmosphere. Thus I don't think it is a reliable way to characterize the external acid sites.
  For XPS, provided the Al is tetrahydrally cordinately in HZSM-5 framework, the total acid sites numbers (by NH3-TPD) has a good linear relationship with the Al content in zeolite (Meshram, Zeolite 1986, 6, 434-438),  and the fact XPS singnal only comes from surface layer less than 3nm, I feel it is reasonalble to estimate HZSM-5 external surface acid change with HZSM-5 surface Si/Al ratio change.
  What's your ideas? Comments welcome!
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but with XPS you will identify number of acid sites and not strength
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what is the significance of the position of H1 type hysteresis loop?
What conclusion can be drawn if the H1 hysteresis loop closes at the relative pressure of close to 1 (0.98) for mesoporous polymer nanofibers?
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As mentioned in the 2nd reply of Christian, you need to edit the method you are using by increasing the equilibrium time. If the hysteresis loop disappears then you had an equilibrium time problem. In general, increasing the equilibrium time increases credibility of the adsorption/desorption data obtained. It would only increase the overall run time.
Considering the response of Tariq, I do not agree that the isotherm obtained is a type-III one. I agree that the the isotherm point-B (inflection point, or knee) is not as steep, but it is there. Moreover, the adsorption branch does not approach the p/po = 1 line asymptotically . It turns towards the pressure axis again and cuts the the p/po = 1 line pointing to a finite value for the volume adsobed, via which one can derive the specific total pore volume. To make sure of what I am saying, I advise Akash to enlarge the low pressure region of the isotherm to see the point-B, and enlarge the high pressure region to see the non-asymptotical approach of the adsorption branch to the pressure axis. As Tariq said, however, the exhibited high-pressure hysteresis loop is indicative of wide mesopores as per the corresponding pore size distribution curve.
Regards,
Mohamed
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i am working  on activated carbon, but i don`t have access to BET .
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surface area of different kinds of activated carbon are now available. but most of the cases they measured it by N2 adsorption. you can directly measured by topographical analysis. but this method is still not established. few researchers just started to measure it directly.  
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Please find the attached figure and paper
  Why when we doped Yb broad peak is coming not intense peaks are coming which sites Yb is going to occupied it size is too bigger as compare to tiania Yb3+ is 86 pm  and Ti4+ is 74 pm. What kind of geometry be possible for Yb3+ ion  if it is in lattice postion.
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The broad maximum corresponds to the amorphous material. It appears due to the synthetic route, not doping.
As for the Yb position, the authors do not show enough proof that Yb really enters the lattice, even though the enhancement of the photocatalytic properties probably means that some degree of doping really exists. The difference of the radii is really large, but not completely forbidding the minor doping. Similar to the famous YSZ, substitution of Ti by Yb will lead to the formation of the oxygen vacations which will partially compensate the strains caused by the large Yb ions.
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For gas phase reactions, such as cracking or methanol-to-olefins, the introduction of  mesopores (2 - 50 nm) and/or macropore (>50 nm) into zeolite structure leads to the occurence of Knudsen diffusion mechanism since diffusion relies on wall collisions to direct molecular flow.
Does this diffusion also occur when hierarchical zeolite used as catalyst in liquid phase reaction, i.e. self condensation of cylohexanone??
Please refer me to articles or books regarding the diffusion of organic liquid phase reaction in hierarchical zeolites.
Thank you
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view the article of sheldon in the hetrogeneous catalysis 
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I am working on mesoporous silica nanoparticles for the treatment of pancreatic cancer. I am planning to put PEG over the surface of the mesoporous silica nanoparticles. I want good suggestions from researchers.
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You can use APTES to functionalize your surface with amino groups, then add glutaraldehyde. Add diamine-peg and finally add your protein and reduce with NaCNBH4. 
For folic acid, I will use the same procedure up to diamine-peg (add NaCNBH4). Then add a carbodiimide and folic acid. 
You will need to look up for reaction conditions as they will depend on the available NH2 groups on the surface and your biofunctionalization needs. 
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I read some papers about chemical dissolution of the matrix, burn it off in an inert atmosphere and TGA.
Do you have any advices or references about it?
Thanks
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Better spending time and harsh acids or solvents for getting accurate and reproducible results, rather than looking for alternative solutions that will give you less accurate and maybe not reproducible results. So, at the end, you'll have to repeat all your experiments and no time will be saved.
Carbonization is influenced by confinement and by the presence of filler : you'll never get the same char yield for your polymer tested with and without filler inside.
Well, I warned you, now you can do what you want.
Alain
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I'm working on mesoporous catalyst experimentally and now I'm going to investigate these catalysts with computational methods so I want to know how can I do this work with MS. Indeed I want to know how can I build a mesoporous structure via the materials studio.
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Hello!
Can you tell me if you were able to obtain the .cif file also for SBA-15? Thank you!
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I have molecularly imprinted polymer samples for the BET analysis.
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Thank you very much I will contact them immediately.
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Why small angle XRD pattern shows peaks for hexagonal and cubic symmetric structure like SBA-15, MCM-41.
Reflection at 100, 110 and 200
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Dear Christian,
I want to know how these intense reflection are coming at low angle for such periodicity
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Two questions.
1.Can I caculate the microporous surface by BET surface -mesoporous surface?
2.Can I compare the micropous surface and volume by the adsorption quantity in the relative pressure range below 0.1?
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The high resolution alphaS plot (SPE method, see attached) can give you the micropore volume, external surface area and total surface area, if you possess a suitable reference. It works like a charm for carbon materials.
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Converting silica NPS to silicon without changing porosity.
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Mr Yuri Mirgorod,
You are right sir, that's the objective. I will try Magnesium reduction.will update the results.
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Pressure-area isotherms obtained for lipid monolayers are constantly shifted after repeating the experiment with the same type of lipid.
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I have been working on Langmuir films for over 4 years and use the same trough as you mentioned (KSV NIMA Finland).  I am suggesting you something from my personal experience.
Some major factors such as quality of subphase, amount of the spread sample, Type of barrier( hydrophobic/hydrophilic), the quality of solvent and its nature (volatile or nonvolatile) impact the Langmuir isotherm a lots. kindly make a note of equilibration time and subphase temperature, and maintain these as accurate as possible. These also affect lift off area.Kindly use micro syringe instead of micro pippett. Cleaning of Langmuir trough after each run is again a very crucial part.
Try to make spreading solution in a non volatile solvent and finish all the experiments withing 1-2 days. Hope you find reproducibility in your P - A isotherm.
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I have a list of CO adsorption isotherms for MOF materials. Could you recommend some books or papers with interpretation of their shape and so on?
For example, why quantity of adsorbed CO decreased with elevating the temperature?
thanks in advance!
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@ Fernando - I was assuming chemisorption at room temperature with CO as the molecule  Obviously physisoprtion (extensively referred to in Gregg and Sing) is usually with liquid N2 at its boiling point (- 196 C).  Some clarification is needed from Vera here.
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How to determine pore size and pore size distribution of mesoporous nanomaterial using micromeritics ASAP 2020
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Did you try having a look at the manual of your ASAP 2020? Everything is explained there.
Section 5.57 contains 6 pages explaining "BJH Adsorption/Desorption Report Options".