Questions related to Surface Adsorption
What does it mean if the constant n of the Sips (Langmuir-Freundlich) model is greater than 1?
Note that in my adsorption data when n(sips) is fixed at 1 the Qmax of Sips = Qmax of Langumir!
I want to do BET surface area analysis of Ni foam sample. what will be the degassing time and temperature and number of points to be consider for analysis. and any other specific details to follow?
I am trying to know if the dendrimer can be covalently bonded to the amine-functionalized magnetic nanoparticles' surface (modified with APTES), if I am only adding pre-synthesized ready dendrimer to the functionalized MNPs, mixing and sonicating them under 70 °C, rather than growing the dendrimer on the MNPs surface which requires a repetition of two type of reaction: alkylation of amine groups through adding methyl acrylate, and then amidation of esters group.
Is it possible for the secondary amine in the amine-functionalized MNPs to form amide through Acylation with Carboxylate salt from sodium carboxylate found in the dendrimer?
Moreover, what is the required test / characterization method required to determine if there is a new bond formed between dendrimer and amine-functionalized MNPs' surface, and how to determine its type (physically or chemically adsorbed / bonded)?
the PAMAM-COO Na dendrimer of G 1.5 structure is attached along with the amine-functionalized MNPs structure.
Hi. I have random questions regarding Langmuir Isotherm Model.
1) What does it means if I have negative intercept value for Langmuir Equation in the graph of:
Ce/qe = 1/Q (Ce) + 1/Qb
2) How do I know whether the obtained value of b constant is logical or not?
We want to make a Self-Assembly of the probe to which -the SH bond is attached for the gold surface. We plan to make an annealing process to reduce residual stress of the 25 nm thick gold surface, which is coated by thermal evaporation. Can you give any advice on temperature?
Thank you for your help:)
The lab I contacted, accept samples in powdered form. Since nanocomposite is bulk obtained from mold, should it be powdered as well ? While powdering will the porosity definition still hold since some pores do not exist when powdered ? or are we talking about pores that are very tiny that are found even on smallest single particle that can be powdered ?
I would like to understand why N2 tends to be adsorbed more or less depend on the type of surfaces. (1 atm, 298 K).
I would like to understand why N2 tends to be adsorbed more or less depend on the type of surfaces. (1 atm, 298 K).
I am looking to find a material (any type) that can offer me CO formation energy (> 2.0 eV) and NO formation energy ( < 0.5 eV) simultaneously. Secondly, how to confirm these formation energies experimentally? Your expert opinion in surface reaction, catalysis would be appreciated. Thanks
I fabricate some gel bead as a kind of biosensor with DNA probe conjugated. However I found there was some kind of dust induced during fabrication. Can I use a stainless still mesh to filter (The reason not the plastic ones is that in my experience it has high affinity to DNA)? If the affinity is high then alternatively how can I isolate my bead with the dust (in centrifuge both appear in sediment)?
I know, or think I do, the basic idea behind these natural structures, as from what I know they form due to water dripping from the top leaving a salt deposit behind. But started to wonder about the principles involved here.
My question is mainly in stalactites, what makes the salt left behind in the process to remain attached to the overlaying rock and keep growing instead of falling down? is there some physical-chemical explanation for this?
Stalactites do fall, which I would guess maybe due to the weight of the column surpassing a certain limit, which makes me believe there maybe something related to the electrostatic attraction of the hydration sphere of the salts/minerals left behind and the rock minerals. Am I even close?
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.
Does anyone know how I can find out parametric values of "Parameter Settings" of isotherms (Freundlich, Langmuir, Dubinin-Radushkevich and Temkin) in OriginLab or MATLAB? E.g. - link (2: 19 min).
I´m making adsorption experiments with peptides onto biomaterials, but I have no idea of calculating the N and K parameters and its error from the plotted data. If anyone can help me I´d be very pleased. Thank you!
I have used FTIR to measure both the gas phase CO and surface adsorbed CO (on Ni powder catalyst with Al2O3 and SiO2 as substrate, DRIFTS mode). The Ni-C bond should lower the strength of the C-O bond (backdonation theory, etc), thus lower its vibrational frequency, but we have consistently observed the opposite: the surface CO has higher wavenumber than the gas phase CO. I am wondering how could this be possible?
I have attached a graph which compare the two spectra.
How to model the isotherm modelling data for a multimetal system? Are Langmuir and Freundlich or other isotherms used to model single metal systems applicable to data obtained in a multimetal system for each metal? It would be nice if someone can share suitable reference/ research paper for the same. Have some papers for binary and ternary system but my system has 7 metals.
I have a graphite coating (50 um thick) on copper foil (10 um thick) and would like to do BET/BJH measurements. Do I need to scrap the graphite samples from copper foil to do BET/BJH analysis? I performed experiments without scraping the graphite (by cutting Cu foil/graphite in to small pieces) and got negative surface area. What is the right way to analyze the surface area and pore size distribution?
Any help will be much appreciated.
The degassing of the sample is carried out before the BET measurement. I want to know how much degassing time and temperature to performe on my sample (my sample is the copper powder with a melting temperature of 1085 ° C).
I am conducting an adsorption test (of Cr6+) on an adsorbent.
I did the adsorption tests without background electrolyte(BE) by just dissolving the Cr source in Milli-Q water. I also did a test with different background electrolytes (0.01-.1M NaCl, KCl, CaCl2, NaNO3).
Can somebody with experience on adsorption tests enlightment me. Thanks a lot!
In many refinery process such as acid gas removal plant, the surface acidity of molecular sieves play a vital role in the formation of green oil. I want to know what is the best way to reduce surface acidity of zeolite molecular sieves.
Type I adsorption may be modeled using Langmuir or Freundlich Adsorption isotherm models. But how do I analyse a system that does not follow the Type I adsorption mechanism?
I have an amino acid interacting weak with a CNT. During the standard MD it adsorbs, desorbs and then re-adsorbs on the CNT surface. Which method does suits to calculate the adsorption energy? Is there any fast and easy way to calculate the adsorption energy?
Thanks in advance,
The universal/molar/ideal gas constant R is given by
R=PV/nT; this however, on an average, is considered true for gases (H2, O2, N2 are excluded). Involving R in chemical expressions dealing with gases is understandable; but could it's inclusion in the chemical equations, primarily evolved for the gases and later being used for liquids as well be justified? To be more specific, I am talking about the Dubinin isotherms which are also being used for modelling the adsorption of adsorbates present in a liquid, uses the term RT for determining the adsorption energy. Is it justified? Please enlighten me; I am eager to hear from you.
In gas hydrates, semiclathrate hydrates by itself participate in hydrate crystalline structures. The studies suggested that Tetrabutyl Ammonium (TBA+) cation were able to induce semiclathratic behavior with different anions, i.e., Bromide (Br-) Chloride (Cl-) or Hydroxyl (OH-), therefore acted as thermodynamic hydrate promoter. However, Tetrapropyl Ammonium (TPrA+) or Tetrapentyl Ammonium (TPA+) cations are not participated in hydrate cage structure therefore, worked as hydrate inhibitor. What could be the possible reason for TBA cation to behave as semiclatharate hydrate instead of usual hydrate formation?
What does complexion stands for, and how complexion is formed or mechanism of complexion. what is its importance in adsorption? Is it any way related to cation exchange?
I am performing pool boiling experiment using water as the working fluid. To avoid any type of solid deposition on the boiling surface (copper in my case), which type of water should be preferred- distilled, deionized or millipore?
The qualitative relationship can be found quite often. But I did not find anything with respect to the attracting forces between clay mineral surfaces and water molecules or salt solutions.
How can I create a water layer with specific thickness using "layer builder" in materials studio? Im going to create a 3 layered structure with water in between, and two crystal surfaces in sides. Inorder to explore the surface energy of different crystal surfaces in the solution.
I studied the effect of temperature on adsorption of methyl orange by carbon and noticed an increase in adsorption capacity with increasing temperature. What may be the reason for this? The carbon used was surface modified with potassium hydroxide.
My enquiry is about any chemical/electrochemical species maybe ions or gas, etc. that adsorbs on Pb surface exposed to that species.
Is it possible to track the complexation behavior of a polymer with an aqueous dispersion of iron oxide (Fe3O4) nanoparticles through potentiometric complexation? And if yes, is it also possible to investigate this complexation behavior in the aqueous solution of Fe2+ and/or Fe3+ representing the surface cationic species of Fe3O4 nanoparticles?
As XPS has the ability to determine the moieties from which the polymers are adsorbed onto the surface of the nanoparticles, can it also give any clues about the number of the adsorbed components?
I am interested in preparing a bimetallic system to run an adsorption study. I want to combine an anion [Cr(VI)- salt used: Potassium dichromate] and a cation [Ni(II)- Ni(NO3)2.6H2O or Cd(II)- CdCl2]. Initially, I combined Lead nitrate and Potassium dichromate, to have a bimetallic system containing Pb and Cr. As my study required a set pH, lead chromate is formed at this pH (2 and 5).
My concern is as follows:
1) Will the state be similar if I combine Ni and Cr salts? OR Cd and Cr salts?
2) Would it result in precipitate formation?
2) Which among the above will be a better combination?
All suggestions will be appreciated. Thank you
I am looking for coupling agent that give a good dispersion of the filler in polymeric matrix and a good bonding strength between the filler and the matrix
I want do calculate the average surface area which each adsorbent molecule occupies Which follows the Langmuir isotherm with chemdraw software
For this equation
active surface area = 1/m× N × A
m is the slope of Langmuir isotherm plot, N is Avogadro’s number, and A is the average surface area which each adsorbent molecule occupies
There are several questions for me.
1- Is adsorb 3d structure should be optimized by Gaussian software or Chem 3D?
2- Are you used connolly molecular surface area function of ChemDraw software or extended Hückel>> calculate surfaces function? (Please explain)
3- Can you help me obtain the average surface area for dopamine and ascorbic acid (step by step)?
Thanks for the good attention
In the guidelines for thermodynamic sorption modelling as outlined in the NEA Sorption Project Phase III report (http://bit.ly/2dhowYs) it is recommended that surface site densities be normalized to a reference site density common for all minerals when formulating surface complexation models.
For a surface complexation reaction between, say a metal cation and a surface binding site, this makes sense and it is easy to demonstrate that altering the site density necessitates an adjustment of the Kint binding constant to obtain the same sorption edge for a given fixed mass and surface area of sorbent (Since Kint values are always calibrated against an assumed, or measured site density when fitting to macroscopic sorption data).
Applying the corresponding correction to surface site protolysis constants (pKa's), however, implies an altered delta_pKa (although unaltered pHpzc) which gives rather different surface charging characteristics. Normalized pKa values give an altered shape for the surface charge inflection point around the pHpzc which makes it very difficult to reconcile a calculated sorption edge with the corresponding sorption edge calculated at the original site density (see attached pdf). The only way to obtain a match with the original sorption edge in calculations seems to be to normalize the metal binding reactions and leave the protolysis constants as they are irrespective of binding site density used in the calculation.
Sverjensky and Sahai's paper (1996) and Sverjenksy's (2003) paper on standard states, (http://dx.doi.org/10.1016/0016-7037(96)00207-4 & http://dx.doi.org/10.1016/S0016-7037(02)01074-8), however, seem to indicate pretty clearly that there is no universally valid delta_pKa that can be given without invoking a reference site density, so I'm wondering whether I have missed something fundamental with the Sverjensky-Kulik normalization theory?
It is related to the pore diameter and the size of the ion which enter in to the pores of the material besides the surface adsorption. Usually the stirring increases the rate of adsorption in to the pores of the material.
I am trying to study the adsorption of Pb2+ ions on biofilms. I have used 0.01 gm of biofilm in 10 ml of 100 ppm Pb2+ solution. After removal of the biofilm, I found the Pb2+ concentration of the supernatant solution using spectrophotometer and dithizone assay. The concentration of Pb2+ was found to be less compared to control which means Pb ions have been adsorbed on the surface of the biofilm. Now for calculate % of the residual metal concentration in media, I used E (%)= (Ci-Cr)/Ci*100 equation. (Ci-initial metal concentration, Cr-residual metal concentration) Can anyone tell me if this is ok for dithizone assay?
My colleague performed BET surface area measurements for my samples Li4Ti5o12.
They gave me this plot, but I am not sure how to interpret, I saw some rudimentary materials and they were able to get surface area (m2/g)
Can I also perform those same calculations? Any materials or links to resolve this will be appreciated!
Besides total surface area (TSA), active surface area (ASA) and reactive surface area (RSA), has concentration of radical reactive sites been estimated for amorphous carbonaceous materials (e.g. coal char, pyrocarbons)? If yes, what would be an average range for such concentration?
Any answer to this question will be highly appreciated. Thanks in advance for all contributions.
By examined the adsorption capacity for a mixture solution of Cu, Zn and Ni onto goethite-rich soil and birnessite-rich soil, we recorded that the affinity of Zn and Ni in goethite-rich soil always higher than their affinity onto the birnessite-rich soil. On the other hand, the affinity of Cu always higher onto birnessite-rich soil than that of goethite-rich soils.
Also, why the adsorption capacity of Ni and Zn declined more by using a mixture of the two oxides (Goethite-Birnessite)? the pH of the metal solution was fixed before the experiments at 6.
1. Surfactant molecule is made from water-loving head and grease-loving tail (Figure 1). My question: How do we measure the cross-sectional area of the alkyl chain of surfactant? Do we measure it vertically (refer to GREEN DOUBLE ARROWS of Figure 1) or horizontally (refer to RED DOUBLE ARROWS of Figure 1)? Or do we just take the “theoretical value" of the alkyl chain from the literature (estimated 20-25 A˚2)?
2. I have read a paper entitled, "New Adsorption Model - Theory, Phenomena and New Concept - " by Shibata et. al. . One of the sentences in para 3 page 2 stated that, i quoted, “The important finding is that molecular surface area is less than the cross-sectional area of the alkyl chain for C16E8 and C18E8. Such small molecular surface areas strongly suggest that Gibbs adsorption just at air/water interface in an adequate. This is one of contradictions for the Gibbs adsorption."
Why does when the molecular surface area is less than the cross-sectional area of the alkyl chain, it is said to be contradicted with the Gibbs adsorption?
Now I have prepared porous Co3O4 concave nanocubes, of which pores is with average of 5 nm. I want to use the Co3O4 to adsorb metal ions into the pores. What kind of knowledge should I learn? Who can provide some paper for me to study? In addition, can Co3O4 be hydroxylated？ Then why? By the way, taking pH into consideration, should I explore the relationship between Zeta poential and pH value?
Thanks in advance.
I modified Si with hexa ethylene glycol then immobilized DNA probe onto the surface. However, by using fluorescence labeled DNA, I've found that there is non-specific adsorption of DNA on the control surface. I'm just wondering if I can use BSA or tween20 or any proper anti-fouling reagent to reduce non-specific adsorption of DNA on Si electrode. It's good to mention, I used 0.05% of tween20 to rinse the surface but DNA still adsorb on the surface.
I would appreciate any suggestions.
In my recent experiments, I found that my equilibrium isotherms data are very different to any types of isotherm models.
I should mention that my tests were conducted by using gas-oil as solvent and adsorption of sulfur component was studied. also i use a high concentration of sulfur (about 18000 ppm) in my liquid mixture.
Is there any people to help me and tell me what are the reasons?
what is the problem?high concentration of sulfur ? or using gas-oil which contains different types of hydrocarbons and other materials?
And my last question is that, can i use this types of isotherm adsorption figures and justify them? I mean, is there any scientific justification?
Regarding multilayer adsorption of water on anatase titanium dioxide, where can I find information on surface reactivity and energies? I am interested in estimating energy required to remove moisture to optimize melt processing.
I synthesise crystals in the presence of organic and inorganic additives. Aqueous chemistry analysis shows that there are surface adsorptions and crystal incorporations. Also there are shifts in XRD peak position. Would you please guide me:
1- Does surface adsorption affect the unit cell volume and XRD peak position?
2- If yes, then how can I find out that the XRD peak position shifts relate to the surface adsorption or crystal incorporation?
I'm working on batch adsorption process.in my last result when i use Langmuir model of adsorption i conclude that my Langmuir constant are in minus sign.
What's the meaning of this result?is that reasonable ?or maybe my test was failed?
I tested the adsorption capacity of the raw materials and activated raw material, i obtain the same results. So what is the Objectif to activate the raw material in this case ?
I tested tow different raw materials and also the activated materials, we found the same results ?
We practical experience to do it with activated carbon, and heterogeneous catalyst, but we cannot understand how you can perform this in a coating on a metal.
We used copolymers of acrylic acid and vinyl imidazole to adsorb three different drugs. It seems that ionic bonding took place and resulted to high retention of the drugs on the polymers. I confirmed hydrogen bonding through FTIR, but in some cases strong ionic interactions caused the adsorption. Which technique can I use to confirm this hypothesis?
The existence of water droplet on hydrophillic or hydrophobic surfaces is in the form of various spherical shapes with either less than 90 deg or more than that. But we have observed the existence of triangular shape with unusual behavior of water droplets on hydromagnesite (HM) surface. It looks like HM swollen in water and could not provide smooth surface for existence of droplets in spherical shape. Can anybody help me how can I explain this results to support my concept of hydrophillic nature of HM (images are attached)
Actually, the initial concentration was chosen more than need.. so distribution coefficient became less than 1; Therefore DG0 was positive... I should say that with increasing the temperature, DG0 became negative.. in mathematical form this is obvious.. because from DG0=DH0 - TDS0, when T increases, ( with considering positive values of DH and DS ), DG is going to get a negative value and the process will be spontaneous.
Thanks in advance.
I have prepared a Carbon/Silica composite and have done its BET analysis and pore size distribution analysis. However my BET isotherm shows Type IV nature which indicates mesoporosity however the pore size distribution data shows maximum distribution of pores in the micro-porous region. Am I doing it wrong? Else if I am doing it right, how can one explain this? Thanks in advance.
Here is the BET and pore size distribution plot.
Is there anyone with experience on the etching process of ZnO from the Cu2ZnSnSe4 absorber layer? (the structure is: ZnO/CZTSe/ZnSe/Mo)
I impregnated polyethyleneimine (PEI) onto an activated carbon.
Just wondering which was the best way to show the distribution of the polymer through the pores. I just thought about plotting the amount of pore blocked for each pore width range (I.e. application of DFT and/or BJH models to N2 adsorption data).
Also, which parameter could give a representative estimation of the dispersion of the polymer through the pores? I was thinking about a sort of polymer coverage but not sure about how to calculate this.
If X is any adsorbent with nitrogen functionality, A (transition metal) and B (Carbon family member, say ) are two adsorbates. A and B were separately allowed to adsorb on the X surface. The amounts of A and B metal ions adsorbed on X's surface were different. Why such a difference?
I have fitted the fluoride adsorption kinetics data to Lagergren’s pseudo-first order and Ho's pseudo-second order kinetic models. What do these kinetic models explain about the adsorption kinetics?
I have read some articles stating that the metal-organic frameworks are not as resistant as expected, specifically in water media.
Therefore, I would like to know if anyone has developed a passivation strategy for one specific MOF, and of what does it consist?
In adsorption process, at different time 0min (0.5Abs ), 15min (0.3Abs.) and 32 minutes (0.78Abs.). Commonly absorbance (Abs) peaks should be decreasing in nature. But in my case the final 32min peak shows higher abs. values than others. Can you suggest why it happens in peak value?