Questions tagged [adsorption]
The adhesion of atoms, ions, or molecules from a gas, liquid, or dissolved solid to a surface.
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New finding in cobalt compound that absorbs oxygen - is it really a breakthrough?
Very recently Chemical Sciences published results of the discovery of a new cobalt compound that can absorb oxygen at presumably a higher capacity than what has been achievable before. The paper is ...
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Do "pseudo Van der Waals" gases exist?
In college, when deriving the Langmuir isotherm for gas-solid adsorption, the professor proposed a modified version of the Van der Waals state equation, what he called the "pseudo Van der Waals ...
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Why is there preferential adsorption of a common ion during preparation of colloids by peptization?
There was a similar question asked here on Chem SE, but the answer was not very satisfactory to me, so I am asking a fresh question.
Peptization is the process of creating a colloid from a precipitate ...
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Equations Used in Isothermal Titration Calorimetry
I have been attempting to understand and derive the formulas used for ITC which can be found here starting on page 310. I am particularly interested in the single set of identical sites. To first ...
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Selective sorption of toxins by polymethylsiloxane polyhydrate
Polymethylsiloxane polyhydrate (PMSPH) is used as enterosorbent for a couple of decades (nowadays under the trademark "Enterosgel"), intended for binding in the gastrointestinal tract and excretion of ...
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Difference between neutral and basic activated alumina
Sigma Aldrich sells two different types of activated alumina for column chromatography: neutral and basic.
Apparently basic alumina is more active and better at adsorbing anions.
Why is this the ...
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Pd-catalysed hydrogenation of imines
Hydrogenation of imines to amines by $\ce{H2}$ on $\ce{Pd/C}$ has been used e.g. in the synthesis of Pumiliotoxin. By contrast, carbonyl groups are rarely reduced in this way, which I though was due ...
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A physical meaning of the Danckwerts boundary condition in terms of concentration profile (adsorption)
Can someone please explain to me in a simplified way, what exactly does a well-recognized Danckwerts boundary condition do to the concentration profile of adsorption phenomena? I just cannot find a ...
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Order of reaction in adsorption process
(1) $\ce{PH3(g) <=>[W]PH3(adsorption)->[W]P(s) + 3/2 H2(g)}$
The decomposition of phosphine on tungsten surface at low pressure is a pseudo first order reaction. This is because the rate of ...
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How to Prepare Vanadium (Na3VO4) solutions buffered at pH = 7.5?
"I need to conduct adsorption studies on Vanadium using various substances like biochars and nanooxides. To prepare Vanadium solutions up to 320 ppm with a pH buffered at 7.5 using PIPES buffer, ...
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Why does the coordination of alkaline earths by graphene oxides increase as a function of the increasing ionic radius of the species?
The literature describes that the affinity of graphene oxides towards alkaline earth metals presents a positive correlation with their ionic radius (for example, Klímová et al. (2016) and Sófer et al. ...
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Why do silver halide crystals in suspension, develop a surface charge
This is a question related to analog photography. Photographic films have a suspension of silver halide crystals in them, and these crystals have adsorptive properties which are used in this ...
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Porous materials: Is the expression of a mean free path $\overline{\ell}$ of the gas molecule valid for a binary mixtures?
Suppose that I have a binary gas mixture at low pressure. Can I calculate the mean free path $\overline{\ell}$ of the gas molecule in a pores of solid material by substituting a molecular weight of a ...
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hydrodynamic thickness of polymer vs. concentration of electrolyte?
I've measured the hydrodynamic thickness of a NaPSS layer on polystyrene latex and plotted it against the concentration of the supporting electrolyte, NaCl.
My graph shows a general decrease in ...
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How did Zyklon hold and release HCN?
$\ce{HCN}$ is notoriously unstable: It boils at room temperature, and it tends to polymerize when concentrated in unbuffered liquid form. Yet $\ce{HCN}$ was for decades widely used as a fumigant ...
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Why does physisorption change to chemisorption at high temperatures?
I read in my textbook:
In certain cases, physisorption changes to chemisorption as temperature is increased.
Could anyone explain why it is so? I know the basics of both physisorption and ...
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How to develop a Reactive Force Field (ReaxFF)? (Molecular simulation)
Currently, I am working on CO2 capture on Hydrotalcites as solid adsorbents. I want to run molecular simulations to analyse the behaviour of the material under different temperatures, pressures and ...
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Langmuir parameters for fixed bed continous column
I have prepared a model of fixed bed adsorption column in MATLAB. I have to insert Langmuir parameter value there, so how can I calculate them in case of continuous fixed bed column. I have calculated ...
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Why we have mass of adsorbent in Freundlich equation?
In Freundlich equation why we have $m$ the mass of adsorbent. I mean it is surface chemistry and on the surface of adsorbent the adsorption takes place so why we have mass of adsorbent in that ...
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Chemical bond of adsorbed atoms
When oxygen is adsorbed on iron metallic surface, does it create $\ce{Fe-O}$ bonds like the one in iron oxide? Can it be considered as a monolayer of iron oxide on the surface?
If not, how is the ...
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DIY method for regenerating activated carbon in air filters
I am interested in regenerating activated carbon used in general house-hold air filters. I am looking for a sufficiently efficient and easy method to do this in home setting. A little tinkering in a ...
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Enthalpy of adsorption and adsorption rate
What I want to know is about the adsorption enthalpy change by the change of surface coverage and the adsorption rate. In general situations, adsorption would be exothermic. So in the Gibbs free ...
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How do metal hydrides behave in a non-hydrogen closed system?
I am curious about the fundamentals of metal hydrides and how adsorption/desorption works in non-hydrogen systems. My understanding is that the atom ratio M/Hx of the metal hydride is a function of ...
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What is the chemical mechanism at work during the carboxylation of graphene oxides?
The literature describes carboxylation as an efficient technique to increase the ability of graphene oxide to adsorb metals, as it increases the content of carboxylic acids in the material, while ...
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How to minimize sample dispersion during spotting for paper electrophoresis?
I am separating highly polar amino acids and their derivatives using paper electrophoresis. This requires pre-wetting a piece of filter paper with electrophoresis buffer (in this case, carbonate-...
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Adsorption of Cu2+ using banana peels for pH 2,2.5,3,3.5,4
so basically I did my experiment which is the title. This is my procedure and results:
Make 0.05M CuSO4
pipette 50ml CuSO4
change to respective pH values using HCl
Add 2g of oven-dried banana peels
...
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Column Dispersive Mass Balance analytical / numerical solution
Is there any analytical solution for the most common expression of column mass balance:
$\dfrac{\partial C}{\partial t} + \left(\dfrac{1+\varepsilon}{\varepsilon}\right)\dfrac{\partial q} {\partial t} ...
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Application of BET to micropore
'application of the BET equation should be restricted to the range where the term n(1 – p/p0) continuously increases with p/p0'see 5.2.2 in the reference
This is one of the criterias IUPAC proposes ...
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Can negative adsorption be considered equal to sorption?
In my book it was written sorption is basically when the substance gets uniformly distributed into the bulk of the solid but at the same time its concentration is higher at the surface then in the ...
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Removing harmful gases from automobile exhaust using electrostatic precipitation
If I attach an electrostatic precipitator to a car's exhaust - and also make the smoke pass through an area containing $\ce{NaOH}$ in order to absorb sulfur dioxide - does that mean that the smoke ...
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Perovskite characterization
Does anyone know of groups working on water sorbtion testing and/or the use of inverse gas chromatography for characterizing Perovskites (as a class of materials)? Especially with regard to ...
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Any references for adsorption of ions to metal surfaces?
I'm specifically interested in ions that would adsorb to gold surfaces, however I would be incredibly appreciative if someone could direct me to a textbook reference or something more expansive, that ...
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Proper batch adsorption mechanism for heavy metals
I'm a college student with scope on environmental science, specifically the adsorption of heavy metals in aquatic media.
Currently, I suffered from serious issue of batch adsorption mechanism, which ...
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Dynamic viscosity of gas mixture (appropriate estimation)
What estimation of the dynamic viscosity $\eta = f(T)$ $([\eta] = \pu{Pa·s})$ of the gas mixture components would you recommend during adsorption at a low temperature, approx. $\pu{293 K}$ to $\pu{333 ...
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Energy and impurities balance for adsorption with a fixed bed (with description)?
Do you have any suggestion where to look for a source of information about energy and impurities (component) balance for adsorption of mixture CO2/H2O in fixed bed?
I have looked into many articles /...
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Preparation of Copper (II) Sulfate Pentahydrate Solution
how would you make a solution of Copper (II) Sulfate Pentahydrate to achieve 150, 200, 250 and 300 mgL−1 concentration of copper? I do not have the anhydrous version of the solute. Also, when I ...
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Diffused Layer ion in Electrix Double Layer
When KI is added to AgNO3 soln, so AgNO3 is in excess, collidal particle is AgI:Ag+ with diffused layer of I-, Why is the diffused layer not of NO3- when the anion in excess is NO3-?
If we had KI in ...
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Type of adsorption in catalysis
why type of adsorption takes place during catalysis? It can't be physisorption because it involves formation of chemical bond. It shouldn't be chemisorption too because it is characterised by ...
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Aren't "lack of specificity" and "nature of adsorbate" contradictory factors in physisorption?
It was mentioned in my course book under "Characteristics of physisorption" that:
Lack of specificity: An adsorbent does not show any preference for a particular gas as the van der Waal's ...
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What are molecular species?
I am in high school learning about adsorption for the first time. My school textbook says:
"The accumulation of molecular species at the surface rather than in the bulk of a solid or liquid is ...
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