On the Applicability of the Langmuir Equation to Estimation of Adsorption Equilibrium Constants on a Powdered Solid from Aqueous Solution

2000 ◽  
Vol 231 (1) ◽  
pp. 8-12 ◽  
Author(s):  
Tao Zuyi ◽  
Chu Taiwei
Keyword(s):  
Aqueous Solution ◽  
Adsorption Equilibrium ◽  
Equilibrium Constants ◽  
Langmuir Equation

Supercritical CO2 regeneration of activated carbon loaded with organic adsorbates

1997 ◽  
Vol 35 (7) ◽  
pp. 261-268 ◽  
Author(s):  
Kazuyuki Chihara ◽  
Kanji Oomori ◽  
Takao Oono ◽  
Yosuke Mochizuki
Keyword(s):  
Activated Carbon ◽  
Cost Estimation ◽  
Supercritical Co2 ◽  
Adsorption Equilibrium ◽  
Equilibrium Constants ◽  
Adsorption Dynamics ◽  
Boiling Points ◽  
Organic Adsorbates ◽  
Carbon Regeneration ◽  
Co2 Density

Supercritical CO2 regeneration is one of the possibilities for spent carbon regeneration loaded with some organics. Here, adsorption equilibrium and adsorption dynamics were evaluated for some typical organic pollutants under some supercritical CO2 conditions. A supercritical CO2 chromatograph packed with activated carbon (F-400, CAL) was used to detect the pulse responses of organics, which were analyzed by moment analysis. Adsorption equilibrium constants of some organics varied with CO2 density and their boiling points. Possibility of regeneration of each substance was discussed. Cost estimation was necessary and was the key point of this technique.

scholarly journals Short beds for chromatographic measurement of adsorption equilibrium constants.

1982 ◽  
Vol 15 (3) ◽  
pp. 232-235 ◽  
Author(s):  
DONG IL LEE ◽  
MOHAMED A. FAHIM ◽  
SEIICHIRO KAGUEI ◽  
NORIAKI WAKAO
Keyword(s):  
Adsorption Equilibrium ◽  
Equilibrium Constants ◽  
Chromatographic Measurement

Thermochromism of Metal Exchange Reaction between Zinc(II) and Mercury(II) Porphyrins

1995 ◽  
Vol 50 (4) ◽  
pp. 545-550 ◽  
Author(s):  
Masaaki Tabata ◽  
Masahiro Ide ◽  
Kentaro Kaneko
Keyword(s):  
Aqueous Solution ◽  
Exchange Reaction ◽  
Thermodynamic Parameters ◽  
Distribution Curve ◽  
Equilibrium Constants ◽  
Metal Exchange ◽  
Free Base ◽  
Temperature Range ◽  
Base Form ◽  
Metal Exchange Reaction

Thermochromism was observed for an aqueous solution containing zinc(II) and mercury( II) cations and N-p-nitrobenzyl-5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin anion (NO2Bz(Htpps)4-) in the temperature range 10 to 70 °C. The equilibrium constants and the thermodynamic parameters of Zn(NO2Bztpps)3- and Hg(NO2Bztpps)3- have been determined spectrophotometrically to elucidate the thermochromism at 10, 15, 20, 25 and 30 °C in 0.1 mol dm-3 NaNO3. The protonation and metalation constants of NO2Bz(Htpps)4- are defined as K2 = [H2P][H+]-1[HP]-1, K3 = [H3P][H+]-1[H2P]-1 and KMP = [M P][H+][M2+]-1[HP]-1, where HP and MP denote the free base form of the prophyrin and the metalloporphyrins of zinc(II) and mercury(II), respectively. Charges of the prophyrin and metalloporphyrins are omitted for simplicity. The following values were found: logK2 = 7.75 ±0.02 (25 °C), ΔH°/kJmol-1 = -21.2±0.5 and ΔS°/Jmol-1K-1 = 77±1, logK3 = 2.55±0.02 (25 °C), ΔH°/kJmol-1 = -25±0.8 and ΔS°/Jmol-1K-1 = -35±3 and log KZnP = 0.63±0.03 (25 °C), ΔH°/kJmol-1 = 31.0±0.8 and ΔS°/Jmol-1K-1 = 116±3, logKHgP = 6.22±0.03 (25 °C), ΔH°/kJmol-1 = 4.5±0.7 and ΔS°/Jmol-1K-1 = 134±2. The distribution curve calculated from the thermodynamic parameters sufficiently agrees with the observed metal exchange reaction between the metalloporphyrins.

scholarly journals Adsorption of Acid Dyes from Aqueous Solution on a Chitosan-cotton Composite Material Prepared by a New Pad-dry Process

2011 ◽  
Vol 6 (3) ◽  
pp. 155892501100600 ◽  
Author(s):  
Mahjoub Jabli ◽  
Mohamed Hassen V. Baouab ◽  
Mohamed Sadok Roudesli ◽  
Aghleb Bartegi
Keyword(s):  
Aqueous Solution ◽  
Indigo Carmine ◽  
Langmuir Equation ◽  
Acid Dyes ◽  
Chain Molecules ◽  
Dry Process ◽  
Dipole Interactions ◽  
Cure Time ◽  
Recovery Angle ◽  
Acid Blue

In this paper, we developed a method that may be considered as an easy and economical way to prepare chitosan-cotton composite (CH-cotton) materials using an electrolytes-free pad-dry process in which the cure step was performed in an oven microwave to provide a cotton fabric with greatly enhanced affinity for acid dyes. Evidence of successful interaction between cotton and CH through formation of hydrogen bonding and/or ion dipole interactions was analysed by FTIR spectroscopy. Influence of cure time onto the weight per surface unit of samples has been studied and five CH-cotton composite materials with different %CH content (I-V) were prepared. Crosslinking of cellulosic chain molecules of cotton fiber through CH segments was confirmed by Wrinkle Recovery Angle (WRA) and Tensile properties measurements. CH-cotton samples were then tested as adsorbent of four acid dyes from no-electrolytes aqueous solution [Indigo Carmine (AB74), Acid Red 183 (AR183), Acid Blue 161 (AB161) and Acid Yellow 17 (AY17)]. Results were monitored using, reflectance spectro-colorimeter and spectrophotometer analyses. Data obtained with treated cotton showed better dye exhaustion than obtained with untreated one. The modelling of the adsorption isotherms was performed by Langmuir equation and the thermodynamic parameters were evaluated. Globally, the lack of affinity of cotton for acid dyes is widely overcome by the use of low %CH content ranging from 0.079 to 0.515

Enhanced Oxidation of Air Contaminants on an Ultra-Low Density UV-Accessible Aerogel Photocatalyst

1996 ◽  
Vol 454 ◽  
Author(s):  
M. Dreyer ◽  
G. K. Newman ◽  
L. Lobban ◽  
S. J. Kersey ◽  
R. Wang ◽  
...  
Keyword(s):  
Reaction Rate ◽  
Adsorption Equilibrium ◽  
Uv Light ◽  
Equilibrium Constants ◽  
Main Stream ◽  
Low Density ◽  
Air Contaminants ◽  
Reaction Rate Constants ◽  
Air Contaminant ◽  
Type Rate

ABSTRACTThis research developed new forms of photocatalysts that could potentially move photocatalytic degradation of air contaminants into the main stream of industrially used remediation technologies. Tests of the photocatalytic activity of the TiO2 aerogel catalysts have been carried out using both acetone and methane as the air contaminant. For comparison, the same tests were carried out on a standard (non-aerogel) anatase powder. Despite having very low crystallinity, the aerogel decontaminates the air far more effectively than an equal volume of the anatase powder which indicates that a much larger fraction of the aerogel is activated by the UV light. Experimental data were used to determine adsorption equilibrium constants for acetone, and to determine reaction rate constants assuming a Langmuir-Hinshelwood type rate expression.

Kinetic and equilibrium studies of fluoride sorption onto surfactant-modified smectites

Clay Minerals ◽  
2012 ◽  
Vol 47 (4) ◽  
pp. 429-440 ◽  
Author(s):  
S. Gamoudi ◽  
N. Frini-Srasra ◽  
E. Srasra
Keyword(s):  
Aqueous Solution ◽  
Thermodynamic Parameters ◽  
Adsorption Kinetics ◽  
Equilibrium Constants ◽  
Second Order ◽  
Operating Conditions ◽  
Polluted Water ◽  
Isotherm Models ◽  
Fluoride Ions ◽  
Pseudo Second Order

AbstractThe use of organoclays as adsorbents in the remediation of polluted water has been the subject of many recent studies. In the present work, a Tunisian smectite modified with two cationic surfactants was used as an adsorbent to examine the adsorption kinetics, isotherms and thermodynamic parameters of fluoride ions from aqueous solution. Various pH values, initial concentrations and temperatures have been tested. Two simplified kinetic models, first-order and pseudo-second-order, were used to predict the adsorption rate constants. It was found that the adsorption kinetics of fluoride onto modified smectites at different operating conditions can best be described by the pseudo-second-order model. Adsorption isotherms and equilibrium adsorption capacities were determined by the fitting of the experimental data to well known isotherm models including those of Langmuir and Freundlich. The results showed that the Langmuir model appears to fit the adsorption better than the Freundlich adsorption model for the adsorption of fluoride ions onto modified smectites. The equilibrium constants were used to calculate thermodynamic parameters, such as the change of free energy, enthalpy and entropy. Results of this study demonstrated the effectiveness and feasibility of organoclays for the removal of fluoride ions from aqueous solution.

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