Properties of Ion-Exchange Resins in Relation to their Structure. III. Kinetics of Exchange

Journal of Colloid and Interface Science

Malviya

et al. 2009

653

210

a b s t r a c tThe present investigation assesses the applicability of waste materials-bottom ash and deoiled soya-for the removal of the colorant Congo red from wastewaters. The adsorption characteristics and dye removal efficiency of adsorbents have been determined by investigating factors such as effect of pH, effect of concentration of the dye, amount of adsorbents, contact time, and temperature. Langmuir, Freundlich, Tempkin, and Dubinin-Radushkevich isotherm models have been used to evaluate the ongoing adsorption. With the help of adsorption isotherm data different thermodynamic parameters such as free energy; enthalpy, and entropy have been calculated. The estimated free energy has been obtained as À21.52 kJ mol À1 for bottom ash and À16.88 kJ mol À1 for deoiled soya. On the basis of pseudo-first-order and pseudo-second-order kinetic equations different kinetic parameters have been obtained. Column operations depicted good adsorptive tendencies for Congo red with 96.95% and 97.14% saturation of dye on bottom ash and deoiled soya, respectively. Regeneration of the saturated columns has been made by eluting NaOH solution and more than 90% dye has been recovered in both cases.

Section: Rate Expression and Treatment Of The Datamentioning

confidence: 99%

Adsorptive removal of hazardous anionic dye “Congo red” from wastewater using waste materials and recovery by desorption

Journal of Colloid and Interface Science

Malviya

et al. 2009

653

210

“…Values of log (q e − q t ) was calculated for each time interval at different temperatures: log(q e − q t ) = log q e − k ad 2.303 t where q e and q t signify the amount adsorbed at equilibrium and at any time t. The graph of log(q e − q t ) versus t ( For an appropriate interpretation of experimental data, it is essential to identify the steps in the adsorption process. The ingenious mathematical treatment recommended by Boyd et al [33] and Reichenberg [34] has been applied for elucidating the kinetics data. These mathematical treatments were found useful to distinguish between particle diffusion and film diffusion.…”

Section: Adsorption Rate Constant Studymentioning

confidence: 99%

“…With the help of Reichenberg's table [34], B t values were evaluated from corresponding F values obtained in above case. The graph is plotted between time and B t , which gives us an idea about the type of step involved during the progress of adsorption process.…”

Section: Adsorption Rate Constant Studymentioning

confidence: 99%

Freundlich and Langmuir adsorption isotherms and kinetics for the removal of Tartrazine from aqueous solutions using hen feathers

Kurup

Journal of Hazardous Materials

2007

389

148

Tartrazine, a yellow menace, is widely being used in cosmetics, foodstuffs, medicines and textile. It is carcinogenic and also catalyzes allergic problems. In the present work the ability to remove Tartrazine from aqueous solutions has been studied using waste material-hen feathers, as adsorbent. Effects of pH, concentration of the dye, temperature and adsorbent dosage have been studied. Equilibrium isotherms for the adsorption of the dye were measured experimentally. Results were analyzed by the Freundlich and Langmuir equation at different temperatures and determined the characteristic parameters for each adsorption isotherm. The adsorption process has been found endothermic in nature and thermodynamic parameters, Gibb's free energy ( G • ), change in enthalpy ( H • ) and change in entropy ( S • ) have been calculated. The paper also includes results on the kinetic measurements of adsorption of the dye on hen feathers at different temperatures. By rate expression and treatment of data it has been established that the adsorption of Tartrazine over hen feathers follows a first-order kinetics and a film diffusion mechanism operates at all the temperatures.

“…The chiral interconversions is favored at low pH indicating a mechanism through proton exchange phenomenon as discussed by other authors. [15][16][17][18]24,[25][26][27][28] …”

Section: Mechanism Of Dynamics At Supramolecular Levelmentioning

confidence: 99%

Supramolecular dynamics of thalidomide and its derivatives in water‐sediment system

2009

The contamination of drug residues, including chiral ones, is not acceptable in earth's ecosystem. The dynamicity of enantiomers of thalidomide and its derivatives (3-methyl thalidomide, 3-ethyl thalidomide, and 3-butyl thalidomide) was ascertained at supramolecular level in water-sediment system using solid phase extraction (SPE) and stereoselective HPLC. Enantiomeric separation of these drugs was carried out on Ceramosphere RU-2 (25 cm 3 0.46 cm, particle size 50 lm) chiral column using pure ethanol (1.0 ml/min) as eluent at 230 nm detection. Retention times, capacity, separation, and resolution factors of the enantiomers of these drugs were in the range of 20.0-36.0, 2.08-3.93, 1.35-1.57, and 1.0-2.0 min, respectively. Percentage recoveries of the enantiomers in SPE were in the range of 90.0 to 95.0 in water-sediment system. Langmuir and Freundlich model were best fitted for dynamic equilibrium concentrations at different experimental parameters. Thalidomide and its derivatives follow first-order kinetics at dynamic equilibrium. The rate constants of chiral interconversions were 0.390 and 0.385 days 21 for S-and R-enantiomers, respectively. The uptake of thalidomide by sediment is quite good and of endothermic nature indicating good self-purification capacity of the nature for such toxic species. Chirality 00:000-000, 2009. V V C 2009 Wiley-Liss, Inc.