Papers by Keyword: Chelating Resin

Abstract: The protonation process, the adsorption equilibrium process, the adsorption isotherms and the adsorption kinetics of adsorbing Ca(II) and Mg(II) onto Lewatit MonoPlus TP 207 and TP 208 chelating resins were studied using the pH titration method and batch experimental method. By omitting the ionic charges, first protonation constants, second protonation constants and equilibrium constants were determined. The adsorption behaviors were found to be dependent on contact time, pH, temperature and initial concentrations. The experimental adsorption isotherms were fitted using both the Freundlich and Langmuir models. The adsorption kinetics was described by means of the pseudo-first-order and pseudo-second-order kinetic models. The adsorption mechanism was found to involve intra-particle diffusion and film diffusion, where both were found to be the rate control steps.

Abstract: Effects of initial concentration of Ag(І), concentration of HNO₃, contact time and adsorption temperature on adsorption capacities of a novel polystyrene modified ethoxycarbonyl thiourea resin were investigated, and the maximum adsorption capacity of Ag(І) reached 4.11 mmol·g^-1. The adsorption kinetics was well fitted Boyd’s diffusion equation of liq·uid film, so the adsorption was controlled by liquid film diffusion. The experimental date fitted Langmuir equation, and the correlation coefficient was close to 1. The positive value of adsorption enthalpy ΔH is indicative of an endothermic process. FT-IR characteristic peaks of ethoxycarbonyl and thiourea groups changed obviously fore-and-aft adsorption, which means that the corresponding functional groups coordinate with Ag during the adsorption process.

Abstract: A new chelating resin, pyrocatechol violet (PV) immobilised on Amberlite XAD-4 polymeric matrix, was prepared. The resulting chelating resin has been characterised by elemental analysis, infrared (IR) spectra and textural analysis (BET). The resin was used for the preconcentration of Zn (II) prior to its determination by flame atomic absorption spectrometry (AAS). The optimization of experimental conditions during the quantitative extraction of Zn (II) by the resin phase was performed using factorial design including pH, amount of resin, and contact time. The phase exchange kinetic studies performed of Zn (II) revealed that equal 40 min was sufficient for reaching equilibrium metal ion sorption. Sorption is quantitative in the pH range of 5 – 5.5 (recovery 98 – 99%).