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Adsorption of boron from aqueous solutions onto tannic acid resin (TR) was investigated in this study as a function of contact time, temperature, initial boron concentration, pH, and adsorbent dosage. TR was prepared from commercial tannic acid by chemical activation with formaldehyde in aqueous ammonia and characterized by using Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and BET surface area analysis. The optimum adsorption conditions were found as 24 h, 308 K, 4 mg L−1, boron, pH = 7.0, and 0.1 g TR. The adsorption data was well suited to Langmuir equation. Monolayer adsorption capacity (Qo) was calculated as 2.56 mg g−1. The pseudo‐second‐order equation, which indicated chemical adsorption, provided the best correlation for the adsorption process. Thermodynamic parameters, such as standard free energy (ΔGo), enthalpy change (ΔHo), and entropy change (ΔSo) were calculated. The thermodynamics of boron adsorption onto TR indicated spontaneous and endothermic nature. Adsorption yield was determined as 88% and then 81% of boron was desorbed with 0.01 M HCl. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 1036–1044, 2013

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Parameters, such as pH, temperature, initial boron concentration, adsorbent dosage, and ionic strength, affecting boron adsorption onto chitosan beads were examined in this study. The following values were obtained as the optimum conditions in our studied ranges: pH 8.0, temperature ¼ 308 K, amount of chitosan beads ¼ 0.15 g, initial boron concentration ¼ 4 mg L À1, and ionic strength ¼ 0.1 M NaCl]. The adsorption kinetics were also examined in terms of three kinetic models: the pseudo-first-order, pseudo-second-order, and intraparticle diffusion models. The pseudosecond-order kinetic model showed very good agreement with the experimental data. Intraparticle plots seemed to have two steps and indicated multilinearity. Equilibrium data were evaluated with nonlinear and linear forms of the Langmuir and Freundlich equations. The experimental data conformed to the Freundlich equation on the basis of the formation of multilayer adsorption. To characterize the synthesized chitosan beads, we used Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) analyses. As shown by FTIR analysis, the boron species may have interacted with the NH 2 groups on chitosan. Microparticles of about 5 lm appeared in the SEM micrographs of the chitosan beads. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122: [657][658][659][660][661][662][663][664][665] 2011

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Cationic starch (CS) was prepared by using epichlorohydrin (EPI) and 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTMA) and ionic liquids (ILs) having different anionic groups [1-butyl-3-methyl imida-were impregnated onto CS. Thorium(IV) ions were preconcentrated by using IL impregnated CS. The effects of ILs were investigated for extraction of Th(IV) by CS and the results were compared. Th(IV) was preconcentrated with approximately 73% sorption capacity by CS and increased up to 98%-100% for IL impregnated sorbents at pH 7.0.The sorption capacities of Th(IV) were 0.453 mmol g −1 , 0.399 mmol g −1 , 0.281 mmol g −1 , and 0.183 mmol g −1 for CS-BMI + Br − , CS-BMI + [(TF) 2 N], CS-BMI + PF − 6 and CS-BMI + BF − 4 , respectively. The elution occurred with HCl and NaOH solutions at pH 7.0.

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