A facile approach toward surface sulfonation of natural cotton fibers through epoxy reaction

Proficiency of some synthetic alginate derivatives for sequestration of Iodine-131 from radioactive liquid waste

The current effort in environmental remediation is aimed at removing iodine-131 radionuclide from radioactive liquid waste produced by an Egyptian nuclear power plant using some synthesised alginate derivatives. Two different copolymers, namely sodium alginate poly (acrylic acid) (P1) and sodium alginate poly (acrylic acid-methacrylic acid) (P2), are prepared using gamma radiation. The ability of these polymers to remove 131I radionuclide as sorbents has been investigated. The synthesised polymers exhibit excellent adsorption performance for 131I ions, and the adsorption equilibrium requires only 30 min, which reveals that the sorption process is kinetically faster than most of the other materials reported previously. The removal percents for 131I radionuclide at a pH of 3.0 at room temperature on P1 and P2 are 77.7% and 84.2%, respectively. The sorption capacities of the two polymers demonstrate that P2 > P1, with capacities of 67.9 and 58.5 mg/g, respectively. Four linear kinetic models are investigated: pseudo-first order, pseudo-second order, Elovich, and Weber-Morris models. Regarding their calculated parameters, these models indicate that the adsorption process of I-ions on both P1 and P2 is controlled by chemisorption. Four equilibrium isotherm models (Redlich-Peterson, Langmuir, Freundlich, and Harkin-Jura) are investigated, revealing that the adsorption process is a monolayer and multilayer process on a heterogeneous surface.

Poly(styrenesulfonic acid)-impregnated alginate capsule for the selective sorption of Pd(II) from a Pt(IV)-Pd(II) binary solution

Poly(styrenesulfonic acid)-impregnated alginate capsule (PSSA-AC) was prepared using a simple fabrication process, and used for selective separation of Pd(II) and Pt(IV) from their mixture. Evaluation of the pH effect revealed that PSSA-AC had good Pd(II) selectivity especially when the pH was between 3 and 5 at which neutral species Pd(OH)2 are present. Experiments on metal penetration through the Ca(2+)-alginate film showed that anionic species hardly penetrate through the alginate film (acting as an ionic barrier). The selective sorption mechanism is proposed as the following steps: (1) selective penetration of the neutral Pd(OH)2 through the ionic barrier (Ca(2+)-alginate shell) and then (2) chelation reaction of the neutral Pd(OH)2 with the SO3(-) groups of PSSA in the core. The maximum Pd(II) uptake was 291.19±17.48mg/g, which was about 32 times higher than that of Pt(IV). The results of the sorption/desorption test indicated that the PSSA-AC has good reusability potential. Even through one cycle of sorption/desorption, Pd(II) and Pt(IV) were successfully separated from their mixture with significantly high purities of 98.65% Pd(II) and 98.71% Pt(IV). This study reports for the first time the feasibility and potential of ionic barrier-based sorbents as selective separation of precious metals which have different speciations.