Carbonate treated coffee powder (CTCP) for selective sorption of Pu4+ over Am3+, Np4+, NpO22+, and PuO22+ from aqueous acidic solution: Investigation on mechanism, kinetics, thermodynamics, stripping and radiolytic stability

Abstract

An attempt was made for understanding the sorption behaviour of different actinide ions Pu⁴⁺, PuO₂²⁺, Am³⁺, Np⁴⁺, and NpO₂²⁺ on carbonate treated exhausted coffee powder (CTCP). Very efficient sorption of Pu⁴⁺ over other actinide ions from aqueous acidic medium was observed. Almost 4 h were required for achieving equilibrium. Experimental results for Pu⁺⁴ were fitted into different sorption isotherm model: Langmuir isotherm, Freundlich isotherm, D.R, isotherm and Temkin isotherm. Based on the linear regression, it was found that, Freundlich isotherm was predominantly operative. Pseudo 2nd order kinetics was found to be effective for the sorption of Pu⁺⁴. More than 80 % of loaded Pu⁴⁺ was found to desorb by 0.25 M oxalic acid solution. CTCP exhibited relatively good radiation stability. Sorption of Pu⁺⁴ on CTCP was exothermic, and spontaneous in nature. The sorption process was simple, cost effective and environmentally benign, as it did not involve any sophisticated, multi-step, sorbent synthesis.

Keywords: Biosorption; Isotherm; Kinetics modelling; Radiation stability; Spontaneous.