STUDIES ON THE USE OF MODIFIED SURFACE ACTIVATED CARBON IN TREATMENT OF RADIOACTIVE WASTE SOLUTIONS

Abstract

A biomass agricultural byproduct, coconut shells, is used for preparation of a high quality chemically modified surface activated carbon using a chemical activation process. The structural morphology and composition of the prepared modified surface activated carbons (MSAC) are evaluated by SEM, XRD, FTIR, XRF, and C, H, N, S elemental analysis. The chemical stability of the prepared sorbent has been tested using solubility experiments in water, HNO3 and HCl acids. The data show that MSAC has reasonably good chemical stability. The prepared MSAC has been investigated for its capability to adsorb some radionuclides from simulated radioactive waste solution including some metal ions, namely Europium, Cerium, Strontium, and Cesium. The influence of solution pH, contact time, adsorbent dosage, adsorption temperature and initial metal ion concentrations, has been studied on the efficiency of adsorption. The effect of presence of competing ions and complexing legands on the adsorption performance of Eu3+, Ce3+, Sr2+ and Cs+ ions onto the prepared MSAC is also examined using batch technique. The thermodynamic parameters, ΔHo, ΔSo and ΔGo are also evaluated using the Van,t Hoff linear plot. It is found that the sorption processes are spontaneous and endothermic in nature. Equilibrium adsorption isotherms and kinetic studies have been investigated. The experimental data are analyzed using the Langmuir, Freundlich and D–R models. The isotherm data fit better to the Freundlich isotherm. The kinetic data obtained are analyzed using a pseudo-first and pseudo-second-order equations and intra particle diffusion equation. The experimental data follow very well the pseudosecond- order kinetic model. It can be concluded that the developed sorbent is considered as a better replacement technology for removal of Eu3+, Ce3+, Sr2+ and Cs+ ions from radioactive waste solutions due to its low-cost and good viii