Removal of cobalt, strontium and cesium from radioactive laundry wastewater by ammonium molybdophosphate–polyacrylonitrile (AMP–PAN)

Applicability of ammonium molybdophosphate–polyacrylonitrile (AMP–PAN) on the adsorptive removal of Co, Sr and Cs in the radioactive laundry wastewater generated from nuclear power plants was investigated. Single- and bi-solute competitive adsorptions of Co2+, Sr2+ and Cs+ onto AMP–PAN were investigated. The influencing factors such as co-existing metal ion and surfactants were investigated. Adsorption of Co2+, Sr2+ and Cs+ onto AMP–PAN occurs via both physical adsorption due to weak van der Waals forces and ion exchange of ammonium molybdophosphate. The results of adsorption model analyses showed that AMP–PAN has high selectivity for Cs+. The maximum adsorption capacities were 0.16, 0.18 and 0.61 mmol/g for Co2+, Sr2+ and Cs+, respectively. In bi-solute competitive adsorptions, adsorption of one metal ion was suppressed by the presence of competing metal ion. Alkali metal (Na+) inhibits adsorption of Cs+ and the presence of Ca2+ ion decreased the adsorption of Co2+ onto AMP–PAN. Adsorption behaviors of Co2+, Sr2+ and Cs+ onto AMP–PAN in the presence of surfactants were quiet different. The presence of cationic (OTMA and HDTMA) and anionic surfactants (SDBS and SOBS) decreased adsorption of Co2+, Sr2+ and Cs+ onto AMP–PAN, but that of non-ionic surfactants (Tween 80 and Triton X-100) did not.