Adsorptive flotation of cesium radionuclides from aqueous solutions using rice straw agriculture waste as a low-cost and eco-friendly adsorbent

Abstract

The removal of caesium radionuclides from an aqueous solution by flotation using rice straw (RS) agricultural waste as a low-cost and eco-friendly adsorbent in the presence of potassium ferrocyanide (KFC) was investigated. The influence of many adsorption parameters and flotation was evaluated on the removal efficiency of 137Cs. The adsorption results demonstrated that the concerned radionuclide was efficiently removed in the presence of 2 × 10−4 mol/L KFC using 10 g/L RS at pH ≥ 7. The double exponential kinetic model and the Freundlich model were the best models for fitting the adsorption kinetic and isotherm data, respectively. The maximum adsorption capacity of RS, calculated from the Langmuir model, was 280.405 mg/g. after being transferred to the flotation cell, 137Cs loaded onto ferrocyanide-modified rice straw (FMRS) was successfully floated at pH 7 using 3 × 10−4 mol/L cetyltrimethylammonium bromide (CTAB) surfactant in the presence of 4% ethanol. Removal percentages of 56% and > 99.5% were achieved for 137Cs-loaded FMRS within 5 min using sodium dodecyl sulphate (SDS) and CTAB, respectively. The results obtained in this investigation indicate the efficiency of the suggested strategy and hence its applicability for the removal of 137Cs+ from radioactive liquid wastes.