Adsorption behavior of ¹³⁷ Cs towards silica modified with polyacrylamide

Abstract Polyacrylamide/silicon dioxide (PAm/SiO 2 ) composite was synthesized via free radical polymerization of acrylamide using potassium persulfate as the initiator. The composite was characterized by Flash EA Analyzer (Elemental analysis, C, H, and N concentrations), X-ray fluorescence (XRF), X-ray diffraction (XRD), thermogravimetric analysis (TGA), attenuated total reflectance infrared spectroscopy (ATR/FT-IR), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) surface area. Adsorption studies were conducted to examine the influence of contact time, solution pH, initial concentration, and adsorbent dose on Cs + adsorption. PAm/SiO 2 composite showed good thermal stability with 78.99 % recovery of adsorbing capacity after drying at 200 °C. Thermodynamic analysis confirmed that Cs + adsorption on the composite is spontaneous and endothermic. Freundlich isotherm model, pseudo-second-order kinetic model, and intraparticle diffusion model successfully explained the adsorption data. Desorption studies have revealed that CaCl 2 is the optimum eluent for full recovery of Cs + (about 90 %). According to column data, Cs + can be loaded and separated from the aqueous environment using different concentrations of CaCl 2 eluent. Practical application experiments also showed the high efficiency of PAm/SiO 2 composite for 137 Cs removal from simulated radioactive liquid solution and contaminated milk, with removal efficiencies of 94.26 % and 90 %, and decontamination factors of 17.43 and 10.25, respectively. These findings validate the promise of the PAm/SiO 2 composite as a highly efficient and economical adsorbent for the remediation of radiocesium in both environmental and food matrices.