Amberlite IRA-93 and modified Amberlite IRA-93 resins for the uranyl ions extraction: optimization through factorial design methodology

This work reports the uranyl (UO22+) extraction from water by the resins Amberlite IRA-93 (A-IRA-93) and the new modified Amberlite IRA-93 (mA-IRA-93), by liquid-solid extraction. A comparative study investigated the extraction procedure for the solid phase extraction of toxic uranyl ions by both the Amberlite IRA-93 (A-IRA-93) and the modified Amberlite IRA-93 (mA-IRA-93) resins in a batch process. The effect of solution pH, contact time, initial uranyl concentration, ionic strength and temperature were evaluated. The extraction process followed a pseudo-second-order kinetics models for both resins. The thermodynamics data led to an endothermic process for the sorption of uranyl ions by both resins. Thermodynamic study showed a negative ΔG values for A-IRA-93 and mA-IRA-93, which indicated that the sorption process of uranyl ions was spontaneous. The ratio ΔGmA-IRA-93/ΔGA-IRA-93 = 10.58 shows that the extraction by the mA-IRA-93 was more spontaneous than the extraction by the A-IRA-93. The outcomes have shown that the optimal experimental conditions without addition of sodium acetate for the present study recommend the use of 0.03 g of A-IRA-93 and 0.02 g of mA-IRA-93 resins for initial uranyl concentration 10–4 mol L–1. Fractional experimental design 3(3–1) may provide a valuable basis for industrial scale applications and was adequate in this study. The best extraction yield for mA-IRA-93 resin was 100% at 3.5 pHi and an equilibration time of 30 min at 250 rpm, provided by experiment: w(mA-IRA-93) = 0.01 g, [UO22+] = 10–5 mol L–1 and [CH3COONa] = 0.2 mol L–1. Modified Amberlite IRA-93 showed better affinity towards UO22+ (a maximal capacity of 8.34 mg g–1) under optimum conditions. Modification of the resin Amberlite IRA-93 increases the retention capacity by a factor of 2.21. The two proposed adsorbents are cost-effective and environmentally friendly and potential candidates for treatment of water containing UO22+. The functionalized adsorbent (mA-IRA-93) has research value and application potential in real waste water treatment.