Search

Phosphoric acid is a key ingredient in fertilizer production and contains many rare earth elements (REEs). Recovering REEs from phosphoric acid can prevent the accumulation of these elements in the soil and help bridge the gap between supply and demand. In this concern, a new material called Si-6G PAMAM-PPAAM dendrimers modified silica gel terminated with phenylphosphonic acid-amide moieties was developed and its ability to adsorb Nd(III) and Er(III) from the phosphoric acid solution was investigated. Kinetics and isotherm of the uptake process were investigated to explore the sorption characteristics. The attained results show that both metal ions exhibit the same adsorption performance, and the uptake process is depicted as a chemisorption, monolayer, uniform, and homogeneous process. The equilibrium state is achieved within 120 min, and the maximum uptake capacity is 16.7 mg Nd(III)/g, and 14.0 mg Er(III)/g. Sorption thermodynamics is an endothermic, spontaneous, and feasible uptake process. Nitric acid (1.0 mol/L) is found to be efficient for adsorbing about 94.3% and 92.5% of neodymium(III) and erbium(III) respectively, and the prepared Si-6G PAMAM-PPAAM demonstrates excellent stability over five consecutive sorption/desorption cycles. Preliminary tests on commercial phosphoric acid demonstrate that Si-6G PAMAM-PPAAM retains its effective REEs uptake from a complex commercial phosphoric acid solution.