Synthesis of amine-functionalized polystyrene resin-based globular adsorbents for efficient and selective removal of As and Sb species

The removal of highly toxic arsenic (As) and antimony (Sb) contaminants in water by adsorption presents a great challenge worldwide. Conventional adsorbents exhibit insufficient efficacy for removing pentavalent oxyanions, As(V) and Sb(V), which are predominant compared with the trivalent species, As(III) and Sb(III), in surface waters. Here, we synthesized a novel composite adsorbent, amine-functionalized polystyrene resin loaded with nano TiO 2 (AmPSd-Ti). The mm-scale spheres showed outstanding adsorption capacities for As(III), As(V), Sb(III), and Sb(V) at 73.85, 153.29, 86.80, and 123.71 mg/g, respectively. AmPSd-Ti exhibited selective adsorption for As and Sb in the presence of Cl - , NO 3 - , SO 4 2- , and F - . As and Sb were adsorbed by the nano-sized TiO 2 confined in the porous resin via forming inner-sphere complexes. The protonated amine groups enhanced the adsorption of As(V) and Sb(V) by electrostatic attraction and hydrogen bonding, which was confirmed by experimental results and molecular dynamics simulations. Fixed-bed column tests showed breakthrough curves with adsorption capacities of 1.38 mg/g (6600 BV) and 6.65 mg/g (1260 BV) upon treating real As-contaminated groundwater and Sb-contaminated industrial wastewater. Our study highlights a feasible strategy by incorporating inorganic metal oxides into organic polymers to achieve highly efficient removal of As and Sb in real-world scenarios.