Synthesis of a granular composite based on polyvinyl alcohol-Fe:Ce bimetallic oxide particles for the selective adsorption of As(V) from water

In this study, Fe:Ce bimetallic oxide particles (BOP) were immobilized in poly(vinyl) alcohol (PVA) hydrogel, aiming to engineer a granular material that preserves the adsorptive properties of BOP powder, allowing their use in conventional water treatment systems. Through a detailed evaluation of the synthesis conditions, we were able to produce a composite (PVA/BOP) with excellent physicochemical properties, while retaining up to 100% of the BOP arsenic adsorption capacity, even at ppb of As(V) concentrations. The composites were characterized by SEM, N-2 physisorption, FT-IR, potentiometric titration, and compression test. Also, adsorption experiments including isotherms, kinetics, pH effect and selectivity were performed. The inclusion of BOP in the PVA hydrogel improved the mechanical properties of the hydrogel, increasing the elastic limit from 60% for PVA to 90% for the composite, making it suitable for packed bed systems. The BOP particles showed a uniform dispersion in the composite as evidenced by SEM. The surface area of the composite reached 10 m2/g and has an acidic surface (pH(pzc) of 4.1). The FTIR analyses allowed us to demonstrate the interactions of BOP with PVA, and to propose the arsenic adsorption mechanism. The dry composite labeled as C7P60 showed excellent arsenic removal: adsorption capacity of 77.62 mg/g measured at 0.8 mg As/L and pH 7; adsorption kinetics of 1.69 mg As(V)/min.g reaching equilibrium in less than 30 min; and a high affinity for arsenic in presence of competing anions, including F-, Cl-, HCO3-, NO3-, SO42- and H2PO4-. The results reported herein suggest that this granular composite PVA/BOP can be an excellent candidate to address arsenic water contamination problems.

Automated summary

In this study, Fe:Ce bimetallic oxide particles (BOP) were immobilized in poly(vinyl) alcohol (PVA) hydrogel to create a composite material that retains the adsorptive properties of BOP powder. The composite showed excellent physicochemical properties and high arsenic adsorption capacity. It also exhibited uniform dispersion of BOP particles, large surface area, and suitability for packed bed systems.