Enhanced removal of As(III) and As(V) from water by a novel zirconium-chitosan modified spherical sodium alginate composite

Most nano-scaled adsorbents have trouble in separating from aqueous solution, thus, a need for new materials of facile separation and predominant adsorption performance has arisen. This present study focused on a novel segregative zirconium-chitosan modified sodium alginate (Zr-CTS/SA) composite preparation and its performance for As(III/V) removal from aqueous solution. The obtained composite presented a spherical structure with a diameter of 2.0-3.0 mm and favorable thermal stability. Experimental data showed that Zr-CTS/SA had considerable adsorbability for As(III) and As(V), the adsorption capacities were enhanced about at least 20 and 6 times separately compared with pristine SA beads. The adsorption processes of As(III) and As(V) could both be described with Langmuir isotherm model and the maximum adsorption capacities reached 43.19 and 76.78 mg g(-1), respectively. The kinetic data of As(III) followed the intra-particle diffusion model while As (V) fitted the pseudo-first-order model. Moreover, the adsorption mechanisms of As(III/V) involved ligand exchange with Cl on the surface of Zr-CTS/SA, another reaction pathway for As(V) was the electrostatic attraction with protonated -OH and -NH2 groups. Note that the employment of Zr-CTS/SA in low-concentration arsenic solution exhibited a residue concentration as low as the 10 mu g L-1 WHO guideline for drinking water. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study successfully prepared Zr-CTS/SA composite material with excellent adsorption performance for As(III/V), achieving high adsorption capacities. The composite material can meet the safety standards for drinking water in low-concentration arsenic solutions.