# Highly Efficient Elimination of As(V) and As(III) from Aqueous Media Utilizing Fe-Ti-Mn/Chitosan Composite Xerogel Beads

## TL;DR

A new composite xerogel bead effectively removes both As(V) and As(III) from water, offering a promising solution for arsenic contamination.

## Contribution

The development of Fe-Ti-Mn/chitosan composite xerogel beads for simultaneous and efficient removal of As(V) and As(III) from water.

## Key findings

- The xerogel beads achieved maximum uptake capacities of 22.6 mg/g for As(III) and 16.2 mg/g for As(V).
- Adsorption kinetics reached equilibrium within 24 hours and followed a pseudo-second-order model.
- The material demonstrated excellent regeneration capacity and operational stability.

## Abstract

Inorganic arsenic species, As(V) and As(III), present significant toxicity and carcinogenic risks in water, making their effective removal critical for global water safety. This study introduces Fe-Ti-Mn/chitosan composite xerogel beads (FTMO/chitosan) designed to overcome the limitations of conventional single-component adsorbents, particularly for simultaneous removal of As(V) and As(III), and to address solid–liquid separation challenges common with powdered adsorbents. The xerogel beads feature a rough, porous surface composed of agglomerated nanoparticles. Batch tests demonstrated that the Freundlich model provided a better fit for the adsorption process, with max uptake capacities of 22.6 mg/g and 16.2 mg/g for As(III) and As(V) at 25 °C, respectively, outperforming most reported adsorbents. Adsorption kinetics were fast, reaching equilibrium within 24 h and fitting well with a pseudo-second-order kinetic model. The adsorption efficiency was strongly influenced by solution pH and the existence of minor coexisting anions. Mechanistically, As(V) removal occurred via inner-sphere surface complexation through the substitution of surface hydroxyl groups, whereas As(III) removal involved a coupled oxidation-adsorption process: MnO2 oxidized As(III) to As(V), which was then adsorbed onto the material surface. Furthermore, the adsorbent confirmed excellent regeneration capacity and operational stability, illuminating its promising potential for frequent utilization in water treatment and environmental remediation applications.