Selective Arsenic Removal Using Epoxy Cross-Linked Guar Gum: Synthesis, Characterization, and Adsorption Mechanism

Arsenic contamination in water poses a significant global challenge, necessitating cost-effective and sustainable remediation solutions. This study evaluates the efficacy of epoxy cross-linked guar gum (CLGG) as a biosorbent for arsenic removal. CLGG was synthesized and characterized using Fourier Transform Infrared Spectroscopy and Thermogravimetric Analysis to confirm structural modifications and thermal stability. Its adsorption behavior was systematically examined under varying conditions, including contact time, pH, and initial arsenic concentration. Iodometric titration was employed to quantify arsenic removal, while the adsorption mechanism was compared with conventional treatment methods. CLGG exhibited a cation exchange capacity of 2.5 meq/g, determined using the Helfferich method. Thermal analysis indicated stability up to 260°C, and its non-electrolytic nature was attributed to the presence of chelating cis-hydroxyl groups, which serve as active binding sites for arsenic (As) and antimony (Sb). The adsorption process involved proton release, as evidenced by a pH drop from 10 to 5 following treatment. CLGG demonstrated a high arsenic uptake capacity of 29.445 mg/g and a binding capacity of 2.58 meq/g. Additionally, its hydrophilic hydroxyl groups facilitated flocculation, enabling efficient separation and removal of arsenic-laden particles. The recyclable and bio-organic nature of CLGG makes it a promising, environmentally friendly alternative for water purification and pollution control.