Iron( <scp>III</scp> )‐loaded cation exchange resin: A dual approach for aqueous H ₂ S removal and biogas desulphurization

Abstract The presence of hydrogen sulphide (H 2 S) in biogas poses significant environmental and operational challenges due to its corrosive and toxic properties. Thus, this study aimed to develop a dual‐function desulphurization system using a cation exchange resin (CIER) loaded with iron(III) ions (Fe 3+ ), to remove H 2 S from aqueous media and upgrade biogas. The Fe 3+ /CIER composite promotes the oxidation of sulphide ions (S 2− ) into elemental sulphur (S 0 ), while Fe 3+ is simultaneously reduced to Fe 2+ . Atmospheric oxygen subsequently reoxidizes Fe 2+ to Fe 3+ , enabling the material to be reused multiple times without the need for chemical additives. Batch experiments demonstrated high Fe 3+ adsorption (47.72 mg g −1 ), with sulphide removal remaining above 72% over five cycles. A central composite rotational design (CCRD) showed that contact time significantly influences removal efficiency, achieving up to 99.9% under optimized conditions. Fixed‐bed experiments confirmed the system's scalability, with 90% removal sustained for 420 min in the first cycle. Morphological and elemental analyses conducted via SEM/EDS verified the formation of S 0 and retention of Fe within the resin. Compared to biological and electrocatalytic methods, this approach offers faster kinetics and simpler regeneration. The overall reaction (H 2 S + ½ O 2 → H 2 O + S 0 ) proceeds under ambient conditions, minimizing energy demand and methane loss. This clean, regenerable system offers a sustainable alternative for decentralized biogas purification, particularly in agro‐industrial applications, contributing to renewable energy development and environmental protection.