Efficient removal of haloacetic acids on coconut shell activated carbon supported chitosan: Batch and column studies

Haloacetic acids (HAAs) constitute a critical concern in drinking water safety due to their high toxicity, persistence, and potential carcinogenicity. The activated carbon-chitosan (CS/CAC) was synthesized and used to eliminate HAAs from drinking water, including monobromoacetic acid (MBAA), bromochloroacetic acid (BCAA), dichloroacetic acid (DCAA), and dibromoacetic acid (DBAA). CS/CAC was described using FTIR, BET, SEM, and XRD techniques. The effects of adsorption time, CS/CAC dosage, pH, initial concentration, temperature, and coexisting anions of HAA adsorption on CS/CAC by batch adsorption mode were studied. Compared with coconut shell activated carbon (CAC), the removal efficiency of MBAA, DCAA, BCAA, and DBAA on CS/CAC was increased by 28 %, 37 %, 35 %, and 49 %, respectively. The adsorption of HAA by CS/CAC was consistent with the Langmuir isotherm (R 2 = 0.985–0.992) and pseudo-second-order kinetic models (R² = 0.991–0.998), indicating a monolayer adsorption mechanism involving both physisorption and chemisorption. Thermodynamic parameters confirmed the spontaneity and endothermic nature of the process. For column experiments, increasing the empty bed contact time (EBCT) enhanced HAA removal performance, achieving up to 94 %, 74 %, 78 %, and 94 % for MBAA, DCAA, BCAA, and DBAA, respectively (EBCT 15 min). The CS/CAC composite exhibited strong reusability after four adsorption/desorption cycles. These findings highlight CS/CAC as a promising adsorbent for HAA removal in water systems.