Experimental Design of Polymer Synthesis for the Removal of 2,4-Dichlorophenoxyacetic Acid and Glyphosate from Water by Adsorption

Water pollution from herbicide contamination poses a significant environmental challenge, necessitating effective regenerative materials for their removal. 2,4-dichlorophenoxyacetic acid and glyphosate are among the most widely used herbicides for weed control. This study aimed to synthesize polymeric materials for the removal of these compounds from aqueous media. The study evaluated adsorption capacity, isotherms, kinetics, regeneration capacity, and the influence of pH on adsorption, alongside disinfection tests. Biodegradable polymers including chitosan, sodium alginate, and guar gum were cross-linked and characterized using infrared and Raman spectroscopy. Two samples (experiment C and M) exhibited adsorption capacities of 49.75 ± 1.474 mg g−1 and 26.53 ± 1.326 mg g−1 for glyphosate and 2,4-dichlorophenoxyacetic acid, respectively. Optimal adsorption was observed at pH 3.00 and 6.00 for glyphosate and 3.00 for 2,4-dichlorophenoxyacetic acid. The Langmuir and Dubinin–Radushkevich isotherms best described the adsorption behavior of glyphosate and 2,4-dichlorophenoxyacetic acid, respectively. Kinetic studies indicated that the adsorption process followed a pseudo-second-order model. Infrared and Raman absorption spectra confirmed cross-linking in the polymer samples. Regeneration tests showed that 2,4-dichlorophenoxyacetic acid adsorption remained consistent over three reuse cycles, while glyphosate adsorption increased. Disinfection tests using Escherichia coli and total coliforms demonstrated a significant reduction in colony-forming units, supporting the suitability of the material for this application.