Efficient adsorption of benzoic acid derivatives by polyethylenimine-coated chitin: Performance evaluation, mechanistic insights, and predictive modeling

초록

This study evaluates the adsorption performance of polyethylenimine-coated chitin (PEI-chitin) for benzoic acid derivatives (BCDs) under both artificial conditions-where a single pollutant is dissolved in pure water-and real municipal wastewater conditions. Under artificial conditions, PEI-chitin showed markedly higher adsorption capacities than granular activated carbon (GAC). Among the BCDs, 4-nitrobenzoate exhibited the highest capacity (931.75 mg/g) and 3,4-dichlorobenzoate showed the highest Freundlich distribution coefficient. In contrast, adsorption efficiency decreased sharply in actual municipal wastewater due to competitive effects from coexisting ions and organic matter. For several BCDs, removal rates fell to below 25% of those measured in artificial conditions. It may be due to competing ions and organic matter in real wastewater occupying or blocking the amine functional groups. Salt effect studies confirmed that increased ionic strength, particularly from multivalent anions like SO42- , inhibited adsorption. A predictive model based on linear free energy relationships incorporating activity coefficients of BCD ions achieved strong predictability (R2 = 0.93). These results highlight the potential of PEI-chitin in low-salinity systems and the need for further material optimization for actual municipal wastewater applications. Environmental implication: This study demonstrates the potential of PEI-coated chitin as an efficient adsorbent for removing anionic benzoic acid derivatives (BCDs) under natural pH conditions, where BCDs are widely used and frequently detected in aquatic environments. Adsorption performance of PEI-chitin surpasses that of granular activated carbon under low-ionic-strength conditions. However, reduced efficiency in real municipal wastewater highlights the need for structural optimization to retain selectivity in complex matrices. The integration of LFER modeling provides predictive insights into adsorption mechanisms, guiding the rational design of selective materials. Additionally, the study addresses the limitations of PEI polymers in real wastewater applications.

키워드