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摘要
Straw fiber was selected as the research object, and then multigroup fiber materials (NCS) were prepared by endowing quaternary amine groups (-N+) and carboxyl groups (-COOH) onto fiber structures through etherification and grafting modification methods. In the single and binary adsorption systems, the removal effects of NCS on copper/sulfamethoxazole (SMZ-Cu) combined pollutants in water at different pHs were investigated. The fitting results of Langmuir adsorption isotherms showed that the maximum theoretical adsorption capacities of NCS to SMZ and Cu (Ⅱ) were 59.76 mg·g?1 and 4.71 mg·g?1, respectively, and the maximum theoretical adsorption capacities of SMZ and Cu (Ⅱ) in the complex were 56.21 mg·g?1 and 5.54 mg·g?1, respectively. The adsorption process also conformed to the pseudo-second-order kinetic equation, and belonged to chemical adsorption. In contrast, NCS was more likely to adsorb SMZ than Cu(Ⅱ) in the single system. Moreover, the multiple interactions caused NCS to mainly adsorb SMZ-Cu in the binary system rather than a single pollutant. Density functional theory (DFT) calculations not only verified the above analysis, but also quantitatively explained the following results in the single adsorption system: In the -N+ structure of NCS, -COOH had the most stable binding energy with sulfonamide nitrogen in SMZ, while C-N had the largest binding energy with Cu. In the binary adsorption system, the most dominant adsorption mechanism was that SMZ-Cu approached NCS in the form of Cu, and the complexation–decomplexation–complexation mode was the reason for increasing Cu adsorption. ? 2023 Science Press.
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