西瓜皮生物炭对水中多种药物分子的吸附性能与机制

Adsorption properties and mechanism of watermelon peels biochar for various drug molecules in water

  • 摘要: 抗生素在环境中的广泛存在带来抗药性威胁,开发高效的抗生素去除技术已成为环境治理的关键挑战,采用来源广泛、价格低廉的生物质炭对抗生素进行吸附,是一种极具潜力的解决方案。西瓜皮含有丰富的氮、氧基团,由其制备的生物炭具备高效吸附抗生素等药物分子的能力。以西瓜皮为原料,通过热解制备西瓜皮生物炭(WBC),并对其进行物化性能表征;研究pH对WBC吸附性能的影响,并在单独吸附(4种典型抗生素)和共存吸附(4种典型抗生素、2种抗精神病药物)体系下,系统研究WBC对多种药物分子的吸附性能与机制。结果表明:pH对WBC吸附抗生素的性能具有显著影响。在单独吸附体系中,WBC对依诺沙星(ENO)的吸附量最高,理论最大吸附量达64.73 mg/g;在共吸附体系中,WBC对不同药物的吸附能力表现出明显差异,这一现象主要归因于药物分子物化性质不同,影响了生物炭与其发生的吸附行为。氯氮平(CLZ)在共吸附体系中表现出竞争吸附优势,吸附模式结合了单层和多层吸附,甲氧苄啶(TMP)的吸附模式与单独吸附体系相异,这是由于CLZ通过疏水作用被WBC吸附,在共吸附过程中有明显吸附优势,而TMP的吸附位点被抢占,在共吸附体系中其吸附模式由单一吸附体系的多层吸附变为单层吸附。另外,WBC在共吸附体系中对药物的吸附容量普遍低于单独吸附体系,这是由于药物竞争WBC上活性位点所致。研究结果进一步表明,氢键相互作用、π—π相互作用是主要吸附驱动力,同时受到静电相互作用、疏水作用的综合影响。本研究揭示了WBC的各种吸附机制在多种药物共吸附过程中表现出的强弱关系,为复杂抗生素污染治理及生物炭材料定向改性研究提供参考。

     

    Abstract: The widespread presence of antibiotics in the environment poses a critical threat of antimicrobial resistance, making the development of efficient antibiotic removal technologies a key challenge in environmental remediation. Utilizing widely available and low-cost biochar for antibiotic adsorption represents a promising solution. Watermelon peel, rich in nitrogen- and oxygen-containing functional groups, serves as an ideal precursor for synthesizing biochar with superior adsorption capacity for pharmaceutical molecules. The watermelon peel-derived biochar (WBC) was synthesized via pyrolysis, followed by comprehensive physicochemical characterization. The effect of pH on the adsorption performance of WBC was investigated, and the adsorption behaviors of WBC toward multiple pharmaceuticals were systematically evaluated in both single- and co-adsorption systems. The single-adsorption system included four typical antibiotics, while the co-adsorption system incorporated four typical antibiotics and two antipsychotic drugs. The results demonstrated that pH significantly influenced WBC's adsorption efficiency of antibiotics. In single-adsorption systems, WBC exhibited the highest adsorption capacity for enoxacin (ENO), with a theoretical maximum of 64.73 mg/g. In co-adsorption systems, WBC exhibited significant differences in adsorption capacity for different drugs, which was mainly attributed to the different physicochemical properties of drug molecules, affecting the adsorption behavior of biochar and its occurrence. Clozapine (CLZ) displayed competitive adsorption dominance in co-adsorption systems, exhibiting a combined monolayer-multilayer adsorption pattern. The trimethoprim (TMP) adsorption mode was different from that of single-adsorption systems, due to CLZ being adsorbed by WBC through hydrophobic interactions and had a significant adsorption advantage in the co-adsorption process. The adsorption sites of TMP were occupied, and TMP adsorption mode shifted from multilayer adsorption in single systems to monolayer adsorption. Notably, reduced adsorption capacities in co-adsorption systems were linked to competitive occupation of WBC's active sites. The research results further revealed that hydrogen bonding and π—π interactions served as primary driving forces, supplemented by electrostatic and hydrophobic interactions. This study elucidated the strength relationship between various adsorption mechanisms on WBC in the co-adsorption process of multiple drugs, providing a reference for the treatment of complex antibiotic pollution and the targeted modification of biochar materials.

     

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