Sun Min, Wang Xian-Zhang, Xiong Ren-Ying, Chen Xiangying, Zhai Lin-Feng, Wang Shaobin
School of Chemistry and Chemical Engineering, Hefei University of Technology, Hefei 230009, China.
School of Resources and Environmental Engineering, Hefei University of Technology, Hefei 230009, China.
Sci Total Environ. 2023 Nov 25;901:165971. doi: 10.1016/j.scitotenv.2023.165971. Epub 2023 Aug 1.
Utilization of sewage sludge for the fabrication of environmental functional materials is highly desirable to achieve pollution mitigation and resource recovery. In the present work, we introduced a novel MgAl-layered double oxide (LDO)@biochar composite adsorbent in-situ fabricated from Al-rich sewage sludge, and its excellent application in nanoplastics adsorption. Initially, fifteen model contaminants with varied conjugate structures, hydrogen bonding and ionic properties were selected for an investigation of adsorption behavior and adsorption selectivity on LDO@biochar. Structural variation of LDO@biochar suggested reconstruction of the layered double hydroxide (LDH) during the adsorption process due to the "memory effect". Under the synergy of LDH and biochar, the contaminants were adsorbed via multiple adsorbent-adsorbate interactions, including anion exchange, electrostatic interaction, hydrogen bonding and π-π conjugation. Then, a quantitative structure-activity relationship (QSAR) model was constructed by integrating the number of hydrogen bond acceptors, polarity surface area, number of aromatic rings, and Fukui index f(-) together to reflect the affinity of each contaminant to the adsorbent. Guided by the QSAR model, the negatively charged polystyrene nanoplastics with continuously conjugated aromatic rings were predicted to be effectively adsorbed on LDO@biochar. Experimental tests confirmed a great capacity of LDO@biochar towards the polystyrene nanoplastics, given the equilibrium adsorption capacity as high as 360 mg g at 30-50 °C. This work not only opened up a new avenue for sustainable utilization of sewage sludge towards high-performance environmental functional materials, but also demonstrated the potential of the QSAR analysis as a rapid and accurate approach for guiding the application of an adsorbent to new emerging containments.
利用污水污泥制备环境功能材料对于实现污染缓解和资源回收非常有必要。在本工作中，我们引入了一种由富铝污水污泥原位制备的新型MgAl层状双氢氧化物负载生物炭（LDO@biochar）复合吸附剂，以及其在纳米塑料吸附方面的优异应用。首先，选择了15种具有不同共轭结构、氢键和离子性质的模型污染物，以研究LDO@biochar对其的吸附行为和吸附选择性。LDO@biochar的结构变化表明，由于“记忆效应”，层状双氢氧化物（LDH）在吸附过程中发生了重构。在LDH和生物炭的协同作用下，污染物通过多种吸附剂-吸附质相互作用被吸附，包括阴离子交换、静电相互作用、氢键和π-π共轭。然后，通过整合氢键受体数量、极性表面积、芳香环数量和福井指数f(-)构建了定量构效关系（QSAR）模型，以反映每种污染物对吸附剂的亲和力。在QSAR模型的指导下，预测具有连续共轭芳香环的带负电荷的聚苯乙烯纳米塑料能被有效地吸附在LDO@biochar上。实验测试证实了LDO@biochar对聚苯乙烯纳米塑料具有很大的吸附容量，在30-50°C下平衡吸附容量高达360 mg g。这项工作不仅为污水污泥向高性能环境功能材料的可持续利用开辟了一条新途径，还证明了QSAR分析作为一种快速准确的方法来指导吸附剂对新出现污染物应用的潜力。
