Fan Zheng, Fang Jie, Zhang Guoliang, Qin Lei, Fang Zhenzhen, Jin Laiyun
Membrane Separation and Water Treatment Center, Zhejiang University of Technology, State Key Lab Breeding Base of Green Chemical Synthesis Technology, Hangzhou 310014, China.
School of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310014, China.
ACS Omega. 2022 Aug 19;7(34):30543-30553. doi: 10.1021/acsomega.2c04033. eCollection 2022 Aug 30.
A potassium modified biochar (KBC) using residue as the raw material was prepared by adopting a two-step method of pyrolysis followed by high-temperature potassium hydroxide activation, and its properties were characterized. Activation using potassium hydroxide under high temperature induced the loss of CaCO and partial C on biochar, which created a high specific surface area (1336.31 m/g) together with a developed pore structure. pH displayed a slight influence on tetracycline adsorption, which signified the slight influence of the existence of tetracycline and the charge potential of biochar. Besides, pore filling, hydrogen bonding and π-π EDA stacking interactions possibly resulted in tetracycline adsorption on biochar. Tetracycline adsorption was fast in the original period, followed by a slower rate of adsorption until equilibrium was reached. Adsorption kinetics of tetracycline could be described using secondary and Elovich kinetic models. Adsorption isotherms for tetracycline were well fitted to the Langmuir isotherm model, and the maximum adsorption capacity of KBC was 830.78 mg/g at 318 K. According to a study of the thermodynamics, the adsorption of tetracycline on KBC was an endothermic reaction process. Corresponding results in the present study demonstrated that high-temperature potassium hydroxide activation enabled biochar to effectively eliminate tetracycline from water and wastewater.
以残渣为原料，采用热解后高温氢氧化钾活化的两步法制备了钾改性生物炭（KBC），并对其性能进行了表征。高温下用氢氧化钾活化导致生物炭上碳酸钙和部分碳的损失，形成了高比表面积（1336.31 m²/g）和发达的孔隙结构。pH值对四环素吸附的影响较小，这表明四环素的存在和生物炭的电荷电位影响较小。此外，孔隙填充、氢键和π-π电子给体-受体堆积相互作用可能导致四环素在生物炭上的吸附。四环素吸附在初始阶段较快，随后吸附速率变慢直至达到平衡。四环素的吸附动力学可用二级动力学模型和埃洛维奇动力学模型来描述。四环素的吸附等温线与朗缪尔等温线模型拟合良好，在318 K时KBC的最大吸附容量为830.78 mg/g。根据热力学研究，四环素在KBC上的吸附是一个吸热反应过程。本研究的相应结果表明，高温氢氧化钾活化使生物炭能够有效地从水和废水中去除四环素。
