School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031, People's Republic of China.
Faculty of Geosciences and Environmental Engineering, Southwest Jiaotong University, Chengdu 610031, People's Republic of China E-mail:
Water Sci Technol. 2022 Mar;85(6):1936-1951. doi: 10.2166/wst.2022.085.
In this study, readily available inexpensive water treatment sludge (WTS) was used to prepare adsorbent for the removal of Congo red (CR) and tetracycline (TC) from aqueous solutions. The structural characteristics and adsorption properties of WTS biochar were characterised via scanning electron microscope, energy dispersive X-ray spectroscopy, Brunauer-Emmett-Teller and Fourier Transform infrared spectroscopy. In batch experiments, the adsorption factors, kinetics, isothermal curves and thermodynamics of the adsorption properties were investigated. The optimum preparation condition of WTS biochar was 400 °C for 4 h under O-limited pyrolysis, which exhibited increased specific surface area and pore structures. The best adsorption was observed when the pH of the CR and TC solutions was 7 and 4, respectively. The adsorption process followed the pseudo-second-order model, indicating that the main control step was the chemical adsorption process. Isotherm data were best described by the Langmuir model, and the maximum adsorption capacities for CR and TC were 116.4 and 58.5 mg·g, respectively. Thermodynamic parameters revealed that the adsorption process was spontaneous and endothermic. According to the analysis, the adsorption mechanism of CR could be attributed to electrostatic attraction, π-π conjugation and hydrogen bonding, whereas that of TC was potentially associated with cation exchange, complex precipitation, π-π conjugation and hydrogen bonding.
在这项研究中，我们利用易得且廉价的水处理污泥（WTS）制备吸附剂，以去除水溶液中的刚果红（CR）和四环素（TC）。通过扫描电子显微镜、能量色散 X 射线光谱、BET 和傅里叶变换红外光谱对 WTS 生物炭的结构特征和吸附性能进行了表征。在批实验中，研究了吸附因素、动力学、等温曲线和吸附热力学。在 O 限制热解条件下，400°C 热解 4 小时是 WTS 生物炭的最佳制备条件，此时比表面积和孔结构增加。当 CR 和 TC 溶液的 pH 值分别为 7 和 4 时，吸附效果最佳。吸附过程符合准二级动力学模型，表明主要控制步骤是化学吸附过程。等温线数据最符合 Langmuir 模型，CR 和 TC 的最大吸附容量分别为 116.4 和 58.5 mg·g。热力学参数表明，吸附过程是自发的和吸热的。根据分析，CR 的吸附机制可能归因于静电吸引、π-π 共轭和氢键，而 TC 的吸附机制可能与阳离子交换、络合沉淀、π-π 共轭和氢键有关。
