万东锦,陈项项,史亚慧,刘杨,刘永德.磁性水滑石双金属催化剂吸附-催化氢还原去除水中高氯酸盐的研究[J].环境科学学报,2021,41(9):3545-3554
磁性水滑石双金属催化剂吸附-催化氢还原去除水中高氯酸盐的研究
- Study on the adsorption and catalytic hydrogen reduction of ClO4- from aqueous solution by magnetic hydrotalcite based bimetallic catalyst
- 基金项目：国家自然科学基金项目（No.51878251）；河南省优秀青年自然科学基金项目（No.212300410034）；河南省青年自然科学基金项目（No.212300410132）
- 万东锦
- 河南工业大学环境工程学院, 郑州 450001
- 陈项项
- 河南工业大学环境工程学院, 郑州 450001
- 史亚慧
- 河南工业大学环境工程学院, 郑州 450001
- 刘杨
- 河南工业大学环境工程学院, 郑州 450001
- 刘永德
- 河南工业大学环境工程学院, 郑州 450001
- 摘要：采用化学共沉淀法制备磁性钯钴水滑石催化剂（M-Pd/Co@CHT），用于吸附催化还原去除水中的高氯酸盐.同时，研究了不同溶液pH值、催化剂投加量、温度、共存离子和氢气流量等因素的影响，考察了吸附动力学和等温吸附过程.最后对反应前后材料进行表征，以明确吸附催化氢还原反应机理.结果表明：在较宽的pH范围（5~10）内，M-Pd/Co@CHT显示出对高氯酸盐较高、较稳定的吸附效率；伪二阶动力学模型和Langmuir模型能很好地拟合催化剂对高氯酸盐的吸附规律，说明该吸附过程是近似单层的化学吸附，最大单层吸附容量为172.65 mg·g-1；温度、投加量和供氢气量对M-Pd/Co@CHT加氢催化还原高氯酸盐有显著的影响，当高氯酸盐初始浓度为10 mg·L-1时，在最优实验条件下30 min可以去除约54%的高氯酸盐；利用XRD、FTIR、BET、XPS及VSM等手段对M-Pd/Co@CHT进行表征，结果表明，介孔M-Pd/Co@CHT可以有效吸附或催化高氯酸盐；高氯酸盐首先被吸附至M-Pd/Co@CHT上从而恢复其层状结构，而后在Pd/Co二元金属催化剂的作用下被氢还原去除；利用外加磁场能够实现材料的固液分离，可以有效地避免二次污染.
- Abstract：The magnetic calcined Mg/Fe hydrotalcite-based Pd/Co catalyst (M-Pd/Co@CHT) was synthesized by the co-precipitation method, and was used to remove perchlorate in water through adsorption and catalytic hydrogen reduction. The effect of factors including initial pH, catalyst dosage, temperature, coexisting ions and H2 flow rate on perchlorate removal was investigated, and the adsorption kinetics and isotherm models were fitted. Meanwhile, the characterization of materials before and after reaction was carried out to elucidate the reaction mechanism of adsorption and catalytic hydrogen reduction. The results showed that in the wide pH range (5~10), M-Pd/Co@CHT exhibited a higher adsorption efficiency. Adsorption kinetics and isotherms data satisfactorily followed the pseudo-second-order kinetics model and the Langmuir model, indicating that the adsorption process is a single-layer chemical adsorption process, with maximum adsorption capacity of 176.9 mg·g-1. The temperature, catalyst dosage and H2 flow rate had the significant effect on catalytic reduction removal of perchlorate, and under the optimal experimental conditions, the remove efficiency of perchlorate with initial concentration of 10 mg·L-1 was 54% during 30 min. The results of XRD, FTIR, BET, XPS and VSM indicated that the mesoporous M-Pd/Co@CHT can effectively remove perchlorates by adsorption or catalysis. Specifically, perchlorate was first adsorbed to M-Pd/Co@CHT to restore its layered structure, and then reduced by atomic H at Pd/Co bimetals active sites. The solid-liquid separation of the material can be easily achieved by using an external magnetic field, avoiding secondary pollution effectively.
