Xiamen Engineering & Technology Research Center for Urban Water Environment Planning and Remediation, College of Civil Engineering, Huaqiao University, Xiamen, Fujian, 361021, PR China; Laboratory of Environmental Technology, INET, Tsinghua University, Beijing, 100084, China; Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment (IUE), Chinese Academy of Sciences, Xiamen, 361021, China.
Laboratory of Environmental Technology, INET, Tsinghua University, Beijing, 100084, China.
Chemosphere. 2021 May;271:129528. doi: 10.1016/j.chemosphere.2020.129528. Epub 2020 Dec 31.
Exploration of renewable materials for efficient elimination of arsenic from water is highly imperative. Herein, one kind of novel porous walnut-like LaOCO composite is reported for the first time, fabricated via direct pyrolysis of La-MOFs at 550 °C under the air atmosphere. The as-synthesized material predominantly consists of LaOCO, featuring micrometer-scale walnut-like morphology and an abundant mesoporous structure. Adsorption experiments demonstrated that a pseudo-second-order model with a high correlation coefficient (0.9976-0.9988) can depict this adsorption process in a good manner and indicates chemical adsorption. Analysis of the isotherms further revealed that this adsorption is a monolayer and homogeneous process, with an excellent adsorption capacity (210.1 As mg/g), as calculated from the Langmuir model. Thermodynamic parameters indicated this adsorption process to be a spontaneous and endothermic, with a positive change in entropy. By characterization results, it can be deduced that the anion-exchange interaction (i.e. carbonate is prone to being replaced by arsenate) and inner-sphere complexation were both responsible for arsenate removal. A broad working pH range (3.0-9.0) and a good cyclic performance (removal rate is above 90% for the fourth cycle) as well as an excellent adsorption capacity make this adsorbent a promising arsenic scavenger.
探索高效去除水中砷的可再生材料势在必行。本文首次报道了一种新型多孔核桃状 LaOCO 复合材料，通过在空气气氛中 550°C 下直接热解 La-MOFs 制备而成。所合成的材料主要由 LaOCO 组成，具有微米级核桃状形貌和丰富的介孔结构。吸附实验表明，准二级动力学模型（相关系数为 0.9976-0.9988）可以很好地描述该吸附过程，并表明这是一种化学吸附。对等温线的分析进一步表明，该吸附是单层和均相的过程，Langmuir 模型计算得到的吸附容量为 210.1 As mg/g。热力学参数表明，该吸附过程是自发和吸热的，熵呈正值变化。通过表征结果可以推断，阴离子交换作用（即碳酸盐易被砷酸盐取代）和内配位络合共同导致了砷酸盐的去除。较宽的工作 pH 范围（3.0-9.0）和良好的循环性能（第四次循环的去除率高于 90%）以及优异的吸附容量使这种吸附剂成为一种很有前途的除砷剂。
