Wang Yanliang, Guo Xiangguang, Bai Yan, Sun Xiaoqi
CAS Key Laboratory of Design and Assembly of Functional Nanostructures, Fujian Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences Fuzhou Fujian 350002 P. R. China
State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences Changchun 130022 China.
RSC Adv. 2019 Oct 22;9(58):33922-33930. doi: 10.1039/c9ra05615g. eCollection 2019 Oct 18.
The wastewater discharged from the rare earth (RE) industry generally contains a high level of calcium and magnesium sulfates, which confers permanent hardness and causes difficulties in recycling this wastewater. In this study, the alkyl phenoxy acetic acid derivatives including 4-methyl phenoxy acetic acid (M-POAA), 4--butyl phenoxy acetic acid (B-POAA) and 4--octyl phenoxy acetic acid (O-POAA), were synthesized the Williamson reaction and characterized by nuclear magnetic resonance (NMR), infrared (IR), and ultra-violet (UV) spectroscopy, as well as elemental analysis and X-ray diffraction (XRD). Synthesis of the POAAs were simple and green, and the raw materials used for their production are widely available and low-cost. The potential for removal of Ca and Mg sulfates from industrial wastewater using POAAs as the organic precipitants was assessed. The total precipitation efficiencies of Ca and Mg from wastewater with the use of POAAs increased with the following order: M-POAA < B-POAA < O-POAA. The residual concentrations of Ca and Mg using O-POAA as the precipitant were lower than 0.099 and 0.089 g L, respectively. The O-POAA could be regenerated five times without any significant change in its structure and precipitation performance. Thus, the use of the novel precipitants is a prospective alternative to the conventional processes for softening wastewater.
稀土行业排放的废水通常含有高浓度的硫酸钙和硫酸镁，这赋予了其永久硬度，并给该废水的循环利用带来困难。在本研究中，通过威廉姆森反应合成了包括4-甲基苯氧基乙酸（M-POAA）、4-丁基苯氧基乙酸（B-POAA）和4-辛基苯氧基乙酸（O-POAA）在内的烷基苯氧基乙酸衍生物，并通过核磁共振（NMR）、红外（IR）、紫外（UV）光谱以及元素分析和X射线衍射（XRD）对其进行了表征。POAAs的合成简单且环保，生产它们所用的原材料广泛可得且成本低廉。评估了使用POAAs作为有机沉淀剂从工业废水中去除硫酸钙和硫酸镁的潜力。使用POAAs时，废水中钙和镁的总沉淀效率按以下顺序增加：M-POAA < B-POAA < O-POAA。以O-POAA作为沉淀剂时，钙和镁的残留浓度分别低于0.099和0.089 g/L。O-POAA可以再生五次，其结构和沉淀性能没有任何显著变化。因此，使用新型沉淀剂是软化废水传统工艺的一种有前景的替代方法。
