Qiu Yiqin, Xiao Xiao, Ye Ziwei, Guan Zhijie, Sun Shuiyu, Ren Jie, Yan Pingfan
School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou, 510006, People's Republic of China.
Key Laboratory of Mining and Metallurgy Industry Heavy Metals Pollution Control and Vocational Education of Environmental Protection of Guangdong Province, Guangzhou, 510006, People's Republic of China.
Environ Sci Pollut Res Int. 2017 Apr;24(10):9294-9304. doi: 10.1007/s11356-017-8563-y. Epub 2017 Feb 23.
This study investigated the deep removal of complex nickel from simulated wastewater using magnetic separation and magnetic seed recycling. Nano-magnetite (FeO) was used as the magnetic seed. The flocculant applied was N,N-bis-(dithiocarboxy) ethanediamine (EDTC), a highly efficient heavy metal chelating agent included in dithiocarbamate (DTC). Important investigated parameters included hydraulic retention time, magnetic seed dosage, and magnetic field strength. The study also explored the magnetic flocculation mechanism involved in the reaction. The result indicated that the residual Ni concentration was reduced to less than 0.1 mg/L from the initial concentration of 50 mg/L under optimal conditions. Magnetic seed recovery reached 76.42% after a 3-h stirring period; recycled magnetic seeds were analyzed using scanning electron microscope (SEM) and X-ray diffraction (XRD). The zeta potential results illustrated that magnetic seeds firmly combined with flocs when the pH ranged from 6.5 to 7.5 due to the electrostatic attraction. When the pH was less than 7, magnetic seeds and EDTC were also combined due to electrostatic attraction. Particle size did affect microfloc size; it decreased microfloc size and increased floc volume through magnetic seed loading. The effective binding sites between flocs and magnetic seeds increased when adding the magnetic seeds. This led the majority of magnetic flocs to be integrated with the magnetic seeds, which served as a nucleus to enhance the flocculation property and ultimately improve the nickel complex removal rate.
本研究利用磁分离和磁性种子循环回收技术，对模拟废水中的复杂镍进行深度去除。纳米磁铁矿（FeO）用作磁性种子。所使用的絮凝剂是N,N-双（二硫代羧基）乙二胺（EDTC），它是二硫代氨基甲酸盐（DTC）中的一种高效重金属螯合剂。重要的研究参数包括水力停留时间、磁性种子投加量和磁场强度。该研究还探讨了反应中涉及的磁絮凝机理。结果表明，在最佳条件下，残余镍浓度从初始浓度50 mg/L降至0.1 mg/L以下。经过3小时搅拌期后，磁性种子回收率达到76.42%；使用扫描电子显微镜（SEM）和X射线衍射（XRD）对回收的磁性种子进行了分析。ζ电位结果表明，由于静电吸引，当pH值在6.5至7.5范围内时，磁性种子与絮凝物牢固结合。当pH值小于7时，磁性种子和EDTC也因静电吸引而结合。粒径确实会影响微絮凝体的大小；它通过磁性种子负载降低了微絮凝体的大小并增加了絮凝体体积。添加磁性种子时，絮凝物与磁性种子之间的有效结合位点增加。这使得大多数磁性絮凝物与磁性种子结合在一起，磁性种子作为核心增强了絮凝性能，最终提高了镍络合物的去除率。
