热镀锌厂酸洗废水和锌灰中回收硫化锌

从热镀锌厂的酸洗废水和锌灰中回收硫化锌,采用X射线能谱仪(EDS),X射线衍射仪(XRD),傅里叶红外光谱仪(FTIR)和场发射透射电镜(FETEM)表征样品ZnS性质,电感耦合等离子发射体(ICP-OES)分析上清液性质,并研究该反应动力学过程。EDS和ICP分析表明,样品ZnS纯度达到85.45%,其上清液含有高浓度铁,含量为2 g/L,可用于制备复合亚铁絮凝剂,而其他重金属离子浓度均低于电镀废水排放标准。XRD分析表明,样品ZnS是立方晶型,调节pH和采用滴加方式能有效改善样品ZnS的晶型。采用Scherrer公式计算晶体粒径,结果表明,晶粒大小在3~6 nm之间。FTIR分析表明,样品ZnS呈现良好的红外透明性,且温度、pH和滴加方式对样品的红外透光性基本没有影响。FETEM结合XRD图表明,该纳米晶呈片状,近似为球形,呈多层叠加,分散性不明显,有团聚现象。动力学实验表明,逆一级动力学方程适合描述硫化沉淀的反应动力学过程,活化能为39.04 kJ/mol,沉淀过程受化学反应和扩散联合控制。

Recovery of zinc sulfide from acidic wastewater and zinc ash of hot galvanizing plants

Recovery of zinc sulfide from acidic wastewater and zinc ash of zinc hot galvanizing plants was investigated in this study. Sample ZnS was characterizd by energy dispersive X-ray spectrometer (EDS),X-ray diffraction (XRD),fourier transform infrared spectroscopy (FTIR),and field emission transmission electron microscopy (FETEM),and the supernatant was analyzed by inductively coupled plasma optical emission spectroscopy (ICP-OES). Also,the dynamics process was performed. EDS and ICP showed that the purity of sample ZnS could reach 85.45% and the supernatant could be made of compound ferrous coagulant because of high concentration of iron with a value of 2 g/L,and low concentrations of the other heavy metals which met the emission standard of pollutants for electroplating. XRD patterns illustrated that a kind of cubic structure dominated its morphology. Adjusting pH and titration could enhance the crystal form of ZnS. The average size of the crystallites has been estimated using the Scherrer formula. It was found that the size of the particles was in a narrow range of 3~6 nm. The FTIR patterns of zinc sulfide precipitates indicated that the ZnS presented good infrared transparency. Moreover,the temperature,pH,and adding mode had insignificantly effects on the infrared transparency. The FETEM image and XRD patterns of ZnS demonstrated that the sample ZnS was flaky and nearly spherical,as well as multilayer stacking with a phenomenon of reunion and weak dispersing. It could be known by dynamics experiments that the sulfide precipitation using Na₂S corresponded with reverse first-order kinetics equation,the activation energy was 39.04 kJ/mol,and the sulfide precipitation was controlled both by the chemical and diffusion process.