镁改性硅藻土回收废水氮磷产物对水中Pb^(2+)和Zn^(2+)的去除

Removal of Pb(Ⅱ) and Zn(Ⅱ) from Wastewater via Magnesium-Modified Diatomite Product Recovering Nitrogen and Phosphorus

通过使用镁改性硅藻土回收废水中的氮磷营养素,优化制备了一种复合材料(D-MAP),并将其用于废水中重金属Pb^(2+)和Zn^(2+)的去除.研究探讨了材料投加量、反应时间、反应温度和溶液初始pH等因素对Pb^(2+)和Zn^(2+)在D-MAP上吸附的影响.D-MAP吸附去除Pb^(2+)和Zn^(2+)的最优条件为:D-MAP投加量分别为0.25 g·L^(-1)和0.30 g·L^(-1),Pb^(2+)和Zn^(2+)初始浓度分别为300 mg·L^(-1)和60 mg·L^(-1),溶液初始pH为5.0.在此条件下,其对Pb^(2+)和Zn^(2+)去除率分别可达78.67%和89.66%.动力学和热力学的结果表明,D-MAP对Pb^(2+)和Zn^(2+)的吸附更符合准二级动力学模型;其吸附等温线可用Langmuir模型描述,吸附是自发吸热的过程.Langmuir等温拟合结果指出,D-MAP对Pb^(2+)和Zn^(2+)的最大吸附容量分别为901.0 mg·g^(-1)和206.2 mg·g^(-1).使用SEM/EDS、XRD和FT-IR等手段对吸附Pb^(2+)和Zn^(2+)前后的吸附剂进行表征,结果表明,D-MAP是一种鸟粪石-硅藻土复合材料,可通过与Pb^(2+)和Zn^(2+)生成Pb_(10)(PO_(4))_(6)(OH)_(2)和Zn_(3)(PO_(4))_(2)·2H_(2) O去除废水中Pb^(2+)和Zn^(2+).D-MAP对Pb^(2+)和Zn^(2+)的去除效果随着pH的增加而增加,且最终产物形态随pH不同产生变化.

By using magnesium-modified diatomite to recover nitrogen and phosphorus nutrients from wastewater,a composite material(D-MAP)was applied to remove the heavy metal ions Pb^(2+)and Zn^(2+)in wastewater.The effects of material dosage,reaction time,reaction temperature,and initial pH of the solution on the adsorption of Pb^(2+)and Zn^(2+)on D-MAP were studied.The optimum conditions were as follows:the dosage of D-MAP was 0.25 g·L^(-1) and 0.30 g·L^(-1),the initial concentrations of Pb^(2+)and Zn^(2+)were 300 mg·L^(-1) and 60 mg·L^(-1),and the initial pH of the solution was 5.0.Under these conditions,the removal rates of Pb^(2+)and Zn^(2+)reached 78.67%and 89.66%.The results of kinetics and thermodynamics showed that the adsorption of Pb^(2+)and Zn^(2+)by D-MAP was more consistent with the quasi-second-order kinetic model,and the adsorption isotherm was described by the Langmuir model.The adsorption was a spontaneous endothermic process,and the maximum adsorption capacities for Pb^(2+)and Zn^(2+)were 901.0 mg·g^(-1) and 206.2 mg·g^(-1),respectively.The adsorbents before and after adsorption of Pb^(2+)and Zn^(2+)were characterized by SEM/EDS,XRD,and FT-IR.The results showed that D-MAP was a struvite-diatomite composite,which could be combined with Pb^(2+)and Zn^(2+)to form Pb_(10)(PO_(4))_(6)(OH)_(2) and Zn_(3)(PO_(4))2·2H_(2)O.The removal efficiency of Pb^(2+)and Zn^(2+)by D-MAP increased with the increase in pH,and the morphology of the final product changed with differing pH.