富磷废弃钙基生物炭对水体中铅的去除

Lead Removal from Water by Calcium-containing Biochar with Saturated Phosphate

基于磷酸盐和碳酸盐对铅的高亲和特性,将蛋壳与厨余垃圾煅烧制备的含钙生物炭除磷后(ES-BC/P),用于水体中铅的去除.结果表明,ES-BC/P在较优的投加量下对不同浓度的铅(1~100 mg·L^(-1))均具有较好的去除性能,去除效率均高于99%,且反应后磷的释放量较低;ES-BC/P偏碱性,因含铅污染液呈弱酸性,ES-BC/P加入后无需调节体系的pH值即可达到较好的去除效果;反应动力学及等温线实验表明,ES-BC/P除铅主要为单层化学吸附,最大吸附容量为493.12 mg·g^(-1)(318 K);表征分析结果表明,铅主要通过与ES-BC/P中的Ca-P化合物和CaCO_(3)进行反应,Pb^(2+)可与Ca^(2+)发生交换作用,形成Pb_(5)(PO_(4))_(3)OH、Pb_(10)(PO_(4))_(6)(OH)_(2)、PbCO_(3)和Pb_(3)(CO_(3))_(2)(OH)_(2)等沉淀而被去除.综上所述,除磷后的ES-BC材料可实现水体中铅的高效去除,从而实现废弃物的资源化利用.

Calcium-containing biochar(ES-BC)was prepared by pyrolyzing eggshell and kitchen wastes,and the ES-BC composite was used to remove phosphate(marked as ESBC/P).Based on the high affinity of phosphate and carbonate to lead,the ES-BC/P was then used to remove lead from the water.The results showed that,in the appropriate dosage,ES-BC/P could remove lead efficiently at different initial concentrations(1-100 mg·L^(-1)),and the removal efficiency could reach to 99%.Meanwhile,the release of phosphorus could be ignored after the reaction.As ES-BC/P was alkaline,and the lead-containing solution was weakly acidic,the addition of ES-BC/P could adjust the pH of the system automatically.The reaction kinetics and isotherm experiments showed that the lead removal by ES-BC/P was mainly monolayer chemisorption with a maximum adsorption capacity of 493.12 mg·g^(-1)(318 K).The characterization results showed that lead was mainly removed through the ion exchanges of Pb^(2+)in the solution with Ca^(2+)in ES-BC/P.Then,the Pb^(2+)combined with CO_(3)^(2-)and PO_(4)^(2-)to form many precipitates,including Pb_(5)(PO_(4))_(3)OH,Pb_(10)(PO_(4))_(6)(OH)_(2),PbCO_(3),and Pb_(3)(CO_(3))_(2)(OH)_(2).In summary,the ES-BC/P material could achieve the efficient removal of lead from the water,thereby realizing the resource utilization of the wastes.