Key Laboratory of Subtropical Agricultural Resource and Environment, Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China.
Key Laboratory of Subtropical Agricultural Resource and Environment, Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China.
J Hazard Mater. 2019 Jun 5;371:191-197. doi: 10.1016/j.jhazmat.2019.02.079. Epub 2019 Feb 22.
When used separately, biochar and orthophosphate are good materials to remove Pb from water, but few studies have been done on Pb removal by biochar-orthophosphate composite. Here biochar-orthophosphate composites were prepared by co-pyrolyzing rape straw with orthophosphate (Ca(HPO)·HO / KHPO) at ratio of 5:1 (W:W), noted as WBC-Ca and WBC-K, respectively, so as to explore the Pb removal capacities and mechanisms of co-pyrolysis biochars. The sorption isotherms of Pb were well fitted with Langmuir model and the maximum sorption capacities of Pb by original biochar, WBC-Ca, and WBC-K were 184.1, 566.3 and 1559 mmol kg, respectively. The results of FTIR, XRD, and XPS analyses showed that phosphorus in biochar played an important role to remove Pb by forming lead-precipitates. However, the species of lead-precipitates in three types of Pb-loaded biochars were Pb(PO)Cl, PbPO, and Pb(PO), individually, and that was because speciation of phosphorus had undergone significant thermochemical transformation during pyrolysis process. Orthophosphate in WBC-Ca was mainly transformed to pyrophosphate, while orthophosphate in WBC-K was transformed to both metaphosphate and pyrophosphate. The present results warrant the promising application of co-pyrolysis biochar derived from rape straw and orthophosphate in removal of Pb from wastewater.
当生物炭和正磷酸盐单独使用时，它们都是去除水中 Pb 的良好材料，但很少有研究关注生物炭-正磷酸盐复合材料去除 Pb 的情况。本研究通过在 5:1（W:W）的比例下共热解油菜秸秆与正磷酸盐（Ca(HPO)·H O / KH PO ），分别制得生物炭-正磷酸盐复合材料 WBC-Ca 和 WBC-K，以探讨共热解生物炭对 Pb 的去除能力和去除机制。Pb 的吸附等温线很好地符合朗缪尔模型，原生物炭、WBC-Ca 和 WBC-K 对 Pb 的最大吸附容量分别为 184.1、566.3 和 1559mmol kg。FTIR、XRD 和 XPS 分析结果表明，生物炭中的磷通过形成铅沉淀物对去除 Pb 起着重要作用。然而，在三种负载 Pb 的生物炭中，铅沉淀物的形态分别为 Pb(PO)Cl、PbPO 和 Pb(PO)，这是因为磷的形态在热解过程中发生了显著的热化学转化。WBC-Ca 中的正磷酸盐主要转化为焦磷酸盐，而 WBC-K 中的正磷酸盐则转化为偏磷酸盐和焦磷酸盐。本研究结果表明，油菜秸秆和正磷酸盐共热解生物炭在去除废水中的 Pb 方面具有广阔的应用前景。
