期刊
JOURNAL OF HAZARDOUS MATERIALS
卷 371, 期 -, 页码 191-197出版社
ELSEVIER
DOI: 10.1016/j.jhazmat.2019.02.079
关键词
Co-pyrolysis biochar; Orthophosphate; Lead removal; Phosphorus speciation; Wastewater
资金
- National Science and Technology Support Program [2015BAD05B02]
- National Key R&D Program of China [2016YFD0800805]
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(H2PO4)(2)H2O / KH2PO4) 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(-1), 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 Pbs(PO4)(3)Cl, Pb2P2O7, and Pb-n/2(PO3)(n), 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.
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