title: Phosphate removal from aqueous solutions using raw and activated red mud and fly ash.
abstract: The effect of acidification and heat treatment of raw red mud (RM) and fly ash (FA) on the sorption of phosphate was studied in parallel experiments. The result shows that a higher efficiency of phosphate removal was acquired by the activated samples than by the raw ones. The sample prepared by using the RM stirred with 0.25 M HCl for 2h (RM0.25), as well as another sample prepared by heating the RM at 700 degrees C for 2h (RM700), registered the maximum removal of phosphate (99% removal of phosphate). This occurred when they were used in the phosphate sorption studies conducted at pH 7.0 and 25 degrees C with the initial PO(4)(3-) concentration of 155 mg P/l. The FA samples treated in the same way described above can achieve 7.0 and 8.2 mg P/l phosphate removal for FA0.25 and FA700 respectively, corresponding to 45.2% and 52.9% removal. The activated materials performed higher phosphate removal over broader pH range compared with the raw ones. The influences of various factors, such as initial pH and initial phosphate concentration on the sorption capacity were also studied in batch equilibration technique. Solution pH significantly influenced the sorption. Each sample achieved the maximal removal of phosphate at pH 7.0. The amount of phosphate removal increased with the solute concentration. The Freundlich and Langmuir models were used to simulate the sorption equilibrium. The results indicate that the Langmuir model has a better correlation with the experimental data than the Freundlich model.
authors.affiliation: State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085, PR China. liyanzhongbj@yahoo.com.cn
authors.forename: Yanzhong
authors.initials: Y
authors.lastname: Li
authors.forename: Changjun
authors.initials: C
authors.lastname: Liu
authors.forename: Zhaokun
authors.initials: Z
authors.lastname: Luan
authors.forename: Xianjia
authors.initials: X
authors.lastname: Peng
authors.forename: Chunlei
authors.initials: C
authors.lastname: Zhu
authors.forename: Zhaoyang
authors.initials: Z
authors.lastname: Chen
authors.forename: Zhongguo
authors.initials: Z
authors.lastname: Zhang
authors.forename: Jinghua
authors.initials: J
authors.lastname: Fan
authors.forename: Zhiping
authors.initials: Z
authors.lastname: Jia
mesh_terms: D000327:Adsorption; D002244:Carbon / Q000737:chemistry*; D060729:Coal Ash; D004305:Dose-Response Relationship, Drug; D006863:Hydrogen-Ion Concentration; D017745:Incineration; D007220:Industrial Waste; D019216:Metals, Heavy; D008855:Microscopy, Electron, Scanning; D052638:Particulate Matter / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry*; D012037:Refuse Disposal; D013696:Temperature; D013997:Time Factors; D014867:Water; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000295:instrumentation* / Q000379:methods*
chemical_list: D060729:Coal Ash; D007220:Industrial Waste; D019216:Metals, Heavy; D052638:Particulate Matter; D010710:Phosphates; D014874:Water Pollutants, Chemical; D014867:Water; D002244:Carbon