title: Application of acid-activated Bauxsol for wastewater treatment with high phosphate concentration: Characterization, adsorption optimization, and desorption behaviors.
abstract: Acid-activated Bauxsol was applied to treat wastewater with high phosphate concentration in a batch adsorption system in this paper. The effect of acid activation on the change of Bauxsol structure was systematically investigated. The mineralogical inhomogeneity and intensity of Bauxsol decreased after acid activation, and FeCl3·2H2O and Al(OH)3 became the dominant phases of acid-activated Bauxsol adsorption. Moreover, the BET surface area and total pore volume of Bauxsol increased after acid activation. Interaction of initial solution pH and adsorption temperature on phosphate adsorption onto acid-activated Bauxsol was investigated by using response surface methodology with central composite design. The maximum phosphate adsorption capacity of 192.94 mg g(-1) was achieved with an initial solution pH of 4.19 and an adsorption temperature of 52.18 °C, which increased by 7.61 times compared with that of Bauxsol (22.40 mg g(-1)), and was higher than other adsorbents. Furthermore, the desorption studies demonstrated that the acid-activated Bauxsol was successfully regenerated with 0.5 mol L(-1) HCl solution. The adsorption capacity and desorption efficiency of acid-activated Bauxsol maintained at 80.48% and 93.02% in the fifth adsorption-desorption cycle, respectively, suggesting that the acid-activated Bauxsol could be repeatedly used in wastewater treatment with high phosphate concentration.
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China; Department of Aquatic Environmental Engineering, Karlsruhe Institute of Technology, Karlsruhe D-76131, Germany. Electronic address: eyejie@126.com.
authors.forename: Jie
authors.initials: J
authors.lastname: Ye
authors.affiliation: The Institute for Applied Materials IAM-WK, Karlsruhe Institute of Technology, Karlsruhe D-76131, Germany. Electronic address: Xiangnacong@hotmail.com.
authors.forename: Xiangna
authors.initials: X
authors.lastname: Cong
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China. Electronic address: zhangpanyue@hnu.edu.cn.
authors.forename: Panyue
authors.initials: P
authors.lastname: Zhang
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China. Electronic address: zgming@hnu.edu.cn.
authors.forename: Guangming
authors.initials: G
authors.lastname: Zeng
authors.affiliation: Department of Aquatic Environmental Engineering, Karlsruhe Institute of Technology, Karlsruhe D-76131, Germany. Electronic address: erhard.hoffmann@kit.edu.
authors.forename: Erhard
authors.initials: E
authors.lastname: Hoffmann
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China. Electronic address: jungsten@163.com.
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China. Electronic address: wuyan19850827@hotmail.com.
authors.forename: Yan
authors.initials: Y
authors.lastname: Wu
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China. Electronic address: haibo_zhang@hnu.edu.cn.
authors.forename: Haibo
authors.initials: H
authors.lastname: Zhang
authors.affiliation: College of Environmental Science and Engineering, Hunan University, Changsha 410082, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082, PR China. Electronic address: fw8905@163.com.
authors.forename: Wei
authors.initials: W
authors.lastname: Fang
authors.affiliation: Department of Aquatic Environmental Engineering, Karlsruhe Institute of Technology, Karlsruhe D-76131, Germany. Electronic address: hermann.hahn@kit.edu.
authors.forename: Hermann H
authors.initials: HH
authors.lastname: Hahn
mesh_terms: D000327:Adsorption; D000536:Aluminum Hydroxide / Q000737:chemistry; D000537:Aluminum Oxide / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D010710:Phosphates / Q000737:chemistry; D012996:Solutions; D013696:Temperature; D014865:Waste Disposal, Fluid / Q000379:methods*; D014866:Waste Products; D062065:Wastewater / Q000737:chemistry
chemical_list: D000536:Aluminum Hydroxide; D000537:Aluminum Oxide; D010710:Phosphates; D012996:Solutions; D014866:Waste Products; D062065:Wastewater; C069471:aluminum oxide hydroxide
keywords: Activation; Central composite design; Desorption; Red mud; Structure change