title: Removal of heavy metal Cu(II) in simulated aquaculture wastewater by modified palygorskite.
abstract: Palygorskite (PAL) is a good heavy metal adsorbent due to its high surface area, low cost, and environmentally compatibility. But the natural PAL has limited its adsorption capacity and selectivity. In this study, a cost-effective and readily-generated absorbent, l-threonine-modified palygorskite (L-PAL), was used and its performance for Cu(II) removal in simulated aquaculture wastewater was evaluated. After preparation, L-PAL was characterized by using Fourier transform infrared spectroscopy, scanning electron microscope, energy dispersive X-ray spectroscopy, X-ray diffractometer, X-ray photoelectron spectroscopy, transmission electron microscopy and thermogravimetric analysis. The impacts of pH, adsorbent dosage, contact time, and initial Cu(II) concentration on the adsorption capacity of L-PAL were examined. The Cu(II) adsorption capacity on L-PAL was enhanced almost 10 times than that of raw PAL. The adsorption isotherms of Cu(II) fit the Langmuir isotherms, and the adsorption kinetics was dominated by the pseudo-second-order model. The thermodynamic parameters at four temperatures were calculated, which indicated that the adsorption was spontaneous and endothermic. The adsorption mechanism involves complexation, chelation, electrostatic attraction, and micro-precipitation. Furthermore, L-PAL is shown to have a high regeneration capacity. These results indicate that L-PAL is a cheap and promising absorbent for Cu(II) removal and hold potential to be used for aquaculture wastewater treatment.
authors.affiliation: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China; College of Environment, Hohai University, Nanjing 210098, China.
authors.forename: Jia-Shun
authors.initials: JS
authors.lastname: Cao
authors.affiliation: College of Environment, Hohai University, Nanjing 210098, China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Wang
authors.affiliation: Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, China; College of Environment, Hohai University, Nanjing 210098, China. Electronic address: ffang65@hhu.edu.cn.
authors.forename: Fang
authors.initials: F
authors.lastname: Fang
authors.affiliation: College of Environment, Hohai University, Nanjing 210098, China; Jiang Su Institute of Urban Planning and Design, Nanjing 210036, China.
authors.forename: Jun-Xiong
authors.initials: JX
authors.lastname: Lin
mesh_terms: D000327:Adsorption; D017756:Aquaculture; D002681:China; D052918:Environmental Restoration and Remediation / Q000379:methods; D017616:Magnesium Compounds / Q000737:chemistry*; D019216:Metals, Heavy / Q000737:chemistry*; D017655:Silicon Compounds / Q000737:chemistry*; D013912:Threonine / Q000737:chemistry*; D062065:Wastewater / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: D017616:Magnesium Compounds; D019216:Metals, Heavy; D017655:Silicon Compounds; D013912:Threonine; D062065:Wastewater; D014874:Water Pollutants, Chemical; C026325:attapulgite
keywords: Adsorption; Aquaculture wastewater; Heavy metal; Palygorskite (PAL); l-threonine modification