title: Capacity and mechanisms of ammonium and cadmium sorption on different wetland-plant derived biochars.
abstract: The objective of this study was to investigate the relationship between Cd(2+)/NH4(+) sorption and physicochemical properties of biochars produced from different wetland plants. Biochars from six species of wetland plants (i.e., Canna indica, Pennisetum purpureum Schum, Thalia dealbata, Zizania caduciflora, Phragmites australis and Vetiveria zizanioides) were obtained at 500°C and characterized, and their sorption for ammonium and cadmium was determined. There were significant differences in elemental composition, functional groups and specific surface area among the biochars derived from different wetland plant species. Sorption of ammonium and cadmium on the biochars could be described by a pseudo second order kinetic model, and the simple Langmuir model fits the isotherm data better than the Freundlich or Temkin model. The C. indica derived biochar had the largest sorption capacity for NH4(+) and Cd(2+), with a maximum sorption of 13.35 and 125.8mgg(-1), respectively. P. purpureum Schum derived biochar had a similar maximum sorption (119.3mgg(-1)) for Cd(2+). Ammonium sorption was mainly controlled by cation exchange, surface complexation with oxygen-containing functional groups and the formation of magnesium ammonium phosphate compounds, whereas for Cd(2+) sorption, the formation of cadmium phosphate precipitates, cation exchange and binding to oxygen-containing groups were the major possible mechanisms. In addition, the sorption of ammonium and cadmium was not affected by surface area and microporosity of the biochars.
authors.affiliation: Ministry of Education Key Laboratory of Environmental Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
authors.forename: Xiaoqiang
authors.initials: X
authors.lastname: Cui
authors.affiliation: Ningbo Raw Water Resource Research Academy, Ningbo, China.
authors.forename: Hulin
authors.initials: H
authors.lastname: Hao
authors.affiliation: Ministry of Education Key Laboratory of Environmental Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
authors.forename: Changkuan
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Indian River Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Fort Pierce, FL 34945, USA.
authors.forename: Zhenli
authors.initials: Z
authors.lastname: He
authors.affiliation: Ministry of Education Key Laboratory of Environmental Remediation and Ecological Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China. Electronic address: xyang571@yahoo.com.
authors.forename: Xiaoe
authors.initials: X
authors.lastname: Yang
mesh_terms: D000327:Adsorption; D064751:Ammonium Compounds / Q000737:chemistry*; D002104:Cadmium / Q000737:chemistry*; D002606:Charcoal / Q000737:chemistry*; D004785:Environmental Pollutants / Q000737:chemistry*; D052918:Environmental Restoration and Remediation / Q000379:methods*; D008956:Models, Chemical; D053833:Wetlands
chemical_list: D064751:Ammonium Compounds; D004785:Environmental Pollutants; C540010:biochar; D002104:Cadmium; D002606:Charcoal
keywords: Biochar; Contaminants; Mechanisms; Sorption characteristics; Wetland plants