title: Effect of biochars on adsorption of Cu(II), Pb(II) and Cd(II) by three variable charge soils from southern China.
abstract: The purpose of this study is to compare the relative contribution of different mechanisms to the enhanced adsorption of Cu(II), Pb(II) and Cd(II) by variable charge soils due to incorporation of biochars derived from crop straws. The biochars were prepared from the straws of canola and peanut using an oxygen-limited pyrolysis method at 350 °C. The effect of biochars on adsorption and desorption of Cu(II), Pb(II) and Cd(II) by and from three variable charge soils from southern China was investigated with batch experiments. Based on the desorption of pre-adsorbed heavy metals, the electrostatic and non-electrostatic adsorptions were separated. EDTA was used to replace the heavy metals complexed with biochars and to evaluate the complexing ability of the biochars with the metals. The incorporation of biochars increased the adsorption of Cu(II), Pb(II) and Cd(II) by the soil; peanut straw char induced a greater increase in the adsorption of the three metals. The increased percentage of Cd(II) adsorption induced by biochars was much greater than that for the adsorption of Cu(II) and Pb(II). Cu(II) adsorption on three variable charge soils was enhanced by the two biochars mainly through a non-electrostatic mechanism, while both electrostatic and non-electrostatic mechanisms contributed to the enhanced adsorption of Pb(II) and Cd(II) due to the biochars. Peanut straw char had a greater specific adsorption capacity than canola straw char and thus induced more non-electrostatic adsorption of Cu(II), Pb(II) and Cd(II) by the soils than did the canola straw char. The complexing ability of the biochars with Cu(II) and Pb(II) was much stronger than that with Cd(II) and thus induced more specific adsorption of Cu(II) and Pb(II) by the soils than that of Cd(II). Biochars increased heavy metal adsorption by the variable charge soils through electrostatic and non-electrostatic mechanisms, and the relative contribution of the two mechanisms varied with metals and biochars.
authors: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, P.O. Box 821, Nanjing, China, rkxu@issas.ac.cn.
authors: Ren-kou
authors: RK
authors: Xu
authors: An-zhen
authors: AZ
authors: Zhao
mesh_terms: D000327:Adsorption; D002104:Cadmium / Q000032:analysis / Q000737:chemistry; D002606:Charcoal / Q000737:chemistry*; D002681:China; D003300:Copper / Q000032:analysis / Q000737:chemistry; D052918:Environmental Restoration and Remediation / Q000379:methods*; D007854:Lead / Q000032:analysis / Q000737:chemistry; D019216:Metals, Heavy / Q000032:analysis / Q000737:chemistry*; D010084:Oxidation-Reduction; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis / Q000737:chemistry*
chemical_list: D019216:Metals, Heavy; D012987:Soil; D012989:Soil Pollutants; C540010:biochar; D002104:Cadmium; D002606:Charcoal; D007854:Lead; D003300:Copper
references: Chemosphere. 2006 Jan;62(2):171-80
references: 16039695
references: J Hazard Mater. 2012 Aug 30;229-230:145-50
references: 22704774
references: J Hazard Mater. 2011 Jun 15;190(1-3):432-41
references: 21489689
references: Chemosphere. 2012 Sep;89(3):249-56
references: 22591849
references: Environ Sci Technol. 2009 May 1;43(9):3285-91
references: 19534148
references: Water Res. 2001 Jul;35(10):2385-94
references: 11394772
references: J Hazard Mater. 2009 Apr 30;163(2-3):563-7
references: 18692313
references: J Colloid Interface Sci. 2005 Apr 1;284(1):22-9
references: 15752780
references: Environ Pollut. 2006 Aug;142(3):530-9
references: 16321462
references: Environ Toxicol Chem. 2006 Sep;25(9):2366-73
references: 16986791
references: J Colloid Interface Sci. 2007 Jun 1;310(1):57-73
references: 17331527
references: J Environ Qual. 2012 Jul-Aug;41(4):1157-65
references: 22751058
references: J Environ Sci (China). 2013 Apr 1;25(4):652-8
references: 23923773
references: Chemosphere. 2010 Jan;78(4):389-96
references: 19962175
references: Chemosphere. 2011 Mar;82(10):1431-7
references: 21147495