title: Remediation of cadmium- and lead-contaminated agricultural soil by composite washing with chlorides and citric acid.
abstract: Composite washing of cadmium (Cd)- and lead (Pb)-contaminated agricultural soil from Hunan province in China using mixtures of chlorides (FeCl3, CaCl2) and citric acid (CA) was investigated. The concentrations of composite washing agents for metal removal were optimized. Sequential extraction was conducted to study the changes in metal fractions after soil washing. The removal of two metals at optimum concentration was reached. Using FeCl3 mixed with CA, 44% of Cd and 23% of Pb were removed, and 49 and 32% by CaCl2 mixed with CA, respectively. The mechanism of composite washing was postulated. A mixture of chlorides and CA enhanced metal extraction from soil through the formation of metal-chloride and metal-citrate complexes. CA in extract solutions promoted the formation of metal-chloride complexes and reduced the solution pH. Composite washing reduced Cd and Pb in Fe-Mn oxide forms significantly. Chlorides and CA exerted a synergistic effect on metal extraction during composite washing.
authors.affiliation: College of Sciences, Nanjing Agricultural University, Nanjing, 210095, China, 2012111009@njau.edu.cn.
authors.forename: Yu-jiao
authors.initials: YJ
authors.lastname: Li
authors.forename: Peng-jie
authors.initials: PJ
authors.lastname: Hu
authors.forename: Jie
authors.initials: J
authors.lastname: Zhao
authors.forename: Chang-xun
authors.initials: CX
authors.lastname: Dong
mesh_terms: D000383:Agriculture; D002104:Cadmium / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification*; D002681:China; D002712:Chlorides / Q000737:chemistry*; D019343:Citric Acid / Q000737:chemistry*; D052918:Environmental Restoration and Remediation / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D007854:Lead / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification*; D012989:Soil Pollutants / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification*; D013054:Spectrophotometry, Atomic
chemical_list: D002712:Chlorides; D012989:Soil Pollutants; D002104:Cadmium; D019343:Citric Acid; D007854:Lead