title: Near-anode focusing phenomenon caused by the coupling effect of early precipitation and backward electromigration in electrokinetic remediation of MSWI fly ashes.
abstract: As electrokinetic remediation (EKR) is used to remediate contaminated soil, the focusing phenomenon is always the inevitable problems needing to be solved during the process. In this paper, EKR was chosen to extract the heavy metals in the municipal solid waste incineration fly ashes (FAs). The focusing phenomenon of FA in the sample region of the rectangular electrolyser was comprehensively studied. The formation of the focusing band was monitored and the redistribution of concentration for Zn, Pb, Cu, and Cd were displayed. The major and minor phases of FA particles have greatly changed before and after the experiment. A variety of carbonate hydroxides and phosphate were found at the end of the test. There are two focusing bands at S2 and S5, separately for all the four elements and the focusing bands in the S2 zone forming at the early stage existed nearly throughout the entire process. The pH gradient between S1 and S2 was detected at the onset of the experiment, and until the 12 day, the gradient barrier was obviously dropped down. The coupling effect of precipitation hindering and backward electromigration of anions is considered as the dominant force for the formation of the focusing band, which is different from the pure ion-induced potential gradient well trapping effect near the anode. The FA matrix enhancing and nitric acid enhancing can alleviate the focusing phenomenon and increase the concentration ratios to some extent.
authors.affiliation: a State Key Laboratory for coal mine disaster dynamics and control , Chongqing University , Chongqing 400044 , People's Republic of China.|b College of Resource and Environmental Science , Chongqing University , Chongqing 400044 , People's Republic of China.
authors.forename: Dongwei
authors.initials: D
authors.lastname: Li
authors.affiliation: a State Key Laboratory for coal mine disaster dynamics and control , Chongqing University , Chongqing 400044 , People's Republic of China.|b College of Resource and Environmental Science , Chongqing University , Chongqing 400044 , People's Republic of China.
authors.forename: Tao
authors.initials: T
authors.lastname: Huang
authors.affiliation: a State Key Laboratory for coal mine disaster dynamics and control , Chongqing University , Chongqing 400044 , People's Republic of China.|b College of Resource and Environmental Science , Chongqing University , Chongqing 400044 , People's Republic of China.
authors.forename: Kexiang
authors.initials: K
authors.lastname: Liu
mesh_terms: D060729:Coal Ash / Q000737:chemistry*; D004566:Electrodes; D004787:Environmental Pollution / Q000517:prevention & control*; D052918:Environmental Restoration and Remediation / Q000295:instrumentation / Q000379:methods*; D017745:Incineration; D007700:Kinetics; D019216:Metals, Heavy / Q000737:chemistry*; D012037:Refuse Disposal; D012987:Soil / Q000737:chemistry*; D062611:Solid Waste
chemical_list: D060729:Coal Ash; D019216:Metals, Heavy; D012987:Soil; D062611:Solid Waste
keywords: EKR enhancement; MSWI fly ash; electrokinetic remediation; focusing phenomenon; leaching toxicity