title: Enhancement of chromate reduction in soils by surface modified biochar.
abstract: Chromium (Cr) is one of the common metals present in the soils and may have an extremely deleterious environmental impact depending on its redox state. Among two common forms, trivalent Cr(III) is less toxic than hexavalent Cr(VI) in soils. Carbon (C) based materials including biochar could be used to alleviate Cr toxicity through converting Cr(VI) to Cr(III). Incubation experiments were conducted to examine Cr(VI) reduction in different soils (Soil 1: pH 7.5 and Soil 2: pH 5.5) with three manures from poultry (PM), cow (CM) and sheep (SM), three respective manure-derived biochars (PM biochar (PM-BC), CM biochar (CM-BC) and SM biochar (SM-BC)) and two modified biochars (modified PM-BC (PM-BC-M) and modified SM-BC (SM-BC-M)). Modified biochar was synthesized by incorporating chitosan and zerovalent iron (ZVI) during pyrolysis. Among biochars, highest Cr(VI) reduction was observed with PM-BC application (5%; w/w) (up to 88.12 mg kg-1; 45% reduction) in Soil 2 (pH 5.5). The modified biochars enhanced Cr(VI) reduction by 55% (SM-BC-M) compared to manure (29%, SM) and manure-derived biochars (40% reduction, SM-BC). Among the modified biochars, SM-BC-M showed a higher Cr(VI) reduction rate (55%) than PM-BC-M (48%) in Soil 2. Various oxygen-containing surface functional groups such as phenolic, carboxyl, carbonyl, etc. on biochar surface might act as a proton donor for Cr(VI) reduction and subsequent Cr(III) adsorption. This study underpins the immense potential of modified biochar in remediation of Cr(VI) contaminated soils.
authors.affiliation: Future Industries Institute (FII), University of South Australia, Mawson Lakes, SA 5095, Australia. Electronic address: mansy043@mymail.unisa.edu.au.
authors.forename: Sanchita
authors.initials: S
authors.lastname: Mandal
authors.affiliation: Future Industries Institute (FII), University of South Australia, Mawson Lakes, SA 5095, Australia.
authors.forename: Binoy
authors.initials: B
authors.lastname: Sarkar
authors.affiliation: Cooperative Research Centre for Contaminant Assessment and Remediation of the Environment (CRC CARE), Callaghan, NSW 2308, Australia; Global Center for Environmental Remediation, University of Newcastle, Callaghan, NSW 2308, Australia. Electronic address: Nanthi.Bolan@newcastle.edu.au.
authors.forename: Nanthi
authors.initials: N
authors.lastname: Bolan
authors.affiliation: Korea Biochar Research Center & School of Natural Resources and Environmental Science, Kangwon National University, Chuncheon 24314, Republic of Korea.
authors.forename: Yong Sik
authors.initials: YS
authors.lastname: Ok
authors.affiliation: Cooperative Research Centre for Contaminant Assessment and Remediation of the Environment (CRC CARE), Callaghan, NSW 2308, Australia; Global Center for Environmental Remediation, University of Newcastle, Callaghan, NSW 2308, Australia.
authors.forename: Ravi
authors.initials: R
authors.lastname: Naidu
mesh_terms: D000327:Adsorption; D000818:Animals; D002244:Carbon / Q000737:chemistry; D002417:Cattle; D002606:Charcoal / Q000737:chemistry*; D048271:Chitosan / Q000737:chemistry; D002840:Chromates / Q000737:chemistry* / Q000633:toxicity; D002857:Chromium / Q000737:chemistry / Q000633:toxicity; D052918:Environmental Restoration and Remediation / Q000379:methods*; D005260:Female; D008372:Manure; D010084:Oxidation-Reduction; D011084:Polycyclic Aromatic Hydrocarbons / Q000737:chemistry; D011200:Poultry; D012756:Sheep; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000737:chemistry*; D013021:South Australia
chemical_list: D002840:Chromates; D008372:Manure; D011084:Polycyclic Aromatic Hydrocarbons; D012987:Soil; D012989:Soil Pollutants; C540010:biochar; D002857:Chromium; D002606:Charcoal; C074702:chromium hexavalent ion; D002244:Carbon; D048271:Chitosan
keywords: Animal manure; Black carbon; Charcoal; Designer biochar; Engineered biochar