title: Chromium(VI) sorption efficiency of acid-activated banana peel over organo-montmorillonite in aqueous solutions.
abstract: In the present study, we examined sorption of chromate (Cr(VI)) to acid-activated banana peel (AABP) and organo-montmorillonite (O-mont) as a function of pH, initial Cr(VI) concentration at a sorbent dose of 4 g L-1and at 20 ± 1°C in aqueous solutions. In sorption edge experiments, maximum Cr(VI) removal was obtained at pH 3 after 2 hours by AABP and O-mont (88% and 69%). Sorption isotherm data showed that the sorption capacity of AABP was higher than O-mont (15.1 vs. 6.67 mg g-1, respectively, at pH 4). Freundlich and Langmuir models provided the best fits to describe Cr(VI) sorption onto AABP (R2= 0.97) and O-mont (R2= 0.96). Fourier transform infrared spectroscopy elucidated that for AABP mainly the -OH, -COOH, -NH2, and for O-mont intercalated amines and -OH surface functional groups were involved in Cr(VI) sorption. The scanning electron microscopy combined with energy dispersive X-ray spectroscopy (SEM-EDX) analyses, although partly, indicate that the (wt. %) proportion of cations (e.g., Ca, Mg) in AABP decreased after Cr(VI) sorption. This may be due to ion exchange of chromite (Cr(III)) (produced from Cr(VI) reduction) with cationic elements in AABP. Also, Cr(VI) desorption (using phosphate solution) from AABP was lower (29%) than that from O-mont (51%) up to the third regeneration cycle. This bench scale comparative study highlights that the utilization of widely available and low-cost acid-activated biomaterials has a greater potential than organo-clays for Cr(VI) removal in aqueous media. However, future studies are warranted to precisely delineate different mechanisms of Cr(VI) sorption/reduction by acid-activated biomaterials and organo-clays.
authors.affiliation: a Institute of Soil and Environmental Sciences, University of Agriculture Faisalabad , Faisalabad , Pakistan.
authors.forename: Anam
authors.initials: A
authors.lastname: Ashraf
authors.affiliation: a Institute of Soil and Environmental Sciences, University of Agriculture Faisalabad , Faisalabad , Pakistan.|b MARUM and Department of Geosciences , University of Bremen , Bremen , Germany.
authors.forename: Irshad
authors.initials: I
authors.lastname: Bibi
authors.affiliation: a Institute of Soil and Environmental Sciences, University of Agriculture Faisalabad , Faisalabad , Pakistan.|b MARUM and Department of Geosciences , University of Bremen , Bremen , Germany.|c Southern Cross GeoScience , Southern Cross University , Lismore , NSW , Australia.
authors.forename: Nabeel Khan
authors.initials: NK
authors.lastname: Niazi
authors.affiliation: d Korea Biochar Research Center and Department of Biological Environment , Kangwon National University , Chuncheon , Korea.
authors.forename: Yong Sik
authors.initials: YS
authors.lastname: Ok
authors.affiliation: a Institute of Soil and Environmental Sciences, University of Agriculture Faisalabad , Faisalabad , Pakistan.
authors.forename: Ghulam
authors.initials: G
authors.lastname: Murtaza
authors.affiliation: e Department of Environmental Sciences , COMSATS Institute of Information Technology , Vehari , Pakistan.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Shahid
authors.affiliation: f Chemical Safety Division , National Academy of Agricultural Science , Wanju , Korea.
authors.forename: Anitha
authors.initials: A
authors.lastname: Kunhikrishnan
authors.affiliation: g College of Resource and Environmental Science , Chongqing University , Chongqing , China.
authors.forename: Dongwei
authors.initials: D
authors.lastname: Li
authors.affiliation: a Institute of Soil and Environmental Sciences, University of Agriculture Faisalabad , Faisalabad , Pakistan.
authors.forename: Tariq
authors.initials: T
authors.lastname: Mahmood
mesh_terms: D000327:Adsorption; D001546:Bentonite; D001673:Biodegradation, Environmental; D002857:Chromium / Q000737:chemistry / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D028521:Musa / Q000378:metabolism*; D012996:Solutions; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000378:metabolism*
chemical_list: D012996:Solutions; D014874:Water Pollutants, Chemical; D002857:Chromium; D001546:Bentonite; C074702:chromium hexavalent ion
keywords: FTIR; biosorption; contaminated water; modeling; organo-clays; remediation