title: Polyethylenimine facilitated ethyl cellulose for hexavalent chromium removal with a wide pH range.
abstract: Ethyl cellulose (EC) composites modified with 20.0 wt % polyethylenimine (PEI) (PEI/ECs) demonstrated effective hexavalent chromium, [Cr(VI)], removal from solutions with a wide pH range. For example, 4.0 mg/L Cr(VI) solution with a pH below 3.0 was completely purified by 3.0 g/L PEI/ECs within 5 min, much faster than the as-received EC (2 h) and activated carbon (several hours). These PEI/ECs adsorbents has overcome the low pH limitation of Cr(VI) removal; for example, 4.0 mg/L Cr(VI) solution with a pH of 11.0 was completely purified within 15 min. These adsorbents followed chemical adsorption as revealed from the pseudo-second-order kinetic study. These PEI/ECs following the isotherm Langmuir model have a maximum adsorption capacity of 36.8 mg/g, much higher than pure EC (12 mg/g), tetrabutylammonium-modified celluloses (16.67 mg/g), and magnetic carbon (16 mg/g). The reduction of Cr(VI) to Cr(III) by the oxidation of amine groups and hydroxyl groups of PEI/ECs was verified as the main mechanism for the Cr(VI) removal.
authors.affiliation: Integrated Composites Laboratory (ICL) Dan F Smith Department of Chemical Engineering Lamar University , Beaumont, Texas 77710, United States.
authors.forename: Bin
authors.initials: B
authors.lastname: Qiu
authors.forename: Jiang
authors.initials: J
authors.lastname: Guo
authors.forename: Xi
authors.initials: X
authors.lastname: Zhang
authors.forename: Dezhi
authors.initials: D
authors.lastname: Sun
authors.forename: Hongbo
authors.initials: H
authors.lastname: Gu
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wang
authors.forename: Huanwen
authors.initials: H
authors.lastname: Wang
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Wang
authors.forename: Xin
authors.initials: X
authors.lastname: Zhang
authors.forename: Brandon L
authors.initials: BL
authors.lastname: Weeks
authors.forename: Zhanhu
authors.initials: Z
authors.lastname: Guo
authors.forename: Suying
authors.initials: S
authors.lastname: Wei
keywords: Cr(VI) removal; adsorption; ethyl cellulose (EC); kinetics; polyethylenimine (PEI); redox reaction