title: Cr(VI) reduction and Cr(III) immobilization by Acinetobacter sp. HK-1 with the assistance of a novel quinone/graphene oxide composite.
abstract: Cr(VI) biotreatment has attracted a substantial amount of interest due to its cost effectiveness and environmental friendliness. However, the slow Cr(VI) bioreduction rate and the formed organo-Cr(III) in solution are bottlenecks for biotechnology application. In this study, a novel strain, Acinetobacter sp. HK-1, capable of reducing Cr(VI) and immobilizing Cr(III) was isolated. Under optimal conditions, the Cr(VI) reduction rate could reach 3.82 mg h(-1) g cell(-1). To improve the Cr(VI) reduction rate, two quinone/graphene oxide composites (Q-GOs) were first prepared via a one-step covalent chemical reaction. The results showed that 2-amino-3-chloro-1,4-naphthoquinone-GO (NQ-GO) exhibited a better catalytic performance in Cr(VI) reduction compared to 2-aminoanthraquinone-GO. Specifically, in the presence of 50 mg L(-1) NQ-GO, a Cr(VI) removal rate of 190 mg h(-1) g cell(-1), which was the highest rate obtained, was achieved. The increased Cr(VI) reduction rate is mainly the result of NQ-GO significantly increasing the Cr(VI) reduction activity of cell membrane proteins containing dominant Cr(VI) reductases. X-ray photoelectron spectroscopy analysis found that Cr(VI) was reduced to insoluble Cr(III), which was immobilized by glycolipids secreted by strain HK-1. These findings indicate that the application of strain HK-1 and NQ-GO is a promising strategy for enhancing the treatment of Cr(VI)-containing wastewater.
authors.affiliation: Key Laboratory of Industrial Ecology and Environmental Engineering (China Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology , # 2 Linggong Road, Dalian 116024, People's Republic of China.
authors.forename: Hai-Kun
authors.initials: HK
authors.lastname: Zhang
authors.forename: Hong
authors.initials: H
authors.lastname: Lu
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Ji-Ti
authors.initials: JT
authors.lastname: Zhou
authors.forename: Meng
authors.initials: M
authors.lastname: Sui
mesh_terms: D000150:Acinetobacter / Q000302:isolation & purification / Q000378:metabolism*; D001673:Biodegradation, Environmental; D002857:Chromium / Q000378:metabolism*; D004583:Electrons; D005947:Glucose / Q000032:analysis; D006108:Graphite / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D018625:Microscopy, Atomic Force; D056951:Photoelectron Spectroscopy; D011809:Quinones / Q000378:metabolism*; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature
chemical_list: D011809:Quinones; D002857:Chromium; C074702:chromium hexavalent ion; D006108:Graphite; D005947:Glucose