The surface properties, chemical compositions, and crystal structures of manganese oxides can be altered by redox reactions, which affect their heavy metal ion adsorption capacities. Here, birnessite nanosheets (delta-MnO2) were synthesized from the photochemical reaction of Mn-aq(2+) and nitrate under solar irradiation, and Zn2+ was electrochemically adsorbed using the as-obtained birnessite nanosheets by galvanostatic charge-discharge. The effects of current density and electrochemical techniques (symmetric electrode and three-electrode systems) on Zn2+ adsorption capacity were also investigated. The results showed that the maximum Zn2+ adsorption capacity of the birnessite in the presence of electrochemical redox reactions could reach 383.2 mg g(-1) (589.0 mmol mol(-1)) and 442.6 mg g-(1) (680.3 mmol mol(-1)) in the symmetric electrode and three-electrode system, respectively; however, the Mn2+ release capacity in the three-electrode system was higher than that in the symmetric electrode system. With increasing current density, the Zn2+ adsorption capacity decreased. In addition, the system for heavy metal ion removal driven by electrochemical redox reactions could also be used as a supercapacitor for power storage. The present work proposes a "green" and sustainable approach for preparing nanosized birnessite, and it clarifies the adsorption mechanism of birnessite for Zn2+ in the presence of electrochemical redox reactions. Publication name | ACS SUSTAINABLE CHEMISTRY & ENGINEERING, 6 (11):13907-13914; 10.1021/acssuschemeng.8b02191 NOV 5 2018 | Author(s) | Liu, Lihu; Tan, Wenfeng; Suib, Steven L.; Qiu, Guohong; Zheng, Lirong; Huang, Qiaoyun; Liu, Chengshuai | Corresponding author(s) | QIU Guohong qiugh@mail.hzau.edu.cn Huazhong Agr Univ, Hubei Key Lab Soil Environm & Pollut Remediat, Key Lab Arable Land Conservat Middle & Lower Reac, Minist Agr,Coll Resources & Environm, Wuhan 430070, Hubei, Peoples R China. | Author(s) from IGCAS | LIU Chengshuai | View here for the details
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