title: Electrochemical properties of the erbium-chitosan-fluorine-modified PbO2 electrode for the degradation of 2,4-dichlorophenol in aqueous solution.
abstract: The erbium (Er)-chitosan-fluorine (F) modified PbO(2) electrode was prepared by electrodeposition method, and its use for adsorption and electrochemical degradation of 2,4-dichlorophenol (2,4-DCP) in aqueous solution was compared with F-PbO(2) and Er-F-PbO(2) electrodes in a batch experiment. The electrodes were characterized by scanning electron microscopy, X-ray diffraction and cyclic voltammetry. Degradation of 2,4-DCP depending on Er and chitosan contents was discussed. The results showed that Er(2)O(3) and chitosan were scattered between the prevailing crystal structure of beta-PbO(2) and thus decreased the internal stress of PbO(2) film. Prior to each electrolysis, the modified PbO(2) anode was first pre-saturated with 2,4-DCP solution for 360 min to preclude the 2,4-DCP decrease due to adsorption. Among the electrodes examined in our study, the highest adsorption and electrochemical degradation for 2,4-DCP and TOC removals that are due to oxidation and adsorption of the organic products onto the chitosan was observed on Er-chitosan-F-PbO(2) electrode. At an applied current density of 5 mAcm(-2), the removal percentages of 2,4-DCP and TOC (solution volume: 180 mL, initial 2,4-DCP concentration: 90 mgL(-1)) were 95% after 120 min and 53% after 360 min, respectively. At Er amount of 10mM in the precursor coating solution, the degradation and mineralization removal for 2,4-DCP on the Er-F-PbO(2) electrode reached a maximum. At chitosan amount of 5 gL(-1), the highest TOC removal on the Er-chitosan-F-PbO(2) electrode was observed. Intermediates mainly including aliphatic carboxylic acids were examined and a possible degradation pathway for 2,4-DCP in aqueous solution involving dechlorination and hydroxylation reactions was proposed.
authors.affiliation: State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, PR China. wangying_21cn@yahoo.com.cn
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
authors.forename: Zhenyao
authors.initials: Z
authors.lastname: Shen
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.forename: Junfeng
authors.initials: J
authors.lastname: Niu
mesh_terms: D000327:Adsorption; D048271:Chitosan / Q000737:chemistry*; D002733:Chlorophenols / Q000737:chemistry*; D055664:Electrochemical Techniques; D004566:Electrodes; D052918:Environmental Restoration and Remediation; D004871:Erbium / Q000737:chemistry*; D005461:Fluorine / Q000737:chemistry*; D007854:Lead / Q000737:chemistry*; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry
chemical_list: D002733:Chlorophenols; D010087:Oxides; D014874:Water Pollutants, Chemical; D005461:Fluorine; D007854:Lead; C047365:lead oxide; D004871:Erbium; D048271:Chitosan; C004762:2,4-dichlorophenol