title: Treatment and toxicity evaluation of methylene blue using electrochemical oxidation, fly ash adsorption and combined electrochemical oxidation-fly ash adsorption.
abstract: Treatment of a basic dye, methylene blue, by electrochemical oxidation, fly ash adsorption, and combined electrochemical oxidation-fly ash adsorption was compared. Methylene blue at 100 mgL(-1) was used in this study. The toxicity was also monitored by the Vibrio fischeri light inhibition test. When electrochemical oxidation was used, 99% color and 84% COD were removed from the methylene blue solution in 20 min at a current density of 428 Am(-2), NaCl of 1000 mgL(-1), and pH(0) of 7. However, the decolorized solution showed high toxicity (100% light inhibition). For fly ash adsorption, a high dose of fly ash (>20,000 mgL(-1)) was needed to remove methylene blue, and the Freundlich isotherm described the adsorption behavior well. In the combined electrochemical oxidation-fly ash adsorption treatment, the addition of 4000 mgL(-1) fly ash effectively reduced intermediate toxicity and decreased the COD of the electrochemical oxidation-treated methylene blue solution. The results indicated that the combined process effectively removed color, COD, and intermediate toxicity of the methylene blue solution.
authors.affiliation: Department of Public Health, Chung-Shan Medical University, Taichung 402, Taiwan, ROC.
authors.forename: Kai-sung
authors.initials: KS
authors.lastname: Wang
authors.forename: Ming-Chi
authors.initials: MC
authors.lastname: Wei
authors.forename: Tzu-Huan
authors.initials: TH
authors.lastname: Peng
authors.forename: Heng-Ching
authors.initials: HC
authors.lastname: Li
authors.forename: Shu-Ju
authors.initials: SJ
authors.lastname: Chao
authors.forename: Tzu-Fang
authors.initials: TF
authors.lastname: Hsu
authors.forename: Hong-Shen
authors.initials: HS
authors.lastname: Lee
authors.forename: Shih-Hsien
authors.initials: SH
authors.lastname: Chang
mesh_terms: D000327:Adsorption; D048908:Aliivibrio fischeri; D002244:Carbon / Q000493:pharmacokinetics*; D060729:Coal Ash; D004396:Coloring Agents / Q000737:chemistry / Q000378:metabolism* / Q000633:toxicity*; D055664:Electrochemical Techniques; D008751:Methylene Blue / Q000737:chemistry / Q000378:metabolism* / Q000633:toxicity*; D010084:Oxidation-Reduction; D052638:Particulate Matter / Q000493:pharmacokinetics*
chemical_list: D060729:Coal Ash; D004396:Coloring Agents; D052638:Particulate Matter; D002244:Carbon; D008751:Methylene Blue