title: Degradation of 1,4-dioxane in water with heat- and Fe(2+)-activated persulfate oxidation.
abstract: This research investigated the 1,4-dioxane (1,4-D) degradation efficiency and rate during persulfate oxidation at different temperatures, with and without Fe(2+) addition, also considering the effect of pH and persulfate concentration on the oxidation of 1,4-D. Degradation pathways for 1,4-D have also been proposed based on the decomposition intermediates and by-products. The results indicate that 1,4-D was completely degraded with heat-activated persulfate oxidation within 3-80 h. The kinetics of the 1,4-D degradation process fitted well to a pseudo-first-order reaction model. Temperature was identified as the most important factor influencing the 1,4-D degradation rate during the oxidation process. As the temperature increased from 40 to 60 °C, the degradation rate improved significantly. At 40 °C, the addition of Fe(2+) also increased the 1,4-D degradation rate. Interestingly, at 50 and 60 °C, the 1,4-D degradation rate decreased slightly with the addition of Fe(2+). This reduced degradation rate may be attributed to the rapid conversion of Fe(2+) to Fe(3+) and the production of an Fe(OH)3 precipitate which limited the ultimate oxidizing capability of persulfate with Fe(2+) under higher temperatures. Higher persulfate concentrations led to higher 1,4-D degradation rates, but pH adjustment had no significant effect on the 1,4-D degradation rate. The identification of intermediates and by-products in the aqueous and gas phases showed that acetaldehyde, acetic acid, glycolaldehyde, glycolic acid, carbon dioxide, and hydrogen ion were generated during the persulfate oxidation process. A carbon balance analysis showed that 96 and 93% of the carbon from the 1,4-D degradation were recovered as by-products with and without Fe(2+) addition, respectively. Overall, persulfate oxidation of 1,4-D is promising as an economical and highly efficient technology for treatment of 1,4-D-contaminated water.
authors.affiliation: State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Dayangfang 8, Beijing, 100012, People's Republic of China.
authors.forename: Long
authors.initials: L
authors.lastname: Zhao
authors.forename: Hong
authors.initials: H
authors.lastname: Hou
authors.forename: Ayuko
authors.initials: A
authors.lastname: Fujii
authors.forename: Masaaki
authors.initials: M
authors.lastname: Hosomi
authors.forename: Fasheng
authors.initials: F
authors.lastname: Li
mesh_terms: D002244:Carbon / Q000737:chemistry; D004146:Dioxanes / Q000737:chemistry*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry; D010084:Oxidation-Reduction; D013431:Sulfates / Q000737:chemistry; D014867:Water; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: D004146:Dioxanes; D013431:Sulfates; D014874:Water Pollutants, Chemical; D014867:Water; D002244:Carbon; D007501:Iron; C025223:1,4-dioxane