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Dechlorination and degradation of 2,4-D by nano-ferric oxide

wallpapers News 2021-11-25
Dechlorination and degradation of 2,4-D by nano-ferric oxide
Reductive transformation of 2,4-Dichlorophenoxyacetic acid (2,4-D) by nanoscale Fe3O4 was studied, and the effects of 2,4-D initial concentration, the dosage of nanoscale Fe3O4, pH, and temperature on the degradation rate of 2,4-D were investigated. The results showed that 48% 2,4-D with the initial concentration of 10 mg/L was transformed within 48 h in the presence of 300 mg/L nanoscale Fe3O4. The degradation of 2,4-D was a reductive dechlorination process, and the concentration of chloride ions increased sharply with the degradation of the 2,4-D. The disappearance of parent species and the formation of reaction intermediates and products were analyzed by LC/MS. The transformation of 2,4-D followed a primary pathway of its complete reduction to phenol and a secondary pathway of sequential reductive hydrogenolysis to 2,4-dichlorophenol (2,4-DCP), 4-chlorophenol (4-CP), or 2-chlorophenol (2-CP) and phenol. The degradation equations of 2,4-D by nanoscale Fe3O4 conformed to pseudo-first-order kinetics, and the reaction rate constant (K) of 4-CP, 2,4-DCP, and phenol were 0.0043 h-1, 0.0026 h-1, and 0.0032 h-1, respectively. The degradation rate increased with an increase in initial concentration of 2,4-D from 0 mg/L to 10 mg/L and increasing the dosage of nanoscale Fe3O4 from 0 mg/L to 300 mg/L. The pH of the reaction solution significantly influenced the reductive degradation of 2,4-D, and the optimum pH value was 3.0. Besides, the high temperature could improve the dechlorination rate of 2,4-D.
Nanometer Fe3O4 (Fe3O4) was used to degrade 2,4-dichlorophenoxyacetic acid (2,4-D) in an aqueous solution, and the initial concentration of 2,4-D, nanometer Fe3O4 dosage, solution pH, and temperature were investigated. The effect of other factors on the degradation rate of 2,4-D. The results show that nano-Fe3O4 has a significant degradation effect on 2,4-D, and the degradation rate of 2,4-D with an initial concentration of 10mg/L can reach 48h within 48h. %. The degradation of 2,4-D by nano-Fe3O4 is a reductive dechlorination process. The chloride ion concentration in the reaction system increases with the decrease of 2,4-D concentration. LC/MS analysis shows that 2,4-D degrades The main product is phenol, and the other intermediate products are 2,4-dichlorophenol (2,4-DCP), 4-chlorophenol (4-CP), and 2-chlorophenol (2-CP). The degradation of D conforms to the quasi-first order reaction kinetics, and the reaction rate constants K of the products 4-CP, 2,4-DCP, and phenol are 0.0043, 0.0026, and 0.0032h-1, respectively. Environmental conditions have a significant effect on the degradation efficiency, 2. The initial concentration of 4-D is within the range of 0-10mg/L and the dosage of nano-Fe3O4 is 0-300mg/L. The degradation rate of 2,4-D increases with the increase of the initial concentration and the dosage of nano-Fe3O4; pH is The dechlorination and degradation of 2,4-D have a significant impact. At a pH of 3.0, nano-Fe3O4 has the best reduction and dechlorination effect on 2,4-D; the increase in temperature can increase the dechlorination reaction rate.
 

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