The novel microwave catalyst MgFe2O4-SiC was synthesized via sol-gel method, to remove azo dye Direct Black BN (DB BN) through adsorption and microwave-induced catalytic reaction. Microwave-induced catalytic degradation of DB BN, including adsorption behavior and its influencing factors of DB BN on MgFe2O4-SiC were investigated. According to the obtained results, it indicated that the pseudo-second-order kinetics model was suitable for the adsorption of DB BN onto MgFe2O4-SiC. Besides, the consequence of adsorption isotherm depicted that the adsorption of DB BN was in accordance with the Langmuir isotherm, which verified that the singer layer adsorption of MgFe2O4-SiC was dominant than the multi-layer one. The excellent adsorption capacities of MgFe2O4-SiC were kept in the range of initial pH from 3 to 7. In addition, it could be concluded that the degradation rate of DB BN decreased over ten percent after the adsorption equilibrium had been attained, and the results from the result of comparative experiments manifested that the adsorption process was not conducive to the process of microwave-induced catalytic degradation. The degradation intermediates and products of DB BN were identified and determined by GC-MS and LC-MS. Furthermore, combined with the catalytic mechanism of MgFe2O4-SiC, the proposed degradation pathways of DB BN were the involution of microwave-induced $OH and holes in this catalytic system the breakage of azo bond, hydroxyl substitution, hydroxyl addition, nitration reaction, deamination reaction, desorbate reaction, dehydroxy group and ring-opening reaction.
The toxicity of pentachlorophenol (PCP) on Chlorella pyrenidosa algae was investigated with specific attention given to possible variation of toxic effects with time. A concentration-effect relationship was observed in which there was significant inhibition of PCP on cell density and chlorophyll A content. The inhibition rate of PCP on cell density was dependent on exposure time. The IC50 values after exposure times of 2, 4 and 6 days for cell growth were 4.18 +/- 0.49, 3.49 +/- 0.40 and 3.30 +/- 0.26 mg/L, respectively. There was also inhibition of chlorophyll A production, which appeared to increase marginally with exposure time for a given concentration of PCP. The corresponding IC50 values on day 2, 4 and 6 were 2.30 +/- 0.12, 2.63 +/- 0.38 and 3.30 +/- 0.34 mg/L, respectively. The effect of PCP on nitrate reductase (NR), was first stimulation followed by an inhibition phase. It is postulated that the observed temporal changes in the activity of nitrate reductase (NR) may occur through the addition or loss of phosphorus in the NR protein. 相似文献