| Dyeing wastewater is a kind of refractory industry waste water, it is particularly important to treat for dyeing wastewater under the situation of environmental pollution and water resource shortage in our country. In this research, the multiple rare earth/biomass charcoal composite material was prepared by dipping-mechanical mixing method with abundant sunflower straw as raw material and then applied for adsorption-catalytic oxidation treatment of cationic dye methylene blue and acid fuchsin using air as oxidant from the utilization of abundant resource and reduction of environmental pollution.SEM measurement result showed that the rare earth oxides were loaded on the surface of straw biochar successfully and the surface pore structure increased obviously. FTIR and Boehm titration results illustrated that the surface of multiple rare earth/biomass charcoal composite material containing different amount of phenolic hydroxyl, lactones, carboxyl and carbonyl functional groups, the number increased significantly compared with before modification. The pHpzc multiple rare earth/biomass charcoal composite material was 5.12.On the basis of determining the preparation temperature of composite material and the capacity of mixed rare earth oxides, this research studied the effect of different influencing factors like aeration time, initial concentration of dye, catalyst dosage, aeration rate, temperature and pH on the removal of methylene blue and acid fuchsin using single-factor experiment under the aeration condition. And then the Box-Behnken experimental design was established for design testing program and optimize the four important factors on the basis of single-factor test. The main process parameters considered for optimization were catalyst dosage, aeration rate, temperature and pH, with the decolorization rate and COD removal rate as the response value. By the optimization of process parameters, the optimum experimental conditions were catalyst dosage of 7.67 g·L-1, aeration rate of 0.39 L·min-1, temperature of 30 °C and pH value of 10, under these optimum conditions, maximum predicted and observed decolorization rate were 100.00% and 97.89% ; the maximum predicted and observed COD removal rate were 77.65% and 75.81%, the observed value was well match with the predicted value, this illustrates that the established model is reasonable and feasible.Kinetics study showed that the adsorption-catalytic oxidation reaction accord with the first order kinetics study, apparent kinetics equation of adsorption-catalytic oxidation treatment of methylene blue were as follows:as to decolorization rate: ln?c0/ct? =3.45×10-3e×?2.5497?×103/RT)×[A]0.9271×[F]0.7711×t,as to COD removal rate: ln?c0/ct? =-1.21×10-3e31.0516×104/RT×[A]0.9379×[F]1.0158×t,FTIR measurement of composite material showed that the carbonyl group played the most important role on the degradation of methylene blue. The possible reaction paths was "thiophenic sulfur + carbonyl = phenolic hydroxyl groups", this illustrated that methylene blue reacted with the carbonyl on the surface of biochar and degraded the organic pollutants.The study of actual dye wastewater from a sewage treatment plant of Ordos showed that , under the optimum condition (catalyst dosage of 7.67 g·L-1, aeration rate of 0.39 L·min-1, temperature of 30? and pH value of 10)of Box-Behnken experiment, the decolorization rate of actual dye wastewater was 93.75%, the COD removal rate was 56.87% and the pH was 7.96,respectively reached the primary, secondary and primary standard of?Integrated wastewater discharge standard? (GB8978-1996). Finally, studied the regeneration capacity of composite material using the microwave heating method, the result showed that the regeneration capacity of composite material is better than the biomass charcoal. |
PDF Full Text Request