| It is said that TiO2 is a perfect environmental photocatalytic material in view of that it has stability, low pollution and strong ability of catalysis. It is limited to apply in the field of industry wastewater since TiO2 has the disadvantage of reuniting easily and narrowing range of spectral absorption. Combining NaOH with CTMAB as composite modification material and making medical stone as the major precursor, I prepare the TiO2/modified composite medical stone photocatalysis by the method of sol-gel to explore the best conditions, degradation pathway of methylene blue and the dynamic model through decomposing simulation printing and dye wastewater made by anthraquinone dyes-methylene blue. My research contents express as follows:(1) I prepare the NaOH/CTMAB composite modified medical stone to explore the best modified conditions are 1mol/L NaOH and 5g/L CTMAB. Disposal of methylene blue dyeing simulation wastewater with it, the best reaction of condition expresses as follows: the initial pH of solution is 5(±0.1), dosage is 0.6g/L, reacting time is 3h, concentration is 30 mg/L, the removal rate of chromaticity and COD are 88.0% and 80.12% respectively.(2) I prepare the TiO2 loading on the compound modification medical stone by sol-gel method to degrade the methylene blue printing and dyeing simulation wastewater according photocatalytic oxidation and adsorption. When the capacity of TiO2 and calcination temperature are 5g and 400℃ respectively, the photocatalytic effect of the TiO2/modified composite medical stone is best. While I use SEM, TEM and XRD et al to analyze and detect the structure and shape of the composite photocatalyst. It shows that the TiO2 keeps a favourable stability because TiO2 disperses on the medical stone particles homogeneously as the anatase type. The removal rate of chrominance and COD reach 97.12% and 88.62% respectively under the optimum reaction conditions as follows: the dosage of TiO2/modified composite medical stone, the UV irradiation time and the initial concentration of methylene blue dyeing simulation wastewater are 0.5g/100 mL, 80 min and 30mg/L respectively.(3) The practical printing and dyeing wastewater is disposed by the TiO2/modified composite medical stone under best conditions. I research the repeating utilization factor of the TiO2/modified composite medical stone at the same time. It shows that the removal rate of chrominance and COD of the practical printing and dyeing wastewater reach 73.65% and 54.44% respectively. The removal rate of chrominance and COD of methylene blue dyeing simulation wastewater reach 55.29% and 51.19% respectively after the TiO2/modified composite medical stone recycles 5 times.(4) The photocatalytic oxidation degradation pathway of methylene blue was investigated by spectral analyses. The results showed that hydroxyl radicals firstly attacked the N-S heterocycle chromophore group of dye molecules. Then the intermediate products were continued to be degraded into small-molecule products after a series of reactions, such as CO2 and H2 O.(5) The dynamic model exploration of deposing methylene blue dyeing wastewater in the way of the TiO2/modified composite medical stone photocatalysis.The experimental figures indicates that the dynamic model of modified composite medical stone photocatalysis applies to the following first-degree reaction model:C=C0exp(0.0082C0-0.32469Q0.47705t)。... |
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