Study On The Photocatalysis Of Several Refractory Organic Pollutants By Modified TiO₂ Photocatalysis

In recent years,the technique of TiO₂ photocatalysis oxidation as a new kind of water treatment process with great potential application especially in the organic substances degradation for its outstanding effect. This paper mainly investigated the photocatalytic degradation of Acid Blue dyeing wastewater, 2,4 - dicholorophenal(2, 4-DCP) simulated wastewater respectively using modified TiO₂ prepared by Sol-Gel method.The photocatalytic reactor which is designed by author and manufactured by Shanghai Organic Chemistry Research Institute is used in this experiment. This experiment showed that in immobility system the photocatalytic degradation of 2,4-dicholorophenal by TiO₂ film modified by the low-cost Active Carbon Powder was significantly improved. The effect of the Active Carbon powder doping content on TiO₂ film,initial concentration,irridation time,pH value,the mechanism and etc.were studied.In suspension system, the photocatalytic degradation of Acid Blue dyeing wastewater by TiO₂ powder modified by both heat treatment and doping with Ag noble metal sedimentated on TiO₂ surface.The decoloring efficiency of AB dye is significantly improved when using photocatalytic method as well as Fenton reagent. With different kind of lamps such as high pressure mercury ultraviolet(UV) lamp and germicidal UV lamp,when the initional contraction is lower,using the germicidal UV lamp can get a better result of higher decoloring efficiency with a lower price and when the initional contraction is higher,the high pressure mercury ultraviolet(UV) lamp may be a better choice. The fundamental react mechanisms in these two different systems have also been dicussed.The process of the photocatalytic degradation of 2,4-dicholorophenal by TiO₂ was studied under high pressure mercury lamp. In order to study the photodegradation dynamics of 2,4-dicholorophenal in water, firstly, to establish the analysis methods of determination of 2,4-dicholorophenal.This part investigates the determination of 2,4-dicholorophenal by ultraviolet spectrophotometry and establishes the analysis methods of determination of 2,4-dicholorophenal by ultraviolet spectrophotometry and ascertain this method to determine the 2,4-dicholorophenal.Secondly, to determine the mechanism of 2,4-dicholorophenal simulated water under different conditions. The Active Carbon powder doping content,initional concentration,pH value,irridation time and repeated times of using TiO₂ film are discussed in details in this experiment.The relationship between the degradation rate and the initial organic concentration was found to follow Langmuir-Hinshelwood model and the result suggested thatphotocatalytic of 2,4-dicholorophenal was zero-order kinetics. The influences of other various parameters were also studied.The process of the photocatalytic degradation of AB dyeing wastewater by Nano-TiO₂ synthesized personally which is modified by heat treatment and Ag sedimentated.Through heat treatment the photocatalytic capability is enhanced in a certain extent,and under the condition of 500 ℃ heated by 2 hours you can get the best compound crystal.The reactivity velocity constant is 0.244min^-1,and half decline time is 13.07min ;While Ag-doped composite powder prepared by sol-gel method can achieve a rather higher degradation on AB simulated water than heat treatment only,and the best dope content is 0.5%(W/W).The experiment showed that using photocatalytic method and Fenton reagent could be more efficient and economic.Considered that the various initional concertration of AB dyeing water such as 10mg/L and 1g/L,from an economic opinion,choose different type of lamp may be sensible.Finally,the recent development of photocatalytic reactor is presented and the trend is also predicted.