Preparation Of TiO₂Composite Photocatalysts For The Degradation Of Organic Dyes

In recent decades, with the rapid development of industrial society, unreasonableusing and discharging of organic dyes has created a serious environmental pollution.These pollutions bother our human’s health all the time. Photocatalysis has gained theupper hand as the subject of much research for environmental contaminants treatmentdue to its cost-optimal, high activity, and no secondary pollution in the environment.In this thesis, three kinds of TiO2hybrid photocatalysts were prepared and theirphotocatlytic activity towardorganic dyes under UV-light and sunlight wereinvestigated. The details are as follows:1. TiO2-SiO2composite photocatalyst (5T/S-500) with remarkable enhancedphotocatalytic performance have been fabricated by sol-gel method. The sample wascharacterized and test. The results show that5T/S-500posesses hollow structure, thesurface area of5T/S-500is1105m2/g. Photocatalytic experiments were carried outunder UV-light and sun-light by degradation on azo dyes (methylene blue, methylorange) and phenol, and the degradation rate with in2h under UV-light is99%,90%,90%respectively. Under sun-light, the degradation rate was almost equal to theformer.The high photocatalytic activities and high adsorption ability for organicpoisonous contaminants under UV-light and sun-light demonstrate that thenanocomposite of TiO2-SiO2is a promising candidate material for future treatment ofcontaminated water.2. Micron hierarchical3D flower-like TiO2/PANI composite with enhancedphotocatalytic activity was synthesized via sol-gel method. The effect of differentmolar ratio, initial concentration and pH on degradation efficiency was studied. Thesurface area of T/P is38.81m2/g, and the outcome of the photocatalytic experimentaldemonstrated that T/P with Ti/ANI (aniline) molar ratio of1:1(denoted as T/P) showed high photocatalytic activity on degradation of Congo red (CR) and Methylorange (MO) under both UV-light and sunlight irradiation. The degradation efficiencyof MO and CR under UV-light was95%and98%, respectively. Under sun-lightirradiation was90%and96%, accordingly. The kinetic mechanism accords withpseudo-first order kinetics. After three times run of degradation reaction, thephotodegradation capability of T/P towards MO/CR remain exceeds90%underUV-light irradiation. Given the unique spatial structure and high photocatalyticcharacteristics of T/P composite, it is looking forward to exhibit great potential forapplications in water treatment.3. TiO2/CdS photocatalyst with hollow structure was synthesized via sol-gelmethod and water bath method. The effect of different Ti/Cd molar ratio, initialconcentration and pH on degradation efficiency was discussed. The results of thephotocatalytic experimental demonstrated the TiO2/CdS hybrid with Ti/Cd molar ratioof1:2(denoted as T/2C) showed high photocatalytic activity on degradation ofMethyl orange (MO) under both UV-light and sunlight irradiation. The degradationefficiency within2h is78%(UV-light) and80%(sun-light) respectively.