Research Of TiO₂Photo-catalytic Materials And Their Application In The Treatment Of Wastewater From Paper Mill

The use of photo-semiconductor such as wide bandgap TiO2has been reported in the literaturefor their optical-electronic properties, photochemical properties and simple preparation method.TiO2mediated based materials has attracted extensive interests owing to their great advantages inthe removal of organic pollutants from wastewater. This is mainly because of its high Fermi level,chemical stability, strong oxygen adsorption and hydroxylation. Considering its application inthe treating of paper-making wastewater and future development potential, the main aim of thispaper is to produce new experimental parameters and evaluate ability on the photo-catalyticdegradation of simulation pollutants and production wastewater, which can serve as a referencefor future scientific research in this area.According to the research purpose, in order to analyze the influence of different soluble saltson photo-degradation of TiO2particles, the traditional sol-gel method was used to preparephotocatalyst. After calcination for2h in the air at500℃and observed by XRD and SEMcharacterization methods, an anatase phase was obtained and its average subgrain size was19.1nm. The results of the photodegradation experiments indicated that NH4Cl、 Na2SO4、NaNO3、FeCl3showed positive effects when adding8mmol/l、16mmol/l、20mmol/l、0.8mmol/lamounts. The introduction of elements of the transition state and electron acceptor benefits in thepromoting of photo catalytic efficiency, the removal rates of organics were increased by3.9%and11.7%, respectively.The loaded TiO2experimental design was used to observe the morphology and build acomposite system for maximizing organics degradation in the water by the use of4A zeolite asthe carrier. Under microwave irradiation, according to the SEM pictures, there were columnarcrystals synthesized on the surface of zeolite, and their size was distributed between100-250nm.The loaded TiO2showed the best photodegradation ability owing to the uniform distribution ofcolumn when two layers TiO2covered. After4times cycles, the residual rate of organics was24.1%, less than the others37.5%,39.9%,42.8%.The talc with an ability of photodegradation was constructed by TiO2loaded on its surface and between layers.5samples were synthesized and used to degrade organics in the water in order todetermine their capabilities of organics degradation. Also a new method was proposed based ondifferent reactor, which can provide the better treatment options. The results indicated that ballliked TiO2around200nm scattered on the surface of talc, and when the calcinations temperaturewas400℃showed better thermal-stability and hydrophilic, respectively the adsorption rateincreased by8.1%and the removal rate of organic reached70.0%within1h under lightirradiation. Considering that the actual effect was in accordance with the theoretical prediction, itis possible to degradate organics exhaustively under photo catalytic oxidation based on theadsorption of loaded materials.Considering the processing methods of papermaking effluents were varied, the materialsprepared above were used to treat regenerated papermaking wastewater. Three materials and tworeaction containers were constructed and used to remove COD and chroma. The results indicatedthat the degradation rates were affected by the initial pH、the equipment、wastewater and H2O2concentration. The removal rate of CODcrreached66.5%when unloaded TiO2was used in outletwater treatment. The CODcrremoval rate of outlet water increased by32.0%after12mmol/lH2O2was added compared to the original effect of63.5%CODcrresidual of4A-Na catalyst. TheCODcrresidual rates of300mg/l and161mg/l wastewater were23.7%and19.8%after treatmentwith air disturbance and at5.02pH value, in the case of using TiO2/Talc. Combining previousresults, this would favor the application of the photocatalytic technology.