Study On Treatment Of DMA Containing Waste-Water With TiO₂/Diatomite Complex Photocatalyst

As a kind of important chemical materials, dimethylamine(DMA) is widely used in pesticides, medicine, textile and industrial solvents, dye, dynamite and other organic chemical industries which produce large number of wastewater containing DMA. With some toxicity and strong irritant, DMA has a great impact on the environment, human and organism. So it is necessary to process the DMA wastewater. The high concentration of DMF waste water suitable for recovery treatment. The low concentration (≤400mg/L) of DMA wastewater generally could not be treatmented ideally, because of its chemically stable and biological toxicity. In this work, the photocatalytic technology was used to deeply degradate the low concentration of DMA wastewater to provide theoretical guidance for further application.The nano-TiO2/diatomite composite catalyst was prepared through the gel-sol with tetrabutyl titanate. The preparation conditions were optimized. The catalyst was characterized by SEM and XRD. At atmospheric pressure UV mercury lamp, the low concentrations (≤400mg/L) of DMA simulated wastewater was degradated by the composite catalyst, and static and dynamic tests, degradation kinetics and degradation mechanism analysis was studied. Influences of initial concentration, pH, photocatalyst amount and additional oxidant on photocatalytic activity were investigated. The biodegradability and degradation pathways were explored.Preparation experiments showed that the best preparation conditions of TiO2/diatomite photocatalyst were::water/alcohol0.6, calcining500°C for5h, the rate of diatomite for2g/9mL loaded once and sol pH2. The important factors in proper order were:water/alcohol> calcination temperature> diatomite amount> sol pH. Composite photocatalyst was well developed and reached nano-level which characterized by SME and XRD.Degradation experiments showed that the degradation rate of400mg/L DMA was up to about70%with3g/L TiO2/diatomite under normal conditions. The hydraulic retention time of6h, the biodegradability of the effluent achieved the best. The photocatalytic degradation matched the Langmuir-Hinshelwood kinetic model and its process was that dimethylamine(DMA)→methylamine(MA)→CO2/CO32-, H2O and NH4+...