The Optimized Photocatalytic Degradation And HPLC Analysis Of N, N-dimethylacetamide

DMAC ,which is a solvent with good solubility, is widely used in film production process, resulting in a large number of DMAC waste water. Therefore, how to eliminate the wastewater caused by pollution of DMAC , has always been concerns of the community. In view of the large number of DAMC solvent waste generated in the film production process, the optimal conditions and photocatalytic degradation mechanism for DMAC had been studied in this paper. We searched for the chromatographic separation conditions of HPLC, used the HPLC to detect degradation and researched the micro-behavior in the degradation process. The conclusions are as follows:(1)Through the exploration, we got that the best chromatographic conditions of separation of DMAC and its degradation products by HPLC were as follows: the methanol to water (0.4% acetic acid) in chromatographic mobile phase is 8:92; the flow rate was 1.0mL/min; the samples was detected by the diode array of whole spectrum scanning of the ultraviolet absorption spectra;(2)In the process of photocatalytic degradation of DMAC , there were a total of four intermediate oxidation products generated in accordance with the order: product I,II,III and IV. Besides product IV, the other oxidation products all followed the same law in the oxidation process :from generation to accumulation, then to disappearance; The Molecular Formula of DMAC is CH3CON (CH3) 2, containing four element of C,H,O and N , of which the content of N is 16%; The DMAC was final mineralized into CO₂, H2O and inorganic salts by photocatalytic oxidation. The final product IV was the resultant converted from the element of N. Using the Colorimetric method of hydrochloric acid naphthylethylenediamine, we proved the final generation product converting from N was not NO₂^-. By the multidimensional chromatography , we further identified the final existing form of N is NO₃^-.Those results provide a basis to explain the degradation mechanism of DMAC.(3)The highest degradation efficiency happened on those conditions when using the method of Photocatalytic oxidation to degrade DMAC:UV-C as the light source, DMAC's concentration of 500mg/L, the amount of catalyst of 3g/L and the neutral samples.(4)According to the HPLC trace determination results of DMAC and its degradation products , on the best conditions, the equations respectively describing the law of the degradation products of DMAC are: Product 1: C = - 0.2147t² + 0.5775t - 0.0047 Product 2: C = 0.0727t² + 0.0095t - 0.0085 Product 3: C = 0.0014t² + 0.0043t - 0.0045 And the formula of final degradation product (NO₃^-) is: y = C = 0.0259t-0.0479 Those formulas provide some dynamic reference for the conversion among products in the process of degradation of DMAC.(5)Through the trend of pH in the process of DMAC's degradation, combined with the related news, 2, there were acid material generated along with the formation of product 1 and product 3, making the pH value of degradation system decreased; There were alkaline substances generated along with the formation of product 4, resulting in the increasing of pH value of degradation system; With the degradation for 14h, the system's pH became stable. At this time, the system produced NO₃^-which was the end product of mineralization of DMAC.(6)We mainly researched the solvent wastewater generated by film production. By measuring the water quality parameters of wastewater, we degraded the film wastewater experimental on the optimized conditions, combining with the optimized degradation of simulated wastewater in the process of photocatalytic oxidation of DMAC. The result showed that we need 36h 42h to oxide the film wastewater of 500g with the catalyst of 3g/L.