Study On Rapid Determination Of COD

Water pollution is an important aspect of environmental pollution, In order to monitor the water quality and control pollution, chemical oxygen demand (COD) must be detected in time. The national standard method for COD determination is dichromate method, which is time-consuming, complicated and harmful to environment. therefore, it has become an important topic to develop a simple, rapid, accurate and non-polluting method for the COD determination, the following works have been studied in this paper:(1) The nano TiO2film was fabricated on the surface of titanium substrate by anodic oxidation, and then be modified by CuO to improve its performance. Based on the photocatalytic mechanism, A CuO/TiO2-K2Cr207synergetic photocatalytic oxidation system was developed to realize simple and convenient detection of COD. Under the optimized conditions of deposition time200s, calcination temperature450℃,initial Cr(VI) concentration0.02mol/L, pH=1, reaction temperature60℃, reaction time15min, the absorbance of the solution responded linearly to COD value in the range of10～300mg/L, The relative standard deviations were less than5%for detection of real water samples, showing the satisfactoty feasibility.(2) The Ti/SnO2-Sb2O3/PbO2electrode was prepared by the poly-meric precursor method and electrodeposition, and the electrochemical perfor-mances were tested. The studied electrod was used as working electrod to detect different water samples by linear sweep voltammetry. When the deposition time of (3-PbO2was60min, the electrolyte was0.1mol/L Na2SO4and regeneration time was4min, the peak current at1.35V in showed good linear relationship with COD in the range of20-140mg/L. the method showed good effects for the determination of real samples with relative standard deviations within10%.(3) the COD value of different water samples were determined by potassium dichromate method and potassium permanganate method to study the correlation. the results showed that the oxidation rate of two methods were different for diverse organic compounds. for industrial wastewater which was heavily-polluted, the linear relationship between CODMn and CODCr was weak and the CODMn is unreliable; For the low polluted underground water and surface water, there was a good linear relationship between the CODMn and CODCr.the chemical oxygen demand could be calculated by CODMn through the standard curve between CODMn and CODCr...