Study On The Oxidative Degradation Of Lignosulfonate

The emissions of a large number of lignin from paper industry results in serious environmental pollution and resource waste. Because of having its own structural characteristics, lignin is very difficult to be transformed and eliminated in the nature environment. How to solve the problem of water pollution, develop new treatment technology for papermaking wastewater, realize society sustainable development are the difficult problems which haven't been fully solved in the international paper industry till now and have become the research priorities of paper industry and environmental protecting departments of countries all over the world.Non-thermal plasma oxidation is a new advanced oxidation technology developed recently, which has the synergystic degradation function from high energy electron radiation, UV photolysis, pyrolysis to ozone oxidation. It is different from the traditional degradation method, this new oxidation technology with the advantages of speedy degradation rate, wide handling range, no pollution, and easy to operate can effectively remove hardly degradable substances from industry wastewater. In this thesis we used dielectric barrier discharge (DBD) plasma or used ozone to degrade lignin.The results of ozone oxidation showed that lignin can be degraded under ambient temperature and atmosphere pressure. Among process condition, catalyst or reaction time had remarkable effect on lignin oxidative degradation rate. However, reaction temperature or ultrasonic had little effect on the degradation rate. CUSO4 or TiO2 /α-Al2O3 catalyst was beneficial to the reaction of lignin oxidative degradation. Under test conditions the reaction of lignin oxidative degradation would reach equilibrium when the lignin degradation rate was about 80%.The reaction of lignin oxidation degradation using DBD plasma carried out by gas-jet expansion method. The degradation of lignosulfonate during this process was characterized by UV, FTIR and 1H NMR spectroscopy. The test results indicated that non-thermal plasma technology was effective to degrade lignosulfonate. The effect of electrode spacing, plasma voltage, catalysts, concentration of catalyst or reaction times on degradation rate was separately studied. Optimum process condition were determined:concentration of lignosulfonate was 1 g/L, electrode spacing was 2 cm, the amount of catalyst CUSO4 was 3.2%, plasma voltage was 3 KV, plasma frequency was 10 KHz, plasma reaction time was 2.3 ms. Under this reaction condition the degradation rate of lignosulfonate can achieved to 50%.