Research On Treatment Process Of Wastewater From Sebacic Acid Production

The sebacic acid is a kind of important organic material which can be widely used to produce the plastics, additive and spicery and so on. Each ton production of sebacic acid will produce 30 tons effluent in present process. What the wastewater contain are sodium sulphate, sebacic acid, phenol and other fatty acids. The effluence of this kind of wastewater not only pollutes the environment, seriously destroys hydrophyte, crops and soil, but also loses the resources which are contained in the wastewater. Therefore, multiple-effect evaporation and resin adsorption was used to treat the wastewater in order to reducing the concentration of phenol and reclaiming sodium sulphate in the wastewater. The research result can provide the basic data for industrial scale process.Differential distillation process is used to simulate multiple effect evaporation process. Sodium hydroxide is added to suppress volatilization of phenol and ensure the purity of condensate. The effects of pH values and filtration times on the treatment process and the purity of sodium sulphate are investigated. The results show that the optimum technology condition is, pH of wastewater is adjusted to 10.00 before evaporation, and both normal temperature filtration and high temperature filtration are used in order to remove fatty acids as more as possible. The purity of sodium sulphate can reached 98.86% under this condition.After the above technology process, the concentration of phenol in condensate can be reduced to 40~50 mg/L, which is still higher than the effluence standard in our country. So NKA-ⅡCrosslinked Polystyrene resin was used to adsorb remained phenol in condensate. Effects of time, temperature, pH value, dosage of resin and the concentration of sodium sulphate on adsorption behavior are investigated in the static adsorption experiment. The results demonstrate that the higher temperature, the lower adsorption capacity, the higher pH value and the more dosage of resin, the better adsorption effect. Furthermore, the concentration of sodium sulphate between 1% and 6% is good for the adsorption process. The optimum technology determined by dynamic adsorption experiment is : temperature is 25℃,pH value is 6, and the velocity of flow is 4ml/min, but considered the special need of plant, 40℃is chosen as the best condition in the practical operation.Furthermore, thermodynamic and kinetics of the adsorption process is studied. Langmuir-Freundlich isotherm models are the best to simulate the adsorption. Three-parameter equilibrium is used to describe the adsorption process and the standardΔG andΔH is concluded under various temperatures. As a result, this heat liberation and physical adsorption process are approved. At the same time, the conclusion of article diffusion is approved as the main control process. A two-order adsorption kinetics equation was developed for the process, and relevant parameters are regressed. In addition, results show that the process in controlled by the particle diffusion, i,e. PDC.