The Study On The Extraction Process Of Precipitated Calcium Carbonate From The Saponification Wastewater Produced By The Chlorohydrin Process(CHPO)

This thesis combines the situation of propylene oxide saponification wastewatertreatment and resource reuse, and then a new green preparation process is developed,which is about using propylene oxide saponification wastewater resources to prepareprecipitated calcium carbonate. First, we use the low concentrations of calciumchloride resources which are in the propylene oxide saponification wastewater toprepare precipitated calcium carbonate; Secondly, we modified the surface ofultra-fine powder precipitated calcium carbonate which obtained from thesaponification wastewater, and then we can get a functional activated calciumcarbonate; Finally, we use the electro-catalytic oxidation to degrade the residual lowconcentration of surfactant which contained in the modified filtrate, and the treatedwastewater further processed through other processes can be reused as industrial water.This process solved the propylene oxide saponification wastewater dischargepollution problems which in the traditional craft by chlorohydrins method, and savedthe resource at the same time, has a very important practical significance andvalue.The main contents include:(a) By examining the various factors and orthogonal experiment of calciumtransformation process, we discussed the influence of these factors on the particle sizeof the precipitated calcium carbonate. What’s more, we get the optimum conditionsfor the preparation of ultra-fine powders precipitated calcium carbonate. Theprecipitated calcium carbonate which was prepared from saponification wastewaterwas pure, and the morphology was calcite type crystal which structure is cube, theminimum size could be about20nm. (b) We have modified the surface of those ultra-fine powder precipitationcalcium carbonate which we got through wet modification experiment. After that, wecan obtain polymorph complete products which dispersibility is good and determinethe optimal modification conditions.(c) Using electro catalytic oxidation to degrade the residual low concentration ofsurfactant (sodium stearate solution) which contained in the simulated organicwastewater and this waste water is in high chlorine conditions. In order to observe thedegradation effect; we studied these influencing factors such as electrode material,current density, plate spacing, the initial concentration of organic compound, andelectrolysis times and so on. The results we got show that, the final COD removalefficiency of wastewater containing sodium stearate can reach70%and the remainingCOD value of wastewater effluent is about70mg/L.