| The environmental pollution is increasingly serious, and the water resources in China are serious shortage, too. Use the industrial wastewater as a useful resource and make it recovery and utilization has become the development trend of industrial wastewater treatment. This paper use calcium ions and carbonic acid ions which are contained in the waste water to prepare nanometer calcium carbonate particles and nano-caco3/sio2 composite material. In order to degradation industrial wastewater, increase the application scope of calcium carbonate products and recycling the alkali in the wastewater, we controlled the reaction conditions and discussed them.(1) In this paper we calculated the content of calcium ions of epoxy propane wastewater is 0.1876mol/L by the titration method. Due to the content of calcium ions we determined the usage amount of sodium carbonate. We discussed the preparation conditions of calcium carbonate, such as reaction temperature, concentration of sodium solution, stirring speed and drop wise rate; these factors could influence the particle size and morphology of nano-CaCO3. Through the experiment we got the best preparation condition to got nanometer calcium carbonate which was small particle size:reaction temperature:25℃, stirring speed:300r/min, sodium carbonate solution concentration:0.1876 mol/1, dropping speed of sodium solution:10ml/min. A series of characterization of calcium carbonate samples proved the nanometer calcium carbonate which was prepared from waste water was pure, and the morphology was calcite type crystal, the minimum size could be 30nm.(2) The raw material we used was the effluent after the preparation of silica from husk ash. We calculated the concentration of sodium bicarbonate and sodium carbonate in the effluent through the titration and conclusion the concentration of calcium hydroxide solution. We prepared calcium carbonate with the sodium bicarbonate and sodium carbonate from the effluent and calcium hydroxide solution. In this paper we examined the different morphology and particle size of the nanometer CaCO3 which we prepared in alkali solution and discussed the reaction mechanism. We also examined the different preparation conditions:the concentration of reaction solution, volume and different filtration method, and we obtained the best conditions of alkali solution recycling. The concentration of the reclaimed sodium hydroxide solution is consistent with the alkali used to cooking husk ash. It can be recycled.(3) In this paper we prepared CaCO3/SiO2 composite particle. We coated fresh nano-CaCO3 with silica by carbonization method. Through the characterization methods of particle size analytical technique, XRD diffraction spectrum diagram and TEM etc we validation the structure of the composite core-shell particle. We also examined the different conditions of CaCO3/SiO2 composite particle preparation:the carbonization temperature, sodium silicate solution concentration, the proportional of gas. We analyzed the influence of the different conditions and examined different samples'acid resistance. We got the best conditions of CaCO2/SiO2 composite particle preparation:carbonization temperature:80℃, sodium silicate solution concentration:20%, the proportional of CO2:30% of total gas. When CaCO3/SiO2 compound particles have the best wrapped layers, the thickness of SiC2 is about 10nm, and the products have a certain acid resistance.In this paper, we achieved the purpose of degradation wastewater and make waste water available by reducing alkali content and calcium ion content of the wastewater. The calcium carbonate and calcium carbonate/silica coated materials we prepared in the waste water can be widely used in plastic, rubber, paint, building etc. These create economic value, realize recycling of alkali and reduce the cost of production.
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