The Study Of Using Coprecipitation Method To Remove Vanadium From Vanadium-containing Wastewater

Recent years,the chemical precipitation method showed a good application prospect in heavy metal wastewater treatment because of its advantages such as convenient operation,low cost,easy reaction conditions,strong stability of the generated slag and no secondary pollution.In order to provide reliable theoretical basis and application experiences for the industrialization of vanadium-containing wastewater,we used coprecipitation method to deal with it.We used trivalent iron salts as precipitant,using from acid to base method and immobilization system pH to neutralize the reaction system at target pH value with NaOH/CaO,respectively.In this paper,we also studied the adsorption of vanadium onto synthesized ferrihydrite at different pH.The experimental results showed that the optimum conditions for the coprecipitation reaction as follows:? The experimental results showed that the initial concentration of vanadium solution is set to 200 mg/L,the initial n(Fe)/n(V)is set to 2,we use CaO emulsion to neutralize reaction system pH value of 4,after 90 hours of reaction,the vanadium remaining concentration was less than 1 mg/L that means mostly vanadium was removed.The results of kinetic experiments showed that the removal rate of vanadium remains unchanged after 378 h,so that,the vanadium coprecipitation system was achieved stability.? The experimental results showed out the adsorption effect increases with the decrease of the pH of the adsorption system,the optimal pH for the adsorption of vanadium onto ferrihydrite is pH 4.After we raised the adsorption system pH from pH 4 to pH 8 or from pH 4 to pH 12,the previously adsorbed vanadium at pH 4 was partly released back to the solution,the desorption phenomenon was appeared.? We also did a comparison of the concentration of vanadium remaining in solution after adsorption on to ferrihydrite with that by coprecipitation at the same pH.The experimental results showed out that vanadium can be removed more effectively by coprecipitation method than adsorption way at pH 4,6,8,respectively.So that,we can get more theoretical guidance from the coprecipitation method for vanadium-containing wastewater treatment process of industrial applications in the future.