The use of calcium peroxide CaO2for wastewater treatment from chromium (VI)

Abstract

The at meant of waste water from hexavalent chromium ions with calcium per oxide CaO2 was investigated. This product is obtained from soda ash production waste. Clarified part of still waste suspension (distillation suspension) contains calcium chloride and sodium chloride. The process of producing calcium peroxide is based on the interaction of calcium chloride with solutions of calcium peroxide and sodium hydroxide. A two-step (reagent) method of purification from hexavalent chromium is proposed. The first stage of the reagent method consists in reducing (conversion) toxic hexavalent chromium to a less dangerous trivalent chromium, and the second - in converting trivalent chromium to an insoluble state (into a hydroxide). The conversion (reduction) of Cr6+ to Cr3+ is carried out using calcium peroxide as a reagent. Reductionis carried out in an acidic medium, and to precipitate trivalent chromium in the form of chromium hydroxide (Cr(OH)3) waste water is neutralized using neutralizer Ca(OH)2. This method of wastewater treatment from hexavalent chromium can be effective in small and medium production, especially in the absence of general treatment facilities.