On the kinetics of precipitate flotation of Cr III using sodium dodecylsulfate and ethanol

Water is considered an important and scarce commodity in many countries around the world. Several industrial wastewater streams may contain heavy metals, including the waste liquids generated by metal finishing or in the mineral processing industries. The toxic metals must be effectively treated or removed from the wastewaters; otherwise, they would be discharged directly into the natural water streams and may constitute a great risk for the aquatic ecosystems. Chromium is a well known highly toxic metal, considered as a priority environmental pollutant introduced into natural waters from a variety of industrial wastewaters. In this paper, the removal of chromium III by precipitate flotation from dilute aqueous solutions, using sodium dodecylsulfate (SDS) as anionic collector and ethanol as frother was investigated at laboratory scale. sults of the zeta potential and the floatability studies of chromium hydroxide precipitates showed that the isoelectric point (IEP) of Cr(OH)3 was around pH = 8.5 and a 96.2% maximum removal was achieved at pH around 8.0. The flotation kinetics of chromium precipitates was studied based on the integral and the differential methods and found to follow a first order rate equation.