Performance evaluation of electrocoagulation using aluminum, iron and copper electrodes for removal of xanthate

The mineral industry consumes a large amount of xanthate as collector, especially for the sulfide mineral's flotation. Nonetheless, the significant amount of xanthate also discharged from the processing plants, in proportion to the amount of used xanthate. In this work, the hazardous aqueous xanthate was aimed to be removed from water using electrocoagulation with three different electrodes: aluminum, iron and copper. Three separate experimental setups and designs were formed. The response surface methodology was implemented for the estimation of mathematical models for each electrode used in the electrocoagulation. All models were found statistically significant with p-values < 0.0015 and adjusted R-2-values > 0.95. According to the formed linear and quadratic models, the commonly used aluminum electrodes in the literature proved to be useless for the elimination of xanthate. The dissolved aluminum could not react with xanthate, and no precipitation was observed during the treatment. Iron electrode yielded better results than aluminum when the system parameters were statistically optimized at pH 6.54 and electrical current of 0.6 A. The most effective formation of hydroxyl ferric xanthates was actualized at these specific levels of parameters, and the maximum removal% of xanthate was obtained as 82.34%. On the other hand, the last electrode made from copper remarkably decreased the concentration of xanthate with a removal% of 100%. The copper ions released from the electrodes with the help of electricity had a great affinity for xanthate. Following the electrocoagulation process, Cu(I) ethyl xanthate/Cu(II) ethyl xanthate efficiently precipitated, forming a yellow solid sediment at the bottom of the reactor. Consequently, the maximum desirability values for the removal of xanthate were found as 0.0037, 0.7700 and 1.000 respectively for aluminum, iron and copper electrodes. Based on this statistical optimization, the copper electrodes enabled the accomplished separation of hazardous xanthate from water using electrocoagulation at pH 9 and electrical current of 0.6 A.