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Homogeneous and heterogeneous peroxymonosulfate activation by transition metals for the degradation of industrial leather dye

Bouzayani, Bakhta, Rosales, Emilio, Pazos, Marta, Elaoud, Sourour Chaâbane, Sanromán, M. Angeles
Journal of cleaner production 2019 v.228 pp. 222-230
alginates, catalysts, cobalt, copper, dyes, iron, leaching, leather, mineralization, nickel, pH, pollutants, pollution control, response surface methodology, sulfates, temperature
Currently, the interest in eco-friendly treatments for the removal of pollutants has increased and more sustainable treatment solutions are required. In this study, the homogeneous and heterogeneous activation of peroxymonosulfate (PMS) was carried out for the degradation of an industrial dye. Initially, the homogeneous PMS activation by different transition metals (Co, Cu, Ni, Fe) was ascertained. Cobalt resulted in the best performance attaining removal levels around 100% in only 30 min. Then, the influence of operational parameters such as pH and pollutant concentration were evaluated. The results displayed a high efficiency in the degradation and mineralisation operating close to neutral pH. The mechanism of the reaction was also studied and the obtained results demonstrated that sulfate radical is the primary reactive specie involved in the pollutant degradation. The optimisation of the degradation process was then carried out by a response surface methodology and several variables (PMS and Co concentration and temperature) were evaluated. The optimisation was performed in order to maximise the degradation and minimise the consumption of catalyst resulting in values of Co concentration 0.0125 mM, temperature 40 °C and PMS concentration 0.895 mM. Finally, heterogeneous activation by Co-catalyst immobilisation using alginate beads (Co-AB) and amberlite (Co-A) was performed. The results showed the superiority of Co-AB maintaining a high removal level after four treatment cycles with low Co leaching.