Low-temperature conversion of Fe-rich sludge to KFeS2 whisker: a new flocculant synthesis from laboratory scale to pilot scale

Abstract

AbstractHerein, a KFeS2 whisker was formed in mass production at a low temperature, with waste cold-rolling sludge as Fe source, which exhibited good performance in the removal of Zn/Ni from real electroplating effluent. At laboratory scale, KFeS2 was generated at 80 °C by the hydrothermal method, and KFeS2 whisker grew radially with the extension of the reaction time. This method was applied at pilot scale, where a similar KFeS2 whisker was also produced with waste cold-rolling sludge as Fe source, and a residual brownish supernatant was observed after the reaction and then completely recycled in the next round for KFeS2 synthesis. After recycling five times, the produced KFeS2 whisker did not change. The drying and storage of KFeS2 have also been verified. Freeze drying and vacuum drying were applicable, whereas air drying was not profitable. Moreover, the efficiency of Zn/Ni removal using undried KFeS2 was similar to that of dried KFeS2. The efficiencies of Zn/Ni removal using KFeS2 were apparently higher those of common reagents for wastewater treatment.