Heterogeneous catalytic activation of percarbonate by ferrocene for degradation of toxic amaranth dye in water

Abstract

While several iron ions and chelated iron species are employed for activating sodium percarbonate (SPC), heterogeneous iron-based catalysts are more advantageous because they can be easily recovered and separated from solutions. However, existing heterogeneous catalysts for activating SPC are limited and their preparation usually involves complexed procedures and reagents. Thus, there is still a need for developing simple but effective heterogeneous catalyst for activating SPC. Herein, ferrocene (Fc) is proposed as a readily available, non-expensive and Fe2+-containing catalyst for activating SPC. While SPC and Fc could not degrade amaranth individually, the combination of SPC and Fc rapidly and effectively degrade amaranth, indicating that Fc can activate SPC. The activation of SPC by Fc can be attributed to Fe2+ contained in Fc; Fe2+@Fc reacted with H2O2 derived from SPC to generate OH•, which decolorize amaranth. The amaranth degradation by Fc-activated SPC can be further improved by elevating reaction temperature and lowering solution pH. Through investigating effects of radical scavengers, the mechanism of amaranth degradation was primarily attributed to OH• and other reactive oxygen species to a lesser extent. Fc was also reusable and remained highly effective for activating SPC to degrade amaranth even without regeneration treatments. These features validate that Fc, a readily available Fe2+-containing organometallic compound, can be a promising heterogeneous catalyst for activating SPC in advanced oxidation processes.