Zero-valent iron-copper bimetallic catalyst supported on graphite from spent lithium-ion battery anodes and mill scale waste for the degradation of 4-chlorophenol in aqueous phase

Abstract

Graphite supported zero-valent iron-copper bimetallic catalysts (ZVI-Cu/C) were successfully prepared from mill scale (MS) waste and spent lithium-ion battery (LIB) anode using carbothermic reduction as a new approach for the recycling and revalorization of these waste. Cu and graphite were obtained from the LIB anodes, while ZVI was provided by MS waste. ZVI-Cu/C were synthesized with different MS to LIB anode powers mass ratios (1 to 4) and used as catalysts for the degradation of 4-chlorophenol (4-CP) in water by both reduction and heterogeneous Fenton reactions. ZVI-Cu/C-2 showed the highest removal percentage of 4-CP in both reactions. The degradation rates fitted well to a pseudo first-order model for both reactions. Moreover, ZVI-Cu/C-2 catalyst showed a relatively low lixiviation of iron and copper ions and a high activity in the 4-CP removal even in the fourth reuse cycle, which supports the high stability of the synthesized catalyst. Hydroquinone and 4-chlorocatechol were identified as the main intermediate by-products of 4-CP degradation. The results of this study support the possibility of synthesizing high active and stable ZVI-Cu/C catalysts using graphite and copper from spent LIB anode and iron oxide from MS waste. These catalysts show promising prospective for the removal of 4-CP in water, with comparable activities to others previously reported. This study reports, for the first time, the combined recycling of MS waste and spent LIB anodes to synthesize ZVI-Cu/C catalysts for water treatment by both oxidation and reduction reactions.