Recyclable copper-decorated magnetic composites as non-precious catalysts for effective removal of 4-nitrophenol and azo dyes

Carbonized lotus leaf (CLL) from agricultural waste is employed as the support to prepare the novel Cu-Fe3O4/carbonized lotus leaf (CuX-FCLL) catalysts. The magnetic catalyst Cu1.5-FCLL demonstrated desirable catalytic activity for the reduction of organic dyes (Congo red, Methyl orange) and nitroaromatic compounds (3- and 4-nitrophenols). The magnetically recoverable catalyst (Cu1.5-FCLL) exhibited ultrafast catalytic activity for 4-nitrophenol reduction with a conversion rate of over 98% within 30 s, which was comparable to those noble metal catalysts widely used. The CLL with unique papillae structures could provide large surface areas and prevent aggregation of metal NPs, and boost the catalytic performance of Cu1.5-FCLL by a synergetic effect. Such a magnetic catalyst was facilely recovered and reused after ten cycles with negligible loss of catalytic performance. This work presents an efficient green catalyst to replace noble metals for wastewater treatment.