Metal oxide-biochar supported recyclable catalysts: A feasible solution for the reduction of 4-nitrophenol in water

Abstract

MOx-biochar (Mox = Cu, Co, Mn or Ni oxides) supported materials were prepared, characterised and tested in the reduction of 4-nitrophenol to 4-aminophenol employing sodium borohydride as reducing agent. The catalyst/reducing agent optimal ratio was determined for the copper oxide-based catalysts obtained by wet impregnation (BC1CuOx) and by an alkaline method followed by a hydrothermal treatment (BC2CuOx), as they proved to be the most active ones. The total reduction of 4NP was reached at 2.1 and 0.80 min for BC1CuOx and BC2CuOx, respectively. BC2CuOx could be reused up to five times in consecutive runs without any treatment between the cycles.