Green synthesis of plant supported Cu-Ag and Cu-Ni bimetallic nanoparticles in the reduction of nitrophenols and organic dyes for water treatment

In the present study, ginger rhizome powder based catalysts were synthesized for the reduction of 2-nitrophenol (2-NP), 4-nitrophenol (4-NP), methyl orange (MO), congo red (CR), and rhodamine B (RhB). Three different bimetallic catalysts copper-silver (Cu-Ag/GP), copper-nickel (Cu-Ni/GP) and nickel-silver (Ni-Ag/GP) loaded on ginger powder were prepared via novel and robust adsorption method. The size, morphology and structure of the synthesized catalysts were measured through X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and energy dispersive X-ray spectroscopy (EDX). Cu-Ag/GP and Cu-Ni/GP exhibit outstanding catalytic activity for the reduction of all tested organic compounds. Turnover frequency of Cu-Ag/GP in the case of 2-NP and 4-NP were outstanding and reached 45.86 and 81.34 h(-1), respectively, while for Cu-Ni/GP, it was 27.16 and 85.83 h(-1) for 2-NP and 4-NP respectively. For Cu-Ag/GP catalyst the rate constants were 1.21 x 10(-3)s(-1), and 4.05 x 10(-3) s(-1) for 2-NP and 4-NP respectively, while for Cu-Ni/GP, it was 1.11 x 10(-3) s(-1), and 6.08 x 10(-3) s(-1) for 2-NP and 4-NP respectively. The prepared catalysts were also used for the reduction of a mixture of dyes and NPs. Besides, the synthesized catalysts showed excellent reusability and stability. (C) 2018 Elsevier B.V. All rights reserved.