Green synthesis of P-aminophenol using natural aragonite as a support from nano-nickel catalyst by reduction of P-nitrophenol.

Natural aragonite was used as a support for different percentages (5%, 10% and 20%) of nano-Ni which obtained from nickel nitrate and reduced by hydrazine hydrate. It was demonstrated that the 20% catalyst has higher activity compared to other nickel percentages for the reduction of p-nitrophenol to p-aminophenol. The reduction process was performed in alkaline medium (NaOH) by using hydrazine hydrate as a source of hydrogen. The catalysts were characterised by using XRD, SEM, FT-IR and XRF. In order to discuss the kinetics of reduction process, the effect of the catalysts load and p-nitrophenol concentration on the initial reduction rate were studied. The value of rate constant, reaction order and the activation energy were estimated. Moreover, thermodynamic functions at different temperatures were obtained. The proposed reaction mechanism was postulated. [ABSTRACT FROM AUTHOR]