Phenol derived molecules are considered as critical pollutants in the environment and need to be decontaminated to safeguard our mother Earth. This may sometimes be achieved by degradation using nanomaterials. Plant mediated biosynthesis of nanoparticles is truly encouraging for environmental safety as well as easy availability of precursor materials. The present report demonstrates the catalytic reduction of 4-nitrophenol using silver nanoparticle, synthesized from rhizome of Cyperus Rotundus. It is characterized by UV-vis and FTIR spectra, DLS, SEM-EDS, AFM, FESEM and TEM. The size of the particle is estimated to be in the range of 10-40 nm. Degradation pathway using NaBH4 and silver nanoparticle catalyst is followed under visible light. The influence of variables such as time, dose of NaBH4, 4-nitrophenol (4-NP) and silver nanoparticle was investigated following response surface methodology. A mathematical model is built up to correlate the interactive influences of the significant variables and the reduction. The mutual interactions of these variables are mapped in the design space by response surface and contour plots. The process follows a pseudo first-order kinetic model and the activation energy was evaluated to be 53.3 kJ mot-1. The conversion of 4-NP-4-AP was confirmed from NMR studies. (C) 2019 Published by Elsevier B.V. on behalf of Institution of Chemical Engineers.