Green synthesized iron nanoparticles supported on pH responsive polymeric membrane for nitrobenzene reduction and fluoride rejection study: Optimization approach

Abstract

Iron nanoparticles (NPs) were prepared via Clove extract mediated green synthesis. Iron NPs were immobilized in flat asymmetric polymeric pH responsive PVDF-co-HFP membranes prepared by blending of Polyethylene glycol methyl ether (PEGME)(Mw = 5000 g/mol) and Humic acid (HA). Iron NPs dispersed in pH responsive polymeric membrane in different weight percentage (0.01, 0.1 and 1) imparted catalytic effect in reducing nitrobenzene to aniline as well as enhanced fluoride rejection by dead end filtration experiment. Both the process of NB reduction and fluoride rejection was dependent on pH responsiveness of the membrane. High performance liquid chromatography (HPLC) analysed formation of aniline and nitrobenzene at different ultra-filtration time. Aniline formation of 15 ppm was found to be highest at pH3 and lowest of 12.8 ppm at pH7 for 0.01 wt% iron NPs impregnated membrane at end of 50 min. Aniline formation increased for pH12 than pH7 due to pH responsiveness. Fluoride rejection was studied on optimized wt% of iron NPs from NB reduction experiments with different pH of fluoride solutions. In order to maximize the Aniline formation and Nitrobenzene reduction, the variables (time, pH and wt% of NPs) was optimized using Design expert software 9.0 TRIAL through ANOVA (analysis of variance) using the combination of response surface methodology (RSM) and central composite design (CCD). The optimization study showed negligible error with experimentally obtained values at optimized conditions for maximizing NB reduction (error 3.37%) and aniline formation (error 3.93%).