Optimization of Lead Adsorption on Rice-Husk Supported Zerovalent Iron Nanoparticles Using Response Surface Methodology

In this study, the Pb(II) ions adsorption unto nanoscale zerovalent iron particles (nZVI) supported on rice husk has been carried out. The challenge of nanoparticles agglomeration makes immobilising them on rice husk desirable. Optimization of process parameters, pH (4 – 10), adsorbent dose (0.5 – 2.0 g) and contact time (60 – 300 min), was carried out using response surface methodology (RSM) based on Box-Behnken design. Optimum condition for maximum Pb(II) ions of 98.74% was predicted at contact time of 60.12 min, pH of 4.01 and adsorbent dose of 0.5 g. At these optimized conditions, 97.23% removal was achieved experimentally. Analysis of variance carried out on the experimental data showed that the model was significant with a R2 of 0.9883. The synthesised adsorbent was characterized with Fourier transform-infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The SEM showed that RH-nZVI has a very porous surface structure. Amine, carboxyl and hydroxyl groups were some of the identified functional groups present in the adsorbent for adsorption. This study suggests that nZVI supported on rice husk is a viable low-cost adsorbent for removing Pb(II) ions from wastewater.