Mechanisms and mass transfer kinetics of Pb(II) adsorption onto rice husk charcoal silica gel

Abstract

Background

Oral intake of Pb(II) from drinking water as an etiological factor for serious damage to human health is of interest to perform this study.

Methods

Synthesis of rice husk charcoal silica gel (RHCSG) as an adsorbent was made by hydrothermal processing and used for the removal of Pb(II) ions by adsorption method from solution.

Significant findings

Using the Langmuir and Freundlich isotherm models enabled the prediction of the behavioral adsorption mechanisms of being dominated by chemisorption on homogeneous surface of the RHCSG adsorbent. The maximal adsorption capacity of the RHCSG adsorbent as high as 102.04 mg/g was verified at pH 4 for 60 min of contact time. The use of Generalized Fulazzaky equations enabled the prediction of the mechanisms and mass transfer kinetics of Pb(II) adsorption onto the RHCSG adsorbent and the determination of the mass transfer resistance depending the external mass transfer. The average efficiencies of 27.01, 98.89 and 97.60% were verified for the adsorption of Pb(II) onto the RHCSG adsorbent from the solutions conditioned at pH 3, 4 and 5, respectively. The efficiencies of RHCSG adsorbent to remove Pb(II) from the solutions conditioned at pH 4 and 5 with the contact times of 10, 35 and 60 min were all higher than 96%, compared to around 27% efficiency at pH 3. The findings of this study contribute to the advancement of adsorption techniques for the remediation of nonbiodegradable elements in the aquatic environment.