Dielectric properties of potassium hydroxide-treated palm kernel shell for microwave-assisted adsorbent preparation

Abstract

This study was aimed to evaluate the dielectric properties of the reactants mixture at varying temperatures and concentrations for microwave-assisted adsorbent preparation, and to study the adsorptive characteristics of the resultant adsorbents. Palm kernel shell (PKS) was used as the precursor while potassium hydroxide (KOH) was employed as the activator. Different concentrations of KOH solution and ratios of KOH:PKS of 0:1, 0.5:1, 1:1, and 2:1 were prepared, and the measurement of the dielectric properties was performed using open-ended coaxial probe method. Results indicate that the relative dielectric constant, εr' is inversely proportional to the frequency, f. The trends of relaxation time, τ and penetration depth, DP with respect to the frequency and temperature were also reported. Adsorbent prepared using a higher ratio of KOH shows a greater removal of methylene blue. Dielectric properties are imperative especially for selecting suitable operating conditions and in designing the applicator for effective preparation of adsorbent.