Study on the optical bandgap of oil palm frond ash (OPFA) treated via acid leaching treatment

Abstract

Acid-leaching oil palm frond ash (OPFA) and non-leached OPFA optical bandgap energy were investigated in this research using diffuse reflectance UV–visible spectroscopy (UV–vis DRS). In this study, ash was obtained from oil palm frond (OPF) via combustion at 600 °C for 3 h. The ash then treated with acid-leaching treatment using 3% citric acid. This acid-leached OPFA and non-acid leached OPFA were analysed using UV–vis DRS as well as Atomic Absorption Spectroscopy (AAS). The indirect and direct bandgap of acid leached and non-acid leached OPFA that obtained via the Tauc plot that calculated Kubelka-Munk function display that acid leached OPFA has lower energy bandgap comparable to non-acid leached OPFA. Tauc plot of both indirect and direct band lie at 0.62 eV and 1.45 eV for the acid-leached OPFA is lower that the non-acid leached OPFA that lie at 1.00 eV and 1.85 eV, respectively. The low energy attribute to the increase presence of silica in acid-leached OPFA due to the removal of other inorganic oxide which validate through AAS analysis.