Use of Activated Palm Kernel Shells on Adsorption of Heavy Metals (Cu2+ and Pb2+) from Contaminated Wastewater

Abstract

This research aimed to evaluate the adsorption capacity of low-cost agricultural waste adsorbent-activated palm kernel shells (APKS) for the removal of Pb2+ and Cu2+ ions from synthetic wastewater that had the concentration of copper and lead ions comparable to that of waste produced in Tanzanian research and teaching laboratories. This study was carried out in batch and continuous column adsorption reactors. The study examined the influence of particle size (0.71 mm–2.36 mm), pH (4.5–8.6), adsorbent dose (5–20 mg/L) and initial concentration Ci (1.93– 4 mg/l) on APKS adsorption removal efficiency. The batch results indicated that under alkali conditions (pH 8.4 -8.6), APKS has an adsorption removal efficiency of 77.3% - 92% and 98.2-98.5% for Cu2+ and Pb2+ ions, respectively. Under acidic conditions (pH: 4.0 - 4.5), the APKS has a lower adsorption capacity of 23.7% and 36.29% for Cu2+ and Pb2+ ions, respectively. The column test results showed that APKS had a removal efficiency of 98.4% and 73.6 for Pb2+ and Cu2+ ions, respectively. The results also showed that both Langmuir and Freundlich adsorption isotherms were the best model for the adsorption of Cu2+ ions on APKS, with R2 of 0.997 and 0.97, respectively. The results also showed that APKS can be utilised to treat wastewater with Pb2+ and Cu2+ concentrations to meet the effluent discharge standards. The study recommends using activated palm kernel shells to remove heavy metals in wastewater before discharging them into the environment.