The removal of Cr(VI) from aqueous solution by almond green hull waste material: kinetic and equilibrium studies

Abstract

The discharge of industrial effluents containing hexavalent chromium into the environment can be very harmful to living things. Therefore, prior to effluent discharge into the environment, hexavalent chromium should be removed from contaminated water and especially from wastewaters. In the present work, almond green hull powder (AGHP) was investigated for the removal of hexavalent chromium from wastewater. The effects of pH (2–10), adsorbent dose (2–24 g L−1), Cr(VI) concentration (10–100 mg L−1), contact time (1–60 min), and temperature (5–50 °C) were studied. All the experiments were performed in triplicate and average results were reported. The surface morphology, pore volume and size, pH of zero point charge (pHZPC) and surface functional groups of AGHP were characterized. Isotherm and kinetic evaluations were also conducted in the present study. The results revealed that the adsorption of Cr(VI) by AGHP was an adsorbate, adsorbent, and temperature dependent process that was favorable under acidic conditions. Furthermore, AGHP absorbed over 99% of chromium from the solutions containing 10–100 mg L−1 of Cr(VI) based on the Freundlich model. In summary, hexavalent chromium was not found in almond kernel. Biosorption onto AGHP is an affordable and economical adsorption process for treating Cr(VI)-laden industrial wastewater.

Keywords

• adsorption
• almond green hull
• almond kernel
• biosorption
• hexavalent chromium
• industrial wastewater