ISSN 2360-7955
Abstract
Chromium pollution from tannery wastewater is a major concern for the environment and public health, especially for developing nations wherein the available treatment technologies do not prove effective and are expensive. Hexavalent chromium (Cr⁶⁺) is known for its toxic nature and high mobility and stability in water bodies. Notably, the identification and development of low-cost and efficient adsorbents for chromium pollution abatement in tannery wastewater is a pressing requirement. Cordia africana sawdust was utilised to develop adsorbent materials, namely raw sawdust (SD), acid functionalised sawdust (AMSD), and iron nanoparticle-loaded polyvinyl alcohol-coated sawdust (FeNP-SD-PVA). The real tannery wastewater, collected from Batu Tannery in Ethiopia, underwent pretreatment followed by characterisation for physicochemical parameters and chromium species. Adsorption experiments using a batch method were done to determine chromium removal capacity. Additionally, interference experiments, which involved selectively excluding dominant co-constituent ions as well as organic components, were done to determine their chromium adsorption effect. All experiments were performed in triplicate. Removal efficiencies of highest values of 90.29% ± 1.24% for Cr⁶⁺, 81.67% ± 1.08% for Cr³⁺, and 83% ± 1.15% for total chromium were shown by the FeNP-SD-PVA composite. Moderate effectiveness of AMSD and poor adsorbing capacity of raw sawdust were observed with lower sensitivities towards interference ions. Robust resistances towards interference ions and high efficiencies were found in the case of the FeNP-based adsorbent. Statistical analysis (one-way ANOVA) confirmed significant differences among adsorbents (p < 0.05). The outcomes of this study show the effectiveness of iron nanoparticle-modified Cordia africana sawdust for the removal of chromium from tannery wastewater. This method has shown promise for being a feasible option for the treatment of tannery wastewater.
Keywords: Chromium, Wastewater, Adsorption, Nanoparticles, Public Health