Introduction: Ethiopian leather industry wastewater often contains poisonous hexavalent chromium (Cr(VI)). The effectiveness of a novel low-cost biosorbent, synthesized by iron nanoparticle-modified Cordia africana sawdust with polyvinyl alcohol (FeNP-SD-PVA), for Cr(VI) removal was investigated in this research.
Methods: Composite FeNP-SD-PVA was prepared using chemical precipitation and characterized using SEM, FTIR, XRD, BET, and TGA. Batch experiments were performed to examine the influence of pH (3–8), initial concentration of Cr(VI) (21–47 mg/L), and contact time (10–120 min). Optimization was performed using response surface methodology (RSM). Desorption and reusability were examined with 0.1 mol/L HCL and NaOH.
Results: The improved adsorbent attained maximum removal efficiency of 97.57% and adsorption capacity of 2.29 mg/g under optimal parameters (pH 5.5, 47 mg/L, 120 min). The material exhibited high surface area (102.81 m²/g), mesoporosity, and thermal stability. The material was also found to possess good reusability, as only 9.52% capacity was lost in three cycles. Desorption was found to be most efficient with HCl, recovering 88% of the Cr(VI).
Conclusion: FeNP-SD-PVA is a promising green, recyclable adsorbent for the removal of Cr(VI) from industrial effluent. Its affordability, effectiveness, and magnetic recoverability make it the most promising candidate for tannery waste water treatment in Ethiopia and other developing nations.