From Waste to Value: Recycling Industrial Waste into Functional ZnO Nanofibers

This study details the sustainable synthesis and characterization of electrospun zinc oxide nanofibers, uniquely derived from industrial waste streams. Our approach leverages diverse industrial byproducts—specifically sal ammoniac skimming from hot-dip galvanizing, electric arc furnace dust, and galvanization flue dust—as sustainable raw materials. Following hydrometallurgical treatment with various leaching agents (HCl, (NH4)2CO3, or H2SO4) to obtain zinc-rich leachates, electrospinning solutions were formulated. The resulting fibers were subsequently calcined, yielding three distinct ZnO-based materials. Comprehensive characterization by XRD, SEM-EDX, and TEM revealed that the choice of leaching strategy significantly influenced the resultant fibers’ morphology and chemical composition. To demonstrate the potential applicability of these waste-derived materials, their photocatalytic activity was assessed through the degradation of methylene blue dye under UVA irradiation. ZnO fibers derived from HCl leaching exhibited remarkable photodegradation capabilities, achieving nearly complete dye removal within 690 min at optimal catalyst-to-dye ratios. Conversely, the H2SO4-prepared sample displayed impaired efficiency, primarily due to the formation of an undesirable Al2ZnO4 phase stemming from high aluminum content in the input waste, a critical consideration for waste-to-product strategies. The results showed that the cost-effective ZnO fibers obtained by electrospinning from industrial waste products have potential for applications in photocatalytic water treatment.