An eco-friendly approach to textile and tannery wastewater treatment using maghemite nanoparticles (γ-Fe2O3-NPs) fabricated by Penicillium expansum strain (K-w)

[Display omitted] •For the first time, γ-Fe2O3-NPs was bio-fabricated using Penicillium expansum.•Characterization of γ-Fe2O3-NPs was accomplished by FT-IR, XRD, TEM, DLS, and XPS.•γ-Fe2O3-NPs exhibit high efficacy in crude textile effluent treatment with 89 % dye removal.•NPs exhibit removal % of 86.8, 71.8, and 89.3 for COD, TDS, and TSS, respectively.•γ-Fe2O3-NPs treated tannery effluent showed high efficacy for heavy metals removal. Wastewater treatment is one of the vital solutions to the global water shortage and many related environmental problems. The present study aimed at biosynthesizing maghemite nanoparticles (γ-Fe2O3-NPs) using Penicillium expansum (K-w) for the purpose of wastewater treatment. The γ-Fe2O3-NPs resultant was characterized using fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), transmission electron microscope (TEM), dynamic light scattering (DLS), and X-ray photoelectron spectroscopy (XPS). The maghemite nanoparticles capacity to mediate decolorization and degradation of textile and tanning wastewater effluents was investigated. Results verified that the successful synthesis of spherical shaped Fe2O3-NPs of 15.0–66.0 nm size, with XRD peaks that match the cubic structure of the γ-Fe2O3. XPS analysis confirmed the presence of iron as Fe2O3. Decolorization and degradation analyses indicated that γ-Fe2O3-NPs are effective biocatalysts for dye degradation under dose- and time-dependent manner. The highest decolorization gain (89 %–90 %) occurred after 6.0–8.0 h of incubation at 1.0 mg mL-1 of γ-Fe2O3-NPs. Quality of the treated textile wastewater was improved, as indicated by the reduction in chemical oxygen demand (COD), total dissolved solids (TDS), and total suspended solids (TSS) by 86.8, 71.8, and 89.3 %, respectively. GC–MS results showed the complete disappearance or reduction of peaks, or peak areas in treated textile wastewater in comparison with the untreated samples. In addition, treatment of tanning wastewater with γ-Fe2O3-NPs has also resulted in decolorization, as well as reduction in COD, TDS, and TSS levels by 93.1, 40.5, and 95.9 %, respectively. The treated tanning wastewater showed low heavy metal levels, with removal percentages ranging from 66 %–98 % for Co, Cr, Pb, Ni, and Cd, indicating the high efficiency of γ-Fe2O3-NPs in improving treated wastewater quality.