Senthil Karuppanan

BACKGROUND: Hematite is a promising material for water purification owing to its visible‐light activity. This study presents a chemical‐free synthesis of hematite via thermal oxidation of naturally occurring magnetite, yielding a sustainable photocatalyst for the treatment of textile industrial wastewater for agricultural reuse. The synthesized hematite was comprehensively characterized to evaluate its physicochemical properties. RESULTS: Structural analysis confirmed the formation of crystalline hematite with a crystallite size of 64 nm. Morphological studies revealed agglomerated particles predominantly distributed within the 50–300 nm size range. Detailed microstructural characterization showed agglomerated particles composed of nanocrystalline domains of 10–20 nm, with an average particle size of 73 nm and distinct lattice fringes of 0.27 nm, confirming the polycrystalline and phase‐pure nature of hematite. Thermal analysis identified the optimal oxidation temperature required for complete phase transformation. Optical characterization revealed a band gap of 1.90 eV, indicating strong visible‐light photocatalytic potential. Vibrational analysis further supported the successful formation of crystalline hematite, while magnetic measurements confirmed its weak ferromagnetic behavior. The catalyst exhibited excellent degradation of malachite green (90%) and rhodamine B (82%) within 2 h, retaining 85% and 78% efficiency after five cycles. Scavenger quenching experiments revealed that superoxide radicals ( ^• O ₂ ⁻ ) were the dominant reactive species driving degradation. In real textile wastewater, 64% degradation was achieved under sunlight. Seed germination assays with treated water indicated nontoxic effects, confirming suitability for agricultural reuse. CONCLUSION: Overall, this work demonstrates an eco‐friendly, scalable route for producing high‐performance hematite catalysts from natural resources for sustainable environmental remediation. © 2026 Society of Chemical Industry (SCI).

Copper oxide/reduced graphene oxide (CuO:rGO) nanocomposites were synthesized through an eco‐friendly, cost‐effective, and time‐efficient green route using Myristica Fragrans Houtt (nutmeg) leaf extract as both reducing and capping agent. The presence of the (002) plane of rGO along with the reduced intensity of CuO peaks confirms the successful integration of CuO nanoparticles onto rGO layers. The absence of impurity peaks or phytochemical signals indicates the high purity of the nanocomposites and further validated by FTIR analysis. FESEM images show CuO forming large clusters of smaller spherical particles, while CuO:rGO images reveal nanoparticles anchored to rGO sheets, suggesting improved aggregation control. HRTEM analysis corroborates the structural and morphological findings. UV–Vis DRS spectra reveal a band gap reduction from 1.89 eV (CuO) to 1.64 eV (CuO:rGO), signifying enhanced optical charge transfer. PL analysis shows defect‐related peaks, which are advantageous for antibacterial activity. Agar well diffusion tests demonstrate superior antibacterial efficacy of CuO:rGO nanocomposites against bacterial pathogens including Escherichia coli ( E. coli ), Bacillus cereus ( B. cereus ), Bacillus subtilis ( B. subtilis ), Staphylococcus epidermidis ( S. epidermidis ), and Staphylococcus aureus ( S. aureus ), compared to pure rGO and CuO. These results highlight the strong potential of CuO:rGO nanocomposites in biomedical applications.

A simple co-precipitation method was used to create pure tungsten oxide (WO₃) nanoparticles using phthalic acid, citric acid, and oxalic acid as chelating agents. The influences of chelating agents on the structural, morphological, and optical properties were investigated. X-ray diffraction (XRD) patterns of WO₃ nanoparticles showed the existence of combined phase of anorthic-monoclinic for all the samples, and the crystalline size was found to be reduced while using oxalic acid. The vibrational band observed in the region around (500–800 cm⁻¹) in the FTIR spectra indicates the formation of WO₃ nanoparticles. SEM images revealed the formation of WO₃ agglomerates. The energy-dispersive X-ray (EDX) spectra of the WO₃ nanoparticles confirmed the purity of synthesized nanoparticles. The enhanced light-absorption ability of oxalic-acid-assisted WO₃ nanoparticles are inferred from the decreased band gap energy in UV–vis absorption spectra. The PL spectra showed emission in both the UV and visible regions. The optimized reaction parameters for obtaining high catalytic efficiency are identified by varying the concentrations of oxidant, catalyst, and dye during the catalytic reaction. The synthesized WO₃ nanoparticles exhibited better catalytic degradation of CV than MB and RB dyes even with the lesser quantity of catalyst material.