Diana Vanda Wellia

Mg-doped ZnFe₂O₄ spinel ferrite nanoparticles (MgxZn1-xFe2O4, x = 0.1–0.3) were synthesized via a sago-starch-assisted sol–gel autocombustion method and evaluated for solar-driven photocatalytic degradation of ciprofloxacin and tetracycline antibiotics. Comprehensive characterization using XRD, FTIR, Raman spectroscopy, TGA, SEM-EDS, TEM, VSM, UV–Vis DRS, and BET confirmed the formation of single-phase spinel structures with tunable physicochemical properties. The materials exhibited superparamagnetic behavior with saturation magnetization values of 11.9–19.6 emu g⁻¹, enabling facile magnetic recovery. Optical analysis revealed visible-light absorption with band gap energies in the range of 1.45–1.67 eV. Morphological observations by SEM and TEM revealed relatively uniform nanoparticles ranging from 15 to 45 nm in size. Among the compositions, MgxZn1-xFe2O4 (x = 0.25) demonstrated superior photocatalytic performance, achieving about 85% degradation of ciprofloxacin and 70% degradation of tetracycline within 120 min under solar irradiation. The enhanced activity is attributed to the synergistic effects of reduced crystallite size, increased surface area, and improved charge separation, which facilitate the generation of reactive oxygen species. The integration of Mg substitution with a sago-starch-mediated green synthesis route offers an environmentally benign approach to producing efficient, magnetically recoverable photocatalysts. These findings highlight the potential of Mg-modified ZnFe2O4 for sustainable treatment of antibiotic-contaminated wastewater.

This research focuses on enhancing hydrogen production via the photocatalytic method using a TiO2 catalyst with nitrogen doping and morphology modification to improve efficiency. Nitrogen-doped TiO2 nanowires (NTN) were successfully hydrothermally grown on titanium foil to produce thin-film photocatalysts for the visible-light-driven production of hydrogen. Nitrogen incorporation induced bandgap narrowing, from 3.18 eV to 2.85 eV, by introducing N 2p states close to the valence band, thereby increasing visible-light absorption. Structural analyses confirmed the formation of lattice strain and oxygen vacancies associated with substitutional doping, while the one-dimensional nanowire architecture enhanced charge transport and reduced carrier recombination pathways. The optimized N–TiO2 NWs demonstrated the highest hydrogen evolution rate of 2.385 µmol/cm2 under 180 minutes of visible-light irradiation, corresponding to a hydrogen evolution rate of 0.795 µmol/cm²/h, without a noble-metal co-catalyst. A strong correlation is established between nitrogen-induced surface electronic modification and the enhancement of nanowire-driven charge separation. This study presents a recyclable and scalable thin-film photocatalyst design suitable for future solar hydrogen production systems. Copyright © 2026 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Microplastic pollution presents a significant challenge globally, posing serious threats to aquatic ecosystems. This study explores the photocatalytic degradation of microplastics in aqueous solutions by applying nitrogen-doped TiO2 (N-TiO2) nanoparticles under visible light. The N-TiO2 nanoparticles were synthesized via the solvothermal method, utilizing chitosan derived from shrimp shell waste as a nitrogen source. The photocatalytic efficacy of the N-TiO2 nanoparticles was assessed for degrading model polyethylene microplastics, illuminated by a 50-watt LED lamp. Characteristic peak shifts in the FTIR absorption spectrum, notably at 3429 cm-1 to lower wavenumbers, and diminished amide I absorption at 1621 cm-1, confirmed the successful extraction of chitosan from shrimp shell waste. The synthesized N-TiO2 nanoparticles were in the pure anatase phase, exhibited a reduced bandgap of 2.97 eV, and showed enhanced absorption in the visible light spectrum (λ=400 – 800 nm) compared to undoped TiO2. The incorporation of nitrogen into the TiO2 matrix was validated by vibration bands at approximately 1035 cm-1 and 535 cm-1, corresponding to the Ti—N and Ti—O—Ti bonds, respectively. Optimal results were attained with TiO2 nanoparticles doped with 50% nitrogen, achieving a degradation rate of approximately 30.45% of a 250 mg/L microplastic solution over 50 hours of visible light exposure—nearly six times more effective than undoped TiO2. This study highlights the sustainable use of shrimp shell waste as a nitrogen source for enhancing TiO2 nanoparticles, showcasing their potential for environmental remediation applications.