Ying-Chin Lim

1. The widespread and indiscriminate use of antibiotics in both human medicine and animal farming has led to the pervasive contamination of aquatic environments [1]. This contamination perturbs mic...

This study reports an HF-free dry-gel conversion route to synthesise MIL-100(Fe) and evaluate its performance for adsorptive removal of salicylic acid from wastewater. Comprehensive characterisation of the material was conducted using XRD, FT-IR, FESEM and zeta potential. The dry gel conversion method successfully produced MIL-100(Fe) with an amorphous structure with an average particle size of 27 μm. Adsorption experiments achieved a maximum salicylic acid removal efficiency of 82.62% across the tested range (10 to 50 µg/mL), corresponding to an adsorption capacity of 80.93 mg/g at 120 minutes. Significant reductions in FT-IR peaks associated with carboxylic acid O–H stretching vibrations were observed, particularly in regions 3600 to 4000 cm−1 and 2500 to 3600 cm−1. These changes indicate strong interactions between the carboxyl groups of salicylic acid and the active sites on the MIL-100(Fe) surface, confirming effective adsorption and removal of salicylic acid. These findings demonstrate that MIL-100(Fe) synthesised through a hydrofluoric acid-free dry gel conversion route is an effective and environmentally benign adsorbent for the removal of pharmaceutical pollutants from wastewater.

Developing an effective, reusable photocatalyst that combines high photocatalytic efficiency with easy separation could significantly enhance the removal of organic pollutants. This study developed reusable photocatalysts by integrating TiO₂ with biomass-derived activated carbon (AC) and magnetite (Fe₃O₄) to enhance the removal of methylene blue (MB), acetaminophen (ACT), and their mixtures. Advanced microscopic and spectroscopic techniques, including FE-SEM, EDX, TEM, FTIR, XRD, and BET, were applied to identify the physicochemical properties of the composites. Both TiO₂/AC-10% (436 m²/g) and TiO₂/AC/Fe₃O₄ (494 m²/g) exhibited high surface areas, suggesting a significant abundance of active sites for pollutant degradation. Optimization of operational parameters, including pollutant concentration, irradiation time, and composite dosage, was conducted via response surface methodology (RSM) with a Box-Behnken design (BBD), using TiO₂/AC-10%. Under optimized conditions, MB and ACT removal reached 98.37% and 87.28%, respectively within 120 min. The TiO₂/AC/Fe₃O₄ composite maintained high efficiency over five reuse cycles. These waste-derived, magnetically separable photocatalysts offer a sustainable, efficient solution for organic pollutant removal in wastewater treatment. Graphical Abstract

The widespread use of hazardous chemicals in traditional methods for synthesizing silver-doped titanium dioxide (Ag-TiO2) nanocomposites poses significant environmental and health concerns, contradicting the goal of sustainable photocatalytic water purification. This study aims to develop a microwave-assisted green synthesis method using plant waste-based material, Allium cepa (onion) peel extract, a readily available material, to deposit silver onto TiO2 with the goal enhancing its photocatalytic and antibacterial properties. The prepared Ag-TiO2 nanocomposite was applied to remove single and mixed dyes. Characterization techniques confirmed the formation of stable Ag-TiO2 nanocomposite with an average size of 7.36 ± 2.01 nm evenly deposited onto TiO2, resulting in improved responsiveness in the visible light region. UV-Vis diffuse reflectance spectroscopy and photoluminescence analysis indicated a reduction in the band gap for Ag-TiO2 nanocomposite. The green-synthesized Ag-TiO2 nanocomposite exhibits exceptional photocatalytic efficiency in degrading both cationic dyes and anionic Congo red and methylene blue dyes with a degradation rate of 99.4% and 99.6% individually under UV irradiation. In a mixed dye solution, the degradation of rhodamine B and methyl orange dyes was significantly accelerated due to the selective interaction of the Ag-TiO2 nanocomposite with anionic dyes. The green synthesized Ag-TiO2 nanocomposite also showed effective antibacterial properties against Gram-positive bacteria, E. coli and Gram-negative bacteria, S. aureus. This study stresses the capability of green synthesis to generate environmentally benign and high-performing photocatalysts for water treatment applications, effectively degrading contaminants and eradicating undesirable waterborne pathogens.

Tetracycline (TC), a widely used antibiotic, is increasingly detected in wastewater, posing a significant environmental and health risk. Zinc oxide nanoparticles are emerging as a promising photocatalyst for TC photodegradation due to their low cost and superior light absorption capabilities at room temperature compared to the widely used titanium dioxide (TiO2). This study explores the efficacy of hydrothermally synthesized ZnO nanoparticles in degrading TC. The photocatalytic degradation efficiency of ZnO was examined under controlled batch conditions by varying parameters like ZnO dosage (0.5-2.5 g/L), TC concentration (5-25 ppm), and light source (solar, visible, and UV). The result showed that the highest TC removal efficiency (70.17%) was achieved under UV light with 1 g/L ZnO for a 5 ppm TC solution. The synthesized ZnO nanoparticles showed excellent reusability, highlighting their potential as a cost-effective and sustainable approach for TC degradation in wastewater treatment applications.