Effect of Europium, Yttrium and Lutetium Doping on the Photocatalytic Property of CeO 2 Nanoparticles in the Reduction of p‐nitrophenol under Visible Light

4-Nitrophenol reduction and antibacterial activity of Ag-doped TiO2 photocatalysts

Water contamination by organic pollutants is a serious environmental problem. 4-Nitrophenol (4-NP) is a potentially harmful chemical, which is commonly present in industrial effluents and can severely damage human health. Photocatalytic reduction of hazardous 4-NP by nano-sized materials to produce 4-aminophenol (4-AP), which is a commercially valuable product, is a promising alternative as the process is framed within the circular economy. In this context, Ag-doped TiO2 (AT) catalysts were synthesized by liquid impregnation and reduction techniques, and their structure, morphology, elemental composition, textural, and light absorption properties were evaluated by XRD, Raman spectroscopy, SEM, TEM, EDS, BET, and DRS spectroscopy. AT catalysts exhibited an enhanced photocatalytic reduction of 4-NP into 4-aminophenol (4-AP) in the presence of NaBH4. Among the tested catalysts, AT21 prepared by a simple aqueous reduction method showed the highest activity reaching about 98% 4-NP reduction within 10 min. Antibacterial tests of these catalysts against Bacillus subtilis, Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa revealed that AT21 also exhibited the lowest minimum inhibitory concentration, suggesting that it has the strongest antibacterial activity. These findings suggest that AT21 catalyst with improved catalytic and antibacterial properties can potentially be utilized for the remediation of 4-NP-contaminated water environment.

Facile synthesis of green and efficient magnetic nanocomposites of carrageenan/copper for the reduction of nitrophenol derivatives

A green and facile method for preparation of Kappa-Carrageenan or Iota-Carrageenan grafted N,N'-methylenebisacrylamide/Fe₃O₄/Cu nanoparticles (κC-g-MBA/MNPs/Cu and ιC-g-MBA/MNPs/Cu) catalysts was developed to place copper on a magnetic carrageenan surface. The structure and morphology of the prepared catalysts were identified using FT-IR, XRD, BET, VSM, TGA, EDX, mapping, FE-SEM, TEM, and ICP-OES analyses. The catalytic activity of the catalysts was investigated to reduce 4-nitrophenol, 2-nitrophenol, 3-nitroaniline, and 4-nitroaniline compounds using the UV-Vis spectrum. To reduce 4-nitrophenol using κC-g-MBA/MNPs/Cu and ιC-g-MBA/MNPs/Cu, the rate constants (K_app) obtained were 0.37 and 0.25 min^-1, and the activity factors (k') were 134 and 193 s^-1 g^-1, respectively. The catalysts had a good performance in reducing the nitrophenol compounds and due to the magnetic properties of the catalysts, they could easily be separated and used multiple times.