Spectroscopy and visible-light driven photocatalytic properties of a microcrystalline Cu-complex derived from a novel Gabapentin Schiff base

A novel Gabapentin derivative Schiff base Gasa was synthesized by condensing Gabapentin with salicylaldehyde, which was further coordinated with Cu2+ in methanol to give a microcrystalline Cu(II) complex Cu(Gasa)2. The synthesized Gasa and Cu(Gasa)2 were further characterized by single-crystal X-ray diffraction, scanning electron microscopy (SEM), as well as the FT-IR, Raman, electronic and fluorescence spectra. Cu(Gasa)2 exhibited excellent visible-light driven photocatalytic activities in removal of Congo red (CR) and Methylene blue (MB) dyes from aqueous solution in the presence of H2O2 as oxidant. It was revealed that ∙OH radicals played the most important role in the photodegradation processes of organic dyes, and the photodegradation of CR and MB fitted well with the pseudo-first-order kinetic model. In addition, solid state luminescent properties of Gasa and Cu(Gasa)2 were also studied in detail.

Highly efficient visible light active ZnO/Cu-DPA composite photocatalysts for the treatment of wastewater contaminated with organic dye

Industrial effluents are a leading major threat for water contamination, subsequently which results in severe health associated risks. Hence, purifying wastewater before releasing into the water resources is essential to avoid contamination. In this study, ZnO/Cu-DPA nano-composites were prepared by altering the percentage of Cu-DPA (20%, 30%, 40%, and 50% which are denoted to be ZnO/20%Cu-DPA, ZnO/30%Cu-DPA, ZnO/40%Cu-DPA and ZnO/50%Cu-DPA) using a simple mechanical grinding process. Several spectroscopic studies were employed such as electron paramagnetic analysis (EPR), powdered X-ray diffractometer (PXRD), UV-Vis absorbance spectroscopy, Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscope to characterize these nano-composites. The photo-catalytic activities of the prepared nano-composites were studied by degrading MB under visible light irradiation. ZnO, ZnO/20%Cu-DPA, ZnO/30%Cu-DPA, ZnO/40%Cu-DPA and ZnO/50%Cu-DPA degradation efficiencies were determined to be 71.8, 78.5, 77.1, and 66.1%, respectively. Among the composite catalysts, the ZnO/20%Cu-DPA coupled system are demonstrated the best efficiency (87%) for photo-degradation of MB within 80 min when exposed to visible light. The ZnO/Cu-DPA nano-composites had a greater MB photodegradation efficiency than pristine ZnO owing to p-n heterojunction in the linked system. Under visible light irradiation, the ZnO/20%Cu-DPA catalysed the conversion of dissolved O2 to hydroxyl radicals (OH·), triggering the reduction of MB. This suggests that ·OH is the primary specific active radical involved in the photo-catalytic decomposition of MB. Furthermore, EPR analysis indicates the existence of ·OH in the photo-catalytic system. The proposed nano-composites (ZnO/20%Cu-DPA) reusability was investigated across three cycles as the most efficient photo-catalyst. The results show that, the ZnO/Cu-DPA nano-catalyst is a potential candidate for the remediation of dirty water.

Photocatalytic remediation of methylene blue and antibacterial activity study using Schiff base-Cu complexes

This work describes the design of novel Cu(II) complexes and their application in the photocatalytic degradation of methylene blue (MB). The same photocatalyst exhibits antibacterial activity against Escherichia coli (gram-negative) and Bacillus circulans (gram-positive). The characterisation of the photocatalysts has been done by several up-to-date physical methods. The rationale behind the photocatalysts' beneficial intervention is discussed in this study. Statistical analysis of the degradation of MB is done using a one-way ANOVA, and the significance of means is determined by a multiple comparison test using Turkey HSD. Also, the degradation of MB follows pseudo first-order kinetics with high correlation coefficient values (R² > 0.95), making them useful as simple and low-cost organic dye degradation agents.