Photocatalytic degradation of Rhodamine B using green-synthesized ZnO nanoparticles from Sechium edule polysaccharides

Peumus boldus Used in the Synthesis of ZnO Semiconductor Nanoparticles and Their Evaluation in Organic Contaminants

The high demand for nanomaterials in the field of industry and science has forced researchers to develop new synthesis methods that are more efficient, economical, and environmentally friendly. At present, the application of green synthesis has taken a great advantage over conventional synthesis methods because it helps with the control of the characteristics and properties of the resulting nanomaterials. In this research, ZnO nanoparticles (NPs) were synthesized by biosynthesis using dried boldo (Peumus boldus) leaves. The resulting biosynthesized NPs had a high purity, quasi-spherical shape with average sizes ranging from 15 to 30 nm and a band gap of ~2.8-3.1 eV. These NPs were used in the photocatalytic activity of three organic dyes. The results showed degradation of 100% methylene blue (MB) in 180 min, 92% methyl orange (MO) in 180 min, and 100% Rhodamine B (RhB) in 30 min of exposure. These results show that the Peumus boldus leaf extract is effective in the biosynthesis of ZnO NPs with good photocatalytic properties.

Preparation of gallotannin loaded chitosan/zinc oxide nanocomposite for photocatalytic degradation of organic dye and antibacterial applications

Chitosan functionalization is a growing field of interest to enhance the unique characteristics of metal oxide nanoparticles. In this study, a facile synthesis method has been used to develop a gallotannin loaded chitosan/zinc oxide (CS/ZnO) nanocomposite. Initially, white color formation confirmed the formation, and physico-chemical natures of the prepared nanocomposite were examined using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). Crystalline of CS amorphous phase and ZnO patterns were demonstrated by XRD. FTIR revealed the presence of CS and gallotannin bio-active groups in the formed nanocomposite. Electron microscopy study exhibited that the produced nanocomposite had an agglomerated sheets like morphology with an average size of 50-130 nm. Further, the produced nanocomposite was assayed for methylene blue (MB) degradation activity from aqueous solution. After 30 min of irradiation, the efficiency of nanocomposite degradation was found to be 96.64 %. Moreover, prepared nanocomposite showed a potential and concentration-dependent antibacterial activity against S. aureus. In conclusion, our findings revealed that prepared nanocomposite can be used as an excellent photocatalyst as well as a bactericidal agent in industrial and clinical sectors.

Construction of SnO2/CuO/rGO nanocomposites for photocatalytic degradation of organic pollutants and antibacterial applications

Water contamination by reactive dyes is a serious concern for human health and the environment. In this study, we prepared high efficient SnO₂/CuO/rGO nanocomposites for reactive dye degradation. For structural analysis of SnO₂/CuO/rGO nanocomposites, XRD, UV-Vis DRS, SEM, TEM-EDAX, and XPS analysis were used to characterize the physicochemical properties of the material. The characterization results confirmed great crystallinity, purity, and optical characteristics features. For both Rhodamine B (RhB) and Reactive Red 120 (RR120) degradation processes, SnO₂/CuO/rGO nanocomposites were tested for their photocatalytic degradation performance. The SnO₂/CuO/rGO nanocomposites have expressed the degradation rate exposed to 99.6% of both RhB and RR120 dyes. The main reason behind the photocatalytic degradation was due to the formation of OH radical's generation by the composite materials. Moreover, the antibacterial properties of synthesized SnO₂/CuO/rGO nanocomposites were studied against E. coli, S. aureus, B. subtilis and P. aeroginosa and exhibited good antibacterial activity against the tested bacterial strains. Thus, the synthesized SnO₂/CuO/rGO nanocomposites are a promising photocatalyst and antibacterial agent. Furthermore, mechanisms behind the antibacterial effects will be ruled out in near future.

Chitosan functionalized bismuth oxychloride/zinc oxide nanocomposite for enhanced photocatalytic degradation of Congo red

The industrial discharge of dye pollutant contaminated wastewater is the major cause of water and soil pollution. Photocatalysis is a promising and green remediation technology, which has received widespread attention in the remediation of hazardous dyes from aqueous environment and convert them into harmless compounds. Herein, we report the synthesis of chitosan (CS) functionalized bismuth oxychloride/zinc oxide (BiOCl/ZnO) nanocomposite by a modified hydrothermal route. The physiochemical characterization revealed that the synthesized nanocomposite have crystalline, agglomerated spherical along with rod shaped morphology and size range from 35 to 160 nm. FTIR peaks at 825, 727, 662 and 622 cm^-1 specified the presence of BiO and ZnO bonds, whereas peak at 1635 cm^-1 revealed the existence of amine groups which confirms the presence of CS in the synthesized CS-BiOCl/ZnO nanocomposite. Catalytic property of synthesized nanocomposite was evaluated by the degradation of Congo red (CR) under UV-light irradiation. CR dye degradation percentage was found to be 93 % within a short period of 40 min by utilizing UV-light. Furthermore, reusability of CS-BiOCl/ZnO photocatalyst was also investigated, and it remained significant photocatalytic activity after three consecutive cycles. Hence, the results obtained in this study revealed that CS-BiOCl/ZnO nanocomposite can be used as a potential photocatalyst to remediate organic pollutants in various industries.

Comparative Study of SnO2 and ZnO Semiconductor Nanoparticles (Synthesized Using Randia echinocarpa) in the Photocatalytic Degradation of Organic Dyes

Symmetry in nanomaterials is essential to know the behavior of their properties. In the present research, the photocatalytic properties of SnO2 and ZnO nanoparticles were compared for the degradation of the cationic dyes Methylene Blue (MB) and Rhodamine B (RB). The nanoparticles were obtained through a green synthesis process assisted by Randia echinocarpa extracts; they were then analyzed through Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) to characterize their structure. Transmission electron microscopy (TEM) was used to identify the morphology and disclose nanoparticle size, and the optical properties were studied through Ultraviolet–visible spectroscopy (UV–Vis). The results show that the synthesized SnO2 and ZnO nanomaterials have quasispherical morphologies with average sizes of 8–12 and 4–6 nm, cassiterite and wurtzite crystal phases, and band gap values of 3.5 and 3.8 eV, respectively. The photocatalytic activity yielded 100% degradation of the MB and RB dyes in 210 and 150 min, respectively. ZnO performed higher photocatalytic degradation of the cationic dyes than SnO2 due to a higher content of Randia echinocarpa extracts remaining after the green synthesis process.

Photocatalytic Activity of Orchid-Flower-Shaped ZnO Nanoparticles, toward Cationic and Anionic Dye Degradation under Visible Light, and Its Anti-Cancer Potential

Orchid-flower-shaped ZnO nanomaterials were successfully synthesized via green synthesis and an eco-friendly approach using an aqueous extract of Lycium chinense fruit as a reducing and capping agent. The synthesized Lycium chinense orchid-flower-shaped ZnO (LC-ZnO/OF) nanoparticles (NPs) were characterized using different analytical methods through X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), photoelectron spectroscopy (XPS), and photoluminescence (PL). The FE-TEM analysis revealed the orchid flower shape of the nanoparticles, and the elemental composition was confirmed via XPS analysis. The photocatalytic activity of the nanoparticles was determined by the degrading cationic dye methylene blue (MB) and the anionic dye Eosin Y (EY) under visible light irradiation at (400 w) within 180 min time, where it showed a significant ability to degrade both cationic and anionic dye by almost 50%. The LC-ZnO/OF photocatalyst was also used to check the toxicity level in human cancer cells, where it exhibited remarkable cytotoxicity to the human lung cancer (A549 cell line) and human gastric adenocarcinoma hyperdiploid (AGS cell line). The present investigation suggests that LC-ZnO/OF has the potential photocatalytic ability to degrade toxic dye as well as have anti-cancer effects. These preliminary results suggest that LC-ZnO/OF could have a significant impact on the environmental and biomedical fields.