Synthesis, characterization and investigation of photocatalytic activity of ZnFe2O4@MnO–GO and ZnFe2O4@MnO–rGO nanocomposites for degradation of dye Congo red from wastewater under visible light irradiation

Eco-benevolent synthesis of ZnO-NPs and ZnO-MFs from Inula oculus-christi L. (Asteraceae) with effective antioxidant, antimicrobial, DNA cleavage, and decolorization efficiencies

As a result of the changes occurring globally in recent years, millions of people are facing challenging and even life-threatening diseases such as cancer and the COVID-19 pandemic, among others. This phenomenon has spurred researchers towards developing and implementing innovative and environmentally friendly scientific methods, merging disciplines with significant technological potential, such as nanotechnology with medicinal plants. Therefore, the focus of this research is to synthesize zinc nanoparticles (ZnO-NPs) and microflowers (ZnO-MFs) using extracts of the medicinal plant I. oculus christi prepared in n-hexane and methanol as new bioreduction and capping agents through a simple and environmentally friendly chemical approach. Optical, thermal, and morphological structural analyses of ZnO-NPs and ZnO-MFs were conducted using Ultraviolet-Visible (UV-Vis) spectroscopy, Fourier Transform Infrared (FT-IR) spectroscopy, Thermogravimetric Analysis (TGA), and Field Emission Scanning Electron Microscopy (FE-SEM). Metabolic profiles of extracts from different plant parts were analyzed using Gas Chromatography-Mass Spectrometry (GC-MS) and supported by visualization of contents through Principal Component Analysis (PCA), hierarchical cluster analysis heatmaps, and Pearson correlation graphs. Interestingly, ZnO-NPs and ZnO-MFs exhibited strong antioxidant properties and demonstrated particularly potent antimicrobial activity against Micrococcus luteus NRRL B-4375, Escherichia coli ATCC 25922, and Candida albicans ATCC 10231 strains compared to standard antibiotics. Furthermore, ZnO-NPs and ZnO-MFs showed excellent plasmid DNA-cleavage activity of pBR322 with increasing doses. The photocatalytic performance of the synthesized ZnO-NPs and ZnO-MFs was evaluated for methylene blue (MB), congo red (CR), and safranin-O (SO) dyes, demonstrating remarkable color removal efficiency. Overall, the results provide a promising avenue for the green synthesis of ZnO-NPs and ZnO-MFs using I. oculus-christi L. inflorescence and pappus extracts, potentially revolutionizing biopharmaceutical and catalytic applications in these fields.

One-step preparation, characterization, and anticancer potential of ZnFe2O4/RGO nanocomposites

Zinc ferrite nanoparticles (ZnFe2O4 NPs) have attracted extensive attention for their diverse applications including sensing, waste-water treatment, and biomedicine. The novelty of the present work is the fabrication of ZnFe2O4/RGO NCs by using a one-step hydrothermal process to assess the influence of RGO doping on the physicochemical properties and anticancer efficacy of ZnFe2O4 NPs. X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy-dispersive X-ray(EDX), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), UV-vis spectroscopy, and Photoluminescence (PL) spectroscopy were employed to characterize prepared pure ZnFe2O4 NPs and ZnFe2O4/ RGO NCs. XRD results showed that the synthesized samples have high crystallinity. Furthermore, the average crystal sizes of ZnFe2O4 nanoparticles (NPs) and ZnFe2O4/RGO nanocomposites (NCs) were 51.08 nm and 54.36 nm, respectively. SEM images revealed that pure ZnFe2O4 NPs were spherical in shape with uniformly loaded on the surface of the RGO nanosheet. XPS and EDX analysis confirmed the elemental compositions of ZnFe2O4/RGO NCs. Elemental mapping of SEM shows that the elemental compositions (Zn, Fe, O, and C) were homogeneously distributed in ZnFe2O4/RGO NCs. The intensity of FT-IR spectra depicted that pure ZnFe2O4 NPs were successfully anchored into the RGO nanosheet. An optical study suggested that the band gap energy of ZnFe2O4/RGO NCs (1.61 eV) was lower than that of pure ZnFe2O4 NPs (1.96 eV). PL spectra indicated that the recombination rate of the ZnFe2O4/ RGO NCs was lower than ZnFe2O4 NPs. MTT assay was used to evaluate the anticancer performance of ZnFe2O4 /RGO NCs and pure ZnFe2O4NPs against human cancer cells. In vitro study indicates that ZnFe2O4 /RGO NCs have higher anticancer activity against human breast (MCF-7) and lung (A549) cancer cells as compared to pure form ZnFe2O4 NPs. This work suggests that RGO doping enhances the anticancer activity of ZnFe2O4NPs by tuning its optical behavior. This study warrants future research on potential therapeutic applications of these types of nanocomposites.

Microplastic contaminants in the aqueous environment, fate, toxicity consequences, and remediation strategies

Microplastic is a fragmented plastic part that emerges as a potential marine and terrestrial contaminant. The microplastic wastes in marine and soil environments cause severe problems in living systems. Microplastic wastes have been linked to various health problems, including reproductive harm and obesity, plus issues such as organ problems and developmental delays in children. Recycling plastic/microplastics from the environment is very low, so remediating these polymers after their utilization is of paramount concern. The microplastic causes severe toxic effects and contaminates the environment. Microplastic affects marine life, microorganism in soil, soil enzymes, plants system, and physicochemical properties. Ecotoxicology of the microplastic raised many questions about its use and development from the environment. Various physicochemical and microbial technologies have been developed for their remediation from the environment. The microplastic effects are linked with its concentration, size, and shape in contaminated environments. Microplastic is able to sorb the inorganic and organic contaminants and affect their fate into the contaminated sites. Microbial technology is considered safer for the remediation of the microplastics via its unique metabolic machinery. Bioplastic is regarded as safer and eco-friendly as compared to plastics. The review article explored an in-depth understanding of the microplastic, its fate, toxicity to the environment, and robust remediation strategies.

Mitigation of environmentally hazardous pollutants by magnetically responsive composite materials

At present, environmental contamination has become an emerging issue among researchers. These facts are due to the adverse impacts of an alarming number of recalcitrant contaminants that can affect both humans and animals. There is an urgent need to develop eco-friendly approaches to mitigate the effects of toxic pollutants from the environment. Magnetically responsive composite-based sorbents are very interesting and popular materials for pollutant abatement owing to the high specific surface area, superior adsorption capacity, and magnetic properties, which make their easy separation from sample solution/media. In this review article, we discuss various synthesis approaches, key physicochemical properties, and applications of magnetic composites for pollutant removal. Current gaps for coping with contamination are identified, and a comprehensive outlook in pollutant treatment using magnetic composites is outlined. This study unveils new horizons to researches for better understanding the properties of magnetically-composite-based sorbents and their application in environmental remediation.

ZnFe2O4-chitosan magnetic beads for the removal of chlordimeform by photo-Fenton process under UVC irradiation

A simple protocol was proposed for the preparation of magnetic chitosan beads ZnFe₂O₄-CS via a co-precipitation method. The use of synthesized magnetic ZnFe₂O₄-CS beads as catalyst for the heterogeneous photo-Fenton treatment of chlordimeform insecticide (CDM) was evaluated. The photo-Fenton experiments were carried out with different synthesized catalysts by varying the molar ratio Zn/Fe in chitosan beads, the catalyst concentration and pH. Under optimal conditions using 1 g of ZnFe₂O₄-CS beads with a molar ratio Zn/Fe = 0.35 and at pH_initial = 3, a real wastewater doped with 20 mg L^-1 of CDM was treated and complete removal of the insecticide was achieved after 7 min with a total TOC removal after 2 h of treatment. The generated carboxylic acids and ions during the photo-Fenton process were identified and quantified. The stability of the photocatalytic activity of the best catalyst in terms of pollutant removal, ZnFe₂O₄-CS(0.35) beads with a molar ratio Zn/Fe equal to 0.35, was satisfactory validated by four consecutive cycles. This optimal catalyst was characterized, before and after use, by Scanning Electron Microscopy/Energy Dispersive X-Ray Spectroscopy, X-Ray Powder Diffraction and Vibrating Sample Magnetometry analysis.