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Due to the dearth of extremely capable, sensitive, and stable catalysts, the efficient detection and catalytic removal of 4-nitrophenol (4-NP) in industrial wastewater remains a serious challenge. The detection and determination of 4-nitrophenol (4-NP) presence in the environment is a matter of paramount importance because it is a high-priority hazardous pollutant that can affect people, animals, and plants. Here, we present a promising and economically viable green synthetic route for fabricating CuFe2O4 and CuFe2O4@Ag hybrid nanocomposites from the leaf extract of Senna didymobotrya. The UV–Vis, FTIR, XRD, FE-SEM, EDXA, BET and VSM analysis were performed to characterize the synthesis of CuFe2O4@Ag nanocomposite. To evaluate the electrocatalytic capacity of CuFe2O4@Ag, electrochemical sensing stratergy was performed with cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The modified CuFe2O4@Ag glassy carbon electrode (GCE) (CuFe2O4@Ag/GCE) demonstrated a linear response in the range of 0.01-15 μg/ml (71 nm-107 μM) and the ability to detect 4-NP at low concentration (0.006 μg/ml (43 nM)). Due to the increased surface area of CuFe2O4@Ag/GCE by ̴ 1.5-fold, a greater cathodic current response (-16 μA/cm2) at a low potential of -0.81 V was observed compared to CuFe2O4/GCE alone for the detection of 4-NP. Additonally, CuFe2O4@Ag showed excellent reduction ability towards 4-NP using NaBH4 with an efficiency of 96.4 % which was higher than the CuFe2O4 (only 87.3 %) in 12 min due to the synergistic relationship among Ag NPs and CuFe2O4 nanostructures. The outcomes from this study shows that the bi-functional electrocatalyst holds vast potential for environmental remediation.

This work demonstrates recent advancements in the phytosynthetic and environmentally friendly method of preparing ZnFe2O4 and ZnFe2O4@Ag hybrid nanocomposites using Pedalium murex L leaf extract as a stabilizing and reducing agent. The synthesized nanocomposite was characterized with UV–vis, FTIR, TGA/DSC, XRD, FE-SEM, and EDX to investigate the electronic as well as morphological properties. Moreover, the photocatalytic behaviour of ZnFe2O4 and ZnFe2O4@Ag hybrid nanocomposites was evaluated with a breakdown of 2,4-dichlorophenoxyacetic acid (2,4-DPA) by exposing to UV–Vis light. The results obtained suggest that ZnFe2O4@Ag hybrid nanocomposite exhibited photocatalytic activity for the degradation of 2,4-DPA by approximately 94% in 60 min compared to ZnFe2O4. The hybrid nanostructure of ZnFe2O4@Ag significantly promoted charge transfer and prevented electron and hole recombination resulting in the enhancement of photocatalytic activity. Furthermore, ZnFe2O4@Ag nanocomposite showed the fair recyclable capacity for up to five catalytic cycles with an acceptable degradation percentage of 2,4-DPA. The findings of this study identify efficient charge transfer factor as a major contributor to the catalytic activity, with promising possibilities for the design of environmental remediation nanocomposite for harmful contaminants.

Iron oxide-Copper oxide nanoparticles composite (Fe2O3CuO NPs) was synthesized through a green phytosynthetic approach using Ocimum sanctum Linn (commonly known as Tulsi) leaf extract. The evaluation of electrocatalytic properties were evaluated by carrying out electrochemical detection of amiprofos-methyl (APM), an organophosphorus herbicide. It is moderately toxic to mammals and aquatic biodiversity and is considered to be an acetylcholinesterase inhibitor. The presence of specific natural phytochemicals such as eugenol, naringenin, apigenin, quercetin, and high amount of ascorbic acid in the aqueous extract of Ocimum sanctum Linn plant parts, has been widely used for the synthesis of various metallic nanoparticles where these compounds serve as reducing, stabilizing, and capping agents. The synthesized Fe2O3CuO NPs were characterized using scanning electron microscope (SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction analysis (XRD), UV–Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The modified electrode was electrochemically characterized by cyclic voltammetry and differential pulse voltammetry (DPV) techniques for the detection of APM. The electrochemical signals have increased by three folds in the detection of APM with Fe2O3CuO nanocomposite compared to the bare glassy carbon electrode. The electrochemical sensor showed a linear range of 0.05 to 30 µg/mL with a limit of detection of 0.0065 µg/mL. The developed electrochemical sensor was successfully applied for the detection of APM in different water and soil samples with recoveries ranging from 96.00−99.00%. The electrode showed good stability and reproducibility over a period of 10 days with a 95% of peak current than the former. The newly synthesized nanoparticles, thus, proved to be an interesting material for electrochemical and biological studies.

The present paper reports on the use of modified activated carbon as an environmental friendly adsorbent, obtained from a green vegetable waste, for the removal of copper (II) from wastewaters. The activated carbon was prepared from green vegetable waste by KOH treatment for 24 h at 60 °C and thereafter evaluated by studying the effects of pH, contact time, dosage and initial concentration and optimized in the batch processing mode. The morphological and chemical changes in activated carbon were fully characterized by SEM, TGA, DSC, FTIR techniques. The Langmuir isotherm, yielded adsorption capacity of 75.0 mg g−1 for a pseudo-second-order model. Overall, these results suggest that green vegetable waste derived activated carbon as a low-cost adsorbent for the removal of copper (II) will be useful for future scale-up for the tertiary treatment of wastewater. Keywords: Green vegetable waste activated carbon (GVW-AC), Copper (II), Adsorption, Flame Atomic Absorption Spectrometer (FAAS), Wastewater