In this work, the excision of hexavalent chromium (Cr(VI)) was studied from an aqueous solution using the chemically modified arecanut leaf sheath (CALS) as a novel bio-adsorbent. The as-prepared adsorbent was characterized by using instrumental methods including Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The effect of several factors, including solution pH, contact time, and sorbent dosages were examined to identify the optimum condition for the sorption ability. The optimal pH of Cr(VI) biosorption was 2.0, and equilibrium was reached in 150 min. Adsorption was shown to be pseudo-second-order in kinetic investigations, and the Langmuir isotherm with maximal adsorption efficiency was determined as 109.89 mg/g. The spent biosorbent can be easily regenerated and reused. For the biosorption of oxyanions of chromium, both electrostatic attraction and ligand exchange mechanism play critical roles. From the results, the CALS appears to be a potential low-cost effective sorbent to remove Cr (VI) from water.

Water pollution from dyes is a major environmental challenge, demanding advanced materials for efficient degradation. In this study, we synthesized iron oxide nanoparticles (IONPs) using an aqueous extract of Senegalia catechu leaves and evaluated their photocatalytic activity in methylene blue (MB) dye degradation under sunlight irradiation. The IONPs were characterized by UV-visible spectroscopy (UV–vis), Fourier Transform Infrared Spectroscopy (FT-IR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray Spectroscopy (EDS). XRD pattern showed a highly crystalline structure with an average crystallite size of 34.7 nm, while SEM images revealed predominantly spherical particles with uneven surface texture. Photocatalytic efficiency exceeded 80% MB dye degradation after 120 min of sunlight exposure. Optimization of catalyst dose, pH, dye concentration, and other parameters is essential for maximizing degradation efficiency. The IONPs demonstrated reusability over four degradation cycles, retaining effective photocatalytic performance. This study underscores the potential of green-synthesized IONPs as eco-friendly photocatalysts for wastewater treatment and environmental remediation.

A novel type of adsorbent, TiO₂ impregnated pomegranate peels (PP@TiO₂) was successfully synthesized and its efficacy was investigated based on the removal of As(III) from water. The adsorbent was characterized using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectrometer (EDS), X-ray Diffraction (XRD) analysis, and Fourier Transform Infrared (FTIR) Spectroscopy, to evaluate its morphology, elemental analysis, crystallinity, and functional groups, respectively. Batch experiments were conducted on PP@TiO₂ for As(III) adsorption to assess the adsorption isotherm, effect of pH, and adsorption kinetics. Characterization data suggested that TiO₂ was successfully impregnated on the biomass substrate. The equilibrium data better fitted to the Langmuir isotherm model having a maximum adsorption capacity of 76.92 mg/g and better distribution coefficients (K_D) in the order of ~10³ mL/g. The highest percentage of adsorption was found at neutral pH. The adsorption kinetics followed the pseudo-2nd-order model. X-ray Photoelectron Spectroscopy (XPS) of the adsorption product exhibited that arsenic was present as As(III) and partially oxidized to As(V). PP@TiO₂ can work effectively in the presence of coexisting anions and could be regenerated and reused. Overall, these findings suggested that the as-prepared PP@TiO₂ could provide a better and efficient alternative for the synergistic removal of As(III) from water.

We studied the sequestration of hexavalent chromium Cr(VI) from an aqueous solution using chemically modified pomegranate peel (CPP) as an efficient bio-adsorbent. The synthesized material was characterized by X-ray diffraction spectroscopy (XRD), Fourier-transform infrared spectroscopy (FTIR), energy dispersive spectroscopy (EDS), and scanning electron microscopy (SEM). The impacts of parameters like solution pH, Cr(VI) concentration, contact time, and adsorbent dosage were investigated. Experimental results of the isotherm studies and adsorption kinetics were found agreeing to the Langmuir isotherm model and pseudo-second-order kinetics, respectively. The CPP showed appreciable Cr(VI) remediation capacity with a maximal loading capacity of 82.99 mg/g at pH 2.0, which was obtained in 180 min at room temperature. Thermodynamic studies revealed the biosorption process as spontaneous, feasible, and thermodynamically favorable. The spent adsorbent was eventually regenerated and reused, and the safe disposal of Cr(VI) was ensured. The study revealed that the CPP can be effectively employed as an affordable sorbent for the excision of Cr(VI) from water.

Aloe vera is effectively utilized to synthesize zinc oxide nanoparticles (Av-ZnO NPs), providing an alternative to traditional chemical and physical methods. This sustainable approach minimizes the environmental impacts and enhances their compatibility with herbal ecosystems. We comprehensively analyzed the optical, structural, morphological, and catalytic properties of Av-ZnO NPs using various analytical methods. The results indicated that the nanoparticles primarily exhibited a spherical shape. X-ray diffraction (XRD) revealed the successful formation of a highly crystalline hexagonal wurtzite structure, with an average size estimated at 12.2 nm. The antimicrobial properties of the Av-ZnO NPs indicated moderate antibacterial effectiveness. Using the DPPH free radical scavenging method, we evaluated the antioxidant properties, where the Av-ZnO NPs exhibited improved the radical scavenging efficiency, reflected by a lower IC₅₀ value compared to the plant extract. Additionally, we assessed the photocatalytic functionality through the degradation of methylene blue (MB) dye, finding that the Av-ZnO NPs achieved approximately 82.43% degradation in 210 min, demonstrating their potential for environmental remediation. These findings suggest that green-synthesized ZnO NPs could play a noteworthy role in various nanotechnology applications and biomedical fields, while also promoting environmental sustainability.

This study demonstrates the synthesis of copper oxide nanoparticles from the leaf extract of Mentha as a natural reducing and stabilizing agent. The synthesized nanoparticles were characterized by UV-visible spectroscopy, Fourier-transform infrared (FTIR) and X-ray diffraction (XRD). UV-vis shows an absorption peak at 275 nm associated with plasmon surface vibrations. FTIR analysis confirmed the reduction and stabilization of CuO nanoparticles, while XRD revealed the monoclinic structure with an average particle size of 19.08 nm, calculated using Debye-Scherrer’s equation. Phytochemical analysis of the methanolic extract identified active components biomolecules such as flavonoids, saponins, and terpenoids, which contribute as reducing and capping agents in nanoparticles. The nanoparticles demonstrated strong antimicrobial activity against Staphylococcus aureus (Gram-positive), Escherichia coli (Gram-negative), and Candida albicans (fungus).