Nworie, et al (2024) Facile fabricated silver Pterocarpus santilinoides biochar-based inorganic–organic hybrid nanocomposite for the photocatalytic decimation of methylene blue
and micro-organisms. Water Quality Research Journal. http://iwaponline.com/wqrj/article-pdf/doi/10.2166/wqrj.2024.006/1446430/wqrj2024006.pdf

A recent study from researchers at Ebonyi State University and Federal Polytechnic in Nigeria explores an innovative approach to tackling water pollution and microbial contamination using a silver biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More nanocomposite. The research focuses on the synthesis, characterization, and testing of a nanocomposite made from silver nanoparticles and biochar derived from Pterocarpus santilinoides, a plant commonly found in tropical regions.

The biochar is produced through the pyrolysisPyrolysis is a thermochemical process that converts waste biomass into bio-char, bio-oil, and pyro-gas. It offers significant advantages in waste valorization, turning low-value materials into economically valuable resources. Its versatility allows for tailored products based on operational conditions, presenting itself as a cost-effective and efficient More of P. santilinoides leaves, which are carbonized at high temperatures in an oxygen-limited environment. Silver nanoparticles are then incorporated onto the biochar surface using an eco-friendly, biogenic method. This process results in a porous, spherical nanocomposite with particles approximately 27 nanometers in size. The composite exhibits strong photocatalytic and antimicrobial properties, making it a promising candidate for environmental and healthcare applications.

In testing the photocatalytic degradation of methylene blue (MB), a common industrial dye, the silver biochar nanocomposite demonstrated a high removal efficiency of 96.33%. This efficiency remained relatively stable at 75% even after five reuse cycles, indicating the material’s robustness and reusability. The degradation process leverages the composite’s low band gap energy, which facilitates effective photocatalytic activity under light exposure. The study measured the rate constant of the degradation process to be 0.008 min⁻¹, comparable to other advanced photocatalysts.

Additionally, the nanocomposite’s antimicrobial efficacy was tested against several common pathogens, including Salmonella, Escherichia coli, Klebsiella, and Staphylococcus aureus. The results showed significant inhibition zones, with the nanocomposite outperforming biochar alone. The inhibition zone diameters were 15 mm for Salmonella, 12 mm for E. coli, 10 mm for Klebsiella, and 8 mm for S. aureus. These findings suggest that the nanocomposite can effectively disrupt bacterial cell membranes and inhibit microbial growth.

Characterization techniques such as UV-Vis spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM) were used to analyze the structural and optical properties of the biochar and the nanocomposite. UV-Vis spectroscopy revealed distinct absorption peaks, indicating the successful formation of silver nanoparticles. The band gap energy of the nanocomposite was determined to be 1.8 eV, lower than that of biochar alone, highlighting the enhanced photocatalytic potential due to the incorporation of silver nanoparticles.

XRD analysis confirmed the crystalline structure of the biochar and nanocomposite, with characteristic peaks corresponding to the presence of silver. SEM images showed the porous nature of the materials, essential for effective adsorption and photocatalysis, while Energy Dispersive X-ray (EDX) analysis identified the elemental composition, further verifying the successful integration of silver into the biochar matrix.

The synergistic combination of silver nanoparticles and biochar not only improves the stability and catalytic efficiency of the nanocomposite but also enhances its antimicrobial properties. This makes it suitable for diverse applications, including water treatment, healthcare, and food packaging, where long-lasting antimicrobial effects and pollutant degradation are critical.

Overall, this study presents a promising eco-friendly solution for addressing environmental pollution and microbial contamination. The silver biochar nanocomposite combines high efficiency, reusability, and broad-spectrum antimicrobial activity, offering a versatile tool for sustainable environmental and health management.