Mahdi Salimi and Amin Abolghasemi Mahani, in their recent study published in Environmental Technology & Innovation, explore an innovative approach to wastewater treatment using biochar-supported CdS-WO₃ nanostructures. This research focuses on the visible-light-driven photocatalytic degradation of malachite green, a toxic dye commonly found in industrial effluents.

The study synthesized a biochar-based nanocomposite (BC-WO₃/CdS) using spent coffee grounds as the carbon source. This eco-friendly material exhibited a remarkable photocatalytic efficiency of 98% in degrading malachite green at a concentration of 2 ppm, using a catalyst dosage of 200 mg at pHpH is a measure of how acidic or alkaline a substance is. A pH of 7 is neutral, while lower pH values indicate acidity and higher values indicate alkalinity. Biochars are normally alkaline and can influence soil pH, often increasing it, which can be beneficial More 8. The degradation process followed a pseudo-first-order kinetic model with an apparent reaction rate constant of 0.0548 min⁻¹.

Structural characterization using FTIR, SEM, and XRD confirmed the successful integration of CdS-WO₃ nanostructures onto the 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 substrate, enhancing charge separation and reducing electron-hole recombination. Notably, the material demonstrated excellent stability, maintaining high degradation efficiency across eight reuse cycles, making it a cost-effective and sustainable solution for industrial wastewater treatment.

This research highlights the potential of biochar-supported photocatalysts in addressing environmental pollution. By utilizing agricultural waste as a carbon source, the study presents a dual benefit of waste valorization and water purification. Future investigations could explore real-world applications and scalability of this technology for broader environmental remediation efforts.

SOURCE: Salimi, M., & Abolghasemi Mahani, A. (2025). Binary CdS-WO₃ nanostructures supported on biochar substrate for visible-light-driven photocatalytic degradation of malachite green. Environmental Technology & Innovation, 37, 104061. https://doi.org/10.1016/j.eti.2025.104061