Biochar-metal nanocomposites for azo dye removal: advancements, mechanisms, and future prospects

Over the past few decades, biochar-a highly porous, carbonaceous, and sustainable material derived from various waste sources-has gained attention for its excellent adsorption properties in environmental bioremediation. However, its adsorption capacity and scalability remain key limitations. These challenges are addressed by incorporating metal nanoparticles to form biochar-metal nanocomposites. This study explores the potential of biochar-metal nanocomposites in mitigating environmental pollution, particularly from azo dyes. Azo dyes, widely used in industrial applications, pose significant risks to ecosystems, agriculture, and human health due to their toxicity and persistence. Conventional wastewater treatment methods often fail to fully remove these pollutants or generate harmful byproducts, exacerbating environmental concerns. In contrast, biochar-metal nanocomposites exhibit synergistic properties that enhance adsorption efficiency, chemical reactivity, and stability, making them highly effective for pollutant removal. With multiple adsorption mechanisms, these nanocomposites can target various contaminants, including synthetic dyes, heavy metals, and organic compounds. However, key operational factors such as pH, temperature, contact time, and dosage concentration significantly influence their performance. Studies using adsorption isotherms and kinetics can optimize these parameters, improving efficiency for both environmental remediation and industrial applications.Despite challenges in scalability and production costs, biochar-metal nanocomposites offer a promising solution for sustainable wastewater treatment, soil restoration, agricultural enhancement, and energy generation. Advancing research in this field can further optimize their performance, making them a viable alternative for large-scale environmental applications. Biochar is a highly suitable, low-cost, and efficient adsorbent for removing dye contaminants from wastewater. Metal nanoparticle-modified biochar boosts dye removal via increased surface area, porosity, and functional groups. Supportive policies boost the economic viability, commercialization, and safe use of biochar metal nanocomposites.