Transforming Commodity Crop Byproducts Into Carbon-Based Adsorbents for Flavonoid Recovery: A Review on Key Pyrolysis Parameters, Chemical Activation, and Adsorption Mechanisms

The development of carbon-based adsorbents for flavonoid purification has gained significant attention due to their high efficiency, sustainability, and cost-effectiveness. Derived from agricultural waste, such as fruit peels, husks, and stems, bio-adsorbents offer an eco-friendly approach to valorizing biomass. These materials are rich in carbon content and can be transformed into highly porous activated carbon through pyrolysis and chemical activation. Chemical activation methods, employing agents like phosphoric acid, zinc chloride, or potassium hydroxide, enhance the surface area, pore volume, and functional groups of the adsorbent, optimizing its adsorption capacity. Advanced carbon-based adsorption techniques leverage these properties to selectively bind flavonoids, benefiting from the high specificity and stability of the adsorbent. Adsorption mechanisms, including hydrogen bonding and van der Waals forces, play a crucial role in the effective capture of flavonoids. These processes are influenced by factors, such as surface chemistry, pore structure, and adsorbate properties, making carbon-based adsorbents a versatile and sustainable solution for purifying valuable bioactive compounds in pharmaceutical and nutraceutical industries.