Waste-to-Wealth: Unlocking the Potential of Pine Sawdust Biochar for Adsorption of Cobalt(II) and Nickel(II) Ions and Sustainable Elimination of Carbamazepine from Aqueous Solutions

Sustainable waste management is the recycling, reusing, and recovery of wastes from natural sources. This research studied the conversion of Pinus sylvestris residues into sustainable biochars with improved properties for the adsorption of Co(II) and Ni(II) with further usage of spent biochars in the removal of carbamazepine. The biochars possessed high surface areas and abundant chemical composition with equilibrium adsorption capacities of 0.38 mmol/g for Co(II) and 0.48 mmol/g for Ni(II), forming cobalt phosphate and nickel hydroxide on the biochar surface. The laden biochars efficiently removed carbamazepine through adsorption and under UV light, following a first-order kinetic model with rate constants ranging from 0.0031 to 0.0042 min^–1 and achieving an efficiency of over 80%. The complex interaction mechanisms were responsible for the reduction of the carbamazepine concentration in the studied systems. This research demonstrates that waste wood raw materials can be used as synergistic multifunctional materials.