Concentrated Seawater-Assisted Greener Production of Biochar: Waste Valorization and Its Implication in Circular Economy

Abstract

Converting waste biomass into functional biochar offers a promising approach to carbon sequestration, but a sustainable manufacturing method is yet to be developed. The current work demonstrates the proof of concept of biochar production using concentrated seawater, a by-product from seawater desalination, as the templating agent. The resulting biochar shows mixed meso- and micropores, high specific surface area and low oxygen content. Owing to these features, the biochar demonstrates applications as a modest methylene blue adsorbent (adsorption capacity up to 8.2 mg/g), satisfactory supercapacitor electrode (specific capacitance up to 135 F g⁻¹), and superior CO₂ adsorbent (maximum capacity 4.05 mmol g⁻¹). Moreover, we propose that the biochar production can be combined with other established processes for implementing circular economy to achieve concentrated seawater valorization, carbon sequestration and waste minimization.