Regenerable chitosan-biochar-TiO2 composite sponges for hazardous pollutants removal from water: The case of carbamazepine.

Water pollution is a significant worldwide problem, and research studies in this field are still in progress to find strategies for removing pollutants from water. Among the others, adsorption process seems to exhibit several advantages, especially when biomasses are in use. This work proposes biochar from olive pomace pyrolysis for adsorbing contaminants from water, in synergistic combination with TiO2, for constituting water-stable and recyclable composite chitosan-based sponges. The photocatalyst and the biochar were embedded into the polymeric chitosan foam network. So, the employed materials were characterized from a physical and chemical point of view, revealing the nature of porous adsorbent substrates having irregular surfaces useful for sequestrating pollutants. UV-Vis spectroscopy was used to monitor the amount of pollutants in water, and the maximum adsorption capacities were calculated. Carbamazepine, was selected as a model contaminant to study the process features under different working conditions. A comparison with the removal of a textile dye was also performed to unveil the mechanism of adsorption. After the pollutant adsorption, its complete desorption was obtained, proposing a way to reuse the adsorbent material, lowering the environmental impact. An alternative to regenerate the adsorbent was also studied by exploiting the photocatalytic role of TiO2.