An innovative nanocomposite for sustainable organic dye removal: Sodium titanate/carbon

Utilizing waste to develop advanced materials for pollutant removal is an innovative and promising strategy for effective environmental management. In this article, a novel bifunctional adsorbent/Fenton-like catalyst, Na4Ti5O12/Na0.23TiO2@carbon (NTC), is prepared using waste polyethylene terephthalate (PET) and commercially available TiO2 through a simple and low-cost molten salt treatment method. This agent exhibits excellent adsorption and catalytic activity for the removal of organic dyes from aqueous solutions across a wide pH range, due to its high surface area (621.0 m2 /g) and total pore volume (0.32 cm3 /g), as well as the presence of abundant oxygen vacancies and graphene layers derived from waste PET. In the presence of H2O2 at concentrations as low as 0.3 g/L, the degradation efficiency of CV exceeds 99 % within 60 min, due to the formation of • OH, • O2− and 1 O2 reactive oxygen species (ROS) as the key reactive agents, with 1 O2 as the major ROS. The reaction rate constant increases by a factor of six to 9.48 × 10− 2 min− 1 upon increasing temperature from 20 to 40 ◦C. In the absence of H2O2, NTC exhibits a CV adsorption capacity of 165.8 mg/g, which is significantly higher than that of the initial TiO2 (13.2 mg/g). In the presence of low concentrations of H2O2, the rate of combined adsorption and Fenton-like reaction is 3.5 to 6.6 times faster than adsorption alone, with total activation energies of 38.3 and 51.0 kJ mol− 1 , respectively. NTC effectively removes cationic dyes, leveraging its negatively charged surface to preferentially adsorb such dye species.