New hydrothermal charcoal TiO2 composite for sustainable treatment of wastewater with dyes and cadmium cations load

Abstract This work was focused on synthesis of the composites from charcoal activated by hydrothermal method, then modified with TiO2 (Degussa P25) by ultrasound treatment. These composites were used to removal of the Crystal Violet (CV), Methylene Blue (MB) from aqueous solutions and from bi-solute aqueous solutions (CV+Cd2+) and (MB+Cd2+). The composites were characterized by using XRD, AFM, SEM and EDX spectroscopy. The micro-porosity and BET specific surface were carried out by N2 adsorption at 77 K. The FT-IR spectroscopy illustrate that hydroxyl, carboxyl groups developed on the composites surface are able to adsorb CV, MB and Cd2+. The pHPZC between 7.50– 8.18 value is favorable to adsorb the cationic dyes and Cd2+ cations. The batch studies were conducted in order to determine the optimal time required to reach the adsorption equilibrium at each adsorbent dose. The adsorption data were modeled by Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherms equations and adsorption of the pollutants followed pseudo-second-order reaction with regard to the intraparticle diffusion rate. The qmax. calculated from Langmuir isotherm were 12.407 mg/g for CV, 14.104 mg/g for MB and 185.18 mg/g Cd2+ onto MCHD2 composite. Corroborated with the properties of the surface, the adsorption mechanism of dyes and cadmium was discussed.