Optimization and comparison study of adsorption and photosorption processes of mesoporous nano-TiO2 during discoloration of Indigo Carmine dye

This study deals with the Indigo Carmine (IC) dye removal using synthetic mesoporous Titanium dioxide (TiO2) nanoparticles. The surface charge investigation shows a pHzc equal to 4.25. The central composite design (CCD) model optimization of the adsorption process identified 57 min as the optimal contact time. For optimum IC contents of 30 and 58 mg/L, the recorded adsorption capacities were 123 and 261 mg/g in the dark reactor (DR) and sunlight reactor (SR), respectively. The thermodynamic investigation suggests an endothermic and spontaneous physisorption process, and the regeneration tests show higher stability of the mesoporous TiO2 in the SR. SEM and TEM analyses show a TiO2 agglomeration in DR and nanoparticles swelling in SR.