Effect of copper doping on CoTiO3 ilmenite type nanoparticles for removal of congo red from aqueous solution

•Use of CuxCo1−xTiO3 nanoparticles for adsorption of congo red from aqueous solution.•Doping of Cu onto CoTiO3 causes the smaller particle size and additional capacity of adsorption of congo red.•The regeneration and recovered of CoTiO3 after sorption of congo red is also interesting.•The adsorption process follows the Pseudo-second-order kinetic model and from thermodynamic view (ΔG°) is suitable.

The CoxCu1−xTiO3 (x = 1, 0.8, 0.5, 0.2, 0) nanoparticles have been prepared. Nanoparticles were prepared by calcination of precursor mixture of TiO2, Cu(OH)2 and Co(OH)2 in aqueous cetyltrimethyl ammonium bromide (CTAB) solution. The nanoparticles were characterized using X-ray powder diffraction (XRD), Fourier infrared spectroscopy (FTIR), Scanning electron microscope (SEM) and Brunauer–Emmett–Teller (BET). The CoxCu1−xTiO3 nanoparticles were used for removal of congo red (CR) from aqueous solutions. The effect of parameters such as contact time, pH and temperature on the adsorption of CR was investigated. Tow common kinetic models, pseudo-first-order and pseudo-second-order were employed to describe the adsorption kinetics. The adsorption of CR followed pseudo-first-order kinetic model. Thermodynamic results revealed that the adsorption of CR onto CoxCu1−xTiO3 particles is endothermic and spontaneously process. The nanoparticles of CoxCu1−xTiO3 can be conveniently regenerated by chemical and physical methods after adsorption. Two common isotherm models, the Langmuir and Freundlich were used to investigate the interaction of CR onto CoxCu1−xTiO3 nanoparticles. The equilibrium adsorption of CuTiO3 was best described by the Langmuir isotherm model. The reused sorbent can be employ after 5 cycle. The results showed that the adsorption capacity of Ilmenite type nanoparticles for CR are as followed: CoTiO3 < Co0.2 Cu0.8TiO3 < Co0.5Cu0.5TiO3 < Co0.8 Cu0.2TiO3 < CuTiO3.