Cr2O3/Al2O3 as adsorbent: Physicochemical properties and adsorption behaviors towards removal of Congo red dye from water

The Cr2O3/Al2O3 catalysts with different contents of Cr2O3 and surfactants modified Cr2O3/Al2O3 has been successfully synthesized via impregnation and surfactants assisted impregnation method. The catalysts were characterized using XRD, TEM coupled with EDS, electron diffraction image, surface area analysis and FTIR. Batch experiments were carried out to study the adsorption of Congo red (CR) dye. The influence of varying parameters like a ratio of Cr2O3, the presence of surfactants, contact time, initial dye concentration, pH, the presence of coexisting ions and temperature on the adsorption process was investigated. The results showed that crystallinity, morphology and surface area affected by a ratio of Cr2O3 and presence of surfactants. The adsorption process was found to be highly at 60% Cr2O3/Al2O3, the presence of Triton as surfactants, low pH, a high concentration of coexisting ions and elevated temperature. The experimental data suggest that the Freundlich isotherm was applicable and pseudo-second order kinetic has the highest correlation coefficients with the best fit. Also, the thermodynamic results showed that the adsorption process is spontaneous, high ordering, endothermic and chemisorptions process. Consequently, these results are important to design efficient adsorbent for removing dyes from wastewater.