Kinetics and mass transfer models for sorption of titanium industry effluent in activated carbon

The batch adsorber data obtained for removal of dissolved solids in titanium industry effluent by sorption in activated carbon was found to fit Freundlich, Langmuir, and Dubinin–Radushkevich isotherm models and the various non-linear error functions evaluated have low error values for these adsorption models. The applicability of pseudo-second-order models in adsorption kinetics has been explained and the predictive models at various dilutions were obtained. The external mass transfer coefficient obtained from various models, such as Mathews–Weber and Furusawa–Smith, was used to calculate the Biot number. The Biot number values were less than 100, which suggest that the external film coefficients control the adsorption process. The change in enthalpy of the adsorption process was −48 kJ mol−1, suggesting the release of exothermic heat during the sorption process. The analysis of various functional groups in the effluent was done using Fourier transform infrared spectroscopy.