Investigation of adsorption characteristics of Basic Red 46 onto gypsum: Equilibrium, kinetic and thermodynamic studies

The adsorption of Basic Red 46 (BR 46) onto gypsum as a low-cost natural adsorbent was studied as a function of initial dye concentration, temperature, contact time and pH regimes. The equilibrium behavior of BR 46 adsorption was examined by the Langmuir, Freundlich and Temkin isotherm models. The equilibrium data fitted well with the Langmuir model. The monolayer adsorption capacity was found as 39.17 mg g−1. The adsorption kinetic was tested by pseudo-first order, pseudo-second order, Elovich and intraparticle diffusion models. The kinetic data were best described by the pseudo-second order model. Thermodynamic investigations indicated that BR 46 adsorption onto gypsum was spontaneous. The results indicated that gypsum could be used as an adsorbent for textile wastewater treatment without high cost.