Removal of Lissamine rhodamine B and acid orange 10 from aqueous solution using activated carbon/surfactant: Process optimization, kinetics and equilibrium

Removals of Lissamine rhodamine B (LRB) and acid orange 10 (AO10) using activated carbon/surfactant from aqueous solution were optimized. Box–Behnken design (BBD) has been employed to investigate the effects of different process variables (such as time of adsorption process, temperature, pH, and initial concentration of the dye) and analyze their interactive effects in the adsorption capacity for the two dye systems. The experimental data could be simulated accurately using second order polynomial regression models because they have high correlation coefficient values ( R 2 ) of 0.9920 and 0.9938, low p -value of 0.000, and their F values of 105.96 and 137.01 for the LRB and AO10 systems, respectively. The optimum conditions were found to be t   =   120   min, T   =   20   °C, pH   =   11.0, and C LRB   =   50   mg/L for the LRB adsorption, and t   =   120   min, T   =   20   °C, pH   =   2.5, and C AO10   =   90   mg/L for the AO10 removal. The measured maximum experimental adsorption capacities for the LRB and AO10 systems under above optimum conditions were 218.08   mg/g and 405.15   mg/g, which agreed with their corresponding predicted values (229.43 and 400.51   mg/g) well due to small relative errors of 4.95% and −1.16%, respectively. The adsorption equilibrium and kinetics of the two dye adsorptions onto AC/DDAC were also investigated. The results indicated that Langmuir model presented the best fit and the pseudo-second-order model showed excellent fit to the kinetic data.