Efficient adsorption of cobalt on chemical modified activated carbon: characterization, optimization and modeling studies

Herein, granular activated carbon (GAC) was modified chemically with sodium dodecyl sulfate (SDS) to prepare MGAC as an efficient adsorbent for removal of Co(II) ion from aqueous solution. The effect of different SDS concentrations and modification time on the adsorption performance was examined. The as-prepared adsorbent was characterized by FESEM and FT-IR techniques. Moreover, some parameters affecting the adsorption efficiency like solution pH, contact time, adsorbent dosages, initial metal ion concentrations, temperature and agitation speed on the adsorption efficiency were evaluated in a batch environment. Under same operational conditions, MGAC showed a much greater adsorption rate than GAC, due to synergistic effect between GAC and SDS. The equilibrium time was 90 min and the maximum adsorption capacity based on the Langmuir was found to be 51 mg/g. Experimental data were in good agreement with Langmuir and pseudo-second-order models. The mechanism of Co ion adsorption on MGAC followed ion-exchange and mono layer chemical adsorption. The adsorption process showed better performance at neutral pH and higher temperatures. Under optimized conditions, complete removal of 20 mg/L of Co(II) was obtained in the presence of 1.2 g/L of MGAC. Thermodynamic studies indicated the adsorption process was endothermic and spontaneous in nature.