Study on simultaneous adsorption of Zn(II) and methylene blue on waste-derived activated carbon for efficient applications in wastewater treatment

Organic and inorganic pollutants often coexist in water bodies due to the influxes of pollutants from various pollution sources. The use of waste-derived adsorbents to remove pollutants is an economical and efficient method of wastewater treatment. The present study was designed to investigate the adsorption and cosorption of Zn and methylene blue (MB) on a capsicum straw derived activated carbon (CSAC), by determining equilibrium adsorption isotherms and simulation. The result showed that Langmuir equation is more suitable for description of the adsorption isotherms of Zn2+ and MB than that of Freundlich equation. The maximum adsorption amounts for both adsorbates were quite the same. The amount of Zn2+ adsorbed decreases with increasing MB and vice versa, suggesting the competitive rather than synergistic adsorption on the activated carbon. Cosorption of Zn(II) and MB on the CSAC showed MB to be preferentially adsorbed. The adsorption kinetic studies showed that the adsorption of Zn2+ comply with pseudo-second-order rate model rather than pseudo-first-order rate model. The findings of the present study helps to carry out an efficient application in waste treatment.