Adsorption characteristics of Sauropus androgynus and its base modified form toward cationic crystal violet dye

Abstract

Waste parts of the plant Sauropus androgynus (SA), an agricultural by-product, and its base-modified form (MSA) have shown potential for the removal of the cationic crystal violet (CV) dye from aqueous solution. The optimum contact time of SA and MSA was found to be 180 and 120 min, respectively, and no changes in the pH of the system were necessary for optimum performance. SA performed well in moderate ionic environments; and MSA tolerated up to 1.0 M ionic strength. The adsorption process was exothermic. The Sips isotherm model is suitable to describe adsorption of CV on both SA and MSA giving adsorption capacities of 326.38 and 489.58 mg g–1, respectively. Regeneration studies showed that acid and base washings of SA and MSA could regenerate the adsorbents and allowed them to be reused. Given the excellent adsorption capacities, stability at different pH and salt concentrations, ability to be regenerated and reused, both SA and MSA would be deemed suitable new, potential low-cost adsorbents to remove the CV dye in wastewater treatment. More importantly, MSA has demonstrated its superior characteristics to be used in real-life situation for removal of CV dye when present in high ionic environments.