Effective removal of methyl violet dye using pomelo leaves as a new low-cost adsorbent

Abstract

A new adsorbent, pomelo leaves (PL), was investigated as a possible low-cost adsorbent for the removal of toxic methyl violet (MV) dye. Adsorption isotherm data when fitted into five different models, namely the Langmuir, Freundlich, Temkin, Redlich–Peterson and Sips models, indicated the Sips model was the best fit with good maximum adsorption capacity (qmax) of 248.2 mg g–1. Adsorption of MV by PL was an endothermic process and obeyed the pseudo-second order kinetics, showing a decrease in k2 with increasing adsorbate concentration. PL’s ability to adsorb MV was influenced by the presence of salts in solutions but is relatively resilient to changes in medium pH. An added attractive feature is its ability to be regenerated and reused, especially under both acid and base treatment, while maintaining good adsorption capacity even after five consecutive cycles. Thus, being readily available in abundance throughout the year, this study points to PL being a good, potential adsorbent in wastewater treatment given its high qmax when compared with many other adsorbents, pH resilience and that the spent adsorbent can be easily regenerated and reused.