Enhancement of adsorption characteristics of methyl violet 2B dye through naoh treatment of cucumis melo var. Cantalupensis (rock melon) skin

Abstract

A new adsorbent derived from the skin of Cucumis melo var. cantalupensis (CMS) through surface modification with 1 M NaOH (MCMS) was investigated for its enhanced ability to adsorb methyl violet 2B (MV 2B) dye. The optimum contact time for both CMS and MCMS to reach equilibrium was at 90 min. The effect of pH indicated that dye removal at higher pH was comparable with the untreated pH. The pseudo-second-order model best described the adsorption kinetics data for both CMS and MCMS. The Sips isotherm model fitted the adsorption process with maximum adsorption capacity (qmax )of 224.56 and 669.73 mg g–1 for CMS and MCMS, respectively, indicating that sim-ple surface modification of CMS with NaOH significantly enhanced the adsorption capacity of the adsorbent toward MV 2B by approximately 200%. Further, it is found that the removal of MV 2B by MCMS was not affected by ionic constituents as much as CMS, demonstrating the superior characteristics of MCMS. Regeneration and reuse of both spent adsorbents are possible, especially when washed with acid. Overall, based on the high qmax values as compared with those of many reported adsorbents, both CMS and MCMS are potentially strong adsorbents for the removal of MV 2B dye in real-life wastewater treatment.