Utilization of pectin isolated from tangerine (Citrus reticulata) peels as an adsorbent for the confiscation of toxic crystal violet dye from aqueous solution

Abstract

Pectin membrane (PMB) isolated from locally available agricultural waste, tangerine peels (TPP), for application as an adsorbent to remove crystal violet dye (CV) from an aqueous medium. The adsorbent was characterized by different methods for surface morphology, functional groups, and crystal structure composition. The adsorptive removal of CV onto PMB was evaluated across different parameters such as pH, adsorption kinetics, rate-controlling step, isotherm, and thermodynamics. The PMB exhibited high adsorption efficiency towards CV at pH 4 (99.83%) and fast removal rate at 20 min (97.82%). Adsorption kinetic and equilibrium data were well described by the pseudo-second-order and Freundlich isotherm models, suggesting multiple-layer adsorption. The Langmuir maximum adsorption capacity was 133.69 mg g-1, which was much higher than the 13.554 mg g-1 recorded with the control adsorbent (TPP). Additionally, thermodynamic investigations revealed that it was a spontaneous and endothermic process presumably relying on chemisorption. Regeneration studies showed that the dye removal percentages ranged from 93.56 to 95.04% up to four adsorptiondesorption cycles. Moreover, in comparison of PMB with other biosorbents, it was found to be highly efficient and could be used as a suitable alternative for adsorbing CV from an aqueous medium.