Agricultural peels for dye adsorption: A review of recent literature

This work summarizes the recently published literature (after 2010) regarding the use of agricultural peels for dye adsorption. The use of peels in decontamination technology is very promising given the near zero-cost for the synthesis of those adsorbents. Banana, orange, and potato peels are the most used types of biomass reported in literature. However, other peels such as pomegranate, citrus, grapefruit, yam, and garlic have been also investigated as potential dye adsorbents. The equilibrium data were analyzed and their fitting to known models (Langmuir, Freundlich, etc.) was discussed in details. Similarly, kinetic modeling applied in those studies was commented comparing the equations used (pseudo-first, -second order, etc.). Thermodynamic aspects also are discussed indicating that in many cases the process was spontaneous (ΔG < 0) and endothermic (ΔH > 0) or exothermic (ΔH < 0).