Emerging contaminants adsorption by beads from chromium (III) tanned leather waste recovered gelatin

Abstract

Tannery industries generate wastes that are rich in collagen and can be used to extract the gelatin. Gelatin is a macromolecule with excellent gel formation capacity, low acquisition cost, in addition to biodegradable and hydrophobic characteristics, with an abundance of chemical groups favorable to the adsorption technique. Thus, this work aimed to produce an alternative adsorbent from gelatin extracted from chromium (III) tanned leather wastes for application to remove emerging contaminants from aqueous solutions. Tartrazine yellow dye (TYD) and diclofenac sodium (DCF) were used as experimental models. The adsorbents were produced in beads shape, by drip emulsification. Commercial gelatin beads were also prepared for comparison purposes. The beads were characterized by SEM, TGA, FTIR, and pHpzc. The beads were subjected to equilibrium, kinetics, and desorption and reuse tests. The RCTLW gelatin beads showed a maximum adsorption capacity of 263.13 and 36.65 mg.g−1, for TYD and DCF, respectively. In kinetics, the adsorption density continued to increase after 300 min for TYD and was reached in the first 80 min for DCF. Mathematical modeling suggests that TYD adsorption follows the Freundlich model, while DCF is better represented by the Langmuir model. The PFO model best predicted TYD adsorption, while for DCF, both models of PFO and PSO can describe the kinetic data. The RCTLW gelatin beads showed promise for use for up to 10 cycles without loss of adsorption capacity, ending the 10th cycle with a capacity of around 100 mg.g−1 and 45% regeneration.