Kinetic and Equilibrium Studies of Fe(III) Sorption from an Aqueous Solution Using Palmyra Palm Fruit Fibres as a Biosorbent

Abstract

This research focused on the removal of Fe(III) ions from an aqueous solution of wastewater through an adsorption process using biosorbents of natural palmyra palm fruit fibres (N–PPF) and chemically modified palmyra palm fruit fibres (C–PPF). BET was used to determine the pore volume and pore size of the biosorbents; the C–PPF was more than N–PPF at 0.01069 cm3/g and 450.2094 Å, respectively. The initial concentration of Fe(III), the adsorbent dosage, solution pH, and contact time for optimal adsorption were investigated for adsorption, and it was found that the dosage of the adsorbent was 2.0 g, pH 4, and 300 min for adsorbent dosage, solution pH, and contact time, respectively. The adsorption data were consistent with the three models, though the Freundlich model provided the best fit. The characteristics for both before/after adsorption were examined by FT–IR, which showed that hydroxyl groups were involved in adsorption. SEM–EDX analysis confirmed the successful increase of containing functional groups during adsorption. Adsorption proceeded according to a pseudo–first–order kinetic model for N–PPF, while the adsorption of C-PPF was according to both kinetic models. It was revealed that Fe(III) adsorption is an exothermic process that occurs on the surface of heterogeneous adsorbents and physisorption. The intra-particle diffusion model is appropriate to explain the rate-controlling step in the Fe(III) adsorption process of natural fibres.