Single-Component and Multi-Component Metal Abatement in Water Using a Hydrogel Based on Chitosan: Characterization, Isotherm, Kinetic, and Thermodynamic Results

Abstract

In this work was studied the single-component and multi-component abatement of metals in water using a hydrogel based on chitosan. The maximum single-component abatement capacities of cadmium (Cd) and lead (Pb) were 234.84 and 482.83 mg of metal per g of dried hydrogel at pH 6 and 40 °C, according to the Sips isotherm. The value for iron (Fe) was 386.59 mg g−1 at pH 4 and 40 °C, according to the Langmuir isotherm. The best kinetic fits were determined using the pseudo-second-order model, whereas the thermodynamic parameters inferred spontaneous, favorable abatement phenomena. Lower abatement capacities were determined for multi-component studies due to the hydrated ionic radius and electronegativity of the metals. The abatement processes were confirmed by scanning electron microscopy coupled to energy-dispersive X-ray spectroscopy and Fourier-transform infrared spectra, indicating reversible chemical interactions between the hydrogel binding groups and Cd, Pb, and Fe. Such hydrogel proved to be a potential functional biopolymer for the treatment of water and wastewater contaminated by heavy metals.