Elaboration, characterization and performance evaluation of a new environmentally friendly adsorbent material based on the reed filter (Typha Latifolia): Kinetic and thermodynamic studies and application in the adsorption of Cd (II) ion

Abstract

• The kinetic study, at constant temperature, shows that the extraction yield and the sorption capacity of Cd (II) on the resin increase rapidly with time, the equilibrium is reached after 40 min for raw reeds (RB) and 60 min for treated reeds (RS). • The adsorption capacity increases with the increase of the initial cadmium concentration and reaches a maximum equal to mg g −1 at a concentration higher or equal to 26.35 mg g −1 and 40.01 mg g −1 , respectively for RB and RS. • This retention capacity is very important which shows that this resin has a high affinity towards cadmium. • The application of the Langmuir and Freundlich adsorption models showed that the Langmuir isotherm better describes the adsorption of Cd (II) on the resin. Heavy metal pollution is a public health problem that should prompt environmental protection authorities to provide appropriate solutions. The objective of this work concerns the liquid-solid extraction of Cadmium by the filtering resin of raw RB and modified RS reeds. The experimental study clarified the influence of some operating parameters. The results of the experiments show that the adsorption process depends on several parameters: the presence of salts, the temperature and the pH of the medium. Equilibrium is reached after 40 min for raw reeds (RB) and 60 min for treated reeds (RS). The pH of the aqueous phase, optimal for this extraction is between 4.5 and 6.0, increasing the temperature of the aqueous phase-adsorbate mixture from 25 to 65 °C decreases the extraction yield and the sorption capacity. The pseudo-second order kinetic model and Langmuir model are the most adequate to describe the adsorption process and the adsorption capacity increases with the increase of initial cadmium. Concentration and reaches a maximum equal to 26.35 mg g −1 and 40.01 mg g −1 , respectively for RB and RS. The thermodynamic study showed that the retention process is spontaneous and exothermic. The cadmium metal Cd (II) adsorption mechanism was also interpreted by spectroscopy FTIR and energy-dispersive X-ray (EDX). Dramatically, the introduction of the chemical treatment allows the increase of the content of activated functional groups in the resin, leading to a higher amount of adsorption on Cd (II). The desorption might of the resin depended on the various parameters like HNO 3 concentration, desorption of the temperature and time. The satisfactory desorption of the capacity and efficiency is 69% RB and 92% RS. Based on these results, RB and RS acid-treated products could be utilized as low-cost, environmentally friendly and effective adsorbents for Cd (II) elimination from water. The various parameters thermodynamic such as ∆G°, ∆S° and ∆H° showed that the adsorption process was feasible, spontaneous and exothermic.