Cellulose hydrogel for enhanced uranium (VI) capture from nitrate medium: preparation, characterisation and adsorption optimisation

A highly efficient cellulose hydrogel (CHG) was synthesised using grafting polymerisation and confirmed for its ability to adsorb uranium from a nitrate solution. The kinetic mechanism and isotherm model were studied to determine the adsorption rate and the mechanism of the adsorption process in the nitrate solution. The adsorption of uranium using CHG was studied with different environments; pH value (from 0.4 to 4.5), contact time (in the range of 5 to 240 min.), uranium initial concentration (from 200 to 1400 mg/L), temperature (from 25 to 50°C), adsorbent dose (from 0.005 to 0.1 g) and interfering ions. The kinetics followed a pseudo-second-order rate equation and the adsorption process was well fitted with Langmuir isotherm model with a maximum monolayer adsorption capacity of 148 mg/g. FTIR, SEM, XRD, and Thermal analysis were used to study the structure of the cellulose hydrogel (CHG) before and after the adsorption process. The thermodynamic parameters ΔH, ΔS, and ΔG were also evaluated indicating exothermic and spontaneous adsorption process.