A study on the adequacy of some actinides adsorption on a modified guanidine Schiff base from laboratory effluents

Besides the distinctive features and medicinal benefits of guanidine Schiff bases, the possibility of their use as a sorbent for radioactive contents of effluents was developed in the current study. A series of adsorption experiments were performed with 2,2-benzene-1,4-dildiguanidine di-salicylate synthesized sorbent from sulphate feed solutions containing UO₂²⁺ and ThSO₄²⁺ species each separately. Infrared studies demonstrated that the sorbent links to both actinides via the azomethine nitrogen atom and the hydroxyl groups on the sorbent. Thermal analyses were also performed. Using the greatest adsorption results, UO₂²⁺ and ThSO₄²⁺ were able to bind to modified guanidine Schiff base (MGSB) sorbent with uptake capacities of 98 and 54 mg/g respectively. The maximal uptake was achieved at pH 5.5 and 3.5 and 90 min contact time for UO₂²⁺ and ThSO₄²⁺, respectively. The equilibrium adsorption results for UO₂²⁺ and ThSO₄²⁺ were in good agreement with Langmuir isotherm and the pseudo-second-order reaction model and demonstrated the endothermic nature and kinetic improvement by increasing temperatures. All kinetic and isotherm results demonstrated the chemical adsorption of both UO₂²⁺ and ThSO₄²⁺ at the MGSB active sites. Positive ∆H (40.54 and 40.16 kJ/mol for UO₂²⁺ and ThSO₄²⁺, respectively) proved the endothermic nature of the adsorption process.