A radioactively durable melamine-styrene based polymer: Highly efficient removal of ⁹⁰ Sr

Removal of strontium has a vital importance for radioactive waste management due to its long half-life. In this context, melamine-styrene based polymer (MSBP)was synthesized and characterized by different spectrophotometric methods. Sr ²⁺ ions were removed from the solution using MSBP sorbent. In this respect, adsorption of Sr ²⁺ onto melamine-based polymer was studied as a part of pH, amount of adsorbent, initial Sr ²⁺ concentration, contact time, temperature and particle size. Also, adsorption rate of radioactive strontium was investigated by using LSC (Liquid Scintillation Counter). The adsorption data were fitted to Langmuir, Freundlich and Dubinin-Radushkevich (D-R)isotherm models. MSBP sorbent reached maximum adsorption capacity for Sr ²⁺ as 142.9 mg.g ⁻¹ . Thermodynamic parameters such as free energy (ΔG ⁰ ), entropy (ΔS ⁰ )and enthalpy (ΔH ⁰ )of Sr ²⁺ adsorption on MSBP were examined at five different temperatures of 293 K, 303 K, 313 K, 323 K and 333 K. 0 < ΔH ⁰ values indicated that sorption mechanism presented endothermic feature. 0 > ΔG ⁰ and 0 < ΔS ⁰ revealed that Sr ²⁺ adsorption on MSBP occurred spontaneously and irreversible, respectively. Pseudo first and second orders were investigated as a part of kinetic parameters and seen that pseudo second order was much more convenient for adsorption of Sr ²⁺ onto MSBP.