EFEKTIVITAS DESORPSI CESIUM OLEH SURFAKTAN KATIONIK BERDASARKAN STRUKTUR HIDROFILIKNYA PADA MONTMORILLONIT K10

Abstract

This study discusses the efficiency of cesium (Cs) desorption from montmorillonite K10 samples (MMTK10) previously contaminated with Cs (MMTK10/Cs) using cationic surfactant desorbents, benzyldodecyldimethylammonium bromide (BDAB) and dodecyltrimethylammonium bromide (DTAB), as well as HCl as a desorption control. The aim of this research is to explore the effects of the different hydrophilic structures of cationic surfactants on Cs desorption from MMTK10, where BDAB has a larger hydrophilic structure compared to DTAB. The results show that cationic surfactants, particularly at high concentrations of 20-50 mM, exhibit higher desorption efficiency compared to HCl, with efficiencies reaching 80-90%. This mechanism is associated with the ability of cationic surfactants to form micelles when their concentration exceeds the critical micelle concentration (CMC) or at high concentrations, which facilitates ion exchange with Cs on the surface of MMTK10/Cs. There is no significant difference in Cs desorption efficiency between BDAB and DTAB, even though the hydrophilic structure of BDAB is larger. This contrasts with previous studies on other montmorillonites, where a larger hydrophilic surfactant structure led to greater opening of the montmorillonite interlayer due to the entry of the larger surfactant, resulting in greater Cs desorption. The lack of a difference in Cs desorption efficiency between the two surfactants in this study is due to the specific characteristics of MMTK10 clay itself, which does not have the ability to expand or enlarge the interlayer due to heat treatment during its production before being sold in the market. Additionally, the similarity in the length of the hydrophobic tail chains between BDAB and DTAB contributes to the identical Cs desorption results from both surfactants. In conclusion, while the nature and structure of cationic surfactants influence the Cs desorption process, the specific characteristics of the used montmorillonite or clay also play a crucial role in this desorption mechanism.