Application of the Langmuir Technique to Study the Response of C-dec-9-en-1-ylcalix[4]resorcinarene and C-undecylcalix[4]resorcinarene Ultra-thin Films' Interactions with Cd2+, Hg2+, Pb2+, and Cu2+ Cations Present in the Subphase

Abstract

The calix [4]resorcinarene macrocycles are excellent oligomers for the design of amphiphilic derivatives; they can form self-assemblies and stable sensing networks. Owing to their favorable properties, they are the focus of many exploitations and studies ranging from biological controls to heavy metal ion sensing. In this perspective, two calix[4]resorcinarene derivatives, namely: C-dec-9-en-1-ylcalix[4]resorcinarene (ionophore I) and C-undecylcalix[4]resorcinarene (ionophore II) were used to form stable ultra-thin Langmuir monolayer films at the air/water interface; their interactions with different harmful metal cations (Cd 2+ , Pb 2+ , Hg 2+ , and Cu 2+ ) were studied and highlighted via the pressurearea (Π-A) isotherms. The obtained results in the current investigation showed a dependence of both macrocycle interactions on the metal cation concentration in the subphase, confirming their complexation. In addition, the ionophore (I) exhibited high selectivity towards Pb 2+ and Cu 2+ cations, whereas the ionophore (II) showed tendency to bind with Cu 2+ cations over others, approving the potential applicability of these macrocycles as ion selective chemical sensors.

Uranium (VI) Recovery from Black Shale Leaching Solutions Using Ion Exchange: Kinetics and Equilibrium Studies

“…The kinetic experimental results were also fitted to the intra-particle diffusion model. It is expressed by the following equation [33]:…”

“…From the obtained data in Table 4, the value of E for Dowex Marathon WBA, Diaion WA30 and Ambersep 900 SO4 is less than 8 k/Jmol for uranium ions indicating that the U(VI) sorption process proceeds via physisorption. The value of E for Puromet MTA4601PF corresponds to 9.28 kJ/mol, so the sorption process is supposed to proceed via chemisorption [33]. The values of correlation coefficient (R 2 ) are 0.849, 0.854, 0.866 and 0.880 for Dowex Marathon WBA, Diaion WA30, Ambersep 900 SO4 and Although the Langmuir and Freundlich isotherm models are widely used, they do not give information on the adsorption mechanism.…”