ABSTRACT
Due to the increased demand for palladium, as well due to its reduced availability in nature, its recovery from diluted waste solutions becomes a necessity, and perhaps an emergency. As a result of economic and technological development, new materials with improved adsorbent properties that are more efficient for metallic ions' recovery were synthesized and introduced to market. The goal of this study was to obtain a new adsorbent material by functionalizing through impregnation a commercial polymeric support that was both inexpensive and environmentally friendly (Amberlite XAD7) with crown ether (di-benzo-18-crown-6-DB18C6). Crown ethers are known for their ability to form complexes within metallic ions, by including them inside of the ring, regardless of its atomic size. Adsorbent material was prepared by impregnation using the solvent-impregnated resin method (SIR). To highlight the presence of crown ether on the resin surface, a new synthesized material was characterized by scanning electron microscopy (SEM), elemental analysis X-ray energy dispersive spectroscopy (EDX) and Fourier transform infrared spectroscopy (FT-IR). The specific surface of the adsorbent material was also determined by the Brunauer-Emmett-Teller (BET) method. Adsorbent performances of the prepared material were highlighted by kinetic, thermodynamic and equilibrium studies and a possible mechanism was also proposed. The influence of specific parameters for the adsorption process (contact time, temperature, Pd(II) initial concentration) on the maximum adsorption capacity was pursued.
ABSTRACT
The aim of this study is to obtain and characterize of alginate-based membranes, as well as to choose the most suitable membrane type for the transdermal release of methotrexate. The paper presents the synthesis of four types of membranes based on alginate to which are added other copolymers (Carbopol, Tween, and Polyvinylpyrrolidone) as well as other components with different roles. Membranes and binary mixtures made between the components used in membrane synthesis and methotrexate are analyzed by thermogravimetric techniques, FTIR and UV spectroscopic techniques as well as SEM. The analyses aim to establish the type of membrane most indicated in the use of the controlled release of methotrexate, namely those membranes in which there are no interactions that could inactivate the active substance. Following these studies, it was concluded that membranes obtained from alginate/alginate and Tw can be used for methotrexate release. The membrane obtained from alginate and carbopol was excluded from the beginning because it is not homogeneous. Regarding the AGP-MTX membrane, it presents interactions with the active substance, carboxylate group interactions argued by TGA and FTIR studies, and interactions that occur in aqueous medium.