Facilitated transport of 5-aminosalicylic acid through bulk liquid membrane

Chitosan-sEPDM and Melatonin-Chitosan-sEPDM Composite Membranes for Melatonin Transport and Release

Melatonin is the hormone that focuses the attention of the researchers in the medical, pharmaceutical, materials, and membranes fields due to its multiple biomedical implications. The variety of techniques and methods for the controlled release of melatonin is linked to the multitude of applications, among which sports medicine occupies a special place. This paper presents the preparation and characterization of composite membranes based on chitosan (Chi) and sulfonated ethylene-propylene-diene terpolymer (sEPDM). The membranes were obtained by controlled vacuum evaporation from an 8% sEPDM solution in toluene (w/w), in which chitosan was dispersed in an ultrasonic field (sEPDM:Chi = 1:1, w/w). For the comparative evaluation of the membranes' performances, a melatonin-chitosan-sulfonated ethylene-propylene-diene terpolymer (Mel:Chi:sEPDM = 0.5:0.5:1.0, w/w/w) test membrane was made. The prepared membranes were morphologically and structurally characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), energy-dispersive spectroscopy analysis (EDAX), thermal analysis (TG, DSC), thermal analysis coupled with chromatography and infrared analysis, and contact angle measurements, but also from the point of view of performance in the process of transport and release of melatonin in dedicated environments (aqueous solutions with controlled pH and salinity). The prepared membranes can release melatonin in amounts between 0.4 mg/cm²·per day (sEPDM), 1.6 mg/ cm²·per day (Chi/sEPDM), and 1.25 mg/cm²·per day (Mel/Chi/SEPDM).

Effects of process factors on performances of liquid membrane-based transfer of indole-3-acetic acid

The paper has aimed at studying the transfer of indole 3-acetic acid (IAA) from a feed aqueous solution to a stripping aqueous solution of NaOH using a chloroform bulk liquid membrane and trioctylamine (TOA) as a ligand (L). Initial molar concentrations of IAA in the feed phase, c_IAA,F0 (10^–4–10^–3 kmol/m³), of TOA in the membrane phase, c_L,M0 (10^–2 and 10^–1 kmol/m³), and of NaOH in the stripping phase, c_NaOH,S0 (10^–2 and 1 kmol/m³), were selected as process factors. Their effects on the final values of IAA concentration in the feed phase (c_IAA,Ff) and stripping solution (c_IAA,Sf), extraction efficiency (E_F), distribution coefficient (K_D), and recovery efficiency (E_R) were quantified using multiple regression equations. Regression coefficients were determined from experimental data, i.e., c_IAA,Ff,ex = 0.02–1 × 10^–4 kmol/m³, c_IAA,Sf,ex = 0.22–2.58 × 10^–3 kmol/m³, E_F,ex = 90.0–97.9%, K_D,ex = 9.0–46.6, and E_R,ex = 66.5–94.2%. It was found that c_IAA,F0 had the most significant positive effect on c_IAA,Ff and c_IAA,Sf, whereas c_NaOH,S0 had a major positive effect on E_F, K_D, and E_R. A deterministic model based on mass transfer of IAA was developed and its parameters, i.e., mass transfer coefficient of IAA-L complex in the liquid membrane (0.82–11.5 × 10^–7 m/s) and extraction constant (1033.9–1779.7 m³/kmol), were regressed from experimental data. The effect of c_L,M0 on both parameters was significant.

Structural landscape of multicomponent solids of 5-aminosalicylic acid

Crystallization of ten new multicomponent solids of 5-aminosalicylic acid with various inorganic and organic coformers has been achieved by mechanochemical and solvent evaporation techniques.