Di-2-ethylhexyl phosphoric acid immobilization with polysulfone microcapsules

The Evaluation of Cellulose Acetate Capsules Functionalized for the Removal of Cd(II)

Cellulose acetate is derived from cellulose and has the characteristics of biodegradability and reusability. So, it has been used for the elimination of toxic compounds capable of producing different diseases, such as cadmium, that result from human and industrial activity. For this reason, capsules functionalized with Cyanex 923 were prepared and characterized by FTIR spectroscopy, Energy Dispersive X-ray Spectroscopy (EDX), and SEM. The functionalized capsules were used for removing and recovering Cd(II) by modifying variables such as HCl concentration in the extraction medium and carrier content in the capsules, among others. The extraction of cadmium from battery leachates and the three isotherm models, Langmuir, Freundlich, and Dubinin Radushkevich, were also tested to model the cadmium removal process. The results showed a favorable physical sorption with a good capacity for extraction and the possibility of reusing the capsules for up to seven cycles without a decrease in the percentage of cadmium recovery.

Stability of composite polymeric beads containing a calix[4]arene-mono-crown-6 ligand for radio-cesium separation

Bis-octyloxy-calix[4]arene-mono-crown-6 (BOCMC) is a selective ligand for Cs(I) cation, and has been used in solvent extraction method for its separation from acidic feed. Looking at the various advantages and ease of extraction chromatography separation method, an attempt was made to prepare stable composite beads containing BOCMC entrapped in a suitable polymeric matrix. Therefore, an attempt was made to prepare a series of composite polymeric beads containing BOCMC in polysulfone (PS), polyether sulfone (PES) and sodium alginate polymeric matrix. Preparations of the beads were attempted by dissolving the solid BOCMC in the polymer solution, and also by using the ligand solution in isodecanol/dodecane and ionic liquids and then mixing in the polymeric solution. Every attempt failed to get the desired quality of beads in PES and sodium alginate matrix. However, very good quality and stable beads were obtained when 25 mM ligand solution dissolved in C₈mim.Tf₂N ionic liquid was used in PS matrix. Detail study for the extraction chromatography separation of Cs(I) was studied with BOCMC/C₈mim.Tf₂N/PS composite beads. Detail investigations on the preparation, characterization, reusability and radiation stability of these beads have been studied and reported in details.

High-capacity extraction chromatographic materials based on polysulfone microcapsules for the separation and preconcentration of lanthanides from aqueous solution

Extractant-loaded polysulfone (PS) capsules suitable for the separation and preconcentration of rare earth ions from acidic media have been prepared and characterized. Specifically, PS macro- and microcapsules have been impregnated with bis(2-ethylhexyl)phosphoric acid (HDEHP), and their performance in the extraction of europium (Eu³⁺) from nitric acid solution evaluated. The HDEHP-loaded microcapsules were found to exhibit sorption efficiency superior to those of analogous macrocapsules. Comparison to a conventional (i.e., commercial) extraction chromatographic (EXC) material (Ln•Resin), comprising HDEHP-loaded beads of poly(methyl methacrylate) (PMMA) of comparable size (50-100 µm), showed that the capacity of the HDEHP-loaded microcapsules for europium is ca. 2.5-fold greater than that of the conventional material. This larger capacity is the apparent result of both the higher extractant loading achievable with the microcapsules and an unexpected change in the complexation stoichiometry of europium by HDEHP upon extractant encapsulation. The microcapsule-based sorbent equaled or exceeded the performance of the commercial EXC material in other respects as well, most notably uptake kinetics and column efficiency, making it a promising alternative to established EXC resins.

Development of Cellulose Acetate Microcapsules with Cyanex 923 for Phenol Removal from Aqueous Media

Microcapsules of cellulose acetate with Cyanex 923 were prepared and used in this study for phenol removal from water and synthetic textile wastewater. The influence of several factors on the microcapsules extraction efficiency was studied, as well as characterization and phenol adsorption isotherm. Microcapsules characterization demonstrated the extractant reagent encapsulation, while in a batch mode procedure, good adsorption of phenol (ca. 5.5 × 10−3 mol Kg−1) has been reached. A slight decrease in phenol extraction percentage was obtained when synthetic textile wastewater was used (ca. 4.955 × 10−3 mol Kg−1), although a decrease in color was observed due to dye microcapsule extraction. Results indicate that this method is a promising alternative to conventional phenol removal technologies for aqueous samples of low phenol concentrations or in textile effluents.

Preparation of capsules containing 1-nonanol for rapidly removing high concentration phenol from aqueous solution

This study investigated the potential of capsules containing 1-nonanol for the adsorption of phenol at high initial concentrations. The polysulfone capsules containing 1-nonanol (PSF@1-nonanol capsules) were successfully prepared with a phase inversion method, and the results showed that 1-nonanol was encapsulated with polysulfone as an encapsulation capacity of 67.99% was achieved. Systematic studies on phenol adsorption equilibrium, kinetics and isotherms by PSF@1-nonanol capsules were carried out. The results showed that the rate of adsorption of phenol is initially quite rapid and equilibrium is reached in about 90 min. Phenol adsorption uptake was found to increase with increase in initial concentration and adsorption time, whereas adsorption of phenol was more favourable at acidic pH and low temperature. The adsorption kinetics of phenol followed pseudo-second-order model, and the best fits of adsorption isotherms were achieved with the Freundlich equation. These results demonstrate that the use of PSF@1-nonanol capsules enhanced the mass transfer rate and the uptakes to phenol at high initial concentrations. Furthermore, after seven times of repeated extraction and stripping, the microcapsules kept almost the same adsorption ability, which indicated that the PSF@1-nonanol capsules have very good stability in the adsorption process. Therefore, PSF@1-nonanol capsules can be taken as an ideal adsorbent for rapid removal of high concentration phenol from aqueous solution.

Effect of poly(ethylene oxide) on the release behaviors of poly(ɛ-caprolactone) microcapsules containing erythromycin

The biodegradable poly(epsilon-caprolactone) (PCL)/poly(ethylene oxide) (PEO) microcapsules and the analyzing of form and features for the manufacturing conditions were investigated in a prospective drug delivery systems (DDS) through drug release. The effects of emulsifier, emulsifier concentration, and stirring rate on the diameter and form of the microcapsules were examined using image analyzer (IA) and scanning electron microscope (SEM). The role of interfacial adhesion between PCL/PEO and drug was determined by contact angle measurements, and the drug release rate of the microcapsules was characterized by UV-vis spectroscopy. As a result, the microcapsules were made in spherical forms with a mean particle size of 170 nm approximately 68 microm. And the work of adhesion between water and PCL/PEO was increased with increasing the PEO content, which is due to higher hydrophilicity of PEO. The drug release rate of the microcapsules was significantly increased as the PEO content increased, which could be attributed to the increasing of the hydrophilic groups or the degree of adhesion at the interfaces.