ABSTRACT
The use of microorganisms in biosorption is one of the most promising ways to remove trace amounts of heavy metal ions. Nevertheless, the enhancement of the successful removal of heavy metal ions by using different combinations of biosorbents is not generally guaranteed which leaves room to explore the application of the technique. In this study, the performance of free and immobilized forms of a yeast strain, Candida krusei (C. krusei), and calcium alginate (CaAlg) are evaluated for their ability to remove copper(II). Infrared spectroscopy, studies on the effects of pH and temperature, and kinetics and isotherm modelling are carried out to evaluate the biosorption. The infrared spectroscopy shows that the primary biosorption sites on the biosorbents are carboxylate groups. In addition, a higher pH and higher temperatures promote biosorption while a decline in biosorption ability is observed for C. krusei at 50 °C. The kinetics study shows that C. krusei, CaAlg and immobilized C. krusei (MCaAlg) conform with good correlation to pseudo-second order kinetics. MCaAlg and CaAlg fit well to the Langmuir isotherm while C. krusei fits well to the Temkin isotherm. From the experimental data, encapsulating C. krusei showed improved biosoprtion and address clogging in practical applications.
Subject(s)
Candida/chemistry , Copper/chemistry , Metals, Heavy/chemistry , Adsorption , Alginates/chemistry , Hydrogen-Ion Concentration , Microspheres , Models, Theoretical , Solutions , Spectroscopy, Fourier Transform Infrared , TemperatureSubject(s)
Antifungal Agents/administration & dosage , Clothing , Clotrimazole/administration & dosage , Tinea Pedis/drug therapy , Antifungal Agents/therapeutic use , Capsules , Chitosan/administration & dosage , Clotrimazole/therapeutic use , Double-Blind Method , Drug Carriers/administration & dosage , Female , Humans , MaleABSTRACT
In this paper, a simple and versatile coacervation technique has been developed by using an ultrasound-assisted oil/water emulsion method for the preparation of antifungal agent-loaded microcapsules. Two types of chitosan microcapsules are successfully prepared. The mean particle size of the chitosan/miconazole nitrate microcapsules is 2.6 µm and that of the chitosan/clotrimazole microcapsules is 4.1 µm. The encapsulation efficiency of the chitosan/miconazole nitrate microcapsules (77.58-96.81%) is relatively higher than that of the chitosan/clotrimazole microcapsules (56.66-93.82%). The in vitro drug release performance of the microcapsules shows that the chitosan/miconazole nitrate microcapsules release about 49.5% of the drug while chitosan/clotrimazole microcapsules release more than 66.1% of the drug after 12h under a pressure of 5 kg at pH 5.5, which is similar to the pH of human skin. The prepared drug-loaded microcapsules could be applied onto bandages or socks, and will continuously release antifungal drugs in a controlled manner under pressure.
