Properties of diclofenac sodium sorption onto natural zeolite modified with cetylpyridinium chloride

• Published in: Colloids and surfaces, B, Biointerfaces B, Biointerfaces, 2011-03, Vol.83 (1), p.165-172
• Main Authors: Krajišnik, Danina, Daković, Aleksandra, Milojević, Maja, Malenović, Anđelija, Kragović, Milan, Bogdanović, Danica Bajuk, Dondur, Vera, Milić, Jela
• Format: Article
• Language: English
• Subjects: Adsorption; aqueous solutions; cation exchange; cation exchange capacity; Cationic surfactant; cations; Cetylpyridinium - chemistry; cetylpyridinium chloride; chemical concentration; Clinoptilolite; Diclofenac; Diclofenac - chemistry; drug formulations; Drug sorption; Drugs; Excipient; Fourier transform infrared spectroscopy; Kinetics; Mathematical models; micelles; Models, Chemical; nonsteroidal anti-inflammatory agents; Partitioning; Sodium; Sorption; sorption isotherms; Spectrophotometry, Infrared; Static Electricity; Surface chemistry; surfaces; Surfactants; Temperature; thermal analysis; Thermogravimetry; Zeolites; Zeolites - chemistry; zeta potential
• ISSN: 0927-7765; 1873-4367
• DOI: 10.1016/j.colsurfb.2010.11.024

[Display omitted] ▶ The modification of clinoptilolite with cetylpyridinium chloride is performed. ▶ The sorbed surfactant forms an organic layer without changing the zeolite structure. ▶ The surfactant molecules associate to produce aggregates of different shape. ▶ Modified zeolites are effective in sorption of diclofenac sodium as a model drug. ▶ Adsorption and partitioning of diclofenac sodium take place simultaneously. In this study an investigation of a model drug sorption onto cationic surfactant-modified natural zeolites as a drug formulation excipient was performed. Natural zeolite was modified with cetylpyridinium chloride in amounts equivalent to 100, 200 and 300% of its external cation-exchange capacity. The starting material and obtained organozeolites were characterized by Fourier transform infrared spectroscopy, zeta potential measurements and thermal analysis. In vitro sorption of diclofenac sodium as a model drug was studied for all surfactant/zeolite composites by means of sorption isotherm measurements in aqueous solutions (pH 7.4). The modified zeolites with three levels of surfactant coverage within the short activation time were prepared. Zeta potential measurements and thermal analysis showed that when the surfactant loading level was equal to external cation-exchange value, almost monolayer of organic phase were present at the zeolitic surface while higher amounts of surfactant produced less extended bilayers, ordered bilayers or admicelles at the zeolitic surface. Modified zeolites, obtained in this manner, were effective in diclofenac sodium sorption and the organic phase derived from adsorbed cetylpyridinium chloride was the primary sorption phase for the model drug. The Langmuir isotherm was found to describe the equilibrium sorption data well over the entire concentration range. The separate contributions of the adsorption and partition to the total sorption of DS were analyzed mathematically. Results revealed that that adsorption and partitioning of the model drug take place simultaneously.