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The performance of a weak base anion-exchange resin in removing Orange G dye from aqueous solutions in batch and column system was investigated. The adsorption capacity was found to depend on: pH, dye concentration, contact time, adsorbent dosage, electrolyte presence and temperature. The adsorption equilibrium is best described by the non-linear Langmuir isotherm model. At the optimum pH of 2, the maximum adsorption capacity was 1,076 and 1,218 mg g −1 , at 20 and 50˚C, respectively. The adsorption kinetics could be described by the pseudo-second-order reaction model. The thermodynamic parameters indicated that adsorption is a spontaneous and endothermic process. FT-IR and SEM analyses provided additional information on adsorption mechanism and on morphological changes of the adsorbent. The breakthrough experimental results were processed by means of Thomas, Yoon-Nelson and Wolborska models. The reusability of the column was examined by conducting several cycles of adsorption and desorption (with 0.05 M NaOH).

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The present study reports the first time use of MCM-41 mesoporous silica as highly efficient carrier for bexarotene -an antineoplastic agent specific for cutaneous T-cell lymphoma treatment. Bexarotene is highly toxic and poor-water soluble, having low bioavailability in the conventional pharmaceutical forms. Comparative uptake of bexarotene on amino-functionalized silica host at various functionalization degrees is discussed in details taking into account all structural features, of matrix as well as properties of the drug molecules. The obtained results proved a successful bexarotene loading on amino-functionalized MCM-41 silica. The bexarotene molecules are adsorbed on the active centers in non-crystalline state proving the major role of the silica amino-functionalization for the drug solubility and bioavailability enhancing. In vitro dissolution tests showed a prolonged release of bexarotene during 12 h, reaching 50% release of loaded active molecules. The prolonged release has been demonstrated to be a result of the presence of aminopropyl groups on the silica pore walls.

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