Uticaj modifikacije na strukturna, teksturalna i adsorpciona svojstva bentonita

Natural bentonite clay from the Bogovina locality in Serbia was Na-exchanged and modified using hexadecyll-trimethylammonium bromide as surfactant and organobentonite was obtained. The influence of modifications on the structural, textural and sorption properties of bentonite was investigated. It was estimated that modifications solely replace exchangeable cations in smectite layers, whereas other admixture minerals (quartz, calcite, feldspar) in bentonite remain unaffected. According to X-ray results the modification lead to changes in the smectite structure by either decreasing, for Na-bentonite, or increasing, for organobentonite, the interplanar spacing, d(001). The appearance of three new bands in IR spectra of HDTMA-bentonite comparing to those of raw and Na-bentonite assigned to the methylene vibrations confirmed the embedding of aliphatic cations into smectite structure. In organobentonite a significant change in textural properties was observed. In particular, specific surface area dramatically decreased while originally meso and microporous material became almost completely non-porous. Despite almost insignificant specific surface area the synthesized organobentonite due to gained organophyllity of its surface exhibits exquisite adsorption properties toward investigated textile dyes having adsorption capacity approx. 2 times higher than activated carbon.Prirodna bentonitna glina sa lokaliteta Bogovina u Srbiji je natrijumski izmenjena i modifikovana heksadeciltrimetil amonijum-bromidom kao surfaktantom, pri čemu je dobijen organobentonit. Ispitivan je uticaj modifikacije na strukturu, teksturalna i adsorpciona svojstva bentonita. Utvrđeno je da primenjeni postupci modifikacije dovode isključivo do izmene katjona u medulamelamom sloju smektita, dok modifikacija ne deluje na druge prateće minerale u bentonitu (kvare, kalcit, feldspat). Uprkos neznatnoj specifičnoj površini sintetizovani organobentonit zahvaljujući novodobijenoj organofilnosti površine pokazuje izuzetna adsorpciona svojstva prema tekstilnim bojama, imajući adsorpcioni kapacitet oko 2 puta veći od aktivnog uglja

DUV fluorescence bioimaging study of the interaction of partially reduced graphene oxide and liver cancer cells

The interaction of partially reduced graphene oxide (prGO) and Huh7.5.1 liver cancer cells was investigated by means of DUV fluorescence bioimaging. The prGO sample was obtained by the reduction (to a certain extent) of the initially prepared graphene oxide (GO) nanosheets with hydrazine. The fluorescence of the GO nanosheets increases with time of the reduction due to a change in ratio of the sp(2) and sp(3) carbon sites and the prGO sample was extracted from the dispersion after 6 min, when the intensity of the fluorescence reached its maximum. The reduction process was left to proceed further to saturation until highly reduced graphene oxide (denoted here as rGO) was obtained. GO, prGO and rGO samples were investigated by structural (scanning electron microscopy (SEM), scanning transmission electron microscopy coupled with energy dispersive spectrometry (STEM-EDS)) and spectroscopic (UV-vis, photoluminescence (PL), Raman) methods. After that, Huh7.5.1 cells were incubated with GO, prGO and rGO nanosheets and used in bioimaging studies, which were performed on DISCO beamline of synchrotron SOLEIL. It was found that the prGO significantly enhanced the fluorescence of the cells and increased the intensity of the signal by similar to 2.5 times. Time-lapse fluorescence microscopy experiments showed that fluorescence dynamics strongly depends on the type of nanosheets used. The obtained prGO nanostructure can be easily conjugated with aromatic ring containing drugs, which opens a possibility for its applications in fluorescence microscopy monitored drug delivery

The application of NIR spectroscopy with chemometric analysis for monitoring a powder blending process

This paper reports the use of near infrared (NIR) spectroscopy as a process analytical technology (PAT) tool for monitoring the metformin (N,N-dimethylimidodicarbonimidic diamide) hydrochloride and poly(vinyl pyrrolidone) (PVP) mixing process, which is the first stage in tablet production. Blend homogeneity was tested using the non-invasive NIR spectroscopy method and the partial least squares (PLS) regression model was applied for the analysis of the obtained spectra. Simultaneously, the critical parameter (metformin hydrochloride content) was monitored by a classical analytical technique, the validated HPLC method, commonly used for this purpose. Based on the high sensitivity of the model developed in this study, as well as the established correlation among the results obtained by different methods, it could be concluded that the proposed rapid and non-invasive technique. could be an effecttive tool for the monitoring of one of the critical manufacturing steps in the production solid dosage forms

Mg-Fe-mixed oxides derived from layered double hydroxides: A study of the surface properties

The influence of surface properties on the selectivity of the synthesized catalysts was studied, considering that their selectivity towards particular hydrocarbons is crucial for their overall activity in the chosen Fischer- -Tropsch reaction. Magnesium- and iron-containing layered double hydroxides (LDH), with the general formula: [Mg1-xFex(OH)2](CO3)x/2?mH2O, x = = n(Fe)/(n(Mg)+n(Fe)), synthesized with different Mg/Fe ratio and their thermally derived mixed oxides were investigated. Magnesium was chosen because of its basic properties, whereas iron was selected due to its well-known high Fischer-Tropsch activity, redox properties and the ability to form specific active sites in the layered LDH structure required for catalytic application. The thermally less stable multiphase system (synthesized outside the optimal single LDH phase range with additional Fe-phase), having a lower content of surface acid and base active sites, a lower surface area and smaller fraction of smaller mesopores, showed higher selectivity in the Fischer-Tropsch reaction. The results of this study imply that the metastability of derived multiphase oxides structure has a greater influence on the formation of specific catalyst surface sites than other investigated surface properties

Synthesis, Characterization, and Impact of Water on the Stability of Postmodified Schiff Base Containing Metal–Organic Frameworks

In this study, the synthesis of a Schiff base containing metal–organic frameworks (MOFs) of the UiO-67 family has been investigated. MOFs featuring free amine groups were successfully synthesized under mild solvothermal conditions using 2-amino-[1,1′-biphenyl]-4,4′-dicarboxylic acid and 2,2′-diamino-[1,1′-biphenyl]-4,4′-dicarboxylic acid as bridging ligands, resulting in MOFs with amine groups covalently linked to the bridging ligands. Both types of functionalized MOFs were post-synthetically modified with 4-formylbenzonitrile that resulted in imine formation. All the obtained compounds were characterized by PXRD, TGA, DTA, BET, NMR, and FTIR spectroscopy, while stability in water was monitored with SEM, EDS, and UV–VIS spectroscopy

Synthesis, Characterization, and Impact of Water on the Stability of Postmodified Schiff Base Containing Metal–Organic Frameworks

In this study, the synthesis of a Schiff base containing metal–organic frameworks (MOFs) of the UiO-67 family has been investigated. MOFs featuring free amine groups were successfully synthesized under mild solvothermal conditions using 2-amino-[1,1′-biphenyl]-4,4′-dicarboxylic acid and 2,2′-diamino-[1,1′-biphenyl]-4,4′-dicarboxylic acid as bridging ligands, resulting in MOFs with amine groups covalently linked to the bridging ligands. Both types of functionalized MOFs were post-synthetically modified with 4-formylbenzonitrile that resulted in imine formation. All the obtained compounds were characterized by PXRD, TGA, DTA, BET, NMR, and FTIR spectroscopy, while stability in water was monitored with SEM, EDS, and UV–VIS spectroscopy