Conversion of liquid and semisolid lipids into free flowing powders is an advantageous technique, as the carriers display high surface area, strong adsorption capacity, ease of processing, and ability to generate lipid loaded free flowing powders which can be converted to solid dosage forms like tablets and capsules. A combination of density, adsorption capacity and desorption is found to be of importance in the selection of the right adsorbent. Adsorbents like magnesium aluminium silicates (MAS), granulated fumed silica (GFS) and mesoporous silica gel (MSG) were characterized by flow property measurements, particle size, scanning electron microscopy (SEM) and pore structure by mercury (Hg) intrusion study. SEM results reveal adsorbent morphology, whereas an intrusion-extrusion study reveal pore size distributions. Tablets and capsules of oil loaded adsorbents were prepared by conventional methods. Oil loaded adsorbents were evaluated for the ability to convert oil into powder, easy of processing into tablets and capsules, and release of the loaded oil (Vitamin E) or active (Glyburide). All adsorbents possess good flow property while MSG has higher density than GFS and MAS. This helps to deliver maximum active per unit volume. A wider pore size distribution of MAS was observed in comparison to MSG and GFS. MAS exhibited poor oil release from powder and its formulations, whereas GFS demonstrated closely similar release to MSG. Maximum 70% oil loaded MSG can be delivered in tablet dosage form and MSG can deliver the highest amount in limited volume capsules due to its high density. Hence, lower density and poor oil release from MAS limit its applications in solid oral drug delivery, while both MSG and GFS proved to be suitable.

Combined X-ray diffraction (XRD), helium ion microscopy (HeIM), and 43 Ca nuclear magnetic resonance (NMR) results provide novel insight into the nano-and microstructure of flocculated NOM; the molecular-scale interaction among natural organic matter (NOM), dissolved Ca 2+ ions, and water in NOM floccs; and the effects of pH and ionic strength on these characteristics. Suwannee River humic acid (HA), fulvic acid (FA), and NOM flocculated from Ca 2+ bearing solutions share similar morphological characteristics on the 100 nm to micron scales, including micron-sized equant fragments and rounded, rough areas with features on the 100 nm scale. HeIM suggests that the NOM floccs are built from a fundamental spheroidal structure that is ∼10 nm in diameter, in agreement with published AFM and small-angle X-ray scattering results. Calcium is incorporated into these floccs at 100% relative humidity in a wide range of disordered structural environments, with basic pH leading to shorter mean Ca−O distances and lower mean coordination numbers with respect to floccs formed under acidic conditions. The NMR results show that dynamical processes involving water and Ca 2+ occurring at frequencies >10 4 Hz are important for hydrated OM floccs, in agreement with published molecular dynamics simulations of OM in solution. From the NMR results, we find evidence for two Ca 2+ dynamic averaging mechanisms: one related to rapid exchange (>100 kHz) between surface proximity-restricted (those within 5 Å of a surface) and bulk solution environments when excess Ca 2+ is present in the pore solution when pore water is unfrozen and a second consisting of intermediate scale (tens of kHz) site exchange among strongly sorbed inner-sphere sites when excess Ca 2+ is absent and the carboxylic and phenolic functional groups of the NOM are deprotonated. ■ INTRODUCTIONNatural organic matter (NOM) and its interaction with mineral surfaces have received considerable attention in the energy science, wastewater treatment, materials, environmental chemistry, and geoscience communities. 1−29 NOM is a complicated mixture of organic molecules derived naturally from the decay of principally plant matter. Because of the multitude of starting materials and complex (bio)chemical pathways involved in NOM formation, it contains a wide variety of chemical structures and functional groups. It also has a range of molecular weights, and the mechanisms of its aggregation to form larger units remain controversial. 1−3,11,30−32 The chemical and structural complexity of NOM and its ubiquitous occurrence in the environment make it an important, chemically active component of surface water, soils, and groundwater. Thus, understanding the behavior and chemistry of hydrated NOM across several length and time scales is important to understanding NOM−mineral interactions, the global carbon balance, soil biogeochemistry, plant nutrition, industrial fouling, and a variety of fundamental chemical processes in the environment, including weathering reactions and the transport of inorga...

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