The transformation of CO2 into a precipitated mineral carbonate through an ex situ mineral carbonation route is considered a promising option for carbon capture and storage (CCS) since (i) the captured CO2 can be stored permanently and (ii) industrial wastes (i.e., coal fly ash, steel and stainless-steel slags, and cement and lime kiln dusts) can be recycled and converted into value-added carbonate materials by controlling polymorphs and properties of the mineral carbonates. The final products produced by the ex situ mineral carbonation route can be divided into two categories-low-end high-volume and high-end low-volume mineral carbonates-in terms of their market needs as well as their properties (i.e., purity). Therefore, it is expected that this can partially offset the total cost of the CCS processes. Polymorphs and physicochemical properties of CaCO3 strongly rely on the synthesis variables such as temperature, pH of the solution, reaction time, ion concentration and ratio, stirring, and the concentration of additives. Various efforts to control and fabricate polymorphs of CaCO3 have been made to date. In this review, we present a summary of current knowledge and recent investigations entailing mechanistic studies on the formation of the precipitated CaCO3 and the influences of the synthesis factors on the polymorphs.

Nanoparticle organic hybrid materials (NOHMs) are self-suspended liquid-like nanoparticle-based functional materials consisting of a surface-functionalized inorganic nanocore and oligomeric or polymeric chains. They often exhibit complex intermolecular and intramolecular interactions among their constituents, resulting in versatile physicochemical characteristics that range from glassy solids to solvent-free nanoparticle fluids. A variety of applications involving NOHMs have been investigated thus far, including thermal management fluids, lubricants, magnetic fluids, nanocomposites, electrolytes, water treatment and biomass pretreatment chemicals, and CO 2 capture solvents. In particular, NOHMs have recently been recognized as a promising CO 2 capture and utilization medium. To capture CO 2 more effectively, a variety of specific functional groups of strong chemical affinity to CO 2 can be added to the polymeric canopy (enthalpic contribution), and various steric considerations induced by attractive/repulsive interactions among the nanocores and canopies can be introduced (entropic contribution). These occur while maintaining negligible vapor pressure and enhanced thermal stability. Here, we investigated the canopy dynamics of NOHMs with different-sized SiO 2 nanocores, aiming to reveal the hidden nature of the entropic interaction occurring in NOHMs. Pulse-field gradient nuclear magnetic resonance spectroscopy (with 1 H) was employed to investigate the canopy dynamics of the NOHMs synthesized using 7, 12, and 22 nm SiO 2 particles, and these results were compared with those from a ternary mix of all three sizes of SiO 2 nanocores. The self-diffusion coefficient and thermal diffusivity were also evaluated.

This study reports the thermochemical transformation of lignin model compounds using nanoparticle organic hybrid materials (NOHMs). NOHMs have recently been developed as an emerging class of self-suspended nanoparticle solvent systems created by ionically or covalently grafting organic oligomers or polymers (canopy) onto surface-modified inorganic nanoparticles (core). Because NOHMs exhibit negligible vapor pressure with the ability to tailor physicochemical properties, they could be a promising catalytic solvent for the lignin thermochemical conversion process. The thermochemical conversion of lignin model compounds was achieved with the synthesized NOHM at an elevated temperature of 473 K, and the results were compared with the case of the ionic liquid [EMIM][ESO 4 ]. The fractured moieties of the lignin model compounds were qualitatively identified by ATR FT-IR and 2D COSY NMR spectroscopies. The results indicated that the NOHM decomposed the C−O and/or C−C bonds of lignin model chemicals more efficiently than [EMIM][ESO 4 ].

Patterns of VOC and BTEX (Benzene, Toluene, Ethylvenzene, and Xylene) distribution at industrial emission sources, proximal residential areas of industrial estates, and ambient air were studied in Daegu, Korea. Daytime and night-time sampling was done at 12 sites and 9 emission sources to provide samples for analyses, using the TO-14 method. Measured BTEX component ratios B/T, T/EB, T/X and EB/X in ambient air were found to be 2.6 g, 11.3 g, 1.0 g and 1.2 g in the residential area; 2.2 g, 11.0 g, 1.0 g and 1.6 g in the commercial area; and 1.0 g, 14.9 g, 1.0 g and 1.3 g in the industrial area. The significant difference observed between the ratios for the residential and commercial areas implies that the two areas have different emission sources. This is also indicated by the significant differences observed between daytime and nighttime BTEX concentrations. Toluene and xylene were detected at very high concentrations, at the sampling sites. This pattern reflects the type of industrial processes and materials that are managed at the emission sources, as well as topographic/climatic factors that impact upon pollutant transport processes in the atmosphere. The BTEX distribution pattern in Daegu is observed to be similar to that of several Asian cities, particularly Hong Kong. These results are useful in the design of emission source control measures for VOCs and BTEX in Daegu.

Drug stability and sustained release issues are important areas in drug-delivery research. The sustained release of proteins can be achieved by their encapsulation with a hydrophobic polymer, but this requires the proteins to be protected from the harsh processing environments of organic solvents and mechanical force. Preencapsulation with poly(vinyl alcohol) (PVA) using a freeze/thaw method has been shown to allow successful protection and sustained release. This study examined the effects of freezing/thawing on PVA encapsulation in the preparation of PVA-PLGA composite particles. Freezing/thawing slightly improved the crystalline peaks and the heat of fusion of PVA, but more distinct differences were observed when the properties of the surface layers were probed by AFM. The hardness of particles' surfaces increased with increasing number of freezing/thawing cycles, whereas the adhesion force with an AFM cantilever tip decreased. The mean particle size and entrapment efficiency decreased. These results suggest that surface hardening is the major mechanism responsible for the sustained release characteristics.