Search

Copyright of Chemical Engineering (China) / Huaxue Gongcheng is the property of Hualu Engineering Science & Technology Co Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The biocatalytic conversion of acetophenone into 1-phenylethanol is a promising way to prepare a natural aroma. This work deals with adsorption on hydrophobic adsorbents as a way of separation of the product from the unreacted substrate. Seventeen types of industrial hydrophobic adsorbents were screened for their application potential in this separation. Batch equilibrium measurements were performed for these adsorbents, and the data were well fitted with the competitive Langmuir isotherm. All adsorbents had good capacities and many of them also exhibited good selectivity. The selectivity of the best was higher than 10. Since 1-phenylethanol was found to have a lower affinity than acetophenone, its recovery from the column outlet stream was first examined via ideal model simulations for a feed containing 5 g/L of 1-phenylethanol and 0.5 g/L of acetophenone. The adsorbent with the highest selectivity, Amberlite FPX68, could deliver a theoretical yield of 92.6 % for pure 1-phenylethanol. A fixed bed verification experiment provided a product collected in 55 bed volumes with 99 % purity and 87.8 % yield. [ABSTRACT FROM AUTHOR]

[Display omitted] • A ZIF-8 gel with high specific surface area (2312 m2/g) was prepared by optimizing the synthesis parameters. • A granular hierarchical porous carbon (ZIF-8-C1000) was obtained by carbonizing ZIF-8 gel. • ZIF-8-C1000 exhibited 55.2 mg/g of 10 % breakthrough capacity for 2 ppm toluene under RH 50 %. • ZIF-8-C1000 exhibited 52.1 mg/g of 10 % breakthrough capacity for 1 ppm hexanal under RH 50 %. • As-synthesized carbon can be efficiently regenerated at 60 °C due to interconnected pores, much lower needed for BPL-AC. The development of granular adsorbents for the efficient capture of low-concentration volatile organic compounds (VOCs) from humid air are highly desirable. Herein, we report the synthesis of granular ZIF-8 monolith (mono ZIF-8) featuring high surface area (2312 m2/g) and mesoporous structure by shortening the synthesis time and optimizing the reactant concentrations, which was further carbonized at 1000 °C to obtain porous granular carbon. As-prepared ZIF-8-C1000 exhibited high surface area (1623 m2/g), hierarchical porous structure (0.5–10 nm) and hydrophobicity (water contact angle 145.8°), thus it showed very high adsorption performance for trace VOCs like toluene and hexanal under both dry and humid conditions (relative humidity 30 %-80 %) at 25 °C, much higher than commercial activated carbon (AC) such as BPL-AC, coconut shell AC, and representative MOFs including HKUST-1, mono HKUST-1, mono MIL-100(Fe), MIL-101(Cr) and MOF-235. Additionally, ZIF-8-C1000 could be rapidly regenerated under mild temperatures (60 °C to 80 °C), while BPL-AC requires a higher desorption temperature and more time due to disordered porosity. The exceptional adsorption and desorption performance of granular ZIF-8-C1000 over BPL-AC can be attributed to its interconnected micropores and mesopores. [ABSTRACT FROM AUTHOR]

Protein hydrogels are water-rich structure of cross-linked protein networks. The preparation of dry gels is conceptually simple. However, reports on innovative use of dry protein hydrogels are scarce, possibly because water removal would diminish intended properties. Here, an oil-like thiol-organosilane is proposed as a protein hydrogel-promoting agent that mediates the formation of hydrophobic composite gel networks with promising properties upon drying. 3-Mercaptopropyltrimethoxylsilane (MPTMS) was used to transform aqueous albumin solutions into hydrogels. The gelation conditions were systematically investigated and optimized by varying various parameters, including temperature, pH, and the concentrations of MPTMS, albumin, and phosphate. The hydrogels were freeze-dried to obtain dry gel monoliths. The morphology of gel structure was evaluated using FE-SEM. The following properties of the dry monoliths were further evaluated: water uptake, floatability, drug loading and release, water contact angles, bulk densities, and oil adsorption. Mechanistic investigation included FTIR and fluorescence quenching determinations, and the study of emulsion properties. An unprecedented protein-organosilane composite hydrogel was synthesized in a one-step reaction, at neutral pH and ambient conditions. Freeze-dried gel monoliths exhibited excellent hydrophobicity and floatability (immediate floating and lasting for >7 days on water). The proposed material may find novel applications in floating drug delivery and environmental clean-up of oil spills. [ABSTRACT FROM AUTHOR]

Abstract: This work is devoted to the application of hydrophobic silica based aerogels and xerogels for the removal of three toxic organic compounds from aqueous solutions. These materials were tested and characterized regarding their morphology, particle size distribution, surface area and porous structure. The equilibrium tests were carried out at different adsorbate concentrations and the experimental data were correlated by means of Langmuir and Freundlich isotherms. The equilibrium data were well described by Langmuir and Freundlich in most cases. The maximum adsorption capacity by Langmuir model was observed for the adsorption of benzene onto aerogel (192.31mg/g), though the most promising results were obtained for toluene adsorption due to the greater adsorption energy involved. Comparing these results with other reported results, the hydrophobic silica based aerogels/xerogels were found to exhibit a remarkable performance for the removal of benzene and toluene. In addition, the regeneration of previously saturated aerogel/toluene was also investigated by using an ozonation process. The adsorption/regeneration tests with ozone oxidation showed that the aerogel might be regenerated, nevertheless the materials lost their hydrophobicity and thus different methods should be evaluated in forthcoming investigations. [Copyright &y& Elsevier]

Published data and the author's own data on the surface energy of hydrophilic oxides, silicates, and hydrophobic adsorbents based on them are reviewed. The prospects of using the combined Gibbs-Helmholtz-Young equation to obtain data on the surface pressure, heat of wetting, and wetting contact angle of hydrophilic and hydrophobic adsorbents are demonstrated. These data are used to estimate the thermodynamic characteristics of the surface and interfacial regions at the boundary between the materials and water. It is shown that the boundary layers of water close to the hydrophobic surfaces are more ordered while those close to the hydrophobic surfaces are less ordered than with liquid water. [ABSTRACT FROM AUTHOR]

• Internally heated / cooled temperature swing adsorption was tested for CO 2 capture. • Two typical hydrophobic adsorbents were employed for wet emission gas processing. • The separation performance of High Silica Zeolite was explored. • The unique separation behavior of Carbon Molecular Sieves was examined. This study focused on the carbon dioxide (CO 2) separation and recovery by an internally heated and cooled thermal swing adsorption process. As part of the preliminary investigation, the CO 2 capture and enrichment performance of carbon molecular sieve (CMS), a typical hydrophobic adsorbent, and high silica zeolite (HSZ), which indicates hydrophobic behavior among zeolites, were examined in a simulated dry exhaust gas. In addition, the hydroscopic adsorbent, CaA type zeolite, was employed for comparison. The effects of the regeneration temperature and the regeneration air flow rate on the separation performance were primarily investigated. In general, the CaA type of zeolite indicated a greater CO 2 concentration performance and recovery ratio due to its relatively larger adsorption capacity. Comparison between HSZ and CMS showed that the CO 2 separation and recovery performance of HSZ were greater than that of CMS. A CO 2 concentration four times higher than that of the feed gas was obtained at a regeneration temperature of 80 °C. Moreover, further enrichment of CO 2 at the desorption outlet was achieved by reducing the regeneration air flow rate to 1/40 of the feed gas of the adsorption process in exchange for lowering the CO 2 recovery ratio. In contrast, CMS could only produce three times greater the concentration of enriched CO 2 when compared to the feed gas. The enriched CO 2 concentration was almost independent of the regeneration air flow rate. This behavior was due to a lower CO 2 adsorption selectivity of CMS; this interpretation was supported by time profiles of desorption gas outlet volume and the CO 2 concentration. [ABSTRACT FROM AUTHOR]