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Subject and Specialty Construction Special Fund of Guangdong Provincial Higher Education Institution[2013KJCX0081]
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Controllable and scalable synthesis of hollow-structured porous aromatic polymer for selective adsorption and separation of HMF from reaction mixture of fructose dehydration
No full textThe hollow-structured porous aromatic polymers (H-PAP) with cavity diameter from 228 +/- 11 to 464 +/- 15 nm were controllably prepared through surface coating and template-etching method under scalable synthesis conditions from standard scale to 20-fold scale-up. It is found that the fill factor (f) of reactor is an important parameter for determining the scalability of synthesis. Benefiting from the favorable textural properties, chemical and thermal stability, surface hydrophobicity and pi electrons, the well-developed H-PAP as adsorbent was investigated in selective adsorption of 5-hydroxymethylfurfural (HMF) under static batch mode from the single-component and multi-component aqueous solutions. The H-PAP shows an exclusive adsorption for HMF, without adsorption of fructose, levulinic acid (LA) and formic acid (FA), and can be recycled three times without significant decrease in adsorption capacity. Structure-performance relationship points out that the apparent amount of HMF adsorbed on H-PAP is related to micropore surface area, micropore volume and cavity diameter, while HMF selectivity depends on surface hydrophobicity. In the case of HMF adsorption from the real reaction mixture of acid-catalyzed fructose dehydration, the HMF constituent with high purity (ca.94.4%) can be recovered. Combining the adsorption isotherms with DFT calculation reveals adsorption mechanism that HMF adsorption on H-PAP proceeds initially via pi -pi stacking interaction, and then assembles into regular array around spherical surface to form monolayer coverage following modified Langmuir model, and finally diffuses into interior cavity until adsorption saturation
Thermal analysis and heat capacity study of polyethylene glycol (PEG) phase change materials for thermal energy storage applications
No full textPhase change materials (PCMs) generally offer high latent heats for a wide range of thermal energy storage technologies. As typical organic PCMs, polyethylene glycol (PEG) has been widely studied due to their high latent enthalpy, non-toxic and non-corrosive natures. However, the thermal properties especially the heat capacities of PEG, which would play a vital role in theoretically and technically investigating PCM thermal performance, have never been studied in a wide temperature region. Herein, we reported the heat capacities of PEG samples with the molar massvarying from 1000 to 20,000 for the first time in the temperature range from (1.9 to 400) K using a combination method of Physical Property Measurement System (PPMS) and differential scanning calorimeter (DSC). Furthermore, the standard molar heat capacity, entropy and enthalpy at 298.15 K and 0.1 MPa were calculated based on the heat capacity curve fitting. Meanwhile, the phase transition temperature and enthalpy, thermal conductivity and thermal stability of these PEG samples were measured using various thermal analysis methods, and these thermal properties were also compared with the previous results. (C) 2018 Published by Elsevier Ltd
