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An in-house method, employing magnetic stirring-assisted aqueous extraction combined with gas chromatography-flame ionization detector, for determination of ethanol in different foods and beverages was validated according to the ISO/IEC 17025 standard. Validation parameters, including selectivity, method limits of detection (approx. 0.006 mg/g) and quantification (approx. 0.02 mg/g), linearity (R2 of >0.999), trueness (relative biases of

This work proposes a practical and systematic model-based approach to identify the optimal operating conditions for a simulated moving bed reactor (SMBR). The SMBR operation is applied to an industrial case study for the continuous production of a solvent, propylene glycol methyl ether acetate (DOWANOL™ PMA), which is produced through an acid-catalyzed esterification reaction of 1-methoxy-2-propanol and acetic acid. The model-based approach is demonstrated by lab-scale SMBR experiments. A multi-objective optimization problem was formulated for developing an SMBR process to maximize the production rate of PMA and the conversion of the esterification reaction simultaneously. In this study, this optimization problem is solved using the epsilon-constrained method and a Pareto plot is presented. The solutions that corresponded to three different values of conversion, 70%, 80%, and 85%, are experimentally validated. The SMBR model that was developed from batch kinetic and single column chromatography experiments demonstrates reasonable agreement with the experimental results. Furthermore, the SMBR experimental data was used to correct the parameters in the model. A validation study at a higher conversion of 95% demonstrates improved predictability of the corrected parameters.

Reactive chromatography using an anion exchange resin is proposed for a transesterification reaction of propylene glycol methyl ether (DOWANOL™ PM) with ethyl acetate to produce propylene glycol methyl ether acetate (DOWANOL™ PMA). This reaction is studied in batch and chromatographic reactors catalyzed by an anion exchange resin. Several anion exchange resins are tested and compared based on the performance of resin as an adsorbent and a catalyst. A chromatographic column is packed with a selected catalyst, AMBERLITE™ IRA904, and both reaction and chromatographic elution are studied at different temperatures and feed concentrations. The resulting chromatograms are fitted to a mathematical model to obtain adsorption equilibrium and reaction kinetic parameters by the inverse method. Compared to esterification investigated in a previous study, transesterification has advantages such as a higher conversion at lower temperature and easy removal of the byproduct which may lead to higher productivity. Deactivation of anion exchange resins is observed and potential solutions are suggested.

In this study, the thermodynamic inhibition effects of choline chloride (ChCl, a hydrogen bond acceptor), urea (a hydrogen bond donor), and their mixture (deep eutectic solvent, DES) on CH4 hydrates were investigated with both experimental and computational approaches. The synthesis of DES from the mixture of ChCl and urea was confirmed by measuring its melting temperature through a high-pressure micro-differential scanning calorimeter. Sigma (σ)-profiles of ChCl, urea, and DES obtained by the COSMO-RS software indicated that these substances have great potential to be used as thermodynamic hydrate inhibitors (THIs). The three-phase (gas hydrate (H) – liquid water (Lw) – vapor (V)) equilibria of CH4 hydrates in the presence of ChCl (1.0, 3.0, and 5.0 mol%), urea (1.0, 3.0, and 5.0 mol%), and DES (3.0 mol%) demonstrated that ChCl, urea, and DES contributed to the significant shift of hydrate equilibrium temperature to inhibition regions at a specified pressure and thus can function as effective THIs. Moreover, quantum theory of atoms in molecules (QTAIM) analysis also demonstrated that the strength of hydrogen bonding between inhibitor molecules and hydrate cages (small 512 and large 51262 cages) of CH4 hydrates was in the order of ChCl > DES > urea, which was consistent with experimental results. The experimental and computational results from this study would be helpful for a better understanding of the inhibition mechanism of ChCl, urea, and DES and for their possible application to flow assurance in oil and gas pipelines.

This study developed an insect-repellent film incorporated with star anise essential oil (SAEO). The insect-repellent emulsion coating (IEC) was applied to a base layer of polyethylene terephthalate. To control the rate of SAEO released from the IEC, three types of laminate film with different gas transmission rates were used, including low-density polyethylene film, polypropylene film of 20-μm thickness, and polypropylene film of 30-μm thickness (PP30). When prepared at a laboratory-scale, the PP30 proved the most efficacious in providing long-lasting insect-repellent activity and the sensory attributes of the PP30 were not significantly different (p > 0.05) from those of the control film (i.e., without the IEC layer). Therefore, the PP30 selected for further analysis. The active film was then manufactured at a pilot-scale using a rotogravure printing press, and its mechanical and optical properties were evaluated. Although the active film had a similar appearance with the control film to the naked eye, the active film had relatively lower tensile strength and elongation at break values, and it was less transparent with a more reddish color. Finally, the active film was applied as bread packaging, and the results suggested that as a food packaging material, the film showed excellent insect-repellent activity. Therefore, the developed active film in the pilot-scale has applicability to a real food system.

As an industrial case study, esterification of acetic acid with 1-methoxy-2-propanol using a cation exchange resin has been investigated using a well-stirred batch reactor and chromatographic reactor. Well-stirred batch reactor experiments were conducted over different operating conditions to analyze the reaction equilibrium and kinetics. It was found that the final conversion was limited by equilibrium, and temperature had no significant effect on increasing the final conversion. Parameters in a reaction rate model were obtained at different temperatures (50–90 °C). Since the well-stirred batch experiment alone was not enough to capture the adsorption behavior of the system, pulse injections of each component into the chromatographic column were conducted to obtain the adsorption parameters. The esterification reaction was performed systematically in a lab-scaled chromatographic reactor at different flow rates (0.2–1 ml/min), injection volumes (0.05 ml, 0.5 ml), and temperatures (70–110 °C). A mathematical model for isothermal equilibrium dispersive model was implemented and parameters were determined by fitting the model to the experimental data. It was observed that when the injection volume of single component was too large, two reaction sites were formed inside the column, resulting in a deformed peak shape of the product in the outlet chromatogram. Nearly 100% of conversion, which was infeasible in the well-stirred batch reactor, was achieved when the flow rate was low and the injection volume was small. The results indicate that the chromatographic reactor enhanced the reaction beyond the equilibrium by separating the products from the reaction sites.

We evaluated the antioxidant and antimicrobial activities of various leafy herbal tea (LHT) extracts, including rooibos, green tea, black tea, rosemary, lemongrass, mulberry leaf, bamboo leaf, lotus leaf, peppermint, persimmon leaf, and mate tea. To compare the antioxidant activities of various LHTs, samples of each were extracted with 80 °C water or 20 °C ethanol, and their total phenolic content (TPC), total flavonoid content (TFC), 2,2-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, 2,2-azinobis-3 ethyl benxothiazoline-6-sulphonic acid (ABTS) radical cation decolorization activity, ferric reducing power, and ferrous ion chelating effect were measured. Green tea ethanol extract showed the highest antioxidant activity in all assays except the ferrous ion-chelating assay. Water extracts of green tea and black tea and ethanol extracts of rosemary, mate, and persimmon leaf teas also exhibited considerable antioxidant potential, followed by the green tea ethanol extract. Minimum inhibitory concentrations (MIC) and minimum lethal concentrations (MLC) were determined to verify the antimicrobial activities of the LHT extracts against two oral pathogens (Streptococcus mutans and Streptococcus sobrinus) and three food-borne pathogens (Listeria monocytogenes, Shigella flexneri, and Salmonella enterica). Among the tested LHTs, green tea ethanol extract had potent antimicrobial activity against all five pathogens, and the mate tea water extract was the most effective against Gram-positive bacteria. Consequently, green tea ethanol extracts had the most powerful antioxidant and antimicrobial properties, suggesting their potential application as a health-promoting functional ingredient or natural preservative in foods.

The full scale Soil Cement Mixing (SCM) wall was constructed to investigate viability of the wall. Long term behavior of the wall resulted in viability of the wall. However, design guidelines on SCM wall are limited due to its complex geometry. In this paper, the three dimensional finite element method is employed to study the influence of various design decisions for SCM wall. The numerical model is first calibrated with an instrumented case history. Then a parametric study is constructed. The results give information on the influence of the following factors on the wall behavior: size of column, column overlapping, column embedment, existence of relieving platform, and column strength. The implications in design are discussed.