Cooling and Evaporative Crystallization of α‐D‐Galactose from a Highly Viscous Industrial Side Stream

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Cooling and Evaporative Crystallization of α-D-Galactose from a Highly Viscous Industrial Side Stream

An industrial side stream was used to crystallize α-D-galactose, applying various crystallization conditions and methods. The dynamic viscosity of galactose- and glucose-containing solution samples was measured, and the crystal size, shape, structure, and purity were analyzed. The crystallization time of α-D-galactose was shortened by cooling crystallization based on stepwise temperature decrease.


Abstract

An industrial side stream containing mainly glucose and galactose was used to crystallize α-D-galactose. The dynamic viscosity of samples containing galactose and glucose solutions was measured and compared with pure glucose and galactose solutions. Various crystallization conditions were investigated in terms of temperature range and batch times in cooling crystallization and their influence on the product crystal properties. The obtained results were compared with the results of evaporative crystallization. Several characterization methods were used for studying crystal size and shape, crystal structure, and purity. The overall crystallization time of α-D-galactose was shortened by cooling crystallization based on stepwise temperature decrease and the desired crystal properties were achieved.

Flow Pattern and Mixing Performance of a Dynamic Impinging Stream Reactor

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Flow Pattern and Mixing Performance of a Dynamic Impinging Stream Reactor

Impinging stream reactors generate a high-turbulence impingement region with enhanced mass and heat transfer and have potential applications in various industrial fields. The mixing process of a dynamic impinging stream reactor was investigated by planar laser induced fluorescence, and the fluid flow pattern and mixing characteristics were studied under different flow and structural conditions.


Abstract

The mixing process of a dynamic impinging stream reactor was measured by planar laser induced fluorescence. The fluid flow pattern and mixing characteristics were studied under different conditions. The flow field was divided into the following regions by flow pattern: free jet region, impingement region, radial jet region, and radial vortex region. The mixing characteristics were analyzed under different operational conditions. The mixing time first decreased and then increased with increasing nozzle spacing. The mixing time decreased with increasing outlet velocity difference and outlet average velocity, and the optimal working conditions were nozzle spacing L = 4d, where d is nozzle diameter, outlet velocity difference v d = 1 m s−1, and outlet average velocity v p = 1.7 m s−1.

The Aptness of Organic Diluents with Tri‐n‐Butyl Phosphate for Liquid‐Liquid Equilibria of Acrylic Acid

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The Aptness of Organic Diluents with Tri-n-Butyl Phosphate for Liquid-Liquid Equilibria of Acrylic Acid

Liquid-liquid extractions of acrylic acid with tri-n-butyl phosphate dissolved in conventional diluents (benzene, toluene, xylene, hexane, petroleum ether) are analyzed. The results are explained in terms of distribution coefficient, extraction efficacy, equilibrium complexation constant, loading ratio, and coextraction of water. These findings are used to design continuous extraction columns.


Abstract

Separation of carboxylic acids from downstream is a bottleneck in the chemical industry since it takes nearly 30–50 % of the overall production cost. In view of this, an attempt was made for the extraction of acrylic acid from aqueous solution with tri-n-butyl phosphate dissolved in organic diluents like benzene, toluene, xylene, hexane, and petroleum ether. The results are explained in terms of distribution coefficient (σ), extraction efficacy (η%), equilibrium complexation constant (Kε ), loading ratio (ϕ), and coextraction of water. At lower concentration of acrylic acid and higher concentration of tri-n-butyl phosphate for the acrylic acid-tri-n-butyl phosphate system, maximum extraction efficacy and distribution coefficient for benzene was found as 88.60 % and 7.772, respectively. Coextraction of water in the extract phase and law of mass action were discussed, too. Diffusivity of acrylic acid to the interface of extract (organic) and raffinate (aqueous) phases was calculated using the Wilke-Chang equation and Reddy-Doraiswamy equation. In view of designing a continuous extraction column, the number of theoretical stages and minimum solvent-to-feed ratio were also determined.

Green Turtle (Chelonia mydas) Blood and Scute Trace Element Concentrations in the Northern Great Barrier Reef

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Abstract

Marine turtles face numerous anthropogenic threats, including that of chemical contaminant exposure. The ecotoxicological impact of toxic metals is a global issue facing Chelonia mydas in coastal sites. Local investigation of C. mydas short-term blood metal profiles is an emerging field, while little research has been conducted on scute metal loads as potential indicators of long-term exposure. The aim of the present study was to investigate and describe C. mydas blood and scute metal profiles in coastal and offshore populations of the Great Barrier Reef. This was achieved by analyzing blood and scute material sampled from local C. mydas populations in five field sites, for a suite of ecologically relevant metals. By applying principal component analysis and comparing coastal sample data with those of reference intervals derived from the control site, insight was gleaned on local metal profiles of each population. Blood metal concentrations in turtles from coastal sites were typically elevated when compared with levels recorded in the offshore control population (Howick Island Group). Scute metal profiles were similar in Cockle Bay, Upstart Bay, and Edgecumbe Bay, all of which were distinct from that of Toolakea. Some elements were reported at similar concentrations in blood and scutes, but most were higher in scute samples, indicative of temporal accumulation. Coastal C. mydas populations may be at risk of toxic effects from metals such as Co, which was consistently found to be at concentrations magnitudes above region-specific reference intervals. Environ Toxicol Chem 2023;00:1–14. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Charge localization in bis(dioxaborine) radical anions

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Charge localization in bis(dioxaborine) radical anions

Bis(dioxaborines) radical anions change from charge-delocalized to charge-localized just by changing the solvent, which is a very rare behavior in mixed valence chemistry.


Abstract

The mixed valence (MV) radical anions of several bis(dioxaborines) with aromatic bridges of different length were studied by Vis/NIR spectroscopy, cyclic voltammetry, and theoretical calculations. The phenyl-bridged (1), the biphenyl-bridged (2), and bithiophene-bridged (5) radical anions show intense low-energy intervalence bands with vibrational structure typical of charge delocalized mixed valence species in the range of solvents studied. However, by subtracting from the experimental spectra of 2 − in MeCN the fraction corresponding to the delocalized part (taken as the spectrum in tetrahydrofuran [THF]), we get a localized charge-transfer bands that show a significant cutoff effect at the low-energy side, as predicted by classical Marcus–Hush theory. In the radical anions with three aromatic rings on the bridge, the localization of the charge changes with solvent. These radicals are predominantly charge-localized in the high λ S solvent MeCN, charge-delocalized in the low λ S solvent THF, and show both type of intervalence bands in DMF. Experimental results and theoretical calculations show that the electronic coupling between dioxaborine units in these three-ring bridged radical anions increases with the number of thiophene rings on the bridge.

SurfinPES: Performing automated analysis of activation strain, energy decomposition, and reaction force

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SurfinPES: Performing automated analysis of activation strain, energy decomposition, and reaction force

SurfinPES is a module of the Eyringpy program, written in Python, to perform automated analysis of the activation strain, energy decomposition, and reaction force from electronic structure calculations. It has a simple input format and is user-friendly.


Abstract

Analyzing activation strain, energy decomposition, and reaction force models is crucial for studying chemical reactivity and gaining quantitative insights into the factors that control energy barriers. However, manually preparing and processing the necessary data can be challenging and prone to errors. To address this issue, we introduce SurfinPES, a Python-based module in Eyringpy that automates data extraction and processing for these analyses. SurfinPES also allows monitoring of the evolution of primitive properties (geometrical and electronic) along the reaction coordinate. The module is user-friendly with a simple input format, making it accessible to any user in the field of computational chemistry.

Study of the chlorogenic acid extraction with choline chloride‐based deep eutectic solvents and its non‐covalent interactions analysis

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Study of the chlorogenic acid extraction with choline chloride-based deep eutectic solvents and its non-covalent interactions analysis

The microwave-assisted extraction of the main phenolic components of green coffee beans, such as chlorogenic acid, was carried with deep eutectic solvents, where the best performance was reached by choline chloride/ethylene glycol and choline chloride/urea. Computational calculations were also carried out, and a variety of hydrogen bond types were found in every structure, as well as the thermochemistry of the formation of the corresponding complexes, where the formation of urea-based structures was slightly more effective by approx. 3 kcal/mol.


Abstract

The microwave-assisted extraction of the main phenolic component of green coffee beans, chlorogenic acid (CGA), was carried out employing deep eutectic solvents based on choline chloride and five different hydrogen bond donors (HBD) in a 1:2 ratio. The best performance for the extraction process of CGA was reached by the mixtures of choline chloride/ethylene glycol and choline chloride/urea. To understand the various interactions between the phenolic compound and the two most efficient deep eutectic solvents, computational calculations were carried out at the density functional theory (DFT) level, as well as Atoms in Molecules (AIM) and Non-Covalent Interactions (NCIs) analyses. In that way, a variety of hydrogen bond types were found in every structure. Nevertheless, the CGA does not disrupt the hydrogen bond network established between ChCl and the HBD. Among the strongest interactions are those hydrogen bonds between the quinic acid moiety and the ethylene glycol or the urea. In addition, the thermochemistry of the formation of the two main deep eutectic solvents and their corresponding complexes with CGA was calculated, where the formation of urea-based structures was slightly more effective by ~3 kcal/mol.