Aqueous Sugar Solutions Research Articles

Experimental investigation of pressure drop in structured packings

Several studies have been performed to measure pressure drop in packed towers, however, most of them have focused on distillation and random packings and the correlations obtained may not be directly applicable to reactive absorption. In this paper, results from a study of pressure drop in 3 different structured packings; Mellapak 2X from Sulzer, Koch-Glitsch Flexipac 2Y HC, and Montz-Pak B1-250M, are presented. The fluid systems tested were: air/water, air/ aqueous sugar solutions with liquid viscosities from 2.5 to 12cP and finally air/30wt% MEA. The column used had a 5m packing height with an inner diameter of 0.5m. Pressure drop across the packing height was obtained as function of gas and liquid flow rate both as total pressure drop and as pressure change along the packing. A slight influence of viscosity on pressure drop and flooding point was found. The experimental results were compared with estimates made using the software packages provided by the various suppliers for their own packings. Comparisons between estimated and experimental results showed that the selected software in general gives reliable predictions of pressure drop up to an F-factor of about 3Pa0.5, but that deviations may occur even for lower F-factors at high liquid loads. For low liquid loads (<10m3/m2h) the software estimations are good in the whole range of measurements (F-factor <4.5–5Pa0.5). For reactive systems at all liquid loads there is hardly any change at all for the Flexipac 2Y HC and B1-250M. For the Mellapak 2X the effect of the reactive system is significant for high liquid loads.

Direct evidence for the ring opening of monosaccharide anions in the gas phase: photodissociation of aldohexoses and aldohexoses derived from disaccharides using variable-wavelength infrared irradiation in the carbonyl stretch region

All eight d-aldohexoses and aldohexoses derived from the non-reducing end of disaccharides were investigated by variable-wavelength infrared multiple-photon dissociation (IRMPD) as anions in the negative-ion mode. Spectroscopic evidence supports the existence of a relatively abundant open-chain configuration of the anions in the gas phase, based on the observation of a significant carbonyl absorption band near 1710 cm −1. The abundance of the open-chain configuration of the aldohexose anions was approximately 1000-fold or greater than that of the neutral sugars in aqueous solution. This provides an explanation as to why it has not been possible to discriminate the anomeric configuration of aldohexose anions in the gas phase when derived from the non-reducing sugar of a disaccharide. Evidence from photodissociation spectra also indicates that the different aldohexoses yield product ions with maximal abundances at different wavelengths, and that the carbonyl stretch region is useful for differentiation of sugar stereochemistries. Quantum-chemical calculations indicate relatively low energy barriers to intramolecular proton transfer between hydroxyl groups and adjacent alkoxy sites located on open-chain sugar anions, suggesting that an ensemble of alkoxy charge locations contributes to their observed photodissociation spectra. Ring opening of monosaccharide anions and interconversion among configurations is an inherent property of the ions themselves and occurs in vacuo independent of solvent participation.

ChemInform Abstract: Functionalization of Carbohydrates in Water

AbstractReview: 219 refs.

Hydration properties and proton exchange in aqueous sugar solutions studied by time domain nuclear magnetic resonance

Proton NMR relaxation rates (R1 and R2) were measured in aqueous solutions of sucrose, d-glucose and d-fructose with increasing concentration. The measurements were carried out using Bruker PC 20 NMR Process Analyzer. Inversion recovery and CPMG pulse sequences are used for the measurement of relaxation rates. Results show that the values of relaxation rate increase as the concentration of the sugar is increased. The relaxation rate appears to be higher for sucrose solutions as compared to glucose or d-fructose solutions. These results were discussed on the basis of molecular association between sugar and water molecules through hydrogen bonding. The water self diffusion coefficient was measured in these sugar solutions by using pulse field gradient NMR method. As expected, the water self-diffusion coefficient was reduced with increased sugar concentrations. The results of translational mobility exhibited a higher mobility for fructose than glucose or sucrose in aqueous solutions.The dependence of R2 on the inter-pulse delay of the CPMG sequence gives information on the proton exchange mechanism involved. The mechanism of exchange was studied using R2 with increasing inter pulse delay of 0.05–2.0ms in aqueous solutions of 10%, 20% and 35% (w/v) of the above sugar solutions. From the plots of relaxation rates (R2) versus the 90°–180° pulse spacing it was possible to calculate the proton exchange rate (kb) of the different sugar solutions. Relaxation rates show characteristic variations with CPMG pulse spacing which can be interpreted on the basis of chemical exchange between solute and solvent molecules.The experimental results namely relaxation rates and CPMG pulse spacing data show the importance of water interactions with sweet molecules and this can lead to a better understanding of the effect of hydration water in taste chemoreception.

Dielectric Relaxation and Water Activity in Aqueous Solution of D-Psicose

Hydration behavior of a rare sugar, D-psicose, was investigated based on measurements of the dielectric relaxation and the water activity in its aqueous solutions. Dielectric relaxation spectra in the frequency domain were obtained from time domain reflectometry. The dielectric relaxation time was then determined by fitting the spectra to a Cole-Cole type equation and used to evaluate the average hydration number representing the average number of water molecules forming a complex with a sugar molecule at infinite dilution. The concentration dependence of the dielectric relaxation time in aqueous solutions of all examined sugars generated a single master cur ve. The average hydration number of psicose was found to be identical with that of fructose. Only slight differences were noticeable among the concentration dependences of the water activity of monosaccharides. The equilibrium constant of hydration of sugar was calculated by considering material balances in an aqueous solution of sugar and using experimentally obtained values of the average hydration number and the water activity. The equilibrium constant values increased in the order of glucose < fructose � psicose < trehalose < sucrose < maltose. The present results suggest that both fructose and psicose interact with water in a similar manner.

From biomass to feedstock: one-step fractionation of lignocellulose components by the selective organic acid-catalyzed depolymerization of hemicellulose in a biphasic system

A concept for a highly integrated fractionation of lignocellulose in its main components (cellulose-pulp, soluble hemicellulose sugars and lignin) is described, based on the selective catalytic depolymerization of hemicellulose in a biphasic solvent system. This leads to an effective disentanglement of the compact lignocellulose structure, liberating and separating the main components in a single step. At mild temperatures (80–140 °C), oxalic acid catalyzes selectively the depolymerization of hemicellulose to soluble sugars in aqueous solution, whereas the more crystalline cellulose-pulp remains solid and inaccessible to the acid catalysis. In the presence of a second organic phase consisting of bio-based 2-methyltetrahydrofuran (2-MTHF), lignin is directly separated from the pulp and the soluble carbohydrates by in situextraction. The oxalic acid catalyst can be crystallized from the aqueous solution, recovered and re-used. The delignified cellulose-pulp obtained from this biphasic system can be directly subjected to enzymatic depolymerization, affording soluble oligomers and glucose at rates almost comparable to those observed for the hydrolysis of commercial microcrystalline Avicel®. Overall, the concept may offer a promising approach for an efficient and selective pre-treatment of lignocellulosic materials under mild and environmentally-friendly conditions.

Renewable gasoline from aqueous phase hydrodeoxygenation of aqueous sugar solutions prepared by hydrolysis of maple wood

In this paper we demonstrate an integrated process for the production of high octane gasoline from maple wood by hydrolysis of maple wood into aqueous carbohydrate solutions followed by aqueous phase hydrodeoxygenation of the sugar solutions. The aqueous carbohydrate solutions were prepared by both hydrolysis in hot water and hydrolysis with dilute acids (H2SO4, oxalic acid). The aqueous carbohydrate solutions were a mixture of xylose, water soluble hemicellulose oligomers, acetic acid, glucose, glucose oligomers, and probably some lignin polymers. Hydrolysis with hot water produced primarily hemicellulose oligomers whereas hydrolysis with acids produced mainly xylose and acetic acid. The hydrolysis co-product was a solid enriched in cellulose and lignin. The aqueous streams were hydrodeoxygenated by a two step catalytic process in which the first catalyst bed contained a Ru/C catalyst at 393 K and the second catalyst bed contained a Pt/zirconium phosphate (Pt/ZrP) catalyst at 518 K. The Ru/C catalyst was able to selectively hydrogenate xylose into xylitol but could not selectively hydrogenate the xylose oligomers. The two stage process was able to convert the aqueous carbohydrate streams derived from maple wood into gasoline range products with carbon yields of up to 57% and an estimated octane number of 96.5. No significant catalyst deactivation was observed indicating that the catalysts are very stable. The highest gasoline yield from this two stage process was obtained from the stream produced by acid hydrolysis of maple wood with 0.5 wt% oxalic acid at 433 K for 0.5 h. These results suggest that aqueous phase processing of sugars obtained by hydrolysis is a promising option for the production of fuels and chemicals from lignocellulosic biomass.

Boiling point of aqueous d-glucose and d-fructose solutions: Experimental determination and modeling with group-contribution method

Boiling points of aqueous solutions affect the design and operation of evaporators. Hence, boiling points of aqueous solutions of d-glucose and d-fructose were experimentally determined at soluble solute concentration from 10 to 60% sugar by mass and pressure from 20 to 93.6 kPa. The experimental data were correlated with data predicted by the calculation of the activity coefficients with the UNIFAC-Lyngby model using different approaches for decomposition of the molecular structure: the aliphatic groups and the cyclic groups. Moreover, the rise in experimental boiling point of the aqueous sugar solutions was evaluated by the Dühring's rule. It was observed that the cyclic approach resulted in better accuracy for liquid–vapor equilibrium prediction and the non-ideality of these solutions are relevant in the boiling point rise, confirming that the rise in boiling point of aqueous d-glucose and d-fructose concentrated solutions is significant to the design of heat and mass transport operations.

Conductometric behaviour of salts in sugar solution

In the present study, conductance data on interaction of sodium, potassium, calcium and magnesium in salt form with aqueous solution of AR sugar and plantation white sugar has been reported. These salts were chosen for this study because they are readily soluble constituents as available in cane juice and provide an opportunity to study the interaction of electrolytes — non electrolytes system in aqueous solution as well as sugar crystallization rate. The observations are critically discussed with the conclusion that hydration of ions and hydrogen bonding tendency of AR sugar / plantation white sugar and water plays a vital role independently as well as in a combined state. In addition inversion mechanism has also been discussed in terms of conductivity generation data.

Nectar to improve parasitoid fitness in biological control: Does the sucrose:hexose ratio matter?

The consumption of saccharide-rich foods such as floral nectar is crucial for the survival of many adult parasitoid wasps. The importance to parasitoids of nectar quality, with regards to its sucrose:hexose ratio, was investigated. Nectar, an aqueous solution of sugars, amino acids and other compounds, differs between plant species. Nectar composition is dominated by sucrose, glucose and fructose. Previous studies have shown that the ratio of sucrose to hexose (glucose+fructose) sugars can explain nectar associations in a range of flower visiting arthropods. It has been suggested that this ratio may be important in terms of parasitoid fitness. Analysis of floral nectar from fourteen plant species confirmed that the sucrose/hexose ratio significantly differed between species. An opportunity to select floral resources based on this measure of nectar quality arose and highlighted the potential to utilize native flowering plant species in place of the seven most commonly deployed, which are usually not native to the countries in which they are used. Results presented in this paper indicate, however, that the sucrose/hexose ratio is not a significant factor explaining parasitoid longevity. The hymenopteran parasitoids Diadegma semiclausum (Ichneumonidae) and Dolichogenidea tasmanica (Braconidae) were fed 40% w/w sugar solutions, differing in their sugar ratios. Solutions were classified as either sucrose-dominant (ratio >0.99), sucrose-rich (ratio 0.5–0.99), hexose-rich (ratio 0.1–0.499) or hexose-dominant (ratio <0.1). No significant differences in parasitoid longevity were found between the different treatments for either species. This suggests there is not an optimal sucrose/hexose ratio for parasitoid wasps, although a greater number of parasitoid species should ideally be tested to confirm if this is true for the wider parasitoid taxonomic groups. Die Nutzung von saccharidhaltigem Blütennektar trägt entscheidend zum Überleben von vielen erwachsenen parasitoiden Wespen bei. Es wurde die Bedeutung der Nektarqualität, gemessen als Verhältnis von Saccharose zu Hexose, für die Parasitoide untersucht. Nektar ist eine wässerige Lösung von Zuckern, Aminosäuren und anderen Bestandteilen, und unterscheidet sich zwischen den Pflanzenarten. Die Nektarzusammensetzung ist von Saccharose, Glukose und Fruktose dominiert. Vorhergehende Untersuchungen haben gezeigt, dass das Verhältnis von Saccharose zu Hexose (Glukose und Fruktose) die Bindungen an Nektar bei einer Reihe von blütenbesuchenden Arthropodengruppen erklären kann. Es wurde vermutet, dass das Verhältnis in Bezug auf die Fitness der Parasitoiden wichtig sein könnte. Die Analyse des Nektars von vierzehn Pflanzenarten bestätigte, dass sich das Verhältnis von Saccharose:Hexose zwischen den Arten signifikant unterschied. Es ergab sich die Gelegenheit die Blütenressourcen auf der Grundlage dieses Maßes für Nektarqualität auszuwählen und sie beleuchtete die Möglichkeit, einheimische Blütenpflanzenarten anstelle der sieben am häufigsten genutzten Arten zu nutzen, die normalerweise in den Ländern, in denen sie genutzt werden, nicht einheimisch sind. Die in dieser Veröffentlichung präsentierten Ergebnisse zeigen jedoch, dass das Verhältnis von Saccharose:Hexose kein signifikanter Faktor ist, um die Lebensspanne der Parasitoiden zu erklären. Die hymenopteren Parasitoide Diadegma semiclausum (Ichneumonidae) und Dolichogenidea tasmanica (Braconidae) wurden mit 40% w/w Zuckerlösungen gefüttert, die sich in ihren Zuckerverhältnissen unterschieden. Die Lösungen wurden entweder als saccharosedominiert (Verhältnis >0,99), saccharosereich (Verhältnis 0.5–0.99), hexosereich (Verhältnis 0.1–0.499) oder hexosedominiert (Verhältnis <0.1) klassifiziert. Es wurden für keine Art signifikante Unterschiede in der Lebensspanne der Parasitoide zwischen den verschiedenen Varianten gefunden. Dies lässt vermuten, dass es kein optimales Verhältnis Saccharose:Hexose für die parasitoiden Wespen gibt, obwohl eine größere Anzahl parasitoider Arten idealerweise getestet werden sollten, um zu bestätigen, ob dies auch für größere parasitoide taxonomische Gruppen gilt.

Production of phenolic compounds from rice bran biomass under subcritical water conditions

This study investigated the application of subcritical water as green and environmentally friendly treatment medium for hydrolysis and decomposition of rice bran in order to obtain phenolic compounds as well as other valuable materials. Experiments were performed in a batch stainless steel reactor at different temperatures ranging from 100 to 360 °C at the residence time of 10 min. The effect of residence time was also studied up to 30 min at 220 °C. After subcritical water treatment, it was evaluated for their individual concentrations of phenolic compounds, total phenolic content, antioxidant activity, total soluble sugars, pH, and electrical conductivity as well as remained solid (solid residue). Eleven phenolic compounds were identified from decomposition of rice bran: caffeic, ferulic, gallic, gentisic, p-coumaric, p-hydroxybenzoic, protocatechuic, sinapic, syringic, vanillic acids and vanillin. Results indicated that total phenolic content and antioxidant activity increased with temperature. They also sharply increased with residence time up to 15 min. Also at an optimum condition, significant amounts of soluble sugars in aqueous solution (approximately 215 glucose equivalents mg/g dry matter) were identified which demonstrated that subcritical water also is a promising treatment medium for hydrolysis of this biomass into water soluble sugars using a short residence time. Changing the pH of the solution due to the hydrolysis of rice bran into phenolic compounds with acidic function and also production of other organic compounds, suggested that autocatalysis may occurred during subcritical water treatment.

Utilização de um espectrógrafo de projeção como uma ferramenta para demonstrações sobre polarização da luz

This article describes the use of a projection spectrograph based on an overhead projector for use in classroom demonstrations on light polarization and optical activity. A simple adaptation on a previously developed apparatus allows illustrating several aspects of optical activity, such as circular and linear birefringence, including their wavelength dependence. Specifically, we use the projection spectrograph to demonstrate the optical activity of an aqueous solution of sugar (circular birefringence), of a quartz plate and of an overhead projector transparence film (linear birefringence). A historical survey about the optical activity discovery and the main principles involved is also presented.

Low-frequency vibrational properties of lysozyme in sugar aqueous solutions: A Raman scattering and molecular dynamics simulation study

The low-frequency (omega<400 cm(-1)) vibrational properties of lysozyme in aqueous solutions of three well-known protecting sugars, namely, trehalose, maltose, and sucrose, have been investigated by means of complementary Raman scattering experiments and molecular dynamics simulations. The comparison of the Raman susceptibility chi(")(omega) of lysozyme/water and lysozyme/sugar/water solutions at a concentration of 40 wt % with the chi(") of dry lysozyme suggests that the protein dynamics mostly appears in the broad peak around 60-80 cm(-1) that reflects the vibrations experienced by atoms within the cage formed by their neighbors, whereas the broad shoulder around 170 cm(-1) mainly stems from the intermolecular O-H...O stretching vibrations of water. The addition of sugars essentially induces a significant high frequency shift and intensity reduction of this band that reveal a slowing down of water dynamics and a distortion of the tetrahedral hydrogen bond network of water, respectively. Furthermore, the lysozyme vibrational densities of states (VDOS) have been determined from simulations of lysozyme in 37-60 wt % disaccharide aqueous solutions. They exhibit an additional broad peak around 290 cm(-1), in line with the VDOS of globular proteins obtained in neutron scattering experiments. The influence of sugars on the computed VDOS mostly appears on the first peak as a slight high-frequency shift and intensity reduction in the low-frequency range (omega<50 cm(-1)), which increase with the sugar concentration and with the exposition of protein residues to the solvent. These results suggest that sugars stiffen the environment experienced by lysozyme atoms, thereby counteracting the softening of protein vibrational modes upon denaturation, observed at high temperature in the Raman susceptibility of the lysozyme/water solution and in the computed VDOS of unfolded lysozyme in water. Finally, the Raman susceptibility of sugar/water solutions and the calculated VDOS of water in the different lysozyme solutions confirm that sugars induce a significant strengthening of the hydrogen bond network of water that may stabilize proteins at high temperatures.

Egg attachment of the asparagus beetle Crioceris asparagi to the crystalline waxy surface of Asparagus officinalis

Plant surfaces covered with crystalline epicuticular waxes are known to be anti-adhesive, hardly wettable and preventing insect attachment. But there are insects that are capable of gluing their eggs to these surfaces by means of proteinaceous secretions. In this study, we analysed the bonding region between the eggs of Crioceris asparagi and the plant surface of Asparagus officinalis using light and cryo-scanning electron microscopy. The wettability of the plant surface by egg secretion was compared with that by Aqua Millipore water, aqueous sugar solution and chicken egg white. Furthermore, the force required to remove C. asparagi eggs from the plant surface was measured, in order to evaluate the egg's bonding strength. Mean pull-off force was 14.7 mN, which is about 8650 times higher than the egg weight. Egg glue was observed spreading over the wax crystal arrays on the plant cladophyll and wetting them. Similar wetting behaviour on the A. officinalis surface was observed for chicken egg white. Our results support the hypothesis that the mechanism of insect egg adhesion on micro- and nanostructured hydrophobic plant surfaces is related to the proteinaceous nature of adhesive secretions of insect eggs. The secretion wets superhydrophobic surfaces and after solidifying builds up a composite, consisting of the solidified glue and wax crystals, at the interface between the egg and plant cuticle.

A combined experimental and theoretical study of benzoxaborole derivatives by Raman and IR spectroscopy, static DFT, and first‐principle molecular dynamics

AbstractPhysicochemical properties of 1,3‐dihydro‐1‐hydroxy‐3‐morpholin‐4‐yl‐2,1‐benzoxaborole (IIa) and 1,3‐dihydro‐1‐ hydroxy‐2,1‐benzoxaborole (IIb) were investigated using a combination of spectroscopic and computational approaches. The compound IIa belongs to the group represented by the prototypical benzoxaborole IIb, which exhibits receptor activity toward sugars in aqueous solution. Additionally, the IIb can serve as a pattern structure for physicochemical description of benzoxaborole derivatives. The infrared and Raman spectroscopy measurements were performed in solvents and in the solid state. Furthermore, experimental findings served as a reference data source for further computational investigations. DFT calculations in vacuo were used to estimate the binding energy of the dimeric forms, indicating the strength of the intermolecular hydrogen bonds. AIM and ELF theories were applied to give an insight into the electronic structure of the studied compounds. The last part of this study contains Car–Parrinello molecular dynamics investigations in the solid state. Computational results indicated that the key intermolecular feature, the pair of hydrogen bonds, is rather harmonic and the extent of the anharmonicity is temperature dependent as shown by the OH stretching envelope calculations performed for IIa. Inclusion of the quantum effects in the proton motion does not significantly change the qualitative description of the intermolecular H‐bond dynamics of the investigated compound. Copyright © 2010 John Wiley &amp; Sons, Ltd.

Modified silica surface by phenylboronic acid derivatives as effective sugar sensor

Abstract Silica surface was modified with phenylboronic acid derivatives. The structures of the functionalized supports were characterized by FT-IR spectroscopy, 13C CP/MAS NMR spectrometry, elemental and thermogravimetric analysis. The solid supports were effectively applied as artificial receptors for sugars in aqueous solutions. Alizarin Red S. (ARS) was used to detect colour change upon carbohydrate (sugar) binding. The association constants of the supports studied-ARS complex and the functionalized silica-sugar (glucose) complex were calculated. The parameters obtained were comparable with those for the phenylboronic acids used for the silica gel modification. The competitive binding of the functionalized silica surface with ARS and sugar were studied by UV/VIS measurements.

Laboratoriums-Untersuchungen zum Vermehrungspotential von Hadronotus carinatus Masner i. l.1(Proct. Telen.)

Summary 1 To obtain the highest possible parasitization of eggs of Eurygaster integriceps Put. by Hadronotus carinatus Masner, freshly laid host eggs are necessary, also daily feeding of the wasps with aqueous sugar solution (14%). 2 The greater part of the host eggs is parasitized by fertilized H. carinatus females in the first four days. If several batches of host eggs are available at the same time, at least 68 (maximum 90) eggs are parasitized by each female. If the host eggs are available at intervals of 1–2 days, then 86–107 eggs, or 6.5–8 batches could be successfully parasitized by each female. In mass rearing each Hadronotus female can be reckoned as equivalent to 5 parasitized egg masses. 3 Fertilized females produce mainly (approx. 90%) females, unfertilized females produce only males. 4 Development of parasitized eggs takes 21–23 days at 18–24°C, 16–20 days at 22–25°C. 5 Successful parasitism of Eurygaster eggs by H. carinatus is only possible in the first third of the normal development time of the host eggs.

Evaluation of the wick method for in situ 13C and 15N labelling of annual plants using sugar-urea mixtures

To investigate the amount and fate of root-derived C and N, often tracer techniques are used, where plants are labelled with isotopes. In the present study, we evaluated the suitability of the cotton wick method for in situ labelling of peas (Pisum sativum L.) and oats (Avena sativa L.) with 13C and 15N simultaneously. With two greenhouse experiments we investigated how the wick method and aqueous urea and sugar solutions at a variety of concentrations affected plant development. In addition, we investigated the distribution of 13C and 15N in plants from column experiments under outdoor conditions. Solution was taken up by the plant from a small vial connected to the stem by a cotton wick which was passed through a hole in the stem of the plants. Generally, solution uptake varied between individual plants and decreased with increasing sugar concentrations. Below-ground, above-ground and total plant dry matter, were not significantly affected by the wick method and the applied solutions. Mixtures of aqueous glucose solutions at 2 to 4% and aqueous urea solutions at 1% are useful carriers of 13C and 15N. However, in the investigated plants isotopes were not homogeneously distributed among plant parts. Above-ground plant biomass was preferentially enriched with 13C and 15N, whereas below-ground plant biomass was generally lower enriched. Moreover, isotope distribution ratio of individual plants varied considerably, independent of plant part or timing of labelling. This must be taken into account when estimating root-derived C and N. Future studies comparing labelling methods need to present the isotope distribution ratios among plant parts to allow a true comparison of the methods and the evaluation of their suitability for estimating rhizodeposition.

PH-Metric study of gamma-irradiated table sugar for dosimetry purpose

Table sugar has been studied for a long time as a dosimeter in radiation accident and in high-dose dosimetry by using different analytical techniques especially electron paramagnetic resonance (EPR) and optical absorption spectrometry (OA). In this work, we report the results obtained by pH-metry on gamma-irradiated sugar. Table sugar samples were exposed to gamma radiation with doses of 0.1–58 kGy. Aqueous solutions of sugar were prepared with different concentrations ranged from 1% to 60% (w/w). It was found that sugar solutions showed strong decrease of pH up to concentration of 10% (w/w) followed by a slow decrease for the concentrations between 10 and 60% (w/w). Two possible mechanisms are proposed to explain the acidity increasing of the sugar solutions based on the existence of a carbonyl radical induced by gamma irradiation in solid table sugar with an open ring structure. Results for radiation response, post-irradiation change, reading temperature, dose-rate effect and repeatability are presented in this study. The results showed that pH-metric/sugar solution is an adequate high-dose dosimetric system in the dose range of 0.1–10 kGy.

Catalytic conversion of biomass-derived carbohydrates to fuels and chemicals by formation and upgrading of mono-functional hydrocarbon intermediates

Aqueous solutions of sugars and polyols can be converted in a single catalytic process to produce a spontaneously separating organic phase consisting of hydrophobic mono-functional hydrocarbons. The process is shown to be stable for over 2 months time on stream at typical reaction conditions (e.g., 503 K and 18 bar total pressure). The composition and yield of this organic phase can be controlled by adjusting process variables, such as temperature, pressure and space velocity. This organic phase contains primarily mono-functional species such as ketones, alcohols, heterocycles, and organic acids. These oxygenated hydrocarbons can serve as an intermediate platform for the conversion of renewable biomass resources into chemicals and fuels. The organic phase can be separated into individual chemicals or can be upgraded to yield specific classes of chemicals. For example, heterocycles can be separated and used as solvents, additives or blending agents for transportation fuels, while aldol-condensation of the ketones and alcohols can produce long chains species for use as alkane fuels. Alternatively, this platform can be tuned to produce alcohols by reducing the ketone and acid groups. Dehydration of these alcohols produces olefins that have use in either the polymer industry, or as feeds for liquid fuels.