Selective fructose dehydration to 5-hydroxymethylfurfural from a fructose-glucose mixture over a sulfuric acid catalyst in a biphasic system: Experimental study and kinetic modelling

A two-step process combining the (equilibrium) glucose isomerization to fructose with selective dehydration of fructose in the obtained sugar mixture to 5-hydroxymethylfurfural (HMF), where glucose is largely unconverted and recycled, represents an attractive concept to increase the overall efficiency for HMF synthesis. This work presents experimental and modelling studies on the conversion of such fructose-glucose mixture to HMF using the sulfuric acid catalyst in a water-methyl isobutyl ketone biphasic system under a wide range of conditions (e.g., temperature, catalyst and sugar concentrations). Through detailed product analyses and ESI-MS spectroscopy, the excess formation of formic acid (together with humins) by the direct sugar/HMF degradation was confirmed and included in the reaction network (neglected in most literatures). The kinetic modelling based on batch experiments in monophasic water well describes the measurements thereof, whereas distinct deviations were found in the prediction of typical literature kinetic models. The incorporation of HMF equilibrium extraction into the developed kinetic model, with consideration of phase volume change as a function of temperature and partial phase miscibility, enables to predict reaction results in the biphasic system in batch. This kinetic model allows to optimize conditions for HMF synthesis that are favored in continuous reactors with minimized back mixing. Based on the model implications, the biphasic system was optimized with slug flow microreactors to better address process intensification and scale-up aspects. Using a simulated fructose-glucose mixture feedstock to represent commercially available high fructose corn syrups, a maximum HMF yield of 81% was obtained at 155 °C over 0.05 M H2SO4 at a residence time of 16 min in the microreactor, with 96% fructose conversion and over 95% of glucose remaining unconverted

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Correction to: Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

The original version of this article unfortunately contained a mistake

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Gas-liquid mass transfer in a rotating liquid redistributor

The mass transfer characterization of a novel design rotating liquid redistributor is presented, where the redistributor has three concentric, perforated rings which act as liquid redistribution rings. Oxygen stripping from water is used to obtain values for the overall mass transfer coefficient of the redistributor. It was found that the main contribution to the overall mass transfer is the impingement of droplets on the redistribution rings, while the mass transfer of suspended droplets in the gas phase was almost negligible. Furthermore, it was shown that the experimentally determined contribution to mass transfer of the droplet impingement correlated strongly to the mean momentum flux of the droplets. Lastly, the energy dissipation rate was compared to a rotating zig-zag bed, where at lower liquid flow rates and rotational speed the energy dissipation rate in the redistributor was lower, while at higher liquid flow rates and rotational speeds it was lower in the rotating zig-zag bed

Conversion of fructose-glucose mixtures to 5-hydroxymethylfurfural (HMF) in a biphasic slug-flow microreactor setup

The production of platform chemicals from lignocellulosic biomass is one of the main targets to enable future sustainable chemical industry.[1][2] 5-hydroxymethylfurfural (HMF) has been identified as one of the most important platform chemicals that can be obtained from the sugar fraction of lignocellulose.[3][4] Cheap mineral acid such as sulfuric acid are very effective at catalyzing the conversion of, in particular, fructose to HMF, however, suffer from the formation of humins as well as levulinic acid and formic acid. Biphasic solvent mixtures of water with organic solvent can significantly improve HMF selectivity.[5] This is due the extraction of HMF from the aqueous layer to ensure separation from the acidic sugar solution, which suppresses undesired side reactions. Currently, we are developing a continuous slug-flow microreactor setup for this process (Figure). We simulate high fructose corn syrup as cheap feedstock by using fructose-glucose mixtures in water and methyl isobutyl ketone (MIBK) as organic solvent. Here, we aim to selectively convert the fructose into HMF, while leaving the glucose untouched for separate use in a follow-up process, for example to produce levulinic acid or bioethanol. Preliminary results have shown that, using this setup, HMF selectivity can be increased to up to 82% at over 90% fructose conversion, with minimal glucose conversion. This was a significant improvement compared to under 75% HMF selectivity at 80% fructose conversion obtained in batch reactor setups. We are currently creating a reactor model to determine reaction conditions for maximum HMF yield at lowest production costs

Improving liquid distribution in a rotating packed bed

A novel design rotating packed bed is presented, aiming at mitigation of liquid maldistribution commonly encountered in rotating packed beds. The design consists of three concentric, perforated rings placed in the packing, which act as liquid redistribution rings. The effectiveness of the redistribution rings in a rotating packed bed was experimentally demonstrated, showing that an induced maldistribution of 3 × 1/16th was mitigated by at least 90 % within the design operating window. Furthermore, an induced maldistribution of 1/4th of the reactor was mitigated by at least 70 %, irrespective of whether a random packing is present or not. The proposed repeated use of redistribution rings therefore enables a more uniform wetting of the whole packing, which potentially enables a more effective scale-up of rotating packed beds. To assist the design of redistribution rings, a design equation for the thickness of the liquid layer on the redistribution rings (which determines the operating window) was developed and shown to be accurate within 10 %