High pressure viscosity measurement with falling body type viscometers

With the increasing number of applications of high pressure chemical and process technologies across a range of engineering fields, there is a corresponding growing interest in the need to measure accurately and reliably important rheological parameters. Of these, the measurement of good and reliable viscosity data is critical in engineering design. The ability to measure viscosity at high pressure, however, presents a number of engineering challenges and a number of innovative viscometers have consequently been devised and operated. This review considers those devices which are based on the falling body principle and considers falling ball, cylinder and needle in open and closed systems. Viscosity is determined from the rate of fall and the usual challenge is to detect its position during descent. While reliable data can be obtained from these viscometers, there is a discrepancy between theoretical values and actual values. This is the result of end effects in the form of vortices, wake oscillations and hedding. Calibration is therefore necessary in all cases. Improvements to analytical models have been attempted and computation fluid dynamics is also used to examine in more detail the flow fields around bodies to understand and appreciate better the performance of these viscometers

Experimental viscosity measurements of biodiesels at high pressure

The viscosity of biodiesels of soybean and rapeseed biodiesels blended with mineral diesel fuel were measured at pressures of up to 200 MPa. Using a falling sinker-type viscometer reproducible viscosity data were obtained based on the time taken for a sinker to descend a fixed distance down an enclosed tube under the influence of gravity. Measurements were taken using pressures which correspond to those of interest in automotive common rail diesel engines, and at temperatures of between 25oC and 80oC. In all cases, the viscosity of the biodiesel blends were found to increase exponentially for which the blends were noted as being more viscous than pure mineral fuels. A pressure-freezing effect was not observed for the blends

Editorial: biodegradable materials

This Special Issue “Biodegradable Materials” features research and review papers concerning recent advances on the development, synthesis, testing and characterisation of biomaterials. These biomaterials, derived from natural and renewable sources, offer a potential alternative to existing non-biodegradable materials with application to the food and biomedical industries amongst many others. In this Special Issue, the work is expanded to include the combined use of fillers that can enhance the properties of biomaterials prepared as films. The future application of these biomaterials could have an impact not only at the economic level, but also for the improvement of the environment

Electrolyte effects on polyacrylic acid-polyvinylpyrrolidone aqueous glycol mixtures for use as de-icing fluids

Rheological and wind tunnels measurements are presented for mixtures of polymers polyacrylic acid [PAA] and polyvinylpyrrolidone [PVP] polymers dispersed in water-1,2 propylene glycol mixture to examine their use as potential aircraft de-icing fluids. PAA solutions which form the basis of de-icing fluids are known to result in undesirable gelation which may lead to undesirable and catastrophic consequences in such applications. In this study, we examine the blending of PVP with PAA blends as alternative de-icing fluid formulations that can reduce the likelihood of forming such irreversible gel deposits. Through adjustment of the electrolyte concentration, the ratio of PAA to PVP as well as the molecular weight of PVP, it is possible to achieve a required viscosity profile to that exhibited by a model de-icing fluid across a range of appropriate temperatures. Wind tunnel tests indicate that the mixtures are capable of meeting the necessary requirements for boundary layer depletion as well as having sufficient capability of retaining a stable layer required during aircraft taxiing

Lipid oxidation kinetics of ozone-processed shrimp during iced storage using peroxide value measurements

In this research, in situ generated ozone exposure/wash cycles of 1, 3, and 5 min applied to shrimp samples either before (BIS) or during iced storage (DIS) has been used to study the lipid oxidation kinetics using the peroxide values (PV). The induction period (IP) as well as PV at end of the IP (PVIP) have been obtained. The rate constants (k) as well as half-lives (t1/2) of hydroperoxides formation for different oxidation stages were calculated. The results showed that both IP and PVIP were lower with BIS (IP between 4.35±0.09 and 5.08±0.23 days; PVIP between 2.92±0.06 and 3.40±0.18 mEq kg−1) compared with DIS (IP between 5.92±0.12 and 6.14±0.09 days; PVIP between 4.49±0.17 and 4.56±0.10 mEq kg−1). The k value for DIS seemed to be the greater compared to BIS. In addition, whilst decreases and increases in t1/2 were found at propagation, respectively, for BIS and DIS, decreases and increases were only found at the induction of oxidation stage(s) for BIS. Further, the PV of ozone-processed samples would fit first order lipid oxidation kinetics independent of duration of ozone exposures. For the first time, PV measurements and fundamental kinetic principles have been used to describe how increasing ozone exposures positively affects the different oxidation stages responsible for the formation of hydroperoxides in ozone-processed shrimp

Is high frequency ultrasound a useful process to add value to out of specification strawberries, raspberries, and blackberries industrially?

Bioactive ingredients can be extracted from surplus soft fruits to add value to them as a fortification ingredient in many new products. Ultrasound‐assisted extraction and spray drying have been heavily studied in the past, with evidence to suggest the positive uptake of these by the food industry. In this paper, strawberries, raspberries and blackberries were examined using a distilled water ‘green’ extraction method with assisted high‐frequency ultrasound and concentration through spray drying. The results showed that crop year and variety had more impact on bioactive concentration than extraction through high‐frequency ultrasound. Two different machines were examined for differences between a cold extraction of water, and a 700 and 2000 Hz industrially relevant probes. Typically, total phenolic content (TPC) was lower in strawberries and blackberries than the control for both methods, however raspberries had a higher GAE mg ml−1 for the 2000 Hz ultrasound than the control. For Radical scavenging (RS) percentage using DPPH Blackberries had higher RS % than the control, whereas strawberries and raspberries had less than the control. These results suggest that ultrasound as a singular method for extracting valuable bioactive ingredients is not suitable with water as the solvent

Dissolution experiments on dolerite quarry fines at low liquid to solid ratio:a source of calcium for MICP

Microbially induced calcite precipitation (MICP) is an emerging soil stabilisation technique consisting of the precipitation of the mineral calcite in the soil matrix. The components required for MICP are currently industry end products. In this study, the calcium release and reusability of calcium-rich silicate quarry fines, dolerite, were investigated in closed (batch reactor) and open (permeability test) systems at liquid-to-solid (L/S) mass ratios ≤ 1·5 for MICP applications. The large specific surface area and reactive surface area accelerated calcium release, achieving calcium concentrations between 10 and 23 mM for different settings. Dissolution in the batch reactor resulted in increased silt (&lt;0·006 mm) and clay fractions. X-ray fluorescence analysis indicated no significant depletion of calcium in the dolerite after dissolution. The study showed that dolerite quarry fines dissolution in distilled water at low L/S ratios is a rich source of calcium for MICP applications.</p

Cow urine as a source of nutrients for Microbial-Induced Calcite Precipitation in sandy soil

Microbial Induced Calcite Precipitation (MICP) via biostimulation of urea hydrolysis is a biogeochemical process in which soil indigenous ureolytic microorganisms catalyse the decomposition of urea into ammonium and carbonate ions which, in the presence of calcium, precipitate as calcium carbonate minerals. The environmental conditions created by urine in soil resemble those induced by MICP via urea hydrolysis. Thus, this study assesses the suitability of a waste product, cow urine, as a source of nutrients for MICP. Urea stability in fresh and sterilised urine were monitored for a month to cover the length of a potential MICP intervention. An experimental soil column set up was used to compare the soil response to the repeated application of fresh and sterilised cow urine, within pH of 7 and 9, and the chemical-based solution. Urea hydrolysis and the carbonate content in solution were monitored to assess the suitability of the proposed alternative. In addition, the nitrification process was monitored. Key findings indicated i) urea concentration and stability in fresh and sterilised cow urine are suitable for MICP application; ii) the soil response to treatments of cow urine within pH of 7 and 9 are similar to the chemical-based solution; and iii) increasing solution pH results in a faster activation of ureolytic microorganisms and higher carbonate content in solution. These results demonstrate that cow urine is a suitable substitute of the chemical-based MICP application

Dolerite fines used as a calcium source for microbially induced calcite precipitation reduce the environmental carbon cost in sandy soil

Microbial-Induced Calcite Precipitation (MICP) stimulates soil microbiota to induce a cementation of the soil matrix. Urea, calcium and simple carbon nutrients are supplied to produce carbonates via urea hydrolysis and induce the precipitation of the mineral calcite. Calcium chloride (CaCl2) is typically used as a source for calcium, but silicate rocks and other materials have been investigated as alternatives. Weathering of calcium-rich silicate rocks (e.g. basalt and dolerite) releases calcium, magnesium and iron; this process is associated with sequestration of atmospheric CO2 and formation of pedogenic carbonates. We investigated atmospheric carbon fluxes of a MICP treated sandy soil using CaCl2 and dolerite fines applied on the soil surface as sources for calcium. Soil-atmosphere carbon fluxes were monitored over two months and determined with an infrared gas analyser connected to a soil chamber. Soil inorganic carbon content and isotopic composition were determined with isotope-ratio mass spectrometry. In addition, soil-atmosphere CO2 fluxes during chemical weathering of dolerite fines were investigated in incubation experiments with gas chromatography. Larger CO2 emissions resulted from the application of dolerite fines (116 g CO2-C m-2) compared to CaCl2 (79 g CO2-C m-2) but larger inorganic carbon precipitation also occurred (172.8 g C m-2 and 76.9 g C m-2, respectively). Normalising to the emitted carbon to precipitated carbon, the environmental carbon cost was reduced with dolerite fines (0.67) compared to the traditional MICP treatment (1.01). The carbon isotopic signature indicated pedogenic carbonates (δ13Cav = 8.2±5.0‰) formed when dolerite was applied and carbon originating from urea (δ13Cav = 46.4±1.0‰) precipitated when CaCl2 was used. Dolerite fines had a large but short-lived (&lt;2 d) carbon sequestration potential, and results indicated peak CO2 emissions during MICP could be balanced optimizing the application of dolerite fines

Electrolyte effects on poly (acrylic acid)-based aircraft de-icing fluids

Poly (acrylic acid) [PAA]-based aircraft de-icing fluids are widely used commercially but are known to be subject to the formation of insoluble gel particles within wing structures. In this study, the rheological effects of the sodium chloride, potassium formate, and calcium acetate with commercially used PAA-based fluids are reported across the temperature range of −15 to 15 °C. Calcium ions have the potential to create gel particles, reflected in the shifts in the viscosity–temperature profile, while PAA aggregation is influenced by the concentrations and compositions of sodium and potassium salts in the water used for dilution. From the data presented, it is possible to create de-icing fluid formulations with the necessary rheological characteristics from stock solutions by dilution using available water sources, providing that the ion concentration is known