Xanthan Gum Solutions Research Articles

Comparative study of mixing performance in non-Newtonian Xanthan Gum solutions and water using various injection techniques in a cylindrical channel with vortex generators

Comparative study of mixing performance in non-Newtonian Xanthan Gum solutions and water using various injection techniques in a cylindrical channel with vortex generators

Determining pore size distribution in rocks using shear‐thinning fluids: Utilisation of the method in geomorphology

AbstractThe pore space characteristics of geological materials are closely related to their mechanical, transport and hydraulic properties. In geomorphology, pore size distribution (PSD) is an important characteristic in rock weathering, evaporation and other studies. In an effort to find novel methods to determine the PSD, perhaps to bypass the disadvantages of the current techniques, there has been a growing interest in the use of non‐Newtonian fluids. In this contribution, we are particularly interested in the method recently introduced by Abou Najm and Atallah (the ANA method), which exploits the way in which the flow of different shear‐thinning fluids distributes differently in the pore space to compute the functional PSD estimation. We performed a set of saturated flow experiments with aqueous xanthan gum solutions of different concentrations, using as simple as possible laboratory settings, and we implemented a modified version of the previously introduced numerical model to obtain the PSDs of four sandstone and one tuff samples. The results are compared with conventional mercury intrusion porosimetry, showing a good agreement regarding the dominant pore size and a notable similarity in the distributions. Several limitations were identified as well, such as the lack of information on relatively small pores (<5–10 μm for the samples studied) and the potential issues in obtaining a more detailed distribution. We conclude that the ANA method is promising for geomorphological evaporation and rock durability studies, particularly for coarser materials such as sandstone, but it also encounters challenges for certain applications, especially for fine‐grained rocks. It must be acknowledged that the ANA method has been tested on a limited range of materials and further investigation is required to fully explore its capabilities and limitations.

Nonlinear Electrophoresis of Microparticles in Shear Thinning Fluids.

The nonlinear electric field dependence of particle electrophoresis has been demonstrated to occur in Newtonian fluids for highly charged particles under large electric fields. It has also been predicted to arise from the rheological effects of non-Newtonian fluids even at small electric fields. We present in this work an experimental verification of nonlinear electrophoresis in shear thinning xanthan gum solutions through a straight rectangular microchannel. The addition of polymer into a Newtonian buffer solution is found to change the electric field dependence from linear to superlinear for electroosmotic, electrokinetic, and electrophoretic velocities. The nonlinear index of each of these electrokinetic phenomena increases with the increasing polymer or buffer concentration, among which electrophoresis exhibits the strongest nonlinearity. Both these observed trends are captured by a dimensionless electrokinetic shear thinning number that depends on the power-law index of fluid viscosity and the Debye length.

Drag reduction performance of binary polyacrylamide and xanthan gum solutions

Drag reduction performance of binary polyacrylamide and xanthan gum solutions

Effect of temperature on the drag reduction characteristics of xanthan gum in the liquid ring vacuum pump

Xanthan gum (XG) solution has been proven to be an effective working fluid in the liquid ring vacuum (LRV) pump to achieve significant energy savings. As an important influencing factor of the LRV pump performance, the effect of temperature on the drag reduction performance, rheological properties, and microstructure of XG solution in the LRV pump were experimentally investigated in this paper. The results indicate that with the increase of temperature, the drag reduction rate of the XG solution in the LRV pump initially rise and subsequently decline, and XG solutions with different concentrations show different optimal drag reduction temperatures. The microscopic parallel double-chain structure of XG has the same change pattern as the drag reduction performance, while the steady-state and dynamic shear characteristics of the XG solution manifest a downtrend. For instance, as the temperature of 4000 ppm XG solution increases from 10 °C to 60 °C, the drag reduction rate decreases by 20 %; the parallel double-chain structure decreases from 91.3 % to 89.9 %; the yield stress and relaxation time decrease from 4.63993 Pa to 4477.56 s to 3.37808 Pa and 143.27 s, respectively; the drag reduction rate reaches the maximum value when the temperature is 40 °C.

Aggregation and Sedimentation Stability of Nanoscale Zeolitic Imidazolate Framework (ZIF‐8) Nanocomposites for Antimicrobial Agent Delivery Applications

ABSTRACTThe applications of nanoscale zeolitic imidazolate frameworks (ZIF‐8) for antimicrobial drug delivery depend on the aqueous suspension stability of the ZIF‐8 which is influenced by their crystallinity, size, shape, aggregation, and surface chemistry. This study evaluated the stability of ZIF‐8 nanoparticles in terms of their aggregation and sedimentation characteristics. ZIF‐8 nanocomposites were synthesized with methanol via sonication at 30°C for 1 h. The effect of drying methods (oven drying at 80°C, and vacuum drying at 35°C), number of washing steps (0 = no wash, 1, 2, 3), and washing medium (washing with water and ethanol instead of methanol, and redispersion in water and ethanol) on the suspension stability was evaluated. The impact of added xanthan gum (XG) and poly‐L‐lysine (PL) as suspension media was also evaluated. ZIF‐8 nanoparticles were also synthesized using ethanol and suspended in PL. % transmittance and zeta potential were measured for freshly prepared ZIF‐8 suspensions in PL and after freeze‐drying and resuspending in water. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and x‐ray diffraction (XRD) analysis were utilized for the assessment of the crystallinity, structure, and morphology of the samples. Antibacterial activity was evaluated by disc diffusion test against Escherichia coli. Dried methanol‐synthesized ZIF‐8 nanoparticles did not suspend in water; only the ZIF‐8 nanoparticles synthesized with reduced washing times and no drying treatment were resuspended in the water, XG and PL solutions. Instead, the ethanol‐synthesized ZIF‐8 nanoparticles were resuspended in water even after being washed three times and dried in a vacuum oven. SEM and TEM images and XRD patterns showed that alcohol can form well‐defined ZIF‐8 nanoparticles. FTIR spectra showed that ZIF‐8 had typical peaks of ZIF‐8 reported by others. Although particle size increased, the PL coating provided a 32.22% increase in zeta potential of ZIF‐8 nanoparticles from 36.25 to 47.93 mV (p < 0.05) and prevented aggregation and sedimentation of the nanoparticles without changing their morphology. All the tested ZIF‐8 nanoparticles showed antibacterial activity with the PL‐coated ZIF‐8 having the highest effect followed by the ZIF‐8 nanoparticles synthesized in ethanol.

Numerical investigation of non-Newtonian droplet collisions: Comparison of volume of fluid and the local front reconstruction method with experimental data

Droplet-droplet collisions of non-Newtonian fluids are often encountered in industrial applications such as spray drying, fluid catalytic cracking, coating and granulation. However, there has been limited focus on a comprehensive analysis of the dynamics of these non-Newtonian binary droplet collisions. In this work, the non-Newtonian binary droplet collisions of 500 ppm xanthan gum solutions are simulated using the Volume of Fluid method and the Local Front Reconstruction Method to determine the applicability of these methods for the simulations of binary non-Newtonian droplet collisions. After verification, the simulations are compared to experimental data from literature. The outcomes for off-center collisions in the simulations resemble the experimental observations, including the oscillation of the ligament. For head-on collisions, the initial interactions and collision dynamics can be predicted with both methods at low Weber numbers, while LFRM shows improved performance at higher Weber numbers. Further, the use of an effective viscosity for the simplified representation of the droplet collision has been proven unsuccessful due to the absence of a universal effective viscosity for all situations.

Experimental Study of the Rising Behavior of a Single Bubble in Shearshinning Fluids

Background: Non-Newtonian gas-liquid two-phase flows are often seen in industrial processes such as petroleum, chemical, and food engineering. The efficiency of mass and heat transfer between phases is significantly impacted by bubble rise motion in liquids. Therefore, it is crucial to deeply study the hydrodynamic characteristics of a bubble rising in non-Newtonian fluids to improve the transfer efficiency between phases and to enhance the operational efficiency of bubbling equipment. Methods: To understand the rising characteristics of a bubble in non-Newtonian fluids, a single bubble rising in shear-thinning fluids was experimentally studied using a high-speed camera. The effects of xanthan gum (XG) concentration and bubble diameter on bubble shape, trajectory, and terminal velocity were investigated. Results: Bubble terminal velocity increased with an increase in the bubble diameter and a decrease in XG concentrations. The increase rate of bubble terminal velocity varied with an increase in bubble diameter for the bubbles with different diameters and XG concentrations for the solutions with varying XG concentrations. For solutions with the same XG concentration, the Galilei and Eötvös numbers for a small bubble were relatively small but relatively large for a large bubble. Thus, the rise motion of a bubble in XG solutions becomes unsteady with an increase in bubble diameter and a decrease in XG concentrations. The unsteady characteristics of bubble motion decrease with an increase in the XG concentration of solutions. Conclusion: It was found that the influence of XG concentrations on bubble motion depends on bubble diameter since the magnitude of bubble diameter has an essential effect on the shear-thinning effect of solutions. An increase in bubble terminal velocity is mainly caused by an increase in buoyancy (i.e., bubble diameter) rather than a decrease in the apparent viscosity of solutions.

Viscosity reduction of xanthan gum through free radical mechanisms mediated by ascorbic acid

Xanthan gum (XG) is a widely used thickener known for its high viscosity and excellent stability. However, the presence of ascorbic acid (AA) leads to a clear decrease in its viscosity, thereby affecting the application of xanthan gum in food products containing AA. Therefore, the aim of this study was to uncover the mechanism by which AA reduces the viscosity of xanthan gum. Ascorbic acid (0.1 mmol/L) caused a viscosity loss reaching up to 96% for xanthan gum solutions (2 g/L). The reaction was further enhanced by heating at 60 °C for 1 h without stirring, a weakly acidic system at pH 5.4, and the addition of hydrogen peroxide or metal ions (Fe2+ and Cu2+). Interestingly, AA induction produces free radicals and changes in their content correlate with a decrease in XG viscosity. Moreover, removing dissolved oxygen by heating and nitrogen purging treatment effectively reduced AA-derived free radical levels and prevented the decrease in XG viscosity. The decrease in viscosity of XG caused by AA involved its free radicals generated through an oxygen-dependent pathway.

Drag Reduction by Dried Malted Rice Solutions in Pipe Flow

In this study, the friction factor of a turbulent pipe flow for dried rice malt extract solutions was experimentally reduced to that of a Newtonian fluid. The friction factor was measured for four types of solutions at different culture times and concentrations. The results indicate that the experimental data points of the test solutions diverged from the maximum drag reduction asymptote at and above Re√f ≅ 200~250 and aligned parallel to those of Newtonian fluids. This drag reduction phenomenon differed from that observed in artificial high-molecular-weight polymer solutions, called Type A drag reduction, in which the drag reduction level is dependent on the Reynolds number in the intermediate region. This is classified as a Type B drag reduction phenomenon in biopolymer solutions and fine solid particle suspensions. The order of drag reduction corresponded to approximately 5–50 ppm xanthan gum solutions, as reported previously. Furthermore, the velocity profile in a turbulent pipe flow was predicted using a semi-theoretical equation in which the friction factors were determined using the difference between the experimental results of the tested solutions and Newtonian fluids. The results indicate considerable thickening of the viscous sublayer in the turbulent pipe flow of the test solutions compared with that of Newtonian fluids.

Sheared settling in viscoelastic shear‐thinning fluids: Empirical studies and model development

AbstractThe hydrotransport of settling particles using laminar flow as opposed to the more energy‐ and water‐intensive turbulent flow has remained a tentative option for industries due to the complexity in characterizing particle settling dynamics in opaque non‐Newtonian fluids under sheared conditions. To provide insight into this unknown physics, this study focused on viscoelastic shear‐thinning fluids and developed a semi‐empirical model to characterize the batch‐settling dynamics of dilute suspensions (<5 vol% solids concentration) experiencing a shear field. These suspensions consisted of spherical glass microparticles in aqueous xanthan gum solutions. Settling profiles were measured with Electrical Resistance Tomography (ERT) while a motorized belt generated a cross‐shear field. The data acquired by the ERT showed that introducing cross‐shear fields into such suspensions increased settling rates when compared with static settling contexts. Then, a semi‐empirical model describing the “acceleration phase” of the settling process was developed and validated at accuracies between 81% and 97%.

Relationship between texture perception and oral function: A preliminary study in young, healthy adults.

Oral frailty, characterised by reduced oral function, is associated with systemic health issues in older adults. Although the criteria for diminished oral function often focus on motor and secretory abilities, texture perception also plays a crucial role in health due to its impact on food intake and palatability. This study aimed to explore the relationship between thickness discrimination ability (TDA) and oral motor and secretory functions in healthy young individuals. Twenty-eight adults were assessed for texture perception using eight concentrations of aqueous xanthan gum solutions to determine TDA scores. Measurements of occlusal force, masticatory performance, tongue pressure, stimulated salivary flow rate and tongue-lip motor function were conducted. Spearman's correlation analysis was used to evaluate the relationship between TDA scores and oral functions. Participants were divided into high-sensitivity and low-sensitivity groups based on their TDA scores to compare oral function test results. The TDA scores varied among the participants, with higher scores correlating with higher masticatory performance (r = 0.41, p < .05). Masticatory performance in the high-sensitivity group was significantly higher than in the low-sensitivity group (211.9 ± 59.2 mg/dL vs. 157.9 ± 43.0 mg/dL, p = .013), with no significant differences in other oral functions. Masticatory performance was correlated with TDA, suggesting a link between the selection function of mastication and thickness discrimination. These findings highlight the potential relevance of texture perception in oral function and indicate the need for further exploration, particularly in older adults with declining oral health.

Heat and mass transfer analysis of a Maxwell-power-law fluid in a laminar planar jet flow with Cattaneo–Christov double diffusion theory

This paper focuses on the heat and mass transfer characteristics of a steady laminar planar jet flow of a Maxwell-power-law (MPL) fluid. MPL is a renowned fluid model with shear thinning and viscoelastic characteristics that can accurately exhibit the rheological features of polymer liquids. In the envisioned study, the MPL constitutive equation is introduced based on an experiment utilizing the Xanthan gum solution. The heat and mass equations are supported by the Cattaneo–Christov double diffusion (CCDD) concept with unique characteristics of thermal conductivity, mass diffusion, and chemical reaction. Thermal conductivity and mass diffusion coefficient are considered to be velocity gradient-dependent. The problem is addressed numerically by the bvp4c method in Matlab after applying the similarity transformations to the governing equations. The impacts of related parameters on velocity, temperature, and concentration are analyzed. Results show that an upsurge in the power-law index hinders momentum, energy, and mass transmission. An interesting phenomenon is that the variation in relaxation time can hinder or promote the heat and mass transfer of a Maxwell-power-law fluid jet before or after the intersection point, respectively. The study can provide a theoretical reference for engineering applications of jets.

Optimization and characterization of xanthan gum based multiparticulate formulation for colon targeting

To optimize and characterize xanthan gum multi-particulate formulation for colon targeting, which increases the residence time at the absorbing surface of the colon. Xanthan gum was dispersed in cold water containing drug and was permitted to expand for 2 ​h. Sodium alginate was blended well in 10 ​ml of water. Xanthan gum solution containing the drug was added to sodium alginate solution and 0.3 ​ml of glutaraldehyde was added to the dispersion, with constant stirring. Then, polymer-drug solution was added dropwise into 5% w/v calcium chloride solution with continuous stirring, producing microspheres filtered by Whatman filter paper and dried at 30 ​°C–40 ​°C. Microspheres were performed by chemical cross-linking with glutaraldehyde, which increased the maximum drug entrapment efficiency up to 73.63 ​± ​0.65% with an increasing concentration of xanthan gum polymer 0.7% w/v for the optimized F6 batch. Better results were found by increasing the polymer concentration along with the glutaraldehyde concentration. The kinetics of drug release for the F6 batch was considered as an optimized batch because the regression value was found to be 0.997 in the peppas model. The accelerated stability study on the optimized F6 batch performed to learn whether the drug has any change during its period of usability. The polysaccharide remains intact in the stomach and intestine and the drug was released in the colon with low toxicity and biodegradability. The present studies showed that optimizing and characterizing xanthan gum multi-particulate formulation for colon targeting gives metronidazole the most effective and controlled delivery.

Identification of lubricant viscosity to minimize the frictional impact of colonoscopy on colonic mucosa

Applying a lubricant to the colonic mucosa and reducing the dynamic friction coefficient (DFC) between the endoscopic shaft and colonic mucosa may reduce colonoscopy invasiveness. However, the ideal lubricant viscosity remains unknown. Here, we developed a DFC measurement model integrating samples of colonic mucosa from forensic autopsy specimens into a simulated bowel bend and determined the low-friction lubricant viscosity that minimizes the DFC. Carboxymethyl cellulose, xanthan gum, hydroxyethyl cellulose, sodium alginate, and sodium polyacrylate aqueous solutions of various concentrations were used as lubricants. Low-friction lubricants minimized the load on the colonic mucosa during colonoscope insertion and reduced the total endoscopy insertion time. The highest correlation was between the DFC and the lubricant viscosity at a shear rate of 100 1/s. The lowest DFC was almost constant at approximately 0.09, irrespective of the chemical composition of the lubricant, and the low-friction lubricant viscosity (100 1/s) was 0.031–0.086 (median: 0.059). The viscosities of conventional colonoscopic lubricants were suitable for lubricating the anorectal skin owing to their low DFC, but too high for lubricating the colonic mucosa because of their high DFC. The utilization of the low-friction lubricants with the optimal viscosity can reduce the stress on colonic mucosa during colonoscopy.

Screening of West Cameroonian edible plant-based mucilage for the production of improved protein-polysaccharide conjugates

In developing countries, blending the powders of locally utilized edible plants for mucilage extraction can be a way to address the growing demand for more viscous and soluble cost-effective hydrocolloids. This study aimed to identify mucilaginous edible plants exploited in the western region of Cameroon in order to enhance the viscosity and water solubility of their mucilages. A semi-administered questionnaire facilitated a comprehensive ethno-nutritional survey. Powders (200 μm) from mucilaginous plants available were defatted, oven dried, and used to produce crude extracts in a water bath (50 °C, 1 h, 2 cycles), with distilled water (1:10, m/v), followed by triple filtration (60 μm, 25 °C) and double centrifugation (2900 g, 20 min). The apparent viscosity of these crude extracts was recorded (spindle 2#, 600 s−1, 60 rpm) at 25 °C, and compared to a 0.2% (m/v) xanthan gum solution (in distilled water). The best plant powders were blended (5 blends) for use under an alkaline condition (pH 10, 0.025 M) for optimal liquid mucilage production and its corresponding powder named hibisanua, derived by coagulating the liquid mucilage (4 °C, 96% ethyl alcohol), oven drying (45 °C), powdering, and sieving (200 μm). Some rheological parameters were determined. FTIR and SEM analysis were carried out with the mucilage hibisanua. Out of 300 surveyed participants, 120 (40%) from 17 ethnicities use the identified plants. Thirty species were found, spanning 27 genera and 19 botanical families. Hibiscus esculentus (okra) pods, Triumfetta annua (nkui) bark, and Corchorus olitorius (lalo) leaves are commonly used in traditional food processing. However, only okra (9.23 Pa s) and nkui (5.54 Pa s) liquid mucilage viscosities were similar to xanthan, making their defatted powders interesting. The validated plant powder mixture (F2) thus comprised 10% nkui and 90% okra (w/w). Their crude extract of concentration 1.51% (w/v) showed the highest dynamic viscosity (23.05 Pa s), not significantly different (p ≥ 0.05) from the control. The resulting dry mucilage with a yield of 215.8 mg/g F2 had the highest solubility (83.05%) with a specific viscosity of 11.519 Pa s upon a desirability of 0.73. All polysaccharides’ solutions exhibited pseudoplastic characteristics and shear-thinning behaviour. A concentrated solution (1.51%) of hibisanua had a rheologic index (0.742) and viscous relaxation time (69.25 s) comparable to xanthan gum. Its structural analysis revealed functional group and morphological changes, typical of highly physical gelling pectic mucilages. These findings support the formulated plant powder approach and the use of its mucilage in the food and pharmaceutical industries.

Dip coating of shear-thinning particulate suspensions.

Dip coating a planar substrate with a suspension of particles in a shear-thinning liquid will entrain particles in the liquid film, facilitating filtration and sorting of particles. Experiments were performed for both monodisperse and bidisperse particle suspensions of shear-thinning Xanthan Gum solutions. Particle entrainment occurs when the coating thickness at the stagnation point of the thin film flow is larger than the particle diameter. A model is developed to predict the entrainment criteria using lubrication theory applied to an Ostwald power-law fluid which yields a modified Landau-Levich-Derjaguin (LLD) law governing the coating film thickness that depends upon a properly defined capillary number Ca. The critical withdrawal velocity for particle entrainment depends upon the particle size and fluid rheology through a relationship between Ca and the bond number Bo, which agrees well with our model predictions and prior experimental results of A. Sauret et al. Phys. Rev. Fluids, 2019, 4, 054303 for the limiting case of Newtonian suspensions. Single particle entrainment and particle clustering is observed for monodisperse suspensions, which depends on Ca and the particle volume fraction ϕ. In bidisperse suspensions, particle sorting can occur whereby only the smaller particles are entrained in the film over an active filtration range of Ca and Bo, which also agrees well with our model predictions.

Analyzing Local Shear Rate Distribution in a Dual Coaxial Mixing Bioreactor Handling Herschel–Bulkley Biopolymer Solutions through Computational Fluid Dynamics

For the aeration of highly viscous non-Newtonian fluids, prior studies have demonstrated the improved efficacy of dual coaxial mixing bioreactors fitted with two central impellers and a close clearance anchor. Evaluating the effectiveness of these bioreactors involves considering various mixing characteristics, with a specific emphasis on shear rate distribution. The study of shear rate distribution is critical due to its significant impact on the mixing performance, gas dispersion, and homogeneity in aerated mixing systems comprising shear-thinning fluids. Although yield-pseudoplastic fluids are commonly employed in various industries, there is a research gap when it comes to evaluating shear rate distribution in aerated mixing bioreactors that utilize this fluid type. This study aims to investigate shear rate distribution in an aerated double coaxial bioreactor that handles a 1 wt% xanthan gum solution, known as a Herschel–Bulkley fluid. To achieve this goal, we employed an experimentally validated computational fluid dynamics (CFD) model to assess the effect of different mixing configurations, including down-pumping and co-rotating (Down-Co), up-pumping and co-rotating (Up-Co), down-pumping and counter-rotating (Down-Counter), and up-pumping and counter-rotating (Up-Counter) modes, on the shear rate distribution within the coaxial mixing bioreactor. Our findings revealed that the Up-Co system led to a more uniform local shear distribution and improved mixing performance.

Dynamics of displacement flows of viscoplastic fluids in obstructed eccentric annuli at moderate Reynolds numbers

As a sequel to Mitishita et al. [“Turbulent displacement flows of viscoplastic fluids in obstructed eccentric annuli: Experiments,” Phys. Fluids 34, 053114 (2022)], we present an experimental study of laminar displacement flows in obstructed eccentric annuli. Xanthan gum (XG) solutions (0.35%, 0.50%, or 0.75%) are used to displace a 0.15% viscoplastic Carbopol solution. The eccentricity of the annulus section is set to near 0.5. We study the effect of a solid obstruction in the narrow side of the annulus, similar to that provided by a consolidated residual cuttings bed, and compare the results to unobstructed displacement flows. While we predicted that all displacements would be in the laminar regime, we actually observe mixed regimes where the initial displacement of Carbopol can be transitional or turbulent. With the obstruction on the narrow side of the annulus, we observe the formation of cavities in the Carbopol layer, both upstream and downstream of the obstruction. We believe that the cavities are formed because the obstruction behaves like an abrupt contraction/expansion. This geometric irregularity affects the velocity profiles of the displacing fluid near the obstruction. Once the cavities reach the bottom of the pipe, we observe that the remaining Carbopol layer is more easily eroded. The dynamics of the Carbopol removal also share similarities to cleaning of soil layers in pipes, as described by Palabiyik et al. [“Flow regimes in the emptying of pipes filled with a Herschel–Bulkley fluid,” Chem. Eng. Res. Des. 92, 2201–2212 (2014)].

Rheological Properties of Xanthan-Gum Solutions and Their Role in Improving River Embankments

Rheological Properties of Xanthan-Gum Solutions and Their Role in Improving River Embankments