Separan AP-30 Research Articles

Extraction of rebaudioside-A by sonication from Stevia rebaudiana Bertoni leaf and decolorization of the extract by polymers.

Optimization of steviol glycosides extraction from Stevia rebaudiana Bertoni leaf was carried out by investigating the effects of isopropyl alcohol concentration (60%, v/v), time (6-24min), temperature (30°C) and sonic power (300-480W) on extraction of rebaudioside A from Stevia rebaudiana leaves and decolorization of the extract by polymer (Separan AP30 and Resin ADS-7). The results showed that isopropyl alcohol was suitable for the extraction of rebaudioside A from Stevia rebaudiana leaves and the yield of rebaudioside A achieved 35.61g/100g when the output power was 360W and treatment time was 18min. The sonication had influence on the particle size of stevia leaf and the color of the extracted solution. As the sonication intensity increased, the particle size decreased. The colour of differently treated stevia solutions were significantly different (P < 0.05). Separan AP30 and adsorption resin ADS-7 were performed to remove the colour impurity. The results showed that more than 65% of the coloured impurity was removed by Separan AP30 combined with Calcium oxide (CaO).

142 平行平板間の粘性指状体の分岐現象(S34-4 複雑流体の流れとその応用(4),S34 複雑流体の流れとその応用)

When air pushes a more viscous fluid in two parallel plates by a syringe pump, viscous fingering pattern have been observed. Water and aqueous glycerin solutions are used as Newtonian fluids, and aqueous glycerin solutions adding polyacrylamide (Separan AP30) are used as non-Newtonian fluids. It was found that it showed the bifurcation of viscous fingering to be different by a kind of solution. It was found that the solution concentration, gap and air pressure influenced a bifurcation pattern. Furthermore, viscosity and air pressure influenced tip speed of bifurcation in Newton fluid.

Estudio del comportamiento de las colas de una planta de beneficio de mineral de fluorita frente a procesos floculación-coagulación

The objective of this work is to carry out a selection study of the most adequate flocculationcoagulation reagents to reduce the solids content in the overflow from the settling lagoons of a fluorspar processing plant. This overflow has 1 % solids content, clarified from a feed of 25% solids in the settling lagoons, and is pilled into a river. The importance of this work is enhanced by the fact that the plant is located in a low water resources area, and that eventually the water from the river is used for agriculture or even human consumption. It is relevant to find a working methodology which allow to improve the efficiency of the clarifying process and minimize the environmental impact. Regarding the research methodology, a series of trials were made at natural pH and 25 °C to evaluate the action of those reagents which previously probed to be more efficient in this case: as flocculants were tried BOZEFLOC C 65, SEPARAN AP 273 P, SEPARAN MG 200, and as coagulant aluminium sulfate. The possible interaction of flocculation-coagulation processes was also studied, to obtain optimum result. As analysis criterium the total flocculation time was used, and as all essays were made in 100 ml probes, it corresponds with flocculation rate. As result of this study it can be concluded that the most efficient floculant was SEPARAN MG 200, at 4 g/T, with the observation that an excess of aluminium sulfate gets down the efficiency.

Fully developed turbulent flow of non–Newtonian liquids through a square duct

The results are reported of an experimental investigation of fully developed turbulent flow through a square duct of water (as a control) and of two polymers, an aqueous solution of 0.1% carboxymethylcellulose + 0.1% Keltrol TF, a xanthan gum (CMC/XG) and a 0.125% aqueous solution of a polyacrylamide, Separan AP 273 (PAA). The more elastic rheology of PAA leads to drag–reduction levels up to 77%, compared with 65% for CMC/XG. There are also substantial reductions in the levels and changes in the spatial distribution of the transverse turbulence intensities and the Reynolds shear stress, again dependent on the degree of viscoelasticity of the working fluid. Concomitant changes are evident in the secondary flow, which depends upon second derivatives of the Reynolds stresses, and also in the primary axial flow due to the redistribution of axial momentum by the secondary flow.

Heat transfer behavior of temperature -dependent viscoelastic non-Newtonian fluid with buoyancy effect in 2:1 rectangular duct

This numerical study investigates the flow characteristics and heat transfer mechanism of a viscoelastic non-Newtonian fluid in a 2:1 rectangular duct. The combined effect of temperature-dependent viscosity, buoyancy, and secondary flow caused by a second normal-stress difference is considered. The Reiner-Rivlin constitutive equation was adopted to model the viscoelastic fluid characteristics. An axially constant heat flux on the bottom wall and peripherally adiabatic boundary condition (H2) were both used. The numerical results for a polyacrylamide (Separan AP-273) solution showed a significant heat transfer enhancement compared to those of a constant property fluid, and exhibited a good consistency with experimental results for both thermal developing and thermally developed regions. In a bottom-wall-heated 2:1 rectangular duct, the main cause of the heat transfer enhancement of the viscoelastic fluid was viscoelastic-driven secondary flow, with temperature-dependent viscosity and buoyancy-induced secondary flow playing supporting roles.

Synergistic Effects in Turbulent Drag Reduction by Riblets and Polymer Additives

Drag reduction was investigated for the combined system of polymer additives and a riblet pipe. The riblet grooves were V-shaped, the spacing of which was 1.3 mm and the height of which was 1.01 mm. For higher h+, a triangular riblet system including other geometries increases the drag to levels similar to those of normal transient roughness. This drag increase was generally given as a function of h+. The polymer additives were Aronfloc N-110 and Separan AP-30. The critical shear stress τ*, at which N-110 started the drag reduction, was approximately eight times higher than τ* for AP-30. In the combined system, the synergistic drag reduction for higher h+ was discussed under the assumption that the additives suppressed the drag increase resulting from riblets. Since the additives thicken a wall layer covering the region from a viscous sublayer to a buffer layer, the relative height of h to this wall layer thickness is lowered. In addition, the flow enhancement due to additives relatively suppresses the riblet-induced drag increase. The analysis based on velocity profiles indicated that these effects can produce synergistic drag reduction for higher h+.

Heat transfer behavior of a temperature-dependent non-Newtonian fluid with Reiner–Rivlin model in a 2 : 1 rectangular duct

The present study investigates the heat transfer enhancement mechanism observed with a non-Newtonian fluid having temperature-dependent viscosity in a 2 : 1 rectangular duct. The Reiner–Rivlin constitutive equation was used to model the non-Newtonian fluid characteristics. The H2 thermal boundary condition, corresponding to an axially-constant heat flux with a uniform heat flux at the top wall, was used. The local Nusselt numbers calculated for a polyacrylamide (Separan AP-273) solution showed significant heat transfer enhancements over those of a constant property fluid and gave excellent agreement with experimental results in both the regions of thermally developing and fully developed. The heat transfer enhancement results from an increased fluid mixing near the heated top wall, which is attributed to both the effects of the temperature-dependent viscosity and secondary flow induced by second normal stress difference. The present study concludes that the heat transfer enhancement of the viscoelastic fluid in a 2 : 1 rectangular duct is caused by the favorably combined effect of temperature-dependent viscosity and normal stress-induced secondary flow.

Heat transfer mechanism for Newtonian and non-Newtonian fluids in 2 : 1 rectangular ducts

A numerical study has been performed on the heat transfer mechanism of Newtonian and non-Newtonian fluids in 2 : 1 horizontal rectangular ducts. The effects of temperature dependence of viscosity, shear thinning, and buoyancy-induced secondary flow are all considered. Experimental data for Newtonian fluid, water, and non-Newtonian fluid, Separan AP-273 solution (0.1%), were chosen for the comparison with the numerical results. For water, the present numerical results are all in good agreement with the experimental data. The heat transfer enhancement is caused by the buoyancy-induced secondary flow. For Separan AP-273 solution (0.1%), the present numerical results agree with the experimental data in the region near the entrance, but the present modeling underestimates the value of Nu in the fully-developed region. In the region near the entrance, the heat transfer enhancement is caused mainly by the axial velocity distortion, which is mainly due to the temperature dependence of viscosity. The effect of buoyancy-induced secondary flow are much weaker in the case for Separan solution rather than that for water. It is mainly caused by the relatively high viscosity of fluid around the central zone of rectangular duct.

The effect of thermal degradation on the non-newtonian viscosity of an aqueous polyacrylamide solution

The objective of the present study was to investigate the effect of thermal degradation on the non-Newtonian viscosity of a dilute polymer solution by measuring the viscosity at a reference temperature before and after heating the solution with different heating temperatures and duration. The test solution was a polyacrylamide (Separan AP-273) 1,000 wppm solution in distilled water. The effect of thermal degradation on the viscosity was greater at relatively low shear rates than at intermediate and high shear rates. The viscosity of the polyacrylamide solution experienced at a relatively high temperature decreased more than that experienced at a relatively low temperature. In addition, the effect of thermal degradation on the viscosity of the polyacrylamide solution showed a strong dependence on the duration of heating.

Flow of non-Newtonian fluids through tubes with abrupt expansions and contractions (square wave tubes)

The steady and dynamic shear properties of three different non-Newtonian fluids (an Acrysol TT615 solution, a 50% creosote-in-water emulsion and a Separan AP-30 solution) are determined. Their flow behaviour through tubes with abrupt expansions and contractions (`square wave tubes') is investigated. The steady shear viscosity of these fluids can be described with a modified Quemada model. The geometric parameter method proposed previously by Kozicki et al. for duct of arbitrary cross section can be extended to the present systems with the use of a volume-average diameter. Flow in square wave tubes can be readily obtained from the straight capillary data by means of a shift factor ( a+ b). The shift factor is related to a pressure-average diameter. Conversely, using the pressure-average diameter eliminates the necessity of the shift factor. Corrections of inertial and entrance effects from Newtonian results can be approximately applied to non-Newtonian results. These corrections are relatively insignificant as compared with the effects of fluid elasticity and elongational-viscosity for viscoelastic fluids.

Effects of nonionic surfactant and associative thickener on the rheology of polyacrylamide in aqueous glycerol solutions

The effect of a low molecular weight nonionic surfactant and an acrylic associative thickener on the rheology of polyacrylamide in aqueous glycerol solutions under steady shear was experimentally investigated. The nonionic surfactant (Tween20), associative thickener (Acrysol TT935) and polyacrylamide (Separan AP30) underwent complex molecular interactions in solution as reflected by rheological measurements. The surfactant also interacted with the glycerol solvent. The addition of surfactant in aqueous glycerol solutions reduced the surface tension, as well as the solution viscosity, at low surfactant concentration. The solution viscosity went through a minimum at certain surfactant concentration, depending on the composition of glycerol/water mixture, before increasing again. Similar behavior was found when the surfactant was added to the polyacrylamide solution, except there was an initial increase in the viscosity before the reduction. The associative thickener, Acrysol TT935 (an anionic acrylic emulsion copolymer) exhibited a strong affinity with polyacrylamide in solution, as indicated by a sharp increase in the solution viscosity. The dilute polyacrylamide solution became highly elastic in the presence of either the nonionic surfactant on the associative thickener. A threestage model was proposed to describe the surfactant/thickener/polymer interactions.

A study on the pressure loss coefficient of non-Newtonian fluids in the stenotic tubes

The pressure loss coefficient of Newtonian and non-Newtonian fluids such as water, aqueous solutions of Carbopol-934 and Separan AP-273 and blood in the stenotic tubes are determined experimentally and numerically. The numerical analyses for flows of non-Newtonian fluids in the stenotic tubes are conducted by the finite element method. The effect of the contraction ratio and the ratio of length to diameter on the pressure drop are investigated by the experiments and numerical analysis. The pressure loss coefficients are significantly dependent upon the Reynolds number in the laminar flow regime. As Reynolds number increases, the pressure loss coefficients of both Newtonian and non-Newtonian fluids decrease in the laminar flow regime. As the ratio of length to diameter increases the maximum pressure loss coefficient increases in the laminar flow regime for both Newtonian and non-Newtonian fluids. Newtonian fuid shows the highest values of pressure loss coefficient and blood the next, followed by Carbopol solution and Separan solution in order. Experimental results are used to verify the numerical analyses for flows of Newtonian and non-Newtonian fluids. Numerical results for the maximum pressure loss coefficient in the stenotic tubes are in fairly good agreement with the experimental results. The relative differences between the numerical and experimental results of the pressure loss coefficients in the laminar flow regime range from 0.5% to 14.8%.

Factors affecting polymer degradation in turbulent pipe flow

A capillary rheometer was used to investigate the effect of various parameters on polymer degradation in turbulent flow. These parameters included polymer concentration, contraction ratio, pipe length, pipe diameter, number of passes, solvent and molecular weight of polymer. A commercial organic drag reducer (ODR), two grades of polyacrylamide (Separan AP 30 and AP 302), and a high-molecular weight polyisobutylene (PIB) were used. The investigation was based on measuring the loss in the drag reduction effectiveness which was manifested by a minimum point on the Fanning friction factor vs Reynolds number plot. In turbulent flow, the polymer degraded more in a poor solvent at low Reynolds numbers; whereas an opposite effect was observed at high Re. The critical Reynolds number Re*, or critical apparent shear/extensional rate ( V/ d)* was found to increase with polymer concentration and molecular weight as represented by the dimensionless concentration c[ν]. There is sufficient evidence to suggest that most fo the degradation takes place at the entrance region due to high extensional straining of polymer molecules. As expected, polymer degradation was found to increase with number of passes. However, the contraction ratio and pipe length did not seem to have much effect. Whilst Re* increased with pipe diameter, the trend was not evident on ( V/ d)*.

Laminar heat transfer in a rectangular duct with a non-Newtonian fluid with temperature-dependent viscosity

The present study investigates the effect of the temperature-dependent and shear-thinning viscosity of a non-Newtonian fluid on the behavior of the laminar heat transfer and friction coefficients in a 2:1 rectangular duct. The H1 thermal boundary condition, corresponding to an axially-constant heat flux and a peripherally-constant temperature, was adopted for a top-wall-heated configuration. The present numerical results of local Nusselt numbers for a polyacrylamide (Separan AP-273) solution show 70–300% heat transfer enhancement over those of a constant-property fluid and give excellent agreement with recent experimental results. The heat transfer enhancement from the heated top wall is due to an increased velocity gradient near the wall, which is attributed to the combined effect of the temperature-dependent and shear-thinning viscosity. Two new correlations for the friction factor and the local Nusselt numbers in the 2: 1 rectangular duct are proposed; these correlations cover both thermally-developing and thermally-fully-developed regions. This study also proposes the use of a temperature-dependent shear-thinning fluid in a rectangular duct in the design of a liquid cooling module for the computer industry.

Determination of the characteristic and diffusion times of polyacrylamide solutions using falling balls and needles

The present study determined the apparent viscosity and the characteristic time of aqueous polyacrylamide Separan AP-273 solutions by using a falling ball viscometer. Two laser beams and a digital timer system were used to accurately measure the terminal velocity of a falling ball or needle in the falling ball viscometer. The diffusion time of the polyacrylamide solution was determined by measuring the terminal velocities of falling balls. A consistent diffusion time was observed for balls, whereas in the case of needles, the diffusion time depended on the ratio of the needles' length to their diameters. The diffusion time decreased as the ratio increased for a given Separan solution. The characteristic time and the diffusion time of the polyacrylamide solution decreased as degradation continued. The effect of degradation on the heat transfer was more significant than that on the friction factor. A computer-aided image-processing technique was employed to visualize the flow phenomena around balls. For a time interval of 3 min, recirculating eddies were formed both upstream and downstream of the falling ball, whereas for a time interval of 10 min the eddies disappeared.

Oleate flotation of dickite from quartz with diluted HCl preconditioning. III. Improvement in fine particle flotation by selective flocculation

In order to improve the separation of dickite from quartz finer than 2 μm, selective flocculation with the polymeric flocculant, Separan AP30, was introduced to the flotation process which includes preconditioning in diluted HCl solution containing CaCl 2. The increase in the flotation recovery of dickite occurred only when Separan AP30 was added after oleate, probably due to an increase in the probability of collision between bubbles and particles through floc formation. The results are consistent with Separan AP30 diminishing the bridging action of hydrolyzed aluminum species between dickite and quartz, resulting in satisfactory selective flotation of dickite from quartz.

Wavelength and depth of ribbing in roll coating and its elimination

AbstractExperiment has been made on ribbing induced on a film coated over a roll surface by a two‐roll system: one roll rotated with a speed and the other fixed or rotated with relatively different speeds. The two rolls have the same diameters and are placed parallel with each other by keeping a gap. Test fluids are Newtonian (glycerin/water) and viscoelastic [polyacrylamide (Separan AP30)/glycerin/water] solutions. Wavelength and depth of ribbing are measured by a newly developed technique utilizing an image of a straight bar placed above the roll and reflected on the ribbing film surface. Nondimensionalized wavelength is correlated with capillary number for Newtonian liquids, but higher for dilute Separan solutions and lower for nondilute Separan solutions than for Newtonian liquids. The depth of ribbing increases for dilute Separan solutions with nearly the same value for nondilute Separan solutions as those for Newtonian liquid. This behavior observed for the ribbing seems to have some relation to the existence of a line of vortices that occurs visibly for nondilute Separan solutions in the entrance region of the gap between the rolls. Increase in the ratio of the velocities of two rolls has an effect of increasing both the wavelength and depth of ribbing for glycerine and nondilute Separan solutions, but it has the effect of decreasing them for dilute Separan solutions. Addition of Separan in glycerine solution promotes the generation of ribbing.A string spanned near over the gap to touch the surface of the liquid pool between the gap has the effect of eliminating the ribbing. This is successful in various combinations between the speeds of the two rolls and the diameters of the string.

Improved correlation for shear-dependent viscosity of polyelectrolyte solutions

The reduced-variable approach developed by Graessley has been widely used for representing shear-dependent viscosities of organic solutions. However, this method is inadequate for describing charged polymeric systems such as polyelectrolytes. Thus a modified reduced approach was developed. The method incorporates the empirical equation of Fuoss and Strauss to account for the strong repulsions between charged groups. It was successfully used to correlate shear-dependent viscosity of polyelectrolytes in aqueous solutions. Six different polymeric systems were examined; namely polyacrylamides (Separan AP30, NP10, AP302; Dow Chemicals), polyethylene oxide (Polyox Coagulant; Union Carbide), carboxymethylcellulose (CMC; Hercules), and xanthan gum (Keltrol; Keico). The polymer concentrations used range from 10 to 40 000 ppm, covering the dilute, semidilute and concentrated regimes. The above method has great practical utility as its usage leads to a significant reduction in the experimental work needed to characterize a polymer solution.

Rheology of Water-Soluble Polymers: A Comparative Study on the Effect of Monovalent Salt

Abstract A comparative study was conducted on three commercial water-soluble polymers: partially hydrolyzed polyacrylamide (Separan AP30—Dow Chemicals), polyethylene oxide (Polyox Coagulant—Union Carbide), and xanthan gum (Keltrol—Kelco). Both the steady shear and the dynamic properties were examined. The presence of salt significantly reduces the viscous and elastic properties of Separan AP30. Negligible changes were observed for Polyox Coagulant. However, some marginal reduction in these properties was evident for xanthan gum at low salt concentration up to cs of 0.05 M, beyond which no effect was observed. The relationship between the rheological properties of the polymers and the salt concentration is governed by the charged characteristics of the polymer chains. The present study suggests that it is more desirable to use xanthan gum than polyacrylamide in a high-salt environment. Polyethylene oxide is usually avoided due to its cost and low resistance to mechanical degradation.

Turbulent heat transfer of polyacrylarnide solutions in the thermal entrance region of circular tube flows

The purpose of this article is to investigate experimentally the heat transfer characteristics of drag reducing polymer solutions in the thermal entrance region of circular tube flows. Two stainless steel tubes with L/D=710 and 1100 are used for the heat transfer tests. Testing fluids are aqueous polyacrylarnide solutions of Separan AP-273 with concentration ranging from 300 to 2000 w.p.p.m. The main assertion of the present study is that the order of magnitude of the thermal entrance length of the maximum drag reducing polymer solutions is much higher than that of Newtonian fluids in turbulent tube flows. Also, by introducing a new dimensionless parameter, the product of Reynolds number and Graetz number, all experimental data are recast in a newly defined parameter.