Applications with keyword: Viscous solutions
Blue dye was removed from a highly viscous liquid using a SpinChem® RBR S2 in an EasyMax™ 102 Advanced Synthesis Workstation. Monitoring of the reaction was easily recorded as no freely suspended ion exchange resin beads or resin debris interfered with the readings. This demonstrates that the RBR technology is extremely well suited for in-line monitoring. The viscosity of the solution was determined to ca 230 cP at 25°C, showing that it is possible to absorb dye even from a highly viscous solution.
The performance of a SpinChem® rotating bed reactor (RBR) in the treatment of highly viscous solutions was compared to that of a conventional stirred tank reactor (STR). Both reactor set-ups were used for the extraction of Allura red dye from a glycerol-dye mixture using an ion exchange resin. The RBR removed 10 times the amount of dye in just over 40 % of the time, compared to the STR. This comparison underlines the efficient mixing and clever design of the SpinChem® RBR, as well as the broad spectrum of applications for which this technology is highly relevant.
Conditions: Glycerol (80%, wt) was mixed with dH2O and Allura red (20 mg/L). The mixture was kept at a temperature of 10°C to achieve a viscosity of around 0.116 · 10¯³ m²/s. A SpinChem® RBR S3 was filled with 41.6 g macroporous strong base anion exchange resin (Purolite® A500 MB Plus) and spun in 1 L of the mixture at 400 rpm. For the STR experiment, 41.6 g of the same ion exchange resin was suspended in 1 L of the viscous dye solution, and stirred by means of an impeller at 400 rpm. Samples for absorbance measurements were taken over time and analysed using UV-Vis spectroscopy.
Log-log plot of how viscosity affects the reaction time for a mass transfer limited reaction at a fixed rotational speed of a rotating bed reactor (RBR). The RBR behaved very predictably and delivered reaction times that increased linearly with reaction media viscosity up to at least 500 mPa·s.
Conditions: Time for neutralization of sodium hydroxide (2 M, 50 µL) by acidic cation exchanger (Amberlite IRN 99, 20 mL) packed into a SpinChem® RBR S311 rotated at 500 rpm within a SpinChem® V311 flower baffled reaction vessel containing 500 mL solution consisting of 0-90% glycerol in water to adjust viscosity. The reaction was followed at two different temperatures (10 °C and 30 °C). Neutralization time was determined manually with 3-9 repeated measurements per viscosity using phenolphthalein (10 mg) as indicator. Viscosity was taken as standard tabulated values from J.B. Segur et al. in Ind. Eng. Chem 43 (1951) 2117. Median relative standard deviations of reaction time was 5.3% but had a tendency to increase at the highest viscosities.