A Method To Estimate the Average Shear Rate in a Bubble Column Using Liposomes

• Published in: Industrial & engineering chemistry research Vol. 52; no. 51; pp. 18498 - 18502
• Main Authors: Natsume, Tomotaka, Yoshimoto, Makoto
• Format: Journal Article
• Language: English
• Published: American Chemical Society 26.12.2013
• Subjects: Bubble columns; buffers; carboxymethylcellulose; Correlation; Devices; Dyes; engineering; Estimates; Industrial engineering; Liposomes; permeability; Shear rate; sodium chloride
• ISSN: 0888-5885; 1520-5045; 1520-5045
• DOI: 10.1021/ie402874q

We describe a novel approach to estimate average shear rate in an external-loop airlift bubble column, based on the shear stress-induced structural change in liposomes. As a shear-sensing probe, the 5(6)-carboxyfluorescein-containing liposome (CFL) was suspended at 40 °C in 50 mM Tris-HCl/50 mM NaCl buffer of pH 7.4 containing 0.3 wt % carboxymethyl cellulose. The CFL was 180 ± 1 nm in mean diameter and physically stable under shear flow. The permeability coefficient (P CF) of the dye molecules through the CFL membrane increased linearly as the shear rate (γ) increased up to 1425 s–1, as revealed using a cone-and-plate device. The P CF value was then determined for the identical CFL suspension in the airlift operated at superficial gas velocity (U G) values up to 0.03 m/s. The shear rate in the airlift could be reasonably estimated through correlating γ with U G, using their quantitative dependence on P CF, obtained as above. The γ value of 2.5 × 103 s–1 was obtained at U G = 0.03 m/s for the airlift.