Ind. Eng. Chem. Res. 1998, 37, 4903
4903
ADDITIONS AND CORRECTIONS
Volume 37, Number 10 Effect of Shear Stress within the Spinneret on Hollow Fiber Membrane Morphology and Separation Performance. T.-S. Chung,* S. K. Teoh, W. W. Y. Lau, and M. P. Srinivasan Page 3936. We have found mistakes in the above paper because the gas conversion factors used for calculating the permeances of gas He and H2 which were measured with a Matheson gas flowmeter are not correct. As a result, the conclusion of this paper remains the same as “Experimental results suggest that hollow fiber membranes spun from this large L/∆D die with high shear have a tighter molecular packing structure and therefore a higher selectivity but a lower permeance”. However, the statement “the selectivity of H2/ N2 for fibers spun with high shear rate is 4-fold of the PES intrinsic value (292-307 vs 73.7)” is not correct. In short, all our measured permeance data in Tables 4-7 and 9 for He should be revised (lowered) by dividing by a factor of 1.88 and those for H2 by a factor of 3.68. For example, the revised Tables 5 and 9 should be as follows: Table 5. Effect of Shear Rate on the Permeance and the Apparent Dense Layer Thickness of Coated Fiber Samples calcd shear rate (s-1) 103 609 862
O2
permeance (GPU) N2 He H2
9.9 6.3 5.0
1.9 1.1 0.9
126 84 72
dense layer thickness calcd based on O2 (Å)
126 88 70
450 706 893
Table 9. Comparison of Gas Selectivity between Our Coated Hollow Fibers and Dense Films
a
shear rate (s-1)
H2/N2
H2/He
He/N2
103 609 862 dense filma
66.9 83.3 79.5 73.71a
1.00 1.06 0.98 0.79a
67.3 78.7 81.4 93.57a
Data at 25 °C and 10 bar (Wang, 1996).
The authors thank Prof. W. J. Koros at The University of Texas for pointing out anomalies in our work. IE980833M 10.1021/ie980833m Published on Web 11/12/1998
