Korean Chem. Eng. Res., Vol. 45, No. 3, June, 2007, pp. 264-268 m l i m so mi m oz i m Ç q, *Ç ij*ç om 305-764 re o 220 * l v l o ~redšl 305-343 re o q 71-2 (2006 11o 10p r, 2007 1o 29p }ˆ) Synthesis of Nanostructures by Direct Growth of Carbon Nanotubes on Micron-sized Metal Fiber Filter and its Filtration Performance Dong Geun Lee, Seok Joo Park, *, Young Ok Park* and Jeong In Ryu Department of Mechanical Engineering, Chungnam National University, 220 Gung-dong, Yuseong-gu, Daejeon 305-764, Korea Clean Energy System Research Center, Korea Institute of Energy Research, 71-2 Jang-dong, Yuseong-gu, Daejeon 305-343, Korea (Received 10 November 2006; accepted 29 January 2007) k p o l ˆ vr q p f p p p pl. ˆ s l p o to s~ o p l p s~ q m. ˆ q m ˆ q v kp p l p r l, kp l pp n l, p ˆ mm pq q p qn m p. h Abstract The filtration performance of micron-sized metal fibrous filter was improved by synthesizing carbon nanotubes grown on the surface of metal fibers. The carbon nanotubes are grown with bush-like nanostructures covered around the micron-fibers or web-like nanostructures crossing between the fibers at different synthetic conditions. Filtration efficiency of CNT-metal-filter was measured and compared with the efficiency of the raw metal filter without CNTs. The developed CNT-metal-filter has higher filtration efficiency without significant difference in pressure drop compared with the conventional metal filter, which is because the carbon nanotubes function as the trap of pollutant nanoparticles. Key words: Micron-Sized Metal Fiber Filter, Direct Growth, Nanostructure, Filtration Efficiency 1. q m rp v p ˆ rq, d, l, l rn o n q f t p [1]. v v ˆ p p vrrp ~ rs l n m r rp kt tp. v, ˆ p l l l ˆ pp rq m p. Walters [2]p l l ˆ pp l. l ˆ p p o l q q kl ˆ o l l rs m. Vander Wal [3] Johnson [4]p l To whom correspondence should be addressed. E-mail: sjpark@kier.re.kr ˆ vrrp rs m. p r p ˆ p dispersion, deposition, binding p rp m. Srivastava [5]p op tˆ l p d p d pp o p r p ˆ m. ˆ 900l p m kl r p l l. ˆ ˆ lr l kp n p. Shimoda [6] p o vv~ l q s l p l p l p ˆ p p p l m. k p o v p p l pp o v p qp v [7]. p l o Ž n, p l pp p Œ l 264
p o l ˆ p vr ql p s~ l 265 lp p. Graham [8]p r p n l p l o Ž l p p mp op v p e tp l p. l l p o l ˆ vr m p o l q ˆ p s m. p rp p o l vrrp ˆ p p n k f pnp e m. ˆ p vv~ o n mp, d pn l o p o, o p ol vrrp ˆ l o p pqp v rp n l. 2. o l ˆ p lv ~ o e p m. (BEKAER, BEKIPORr ST 7CL4) 316L d p d dž o p lv o p. Fig. 1l m p ˆ p vv~ n v 12 µmp d p d dž o p lv v dp p s p o l kp (grain boundary) p sq p p. o p p ~ v k p v ˆl m. o v q l q l pm 600 o Cp s l 6 min k k d 1,000 sccmp el d o p 200, 400, 600 sccm v o p o }, k Ž d ˆ m. ˆ p k d o l m v m. ˆ o p k l p o e p m. p k l p o l pq (atomization aerosol generator; TSI 3079), s,, k, DMA(differential mobility analyzer; TSI 3081), UCPC(ultra condensational particle counter; TSI 3025A) e edšp n m. e l n e p q 0.2 Mp m nkp pq l }o m krp, s ~ krp p } l pq n m. e pqp p l p l DMAm UCPC n l r mp, l pp m. p l q ˆ p ˆ p v NaCl pqp o ˆ p p SEM (scanning electron microscope; HITACHI S-4700)p m mp, ˆ p sm rp q s o l ˆ q k mp }or p ek l 1p k pž o l ˆ m. ˆ k mp TEM l l FE-TEM(field emission transmission electron microscope; FEI Technai G2 F30 S-TWIN)p m. 3. Fig. 1. SEM images of the micron-fibrous metal filter and it nascent surface. Fig. 2 p l ˆ p q SEM vp lt. q ˆ sp p p p p p v k ov ˆl o tol bush-like o p l web-like kp ˆ s ppp k p. q bush-like ˆ p tp ˆ pl p p k pp, p p mm vp v r rp qn p. s p Table 1l ˆ m p k d 1 slm, k Ž d 10 sccm, e 6 min, m 600 o Cp d 200, 400, 600 sccm ˆ m. Fig. 2(a) d 200 sccm ˆ p o tol bush-like ˆ q mp, ˆ p q p v kk mmpq ˆ l l d v r. Fig. 2(b)l d 400 sccm dp r l ~ p o p l web-like ˆ q m. v d 600 sccm mp Fig. 2(c)l m p web-like ˆ tl p p. d o p 200, 400, 600 sccmp v 316 L d p d dž p o} Park Lee[9]l p, d o p 200 sccmp n q(faceted lattice) p r(catalytic site) p m. d o p 400 Korean Chem. Eng. Res., Vol. 45, No. 3, June, 2007
266 p Ë të mmë rp Fig. 2. SEM images of CNTs grown directly onto micron-fibers along H 2 gas of the different flow rates, (a) 200 sccm, (b) 400 sccm and (c) 600 sccm. Table 1. Synthesis condition for CNT-growth on the metal filters Q C2H2 (sccm a ) Q H2 (sccm) Q Ar (slm b ) T s ( o C) t s (min) SEM image 10 200 1 600 6 Fig. 2(a) 10 400 1 600 6 Fig. 2(b) 10 600 1 600 6 Fig. 2(c) 5 400 1 600 6 Fig. 3(a) 10 400 5 600 6 Fig. 3(b) 10 400 1 700 6 Fig. 3(c) 10 400 1 600 3 Fig. 3(d) sccm means standard cubic centimeter per minute slm means standard cubic liter per minute a b sccmp v l p pq qp pq p pt (bi-mode) mp, d o p 600 sccmp v l pq p v p m. Table 1l web-like p p ~ q Fig. 2(b) np s l d rn e s p ˆ m. Fig. 3(a) k Ž dp o 5 sccm mp v s p Fig. 2(b)m. Fig. 3(b) k dp o p 5 slmp v mp v s p 2(b) m. Fig. 3(c) m 700 C v m v s o p 2(b)m. Fig. 3(d) e p 3 p tmp v s p 2(b)m. Fig. 3(a)~3(c)l m p Fig. 2(b)p s l k Ž d, k d, m mp n p o l web-like ˆ q v kk. evl p ol q ˆ p p. Fig. 3(a) bush-like ˆ ol p ˆ q m. Fig. 3(b) p o to o45 o3 2007 6k Fig. 3. SEM images of CNTs grown directly onto micron-fibers at several conditions such as (a) the C 2 H 2 flow rate of 5 sccm, (b) the Ar flow rate of 5 slm, (c) the synthesis temperature of 700 o C and (d) the synthesis time of 3 min. n ˆ p p Fig. 3(c) rp sk ˆ o e p. Fig. 3(d) e p web-like ˆ p p r p pv l ˆ web qp f p o o l q p p. Table 1l nk m p ˆ s l k ~ p p l q Fig. 2(b) s l web p ~ q m. ˆ q~p o l ˆ q ˆ l TEM vp m m. ˆ o l k mp }ov
p o l ˆ p vr ql p s~ l 267 Fig. 4. TEM images of CNTs separated from the filters synthesized at the condition web-like CNT. pƒ l ˆ q p e p 1p k pž } } mp, p p p ˆ p p ˆ l k ppp k p. p l q ˆ p p n lp l k ˆ p pp k p. Fig. 4l ˆ m p, ˆ t p l p t p p, p ˆ p n t p Ž o l pq sq p k p. p p pq p p lv p k p. p TEM vp ˆ graphene p p lv t p pp, l p p ˆ p. ˆ p v p 20~50 nmp. Fig. 5 m s l ˆ q CNT-filterp kp lt p. Raw filter ˆ rp kp lt p v s l ˆ p o tol ~ m. Web-like(reference) ˆ p k p raw filter j. p ˆ p Fig. 5. Pressure drops versus filtration velocities of the filters on which the CNTs are grown at different synthesis condition. Fig. 6. Filtration efficiencies of the filters on which the CNTs are grown at different synthesis conditions. k p v p o p l q m p. vv~ f kp p p p n web-like ˆ l p lv CNT-filter p kp ˆ p. l web-like ˆ bushlike ˆ l p lv CNT-filterp kp k. k Ž dp o p qp s l p v p bush-like ˆ p Fig. 3(a) raw filterm l k p l v kk. p k Ž dp l ˆ p qp v kk p. Fig. 6p raw filterm l s l CNT-filterp l pp p. l 3 cm/sp p p 130 nmp l raw filterp l pp 75%. bush-like ˆ q p pp k 90% v m, weblike(reference) ˆ q k 98% v v m. ˆ q p l pp p o p l q ˆ p mm pq v kp ~ qn p. ˆ p q l e pqp Korean Chem. Eng. Res., Vol. 45, No. 3, June, 2007
268 p Ë të mmë rp Fig. 7. SEM images of NaCl particle collected onto the filter that the CNTs are grown with (a) bush-like, (b) and (c) web-like microstructures onto the micron-fibers. ˆ o l SEM vp m, Fig. 7l m p p NaCl pq p bush-like CNT-filter web-like CNT-filter l p ppp k p, ˆ p e pqp vl v rp qn p k p. p ˆ p p l pp rp ppp q p p. p rp pq vr, n p l vp p o l v [10, 11]. ˆ p ~ p o to o pqp l vp ˆ q v kp p o to o l v p k. 4. v q l d n l p l pq, ˆ l ˆ ~ rs m. p o l ˆ vr n, p o tol q bush-like ˆ o p l l q web-like ˆ p k ˆ q m. s m ˆ q p l pp l r, s p kl m p v k tl ˆ q p p l pp ppp p m. rp o p p o } l pqm pq ˆ q p f sp p ~m ~ kyp qrp p Œ p p l pp o n p pq v r n ~ rs p. y 1. Park, C., Engel, E. S., Crowe, A., Gilbert, T. R. and Rodriguez, N. M., Use of Carbon Nanofibers in the Removal of Organic Solvents From Water, Langmuir 16(21), 8050-8056(2000). 2. Walters, D. A., Casavant, M. J., Qin, X. C., Huffman, C. B., Boul, P. J., Ericson, L. M., Haroz, E. H., O Connells, M. J., Smith, K., Colbert, D. T. and Smalley, R. E., In-plane-aligned Membranes of Carbon Nanotubes, Chem. Phys. Lett. 338(1), 14-20 (2001). 3. Vander Wal, R. L. and Hall, L. J., Carbon Nanotube Synthesis Upon Stainless Steel Meshes, Carbon 41(4), 659-672(2003). 4. Johnson, D. F., Craft, B. J. and Jaffe, S. M., Adhered Supported Carbon Nanotubes, J. Nanopart. Res. 3(1), 63-71(2001). 5. Srivastava, A., Srivastava, O. N., Talapatra, S., Vajtai, R. and Ajayan, P. M., Carbon Nanotube Filters, Nature Mater 3(9), 610-614(2004). 6. Shimoda, H., Fleming, L., Horton, K. and Zhou, O., Formation of Macroscopically Ordered Carbon Manotube Membranes by Self-assembly, Physica B 323(1-4), 135-136(2002). 7. Hinds, W. C., Aerosol Technology : Properties, Behavior, and Measurement of Airborne Particles A Wiley-Interscience Publication, JOHN WILEY & SONS(1982). 8. Graham, K., Ouyang, M., Raether, T., Grafe, T., McDonald, B. and Knauf, P., Advances in Filtration and Separation Technology, Proceedings of the American Filtration and Separation Society 16, paper 1 session 14(2002). 9. Park, S. J. and Lee, D. G., A Study on the Growth Morphology of VGCF Nano-Materials by Acetylene Pyrolysis over Stainless Steel Catalyst- Effect of Reduction Pretreatment and Hydrogen Supply, Kor. Chem. Eng. Res, 44(6), 563-571(2006). 10. Friedlander, S. K., Smoke, Dust, and Haze, Fundamentals of Aerosol Dynamics, OXFORD UNIVERSITY PRESS(2000). 11. Brown, R. C., Air Filtration, An Integrated Approach to the Theory and Applications of Fibrous Filters, PERGAMON PRESS (1993). o45 o3 2007 6k