|Table of Contents|

Effects of Pore Sizes of Silica Gels on Desorption Activation Energy of Water Vapor

《南京理工大学学报》(自然科学版)[ISSN:1005-9830/CN:32-1397/N]

Issue:
2006年06期
Page:
787-792
Research Field:
Publishing date:
2006-12-30

Info

Title:
Effects of Pore Sizes of Silica Gels on Desorption Activation Energy of Water Vapor
Author(s):
LI XinLI Zhong
The Key Lab of Enhanced Heat Transfer and Energy Conservation,South China University of Technology,Guangzhou 510640,China
Keywords:
silica gels adso rpt ion k inetics pore sizes w a ter vapor adsorption desorption activat ion energy
PACS:
TQ028
DOI:
-
Abstract:
The effects of pore sizes o f silica ge ls on the adso rption rate and the desorption activat ion energy ofw ater vapor are studied. K inet ic experiments o fw ater vapor adsorption on the silica gels are carried ou t by themethod of stat ic adso rption, and the temperature program desorption (TPD ) exper-i ments are conducted to est imate the desorption activat ion energy o fw ater on silica gels. Results show that the average pore diameter of the A-type, the B-type and the C-type silica gel is separately 2106 nm, 5. 28 nm and 10. 65 nm; at low relative hum idity ( 10% ~ 45% ) w ith the increases o f the pore diameter of the silica ge,l the adsorption rates increase at the initial stage of the adsorption and the amount o f equ ilibrium adsorption decreases; at h igh relative hum id ity, w ith the increase of the pore d-i ameter of the silica ge,l the adsorption rates decrease at the initial stage of the adsorption, the amount of equ ilibrium amount adsorption increases. The desorption activation energy o fw ater on the A-type, the B-type and the C-type silica gel is respect ively 35. 54 kJ/mo,l 31. 41 kJ/mol and 26. 16 kJ/mol ,w hich suggestes that the desorption act ivation energy of thew ater on the silica ge ldecreases as its pore diameter increases. A tmedium and h igher relative hum idity, the amount o f equilibrium adsorpt ion o f w ater becomes larger and the act ivation energy of thew ater desorption on themesoporous silica gel becomes lower in comparison w ith those on the m icroporous silica gel.

References:

[ 1] 李鑫, 李忠, 韦利飞, 等, 除湿材料研究进展[ J], 化 工进展, 2004, 23 ( 8) : 811- 815.
[ 2] Tash iro Y, KuboM, K atsum iY, et a.l Assessment o f adsorption-deso rption character istics o f adsorbents fo r adsorptive desiccant cooling system [ J ]. Jou rna l o f M ateria ls Sc ience, 2005, 39( 4): 1 315- 1 319.
[ 3] Ng K C, ChuaH T, Chung C Y, e t a.l Exper imenta l investiga tion o f the silica ge-l wa ter adsorption iso the rm character istics [ J ]. App lied The rm al Eng ineering, 2001, 21( 16): 1 631- 1 642.
[ 4] M uster T H, Prestidge C A, H ayes R A. W ater adso rption k inetics and contact ang les o f silica partic les [ J]. Collo ids and Surfaces A: Physico chem ica l and Eng inee ringA spects, 2001, 176( 2- 3): 253– 266.
[ 5] Chung T W, Chung C C. Increase in the am ount o f adso rption on mod ified silica ge l by us ing neutron flux irradiation[ J]. Chem ical Eng ineering Science, 1998, 53( 16) : 2 967- 2 972.
[ 6] Chang K S, Chen M T, Chung T W. Effects o f the thickness and partic le size of silica ge l on the heat and m ass transfer performance o f a silica ge-l coa ted bed fo r air-cond itioning adso rption system s[ J]. Applied The rm al Eng ineering 2005, 25( 14- 15): 2 330- 2 340.
[ 7] Chang K S, W ang H C, Chung T W. E ffect of regenera tion cond itions on the adsorption dehum idifica tion process in packed silica ge l beds[ J]. Applied The rm a lEng ineering, 2004, 24( 5- 6) : 735- 742.
[ 8] Daou K, W ang R Z, X ia Z Z. Developm ent o f a new synthesized adsorbent for re frigeration and a ir cond-i tion ing app lications[ J] . App lied Therm a l Eng ineer ing 2006, 26( 1): 56- 65.
[ 9] X iH X, L i Z, ZhangH B, et a.l E stim ation of activated energy and isothe rm o f low-vo latility d iox in by TPD technique [ J] . Separation and Purifica tion Techno logy, 2003, 31( 1): 39- 43.
[ 10] Li Z, W ang H J, XiH X, et a.l Estim ation o f activation energy of desorp tion o f n-hexane on activ ated ca rbons by TPD techn ique [ J]. Adso rption Sc ience and Techno logy, 2003, 21( 2): 125- 132.
[ 11] X ia Q B, L i Z, X iH X, et a .l A ctiva tion energy for d ibenzo furan desorption from Fe3+ /T iO2 and Ce3+ / T iO2 pho tocatalysts coated onto g lass fibres[ J]. Adsorption Science and Technology, 2005, 23 ( 5): 357 - 366.
[ 12] 何余生, 李忠, 奚红霞, 等. 气固吸附等温线的研究 进展[ J] . 离子交换与吸附, 2004, 20 ( 4 ): 376 - 384.

Memo

Memo:
-
Last Update: 2006-12-30