Effect of Desorption Purge Gas Oxygen Impurity on Heel Formation During Regeneration of Beaded Activated Carbon Saturated with Organic VaporsReportar como inadecuado




Effect of Desorption Purge Gas Oxygen Impurity on Heel Formation During Regeneration of Beaded Activated Carbon Saturated with Organic Vapors - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Adsorption, Regeneration, Heel formation, Purge gas, Activated carbon, VOC

Hashemi, Seyed Mojtaba

Supervisor and department: Hashisho, Zaher Civil and Environmental Engineering

Examining committee member and department: Trivedi, Japan Civil and Environmental Engineering Dhar, Bipro Civil and Environmental Engineering

Department: Department of Civil and Environmental Engineering

Specialization: Environmental Engineering

Date accepted: 2017-05-30T11:04:09Z

Graduation date: 2017-11:Fall 2017

Degree: Master of Science

Degree level: Master's

Abstract: Irreversible adsorption or heel formation during cyclic adsorption-regeneration of high molecular weight volatile organic compounds VOCs onto activated carbon decreases its adsorption capacity and lifetime. The effect of regeneration purge gas oxygen impurity on activated carbon performance, specifically during successive adsorption-regeneration cycles was investigated. 5-cycle adsorption-regeneration tests were performed on microporous beaded activated carbon BAC using 11 different aliphatic and aromatic organic compounds representative of VOCs produced from painting booths. Nitrogen with different oxygen concentrations ≤ 5 to 20,000 ppm was used as regeneration purge gas during thermal desorption of 1,2,4-trimethylbenzene TMB. Cumulative heel formation increased from 0.5% to 15.4% as the oxygen concentration in the desorption purge gas increased from ≤ 5 ppm to 20,000 ppm, respectively, in case of TMB adsorption. For regeneration of BAC saturated with all other VOCs, nitrogen with two levels of oxygen impurity ≤ 5 ppm and 10,000 ppm was used as regeneration purge gas. At 10,000 ppm oxygen concentration, the cumulative heel was 0.7-3.2% for aliphatic compounds and 0-13% from for aromatic compounds while at ≤ 5 ppm, it was 0.3-1.3% for aliphatic compounds and 0.0-4.6% for aromatic compounds. Overall, regeneration of alkyl-aromatics was impacted by presence of oxygen in the purge gas to a greater degree compared to aliphatic compounds. Thermogravimetric analysis of the regenerated samples showed desorption of species at high temperatures 400-600°C which shows that these compounds are strongly attached to the adsorbent surface. The results suggest that the effect of regeneration purge gas oxygen impurities on the irreversible adsorption of VOCs is dependent on the nature of the adsorbate- likely its tendency to react with oxygen. The results from this study help explain the heel formation mechanism and how it relates to regeneration purge gas purity.

Language: English

DOI: doi:10.7939-R3WD3QD3Q

Rights: This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for the purpose of private, scholarly or scientific research. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.





Autor: Hashemi, Seyed Mojtaba

Fuente: https://era.library.ualberta.ca/


Introducción



Effect of Desorption Purge Gas Oxygen Impurity on Heel Formation During Regeneration of Beaded Activated Carbon Saturated with Organic Vapors by Seyed Mojtaba Hashemi A thesis submitted in partial fulfillment for the requirements for the degree of Master of Science in ENVIRONMENTAL ENGINEERING Department of Civil and Environmental Engineering University of Alberta © Seyed Mojtaba Hashemi, 2017 Abstract Irreversible adsorption or heel formation during cyclic adsorption-regeneration of high molecular weight volatile organic compounds (VOCs) onto activated carbon decreases its adsorption capacity and lifetime.
The effect of regeneration purge gas oxygen impurity on activated carbon performance, specifically during successive adsorption-regeneration cycles was investigated.
5-cycle adsorption-regeneration tests were performed on microporous beaded activated carbon (BAC) using 11 different aliphatic and aromatic organic compounds representative of VOCs produced from painting booths.
Nitrogen with different oxygen concentrations (≤ 5 to 20,000 ppm) was used as regeneration purge gas during thermal desorption of 1,2,4-trimethylbenzene (TMB).
Cumulative heel formation increased from 0.5% to 15.4% as the oxygen concentration in the desorption purge gas increased from ≤ 5 ppm to 20,000 ppm, respectively, in case of TMB adsorption.
For regeneration of BAC saturated with all other VOCs, nitrogen with two levels of oxygen impurity (≤ 5 ppm and 10,000 ppm) was used as regeneration purge gas.
At 10,000 ppm oxygen concentration, the cumulative heel was 0.7-3.2% for aliphatic compounds and 0-13% from for aromatic compounds while at ≤ 5 ppm, it was 0.3-1.3% for aliphatic compounds and 0.0-4.6% for aromatic compounds.
Overall, regeneration of alkylaromatics was impacted by presence of oxygen in the purge gas to a greater degree compared to aliphatic compounds.
Thermogravimetric analysis of the regenerated samples showed desorption of species at high temperatures (400-60...





Documentos relacionados