Catalytic ozonation for the removal of organic contaminants in water on ZSM-5 zeolites

Amir Ikhlaq, David R. Brown, Barbara Kasprzyk-Hordern

Research output: Contribution to journalArticle

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Abstract

The results presented in this study aim to show the potential of ozonation of common water pollutants (volatile organic chemicals, pharmaceuticals and carboxylic acids, ozonation by-products) on ZSM-5 zeolites and to investigate the effect of the nature of pollutants on the efficiency of catalytic ozonation. Both the H-ZSM-5 and Na-ZSM-5 forms with different SiO2/Al2O3 ratios and counter ions (Z1000H:SiO2/Al2O3 = 1000, Z900Na:SiO2/Al2O3 = 900, Z25H:SiO2/Al2O3 = 25 and Z25Na:SiO2/Al2O3 = 25) have been used. The effects of pH, adsorption, presence of hydroxyl radical scavengers, phosphates and humic acids on the efficiency of catalytic ozonation have been investigated. The results revealed that catalytic ozonation on zeolites could substantially enhance the removal of VOCs and ibuprofen when compared with ozonation alone and that adsorption plays a key role in the effectiveness of this process. Zeolites with high SiO2/Al2O3 ratios were found to have a high adsorption capacity towards VOCs and as a result high catalytic activity. On the other hand zeolites with low SiO2/Al2O3 ratios had a high adsorption capacity towards ibuprofen in its ionised form. Catalytic processes have been found to be pH dependent with the highest activity at acidic pH. The presence of hydroxyl radical scavengers (phosphates and humic acid) did not have a significant effect on the removal of contaminants on ZSM-5 zeolites. Despite high activity towards VOCs and ibuprofen, zeolites did not catalyse the removal of acetic acid in water at studied pH values. It is therefore suggested that catalytic ozonation of organic pollutants on ZSM-5 zeolites proceeds via direct reactions of molecular ozone with pollutants adsorbed on the surface of zeolites.
Original languageEnglish
Pages (from-to)110-122
Number of pages13
JournalApplied Catalysis B: Environmental
Volume154-155
Early online date15 Feb 2014
DOIs
Publication statusPublished - Jul 2014

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Zeolites
Ozonization
Impurities
pollutant
Water
Ibuprofen
volatile organic compound
adsorption
Volatile organic compounds
Humic Substances
Adsorption
water
scavenger
hydroxyl radical
humic acid
Hydroxyl Radical
phosphate
Phosphates
Water Pollutants
Organic Chemicals

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Catalytic ozonation for the removal of organic contaminants in water on ZSM-5 zeolites. / Ikhlaq, Amir ; Brown, David R. ; Kasprzyk-Hordern, Barbara.

In: Applied Catalysis B: Environmental, Vol. 154-155, 07.2014, p. 110-122.

Research output: Contribution to journalArticle

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abstract = "The results presented in this study aim to show the potential of ozonation of common water pollutants (volatile organic chemicals, pharmaceuticals and carboxylic acids, ozonation by-products) on ZSM-5 zeolites and to investigate the effect of the nature of pollutants on the efficiency of catalytic ozonation. Both the H-ZSM-5 and Na-ZSM-5 forms with different SiO2/Al2O3 ratios and counter ions (Z1000H:SiO2/Al2O3 = 1000, Z900Na:SiO2/Al2O3 = 900, Z25H:SiO2/Al2O3 = 25 and Z25Na:SiO2/Al2O3 = 25) have been used. The effects of pH, adsorption, presence of hydroxyl radical scavengers, phosphates and humic acids on the efficiency of catalytic ozonation have been investigated. The results revealed that catalytic ozonation on zeolites could substantially enhance the removal of VOCs and ibuprofen when compared with ozonation alone and that adsorption plays a key role in the effectiveness of this process. Zeolites with high SiO2/Al2O3 ratios were found to have a high adsorption capacity towards VOCs and as a result high catalytic activity. On the other hand zeolites with low SiO2/Al2O3 ratios had a high adsorption capacity towards ibuprofen in its ionised form. Catalytic processes have been found to be pH dependent with the highest activity at acidic pH. The presence of hydroxyl radical scavengers (phosphates and humic acid) did not have a significant effect on the removal of contaminants on ZSM-5 zeolites. Despite high activity towards VOCs and ibuprofen, zeolites did not catalyse the removal of acetic acid in water at studied pH values. It is therefore suggested that catalytic ozonation of organic pollutants on ZSM-5 zeolites proceeds via direct reactions of molecular ozone with pollutants adsorbed on the surface of zeolites.",
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N2 - The results presented in this study aim to show the potential of ozonation of common water pollutants (volatile organic chemicals, pharmaceuticals and carboxylic acids, ozonation by-products) on ZSM-5 zeolites and to investigate the effect of the nature of pollutants on the efficiency of catalytic ozonation. Both the H-ZSM-5 and Na-ZSM-5 forms with different SiO2/Al2O3 ratios and counter ions (Z1000H:SiO2/Al2O3 = 1000, Z900Na:SiO2/Al2O3 = 900, Z25H:SiO2/Al2O3 = 25 and Z25Na:SiO2/Al2O3 = 25) have been used. The effects of pH, adsorption, presence of hydroxyl radical scavengers, phosphates and humic acids on the efficiency of catalytic ozonation have been investigated. The results revealed that catalytic ozonation on zeolites could substantially enhance the removal of VOCs and ibuprofen when compared with ozonation alone and that adsorption plays a key role in the effectiveness of this process. Zeolites with high SiO2/Al2O3 ratios were found to have a high adsorption capacity towards VOCs and as a result high catalytic activity. On the other hand zeolites with low SiO2/Al2O3 ratios had a high adsorption capacity towards ibuprofen in its ionised form. Catalytic processes have been found to be pH dependent with the highest activity at acidic pH. The presence of hydroxyl radical scavengers (phosphates and humic acid) did not have a significant effect on the removal of contaminants on ZSM-5 zeolites. Despite high activity towards VOCs and ibuprofen, zeolites did not catalyse the removal of acetic acid in water at studied pH values. It is therefore suggested that catalytic ozonation of organic pollutants on ZSM-5 zeolites proceeds via direct reactions of molecular ozone with pollutants adsorbed on the surface of zeolites.

AB - The results presented in this study aim to show the potential of ozonation of common water pollutants (volatile organic chemicals, pharmaceuticals and carboxylic acids, ozonation by-products) on ZSM-5 zeolites and to investigate the effect of the nature of pollutants on the efficiency of catalytic ozonation. Both the H-ZSM-5 and Na-ZSM-5 forms with different SiO2/Al2O3 ratios and counter ions (Z1000H:SiO2/Al2O3 = 1000, Z900Na:SiO2/Al2O3 = 900, Z25H:SiO2/Al2O3 = 25 and Z25Na:SiO2/Al2O3 = 25) have been used. The effects of pH, adsorption, presence of hydroxyl radical scavengers, phosphates and humic acids on the efficiency of catalytic ozonation have been investigated. The results revealed that catalytic ozonation on zeolites could substantially enhance the removal of VOCs and ibuprofen when compared with ozonation alone and that adsorption plays a key role in the effectiveness of this process. Zeolites with high SiO2/Al2O3 ratios were found to have a high adsorption capacity towards VOCs and as a result high catalytic activity. On the other hand zeolites with low SiO2/Al2O3 ratios had a high adsorption capacity towards ibuprofen in its ionised form. Catalytic processes have been found to be pH dependent with the highest activity at acidic pH. The presence of hydroxyl radical scavengers (phosphates and humic acid) did not have a significant effect on the removal of contaminants on ZSM-5 zeolites. Despite high activity towards VOCs and ibuprofen, zeolites did not catalyse the removal of acetic acid in water at studied pH values. It is therefore suggested that catalytic ozonation of organic pollutants on ZSM-5 zeolites proceeds via direct reactions of molecular ozone with pollutants adsorbed on the surface of zeolites.

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