TY - JOUR

T1 - Structural elucidation of main ozonation products of the artificial sweeteners cyclamate and acesulfame

AU - Scheurer, Martin

AU - Godejohann, Markus

AU - Wick, Arne

AU - Happel, Oliver

AU - Ternes, Thomas A.

AU - Brauch, Heinz-Jürgen

AU - Ruck, Wolfgang

AU - Lange, Frank Thomas

N1 - Umweltchemie_2011_2_Scheurer.pdf

PY - 2012/5

Y1 - 2012/5

N2 - Purpose: The two artificial sweeteners cyclamate (CYC) and acesulfame (ACE) have been detected in wastewater and drinking water treatment plants. As in both facilities ozonation might be applied, it is important to find out if undesired oxidation products (OPs) are formed. Methods: For the separation and detection of the OPs, several analytical techniques, including nuclear magnetic resonance experiments, were applied. In order to distinguish between direct ozone reaction and a radical mechanism, experiments were carried out at different pH values with and without scavenging OH radicals. Kinetic experiments were used for confirmation that the OPs are formed during short ozone contact time applied in waterworks. Samples from a waterworks using bank filtrate as raw water were analyzed in order to prove that the identified OPs are formed in real and full-scale ozone applications. Results: In the case of CYC, oxidation mainly occurs at the carbon atom, where the sulfonamide moiety is bound to the cyclohexyl ring. Consequently, amidosulfonic acid and cyclohexanone are formed as main OPs of CYC. When ozone reacts at another carbon atom of the ring a keto moiety is introduced into the CYC molecule. Acetic acid and the product ACE OP170, an anionic compound with m/z=170 and an aldehyde hydrate moiety, were identified as the main OPs for ACE. The observed reaction products suggest an ozone reaction according to the Criegee mechanism due to the presence of a C=C double bond. ACE OP170 was also detected after the ozonation unit of a full-scale drinking water treatment plant which uses surface water-influenced bank filtrate as raw water. Conclusions: Acesulfame can be expected to be found in anthropogenic-influenced raw water used for drinking water production. However, when ACE OP170 is formed during ozonation, it is not expected to cause any problem for drinking water suppliers, because the primary findings suggest its removal in subsequent treatment steps, such as activated carbon filters.

AB - Purpose: The two artificial sweeteners cyclamate (CYC) and acesulfame (ACE) have been detected in wastewater and drinking water treatment plants. As in both facilities ozonation might be applied, it is important to find out if undesired oxidation products (OPs) are formed. Methods: For the separation and detection of the OPs, several analytical techniques, including nuclear magnetic resonance experiments, were applied. In order to distinguish between direct ozone reaction and a radical mechanism, experiments were carried out at different pH values with and without scavenging OH radicals. Kinetic experiments were used for confirmation that the OPs are formed during short ozone contact time applied in waterworks. Samples from a waterworks using bank filtrate as raw water were analyzed in order to prove that the identified OPs are formed in real and full-scale ozone applications. Results: In the case of CYC, oxidation mainly occurs at the carbon atom, where the sulfonamide moiety is bound to the cyclohexyl ring. Consequently, amidosulfonic acid and cyclohexanone are formed as main OPs of CYC. When ozone reacts at another carbon atom of the ring a keto moiety is introduced into the CYC molecule. Acetic acid and the product ACE OP170, an anionic compound with m/z=170 and an aldehyde hydrate moiety, were identified as the main OPs for ACE. The observed reaction products suggest an ozone reaction according to the Criegee mechanism due to the presence of a C=C double bond. ACE OP170 was also detected after the ozonation unit of a full-scale drinking water treatment plant which uses surface water-influenced bank filtrate as raw water. Conclusions: Acesulfame can be expected to be found in anthropogenic-influenced raw water used for drinking water production. However, when ACE OP170 is formed during ozonation, it is not expected to cause any problem for drinking water suppliers, because the primary findings suggest its removal in subsequent treatment steps, such as activated carbon filters.

KW - Chemistry

KW - Acesulfame

KW - Artificial sweeteners

KW - Cyclamate

KW - Ozonation

KW - Ozone

KW - Water treatment

UR - http://www.scopus.com/inward/record.url?scp=84860519107&partnerID=8YFLogxK

U2 - 10.1007/s11356-011-0618-x

DO - 10.1007/s11356-011-0618-x

M3 - Journal articles

C2 - 21964549

VL - 19

SP - 1107

EP - 1118

JO - Environmental Science and Pollution Research

JF - Environmental Science and Pollution Research

SN - 0944-1344

IS - 4

ER -