1. UV-C and UV-C/H2O2 degradation of two artificial sweeteners, Acesulfame_K and Sucralose C.Drosou1, K. Tyrovola1, T. Neromilioti1, E. Kourounioti1, N.P.Xekoukoulotakis1 1 School of Environmental Engineering, Technical University of Crete, Polytechneioupolis,
GR-73100, Chania, Greece
1. Introduction
The Artificial Sweeteners (ASs) were identified as
emerging contaminants due their substantial resistance
to common wastewater treatment and their presence to
the water bodies [1] .Acesulfame and Sucralose have been
reported as the most persistent sweeteners with removal
rates 40% and 20%, respectively [2].The occurrence of
acesulfame and sucralose in waste water treatment plant
effluents has been reported up to 2.5mg/L and 0.119mg/L,
respectively [3].
The aim of the present work was to study the
degradation of the above artificial sweeteners,under UV-C
(λ = 254 nm)irradiation, either alone or in the presence
of H2O2, in aqueous matrices.
2. Experimental
LC-MS/MS and LC coupled with a diode array
detector (Waters Alliance).
Total organic carbon (TOC)
concentration was measured
with a TOC analyzer
(Shimadzu 5000A).
UV-C radiation was
provided by an 11 W, low pressure mercury lamp, emitting predominately at 254 nm.
Picture 1. (a) TOC analyzer, (b) HPLC,
(c) Batch type, laboratory scale
photochemical reactor
3. Results
Complete removal of ACE under
UV-C irradiation(in few minutes)
but TOC concentration remained
stable (Figure 1)
85% removal of TOC was
achieved under UV-C/H2O2 process
(240 minutes of treatment, Figure 1).
The continuous increase of the initial
dosage of H2O2(8-95mg/L) improved the
degradation of Acesulfame_K (Figure 2
& Table 1).
Table 1 Pseudo-first order rate constants for
Acesulfame_K degradation by UV-C/H2O2
process
H2O2 (mg/L)
k1 (min-1) r2
0.97
0.99 8
1.51 19
1.66
0.96 54
1.77 95
2.58
Figure 1 Acesulfame-K and TOC removal under UV-C
irradiation either alone or in the presence of
H2O2 ([ACE]=10mg/L, ultrapure water, [H2O2]= 19mg/L)
Figure 2 Acesulfame-K degradation under UV-C /H2O2
treatment ([ACE]=10mg/L, ultrapure water, [H2O2]= 0-95 mg/L) Inset: Pseudo-first order constants, k, versus initial H2O2 dosage
UV-C irradiation is ineffective for
the degradation of sucralose (Figure 3).
UV-C/H2O2 treatment enhances the
complete degradation of sucralose
(15 minutes, Figure 3) and TOC
removal (80% in 120 minutes).
The continuous increase of H2O2
concentration no further enhances
decomposition of the substance as
formed hydroxyl radicals are
consumed to form hydroperoxyl radicals
which have lower oxidation capability
(Figure 4 and Table 2).
Table 2 Pseudo-first order rate constants for
Sucralose degradation by UV-C/H2O2
process
H2O2 (mg/L)
k1 (min-1) r2
4.5
0.06
0.98 15
0.25
0.97 30
0.36 57
0.55
104
0.41
0.99
Figure 3 Sucralose and TOC removal under UV-C
either alone or in the presence of H2O2 ([SUC]=10mg/L,
ultrapure water, [H2O2]= 19 mg/L)
Figure 4 Sucralose degradation under UV-C /H2O2
treatment ([SUC]=10mg/L, ultrapure water, [H2O2]= mg/L)
Inset: Pseudo-first order constants, k, versus initial H2O2 dosage
4. Conclusions
5. References
[1] Z. Gan, H. Sun, R. Wang, H. Hu, P. Zhang, X. Ren,
Water Research 64 (2014),
[2] Z. Sang, Y. Jiang, Y. Tsoi, K. S Leung, Water Research
52 (2014),
[3] M.Scheurer, B. Schmutz, O. Happel, H.J. Brauch,
R. Wulser, F. R. Storck, Science of the Total Environment
481 (2014),425–432
UV-C/H2O2 is a very effective process for the complete degradation and the substantial mineralization of the artificial sweeteners compounds studied in the present work.
Specifically, UV-C was extremely efficient for the removal of Acesulafame (in few minutes) and UV-C/H2O2 treatment was very efficient for the degradation of both Acesulfame-k and Sucralose. The TOC concentration of the solutions was substantially decreased, showing that photochemical degradation resulted in mineral end-products, due of hydroxyl radicals, HO•, which further react with the organic pollutants found in the aqueous phase resulting in mineral end-products.