Efficiency of ozonation and sulfate radical - AOP for removal of pharmaceuticals, corrosion inhibitors, x-ray contrast media and perfluorinated compounds from reverse osmosis concentrates.

This study investigated the elimination of pharmaceuticals, corrosion inhibitors, x-ray contrast media and perfluorinated compounds from reverse osmosis concentrates during ozonation and UV/persulfate processes. Second-order rate constants for the reactions of candesartan, irbesartan, methyl-benzotriazole, and chloro­benzotriazole with sulfate radical (SO4·-) were determined for the first time. Experiments were conducted in buffered pure water, in buffered water added with the matrix substituents chloride, carbonate, NOM, and reverse osmosis concentrate with spiked micropollutants (MP). UV/persulfate eliminated all MP to a higher extent than ozonation in RO concentrates due to the higher yield of oxidative species and photolytic degradation. Compounds with electron-rich moieties such as carbamazepine, diclofenac, metoprolol, and sulfamethoxazole were completely eliminated with small ozone doses (< 0.5 mg O3 / mg DOC) and with a small fluence (< 5000 J m-2) in UV/persulfate processes. Photosensitive compounds with high reactivity towards hydroxyl radicals (·OH) and SO4·- like the x-ray contrast media Iopamidol, Iohexol, and Amidotrizoic acid were successfully eliminated with a reasonable fluence in UV/persulfate, whereas these compounds persist in ozonation at common ozone dosages. However, much higher fluences and ozone dosages were required for the least reactive compounds like the class of benzotriazoles. Comparing the application of both oxidative processes to the RO concentrate, ozonation has the disadvantage of forming bromate. The energy input of both processes strongly depends on the target compounds to be eliminated. For the elimination of compounds such as sulfamethoxazole, ozonation is a feasible technique, whereas UV/persulfate is better suited for the elimination of recalcitrant compounds such as x-ray contrast media. In general, oxidative process treatment of RO concentrate could be applied to partly abate micropollutants before discharge.

Aromatic amines contents of cigarette butts: Fresh and aged cigarette butts vs unsmoked cigarette.

Cigarette butts (CBs) are some of the most abundant waste items in the environment and may contain high levels of different toxic chemicals, such as aromatic amines (AAs). However, to this date, there is no comprehensive study on the role of CBs in the emission of AAs into the environment. The present study investigated for the first time the concentration levels of 10 primary aromatic amines (PAAs), including ANL, p-TOL, m-TOL, o-TOL, 2,6-DMA, o-ASD, 2-NA, 1-NA, 3-ABP, and 4-ABP that were measured and compared in unsmoked cigarette, freshly smoked CBs, and CBs collected from urban streets (named here aged CBs). The mean levels of ∑PAAs in different sample categories were statistically significantly different and the mean level order was as freshly smoked CBs > aged CBs > unsmoked cigarette with the values of 3.43, 2.12 µg g-1, and 0.28 µg g-1, respectively. The levels of ∑PAAs, ANL, o-ASD, 2,6-DMA, 2-NA, and ∑TOL dramatically increased by 12.26, 4.05, 8.46, 10.41, 4.78, and 28.84 times, respectively, right after smoking comparing the freshly smoked CBs samples and unsmoked cigarette. The results also showed a substantial decrease in the levels of PAAs (except o-ASD) in the aged CBs samples compared to freshly smoked CBs. The levels of ∑PAAs, o-ASD, 2,6-DMA, ∑TOL, ANL, 2-NA, 1-NA, and ∑ABP decreased 1.62, 1.09, 1.91, 3.20, 3.42, 2.63, 2.00, and 1.88 times, respectively. Considering the average PAAS content and estimated CBs littered worldwide every year, freshly smoked CBs can theoretically emit 2.9 tons of ∑PAAs into the environment annually. Considering other chemicals that may also be released into the environment via CBs (beside PAAs), we can consider CBs as a critical source of toxic compounds into the environment and water bodies.