Catalytic Advanced Oxidation Processes for Sulfamethoxazole Degradation

Abstract

The degradation of sulfamethoxazole (SMX) by several advanced oxidation processes (AOPs) is carried out in the presence of different catalysts. The catalysts used consisted of carbon nanotubes (CNT), titanium dioxide (TiO2), a composite of carbon nanotubes and titanium dioxide (TiO2/CNT), and iron supported on carbon nanotubes (Fe/CNT). SMX removal was evaluated by catalytic ozonation, photocatalysis, catalytic oxidation with hydrogen peroxide, and combinations of these processes. The evolution of the SMX concentration during reaction time, the mineralization degree, the toxicity of the treated solution, and the formation of organic intermediates and ions were monitored. Ozonation catalyzed by Fe/CNT and CNT and photocatalytic ozonation in the presence of CNT presented the fastest degradation of SMX, whereas photocatalytic ozonation with CNT showed the best results in terms of organic matter removal (92% of total organic carbon (TOC) depletion). Total mineralization of the solution and almost complete reduction of toxicity was only achieved in the photocatalytic ozonation with H2O2 and Fe/CNT catalysts. The compound 3-amino-5-methylisoxazole was one of the first intermediates formed during SMX degradation. p-Benzoquinone was only formed in photocatalysis. Oxalic and oxamic acids were also detected and in most of the catalytic processes they appeared in small amounts. Ion concentrations increased with the reaction time.

Composition Characteristics of Organic Matter and Bacterial Communities under the Alternanthera philoxeroide Invasion in Wetlands

“…Furthermore, the ON storages were also much higher in the invaded habitats than in the normal habitats (Table 2). However, the invasion of S. alterniflora and Lythrum salicaria dramatically stimulated N mineralization and nitrification, by adding N input, thus the storage of ON was unchanged [50][51][52]. Therefore, this study demonstrated that alligator weed invasion could be beneficial to the net storage of N fractions.…”

Emerging pollutants—Part II: Treatment

“…In addition, the cost of AO is high, and the intermediate degradation products are difficult to be completely oxidized. In view of this, the combination of a variety of treatment processes to improve the treatment effect of pollutants has gradually become the focus of current research (Huang et al, 2019;Jourshabani, Dominic, Achari, & Shariatinia, 2019;Martini, Orge, Faria, Pereira, & Soares, 2019;Wu, Zhou, Lu, Zhou, & Shen, 2019). Hylling et al (2019) reported a method to remove micropollutants in drinking water by combining RO filtration with biodegradation.…”

Efficient Malathion Removal in Constructed Wetlands Coupled to UV/H2O2 Pretreatment

“…Such conditions enhance organophosphate pesticides degradation through advanced oxidation processes [37]. The H2O2 oxidation generates •OH, and in turn releases hydronium ions, The differences between malathion and TOC removal behavior is related to the degradation of pesticide to less complex organic molecules, in terms of chemical structure, but together contributes to the same organic carbon concentration [31]. Regarding TOC removal, it is only observed if the degradation product is CO 2 , equivalent to mineralization.…”