Non‐traditional atrazine degradation induced by zero‐valent‐copper: process optimization by the Doehlert experimental design, intermediates detection and toxicity assessment

Abstract

BACKGROUND Over recent years, several studies exploring new technologies capable of degrading persistent organochlorine compounds have been published. Special attention has been dedicated to atrazine (ATZ), due to its ecotoxicological relevance together with its frequent detection in the environment. Degradation of organochlorines via zero‐valent metals has gained great importance given its practicality and versatility, zero‐valent‐iron (ZVI) being the most applied metal for this purpose. Alternatively, zero‐valent‐copper (ZVCu) was proved to exhibit higher reactivity against chlorinated aromatics, therefore deserving further investigation. RESULTS The optimum degradation conditions for ATZ removal with ZVCu were explored through a Doehlert experimental design. The same conditions were tested for the traditional ZVI, which confirmed that ZVCu was more reactive. The analysis of the degradation products suggests that both reductive and oxidative pathways coexist in the studied process. CONCLUSIONS ZVCu was effective in ATZ degradation, both by reductive and oxidation pathways, within a wide range of pH values, although faster in acidic media. The resulting solution from the experiment that promoted the fastest degradation is less toxic than ATZ against microalgae Chlorella vulgaris, which is a positive output regarding the application of this process as a pre‐treatment step of ATZ‐contaminated water matrices. © 2018 Society of Chemical Industry

Oxidation Towards Enrofloxacin Degradation Over Nanoscale Zero-Valent Copper: Mechanism and Products

“…This suggests that H + was used in the nZVC/O 2 system, as the rise in pH indicates. Although the dissolved Cu concentrations in acidic solutions were higher than those allowed in the Chinese discharge standard for wastewater (2.0 mg•L -1 ), which may raise questions about the nZVC application Cu + /Cu 2+ might be readily eliminated by precipitation techniques, such as combining with a solution containing sul de or phosphorus and adjusting the pH value (Hollanda et al 2019). The previous methodology was used for this investigation, and over 99.98% of Cu in the solution was precipitated.…”

Insights into the reactivity of zero-valent-copper-containing materials as reducing agents of 2,4,6-trichlorophenol in a recirculating packed-column system: Degradation mechanism and toxicity evaluation

“…In the particular case of TCP, besides ZVI (Dorathi and Kandasamy, 2012;Shengyang et al, 2010), zero-valent-zinc (ZVZ) (Kim and Carraway, 2003;Choi and Kim, 2009) and zero-valent-magnesium (ZVMg) (Morales et al, 2002) were also tested as reducing agents, presenting better reductive performances as the reduction potential decreases (E 0 Mg = −2.2 V < E 0 Zn = −0.76 V < E 0 Fe = −0.44 V, standard hydrogen electrode -SHE). However, recent investigations indicated zero-valent-copper (ZVC), a metal with positive reduction potential (E 0 Cu = +0.334 V, SHE) (Bratsch, 1989), as very reactive against other aromatic organochlorines, namely 4-chlorophenol (Duan et al, 2016) and atrazine (Hollanda et al, 2019), thus contradicting the expected trend and deserving further investigation. For the exception of ZVI, all these metals were only tested in the suspension form, requiring separation afterwards.…”