Mechanistic Investigation of Enhanced Photoreactivity of Dissolved Organic Matter after Chlorination

Wan, Dong; Wang, Haiyue; Sharma, Virender K.; Selvinsimpson, Steplinpaulselvin; Dai, Hongliang; Luo, Fan; Wang, Chengjun; Chen, Yong

doi:10.1021/acs.est.1c02704

Cited by 41 publications

(43 citation statements)

References 65 publications

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“…Previous work found that the amount of terrigenous DOC mineralized by photodegradation is higher in the ocean than in inland waters. 11 Increasing concentrations of halides, 50,51 higher pH, and increased penetration of ultraviolet radiation 52 enhance DOM photobleaching in the coastal ocean. Our work also suggests that aged DOM is more vulnerable to photobleaching based on the observation that CDOM photobleaching rates increased slightly with DOM aging in irradiation experiments.…”

Section: Discussionmentioning

confidence: 99%

Biodegradation of Terrigenous Organic Matter in a Stratified Large-Volume Water Column: Implications of the Removal of Terrigenous Organic Matter in the Coastal Ocean

Xiao

Powers

Liu

et al. 2022

Environ. Sci. Technol.

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Large amounts of terrigenous organic matter (TOM) are delivered to the ocean every year. However, removal processes of TOM in the ocean are still poorly constrained. Here, we report results from a 339-day dark incubation experiment with a unique system holding a vertically stratified freshwater–seawater column. The quality and quantity of dissolved organic matter (DOM), RNA-based size-fraction microbial communities, and environmental factors were high-frequency-monitored. Microbial processes impacted TOM composition, including an increased DOM photobleaching rate with incubation time. The mixed layer had changed the bacterial community structure, diversity, and higher oxygen consumption rate. A two-end member modeling analysis suggested that estimated nutrient concentrations and prokaryotic abundance were lower, and total dissolved organic carbon was higher than that of the measured values. These results imply that DOM biodegradation was stimulated during freshwater–seawater mixing. In the bottom layer, fluorescent DOM components increased with the incubation time and were significantly positively related to highly unsaturated, oxygenated, and presumably aromatic compound molecular formulas. These results suggest that surfaced-derived TOM sinking leads to increased DOM transformation and likely results in carbon storage in the bottom water. Overall, these results suggest that microbial transforming TOM plays more important biogeochemical roles in estuaries and coastal oceans than what we know before.

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Section: Discussionmentioning

confidence: 99%

Biodegradation of Terrigenous Organic Matter in a Stratified Large-Volume Water Column: Implications of the Removal of Terrigenous Organic Matter in the Coastal Ocean

Xiao

Powers

Liu

et al. 2022

Environ. Sci. Technol.

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“…After ruling out the contribution of Fe(III) and TPP substitution to the Cu(II)-EDTA decomplexation in the Na 6 TPP-EF process, we thus investigated the roles of ROS, which might destruct the Cu(II)-EDTA bonds to release Cu(II) ions. The •OH and •O 2 – radicals were measured using the DMPO spin-trapping ESR spectra at pH 7.5 in deionized water and methanol solution, respectively. ,, A typical •OH signal was observed at 10 min during the Na 6 TPP-EF process, and the time-dependent enhanced signals demonstrated the gradual accumulation of •OH radicals during the reaction (Figure b). In contrast, the signals of the DMPO-•O 2 – spin adduct were weakened along with the reaction (Figure c) .…”

Section: Resultsmentioning

confidence: 94%

An Electrochemical Strategy for Simultaneous Heavy Metal Complexes Wastewater Treatment and Resource Recovery

Chen

Shang

et al. 2022

Environ. Sci. Technol.

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Heavy metals chelated with coexisting organic ligands in wastewater impose severe risks to public health and the ambient ecosystem but are also valuable metal resources. For sustainable development goals, the treatment of heavy metal complexes wastewater requires simultaneous metal–organic bond destruction and metal resource recovery. In this study, we demonstrated that a neutral pH electro-Fenton (EF) system, which was composed of an iron anode, carbon cloth cathode, and sodium tetrapolyphosphate electrolyte (Na6TPP), could induce a successive single-electron activation pathway of molecular oxygen due to the formation of Fe(II)-TPP complexes. The boosted •OH generation in the Na6TPP-EF process could decomplex 99.9% of copper ethylene diamine tetraacetate within 8 h; meanwhile, the released Cu ions were in situ deposited on the carbon cloth cathode in the form of Cu nanoparticles with a high energy efficiency of 2.45 g kWh–1. Impressively, the recovered Cu nanoparticles were of purity over 95.0%. More importantly, this neutral EF strategy could realize the simultaneous removal of Cu, Ni, and Cr complexes from real electroplating effluents. This study provides a promising neutral EF system for simultaneous heavy metal complexes wastewater treatment and resource recovery and sheds light on the importance of molecular oxygen activation in the field of pollutant control.

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“…As generally known, DOM acts as a UV filter, consumes HOCl/OCl – ( k = (0.7–5) M c –1 s –1 ), and is a typical radical scavenger of HO· and RCS (details shown in the Supporting Information). ,, In addition, antioxidant moieties in DOM can reduce intermediate radicals of contaminants back to their parent compounds. , Meanwhile, DOM can promote the abatement of some contaminants, as it can generate 3 DOM*, 1 O 2 , and HO· under UV or solar irradiation . All these reactions involving DOM can alter the radical chemistry in UV/chlorine (Figure S2), while the related knowledge is still limited.…”

Section: Radical Chemistry Of the Uv/chlorine Processmentioning

confidence: 99%

UV/Chlorine Process: An Efficient Advanced Oxidation Process with Multiple Radicals and Functions in Water Treatment

et al. 2022

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Metrics & More Article Recommendations * sı Supporting Information CONSPECTUS: Because of the deterioration of global water quality, the occurrence of chemical and microbial contaminants in water raises serious concerns for the health of the population. Identifying and developing effective and environmentally friendly water treatment technologies are critical to obtain clean water. Among the various technologies for the purification of water, ultraviolet photolysis of chlorine (UV/chlorine), an emerging advanced oxidation process (AOP), has multiple functions for the control of contaminants via the production of hydroxyl radicals (HO•) and reactive chlorine species (RCS), such as Cl•, ClO•, and Cl 2 • − . This Account centers around the radical chemistry of RCS and HO• in different water matrices and their roles and mechanisms in the abatement of contaminants. The concentrations of Cl•, ClO•, and Cl 2 • − are comparable to or higher than those of HO• (10 −14 to 10 −13 M). The reactivities of RCS are more selective than HO• with a broader range of second-order rate constants (k). The k values of Cl• toward most aromatics are higher or similar as compared to those of HO•, while those of Cl 2 • − and ClO• are less reactive but more selective toward aromatics containing electron-donating functional groups. Their major reaction mechanisms with Cl• are electron transfer and addition, while those with ClO• and Cl 2 • − primarily involve electron transfer. As for aliphatics, their reactivities with both HO• and RCS are much lower than those of aromatics. The reaction mechanisms for most of them with Cl• and Cl 2 • − are hydrogen abstraction, except for olefins, which are addition. In addition, RCS greatly contribute to the inactivation of microbial contaminants.Toward future application, the UV/chlorine process has both pros and cons. Compared with the traditional HO•-based AOP of UV/ H 2 O 2 , UV/chlorine is more efficient and energy-saving for oxidation and disinfection, and its efficiency is less affected by water matrix components. However, the formation of toxic byproducts in UV/chlorine limits its application scenarios. In dissolved organic matter (DOM)-rich water, the formation of halogenated byproducts is enhanced in UV/chlorine. In the presence of ammonia, reactive nitrogen species (RNS) (e.g., •NO and •NO 2 ) are involved, and highly toxic nitro(so) products such as nitro(so)-phenolics and N-nitrosodimethylamine are generated. For a niche application, the UV/chlorine process is recommended to be utilized in water with low levels of DOM and ammonia.Strategies should be developed to make full use of highly reactive species (RCS and HO•) for the abatement of target contaminants and to reduce the formation of toxic byproducts. For example, the UV/chlorine process can be used in tandem with other treatments to create multiple barriers for the production of safe water. In addition, halogen radicals are very important in ecosystems as well as other areas such as medical therapy and organic synthesis. UV/chlorine is th...

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Mechanistic Investigation of Enhanced Photoreactivity of Dissolved Organic Matter after Chlorination

Cited by 41 publications

References 65 publications

Biodegradation of Terrigenous Organic Matter in a Stratified Large-Volume Water Column: Implications of the Removal of Terrigenous Organic Matter in the Coastal Ocean

Biodegradation of Terrigenous Organic Matter in a Stratified Large-Volume Water Column: Implications of the Removal of Terrigenous Organic Matter in the Coastal Ocean

An Electrochemical Strategy for Simultaneous Heavy Metal Complexes Wastewater Treatment and Resource Recovery

UV/Chlorine Process: An Efficient Advanced Oxidation Process with Multiple Radicals and Functions in Water Treatment

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