Humic substances reduce the oxygen mass transfer in the air–water interface

Silva, Pedro de Souza Lopes; Mateus, Marcos Vinícius; Ferreira, Deusmaque Carneiro; Luz, M. S. da; Naves, Emiliane Andrade Araújo; Martins, Mário Machado; Goulart, Luíz Ricardo; Cunha, Luís Carlos Scalon; Gonçalves, Julio Cesar de Souza Inácio

doi:10.1002/aic.16971

Cited by 2 publications

(1 citation statement)

References 49 publications

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“…Thus, avoiding mechanisms accountable for the formation of these species is extremely important for human health and environmental maintenance (FILHO and SAKAGUTI, 2008;SILVA and MELO, 2015). In addition, Lopes Silva et al (2020) have also shown that NOM, besides allowing BDPs' formation, can reduce waterbodies' selfdepuration ability, since NOM molecules form a film in the air-water interface; this film makes oxygen transfer to water more difficult. NOM in natural water, mainly in high-turbidity surface fresh water, encompasses a whole variety of organic chemical compounds that present several functional groupings and different molecular weights, which makes it possible featuring three fractions: hydrophobic, hydrophilic and transphilic.…”

Section: Introductionmentioning

confidence: 99%

Removal of natural organic matter in waters using hydrodynamic cavitation and hydrogen peroxide (HC-H2O2)

Araujo

Soeira

Poleto

et al. 2020

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The presence of natural organic matter (NOM) in water does not present direct risk to the human body or to the environment. However, its presence along with other pollutants can lead to countless issues and damage human health and the environment. The hydrodynamic cavitation (HC) phenomenon started being used in the early 21st century as a process capable of treating supply-water and wastewater based on pollutant and pathogen degradation. Process effectiveness increases when it is combined to chemical agents, creating an advanced oxidation process (AOP). Although several studies have presented broaden applications for the HC process, its use for NOM removal from supply-water was not yet assessed; therefore, it remains a gap in scientific knowledge. The aim of the current study is to assess HC potential in NOM removal. In order to do so, the experiments were carried out in bench scale hydrodynamic cavitation system operated at batch model within 15-min duration period-of-time. In addition, decantation experiments (24-h period-of-time) were performed in order to check HC influence on molecules found in reaction medium after the exposure of NOM to the phenomenon. NOM was produced by a synthetic humic acid (HA) matrix at fixed concentration of 100 ppm. In total, 16 experiments were carried out; each experiment was featured by the following pair: pH (2.6, 3.0, 3.5 and 5.5) and hydrogen peroxide (0, 1, 5 and 30 mL). The best removal efficiencies (34%-36%) were observed in the most acidic pH ranges (2.6-3.0) at H2O2 concentration of 15mL. Results have presented high NOM removal efficiency (approximately 90%) after decantation at the most acidic pH ranges, as well. It can be explained by the fact that hydrodynamic cavitation in acid solution can break molecular structures suspended in the liquid medium, which favors decantation. Based on the present study, hydrodynamic cavitation with hydrogen peroxide addition can remove NOM from water; moreover, pH control is an essential factor for process development.

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Section: Introductionmentioning

confidence: 99%

Removal of natural organic matter in waters using hydrodynamic cavitation and hydrogen peroxide (HC-H2O2)

Araujo

Soeira

Poleto

et al. 2020

REGET

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The effect of SDS surfactant on surface reaeration coefficient: a laboratory scale approach

Ferreira¹,

Soeira

Ferreira

et al. 2020

Rev. ambiente água

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Surface reaeration coefficient (K2), which represents the transfer of oxygen at the air-water interface, is an important variable in aquatic ecosystems. K2 is influenced by several factors, including surfactants; furthermore, this coefficient is used in water-quality models, which requires its correct estimation. This study evaluated the effects of the surfactant Sodium Dodecyl Sulfate (SDS) on K2 in two different experimental systems. In a cylindrical reactor with a turbine-type mechanical stirrer, 15 reaeration experiments were carried out with SDS concentrations of 0.0; 0.25; 0.5; 1.0 and 1.5 mMol L-1 and stirrer rotation velocities of 25, 50 and 100 rpm. In a circular hydraulic channel, 8 reaeration experiments were carried out, in triplicate, with SDS concentrations of 0 and 1.5 mMol L-1 and agitation levels of Reynolds 4,500, 37,500; 49,200 and 54,000. In the reactor, regardless of the rotation velocity, the surfactant reduced K2 by 20%, due to a superficial film formation at the interface that made oxygen transfer difficult, due to a phenomenon known as “barrier effect”. In the channel, an approximate K2 reduction of 15% occurred at higher levels of water agitation. In the presence of surfactants, and at low levels of agitation, phenomena that increase K2 (i.e., Marangoni effect) may coexist with those that reduce K2 (i.e., barrier effect). We concluded that the presence of SDS in aquatic environments should be considered when estimating the surface reaeration coefficient, because this surfactant can contribute to uncertain K2 estimation.

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Humic substances reduce the oxygen mass transfer in the air–water interface

Cited by 2 publications

References 49 publications

Removal of natural organic matter in waters using hydrodynamic cavitation and hydrogen peroxide (HC-H2O2)

Removal of natural organic matter in waters using hydrodynamic cavitation and hydrogen peroxide (HC-H2O2)

The effect of SDS surfactant on surface reaeration coefficient: a laboratory scale approach

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