Adsorption properties of anionic surfactants onto humic acids.

Abstract Due to the widespread use of nanoparticles in surfactant-based formulations, their release into the environment and wastewater is unavoidable, causing a toxic effect to biota and/or wastewater treatment processes. Because of concerns about the environmental impact of nanofluids, the study of the fate and environmental impact, hazards and toxicity of nanoparticles is beginning. However, the interactions between nanoparticles and surfactants as well as the biodegradability in mixtures have been little studied until now. In this work the environmental impact of nanofluids containing mixtures of surfactants and silica nanoparticles were evaluated. The systems studied were hydrophilic silica nanoparticles (size 7 and 12 nm), a non-ionic surfactant (alkyl polyglucoside), an anionic surfactant (ether carboxylic acid), and mixtures of them. The aerobic ultimate biodegradation and interfacial and adsorption properties of surfactants, nanoparticles and mixtures during the biodegradation process were also evaluated. Aerobic biodegradability was determined by measurements of dissolved organic carbon for solutions with variable concentrations of surfactants and nanoparticles. The ultimate biodegradation was studied below and above the CMC of the individual surfactants. Interfacial and adsorption properties of surfactants solutions containing nanoparticles are influenced by the addition of silica particles. It was determined that silica nanoparticles reduced the capability of non-ionic surfactants to decrease the surface tension. Thus, silica NP promoted a considerable increase of their CMC, whereas the effect was the opposite in case of anionic surfactants. The increasing concentration of surfactant and nanoparticles in the test medium causes a decrease in the maximum levels of mineralization reached for both types of surfactants. The presence of silica nanoparticles in the medium reduces the biodegradability of binary mixtures non-ionic-anionic- surfactants solutions, being this effect more intense for larger nanoparticles. These results could be taken into account to model the behavior of nanofluids in aquatic environments and to select appropriate nanofluids containing nanoparticles and surfactants with low environmental impact.

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Phase behavior of cationic and anionic surfactants at low concentrations

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100123878 ◽

1992 ◽

Vol 50 (1) ◽

pp. 694-695

Author(s):

E. Naranjo

Keyword(s):

Phase Behavior ◽

Structural Characterization ◽

Dynamic Systems ◽

Anionic Surfactants ◽

Intermolecular Forces ◽

Stable Form ◽

Surfactant Mixtures ◽

Low Concentrations ◽

Cationic And Anionic Surfactants ◽

General Method

Equilibrium vesicles, those which are the stable form of aggregation and form spontaneously on mixing surfactant with water, have never been demonstrated in single component bilayers and only rarely in lipid or surfactant mixtures. Designing a simple and general method for producing spontaneous and stable vesicles depends on a better understanding of the thermodynamics of aggregation, the interplay of intermolecular forces in surfactants, and an efficient way of doing structural characterization in dynamic systems.

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ROLE OF ADDED PHOSPHOGYPSUM AND HUMIC ACIDS IN THE KINETIC RELEASE OF SALT FROM SALT AFFECTED SOIL (SALINE – SODIC)

Anbar Journal of Agricultural Sciences ◽

10.32649/ajas/2020/2 ◽

2020 ◽

pp. 15-27

Keyword(s):

Electrical Conductivity ◽

Humic Acids ◽

Release Rate ◽

Release Kinetics ◽

Sodium Adsorption Ratio ◽

Salt Affected Soil ◽

Two Factors ◽

Dissolved Ions ◽

Kinetic Release

In order to study the effect of phosphogypsum and humic acids in the kinetic release of salt from salt-affected soil, a laboratory experiment was conducted in which columns made from solid polyethylene were 60.0 cm high and 7.1 cm in diameter. The columns were filled with soil so that the depth of the soil was 30 cm inside the column, the experiment included two factors, the first factor was phosphogypsum and was added at levels 0, 5, 10 and 15 tons ha-1 and the second-factor humic acids were added at levels 0, 50, 100 and 150 kg ha-1 by mixing them with the first 5 cm of column soil and one repeater per treatment. The continuous leaching method was used by using an electrolytic well water 2.72 dS m-1. Collect the leachate daily and continue the leaching process until the arrival of the electrical conductivity of the filtration of leaching up to 3-5 dS m-1. The electrical conductivity and the concentration of positive dissolved ions (Ca, Mg, Na) were estimated in leachate and the sodium adsorption ratio (SAR) was calculated. The results showed that the best equation for describing release kinetics of the salts and sodium adsorption ratio in soil over time is the diffusion equation. Increasing the level of addition of phosphogypsum and humic acids increased the constant release velocity (K) of salts and the sodium adsorption ratio. The interaction between phosphogypsum and humic acids was also affected by the constant release velocity of salts and the sodium adsorption ratio. The constant release velocity (K) of the salts and the sodium adsorption ratio at any level of addition of phosphogypsum increased with the addition of humic acids. The highest salts release rate was 216.57 in PG3HA3, while the lowest rate was 149.48 in PG0HA0. The highest release rate of sodium adsorption ratio was 206.09 in PG3HA3, while the lowest rate was 117.23 in PG0HA0.

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