Two types of electrokinetic behavior of solid particles in the presence of anionic surfactants

Kosmulski, Marek; Mączka, Edward; Ruchomski, Leszek

doi:10.1016/j.jcis.2018.08.050

Cited by 9 publications

(10 citation statements)

References 39 publications

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“…In Figures 1-8, we show the electrokinetic curves in dispersions aged from one to eight days. The ζ potentials shown in Figures 1-8 are very similar to the results reported for fresh dispersions [20]; that is, aging has rather insignificant effect on the ζ potentials of metal oxides in the presence of alkylsulfates. Two types of electrokinetic behavior have been observed.…”

Section: Resultssupporting

confidence: 80%

“…The electrokinetic behavior of metal oxides in fresh dispersions containing different amounts of anionic surfactants was presented and discussed in detail in our previous paper [20]. In Figures 1-8, we show the electrokinetic curves in dispersions aged from one to eight days.…”

Section: Resultsmentioning

confidence: 92%

“…In contrast, in dispersions containing sodium hexadecylsulfate, the presence of the surfactant resulted in a shift in the IEP to low pH (no clear maximum in the electrokinetic curves), which is a typical behavior observed in most anions other than SDS, and discussed in the introduction. The unusual electrokinetic behavior observed in the presence of SDS was interpreted in terms of surfactant adsorption in aggregated form (admicelles, hemimicelles) [20]. It should be emphasized that the ζ potentials shown in Figure 1-8 are only valid for certain solid-to-liquid ratios (here 1:10,000).…”

Section: Resultsmentioning

confidence: 98%

“…In this respect, dodecylsulfate is different from most other anions, which cause a shift in the IEP of metal oxide to low pH, but the electrokinetic curves do not show a maximum. The reasons for nonstandard behavior of SDS have been discussed in detail elsewhere [20]. The other unusual property of dispersions of metal oxides containing SDS is a high degree of aggregation of particles in spite of high absolute values of the ζ potential.…”

Section: Introductionmentioning

confidence: 98%

“…Dispersions of metal oxides containing sodium dodecylsulfate (SDS) have been extensively studied by different methods [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. The specific adsorption of dodecylsulfate anions results in a reversal of the sign of the ζ potential of metal oxide particles from positive to negative in the acidic range.…”

Section: Introductionmentioning

confidence: 99%

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Dispersions of Metal Oxides in the Presence of Anionic Surfactants

Ruchomski

Mączka

Kosmulski

2018

Colloids and Interfaces

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We studied the behavior of dilute dispersions of nanoparticles of hematite, alumina, and titania in the presence of various concentrations of very pure sodium dodecyl-, tetradecyl-, and hexadecylsulfate. The concentrations studied were up to critical micelle concentration (CMC) for sodium dodecylsulfate, and up to the solubility limit in case of sodium tetradecyl- and hexadecylsulfate. The dispersions were adjusted to different pH (3–11), and 10−3 M NaCl was used as the supporting electrolyte. The solid-to-liquid ratio was strictly controlled in all dispersions, and the behavior of fresh dispersions was compared with dispersions aged for up to eight days. The presence of very low concentrations of ionic surfactants had rather insignificant effects on the ζ potentials of the particles. At sufficient concentrations of ionic surfactants the isoelectric point (IEP) of metal oxides shifted to low pH, and the long-chain surfactants were more efficient in shifting the IEP than their shorter-chain analogues. Once the surfactant concentration reached a critical value, the ζ potentials of the particles reached a pH-independent negative value, which did not change on further increase in the surfactant concentration and/or aging of the dispersion. This critical concentration increases with the solid-to-liquid ratio, and it is rather consistent (for certain oxides and certain surfactants) when it is expressed as the amount of surfactant per unit of surface area. Surprisingly, the surfactant-stabilized dispersions always showed a substantial degree of aggregation; that is, the particle size observed in dispersions by dynamic light scattering was higher than the size of particles observed in dry powders by electron microscopy. Apparently, in spite of relatively high ζ potentials (about 60 mV in absolute value), the surfactant-stabilized dispersions consist of aggregates rather than of primary particles, and in certain dispersions the high concentration of surfactant seems to induce aggregation rather than prevent it.

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Section: Resultssupporting

confidence: 80%

Section: Resultsmentioning

confidence: 92%

Section: Resultsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Dispersions of Metal Oxides in the Presence of Anionic Surfactants

Ruchomski

Mączka

Kosmulski

2018

Colloids and Interfaces

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In situ ATR‐FTIR spectroscopy for evidencing the adsorption mechanism of ammonium on a pinewood‐derived biochar

Saini

Koff

Rakshit

2023

Agricultural & Env Letters

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Biochar is used as a soil amendment for improving soil health. Biochar is known to possess high adsorption capacity for nutrient ions, especially toward NH 4 + . However, there is limited information regarding the direct binding mechanisms of NH 4 + on biochar. Although few infrared spectroscopic studies were conducted by characterizing the biochar solid phase, no research was reported, in which the adsorption mechanism was deciphered in the presence of water. Here we report NH 4 + adsorption mechanism on pinewood biochar using in situ attenuated total reflectance Fourier transform infrared spectroscopy. The results indicated that NH 4 + adsorbed strongly on pinewood biochar at pH 8.5 and less at pH 5.5 as revealed by infrared band shifts and symmetry change. Macroscopic adsorption envelope corroborated the spectroscopic finding by resulting in higher adsorption capacity with increasing pH.

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