Molecular dynamics simulation of primary ammonium ions with different alkyl chains on the muscovite (001) surface

Xu, Yi–Jun; Liu, Yuelong; Liu, Gousheng

doi:10.1016/j.minpro.2015.07.003

Cited by 35 publications

(16 citation statements)

References 40 publications

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“…The addition of NaOL decreased the electrostatic head–head repulsion between ammonium ions and the Mcv surface, while it enhanced the lateral tail–tail hydrophobic bonds. Therefore, MDS can be used as an advanced tool to explore the adsorption behavior and microscopic flotation mechanism of collector on minerals, which is generally consistent with the experimental results [ 28 , 29 ].…”

Section: Introductionsupporting

confidence: 63%

“…The positively charged H atoms of the DDAHC head group (-NH 3 ) and water could be attracted by the electronegative Mcv surface, leading to DDAHC adsorption. In addition, the H atoms of water also can form hydrogen bonding interaction to the O atoms of the Mcv surface and head groups of DDAHC [ 8 , 24 , 28 ], resulting in the formation of a water film between the adsorbed DDAHC collector and the Mcv surface. The distances from the peak positions of S and C12 atoms in SDS to those of N and C12 atoms in DDAHC were compared ( Figure 18 ).…”

Section: Resultsmentioning

confidence: 99%

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Molecular Dynamics Simulation Study on the Interactions of Mixed Cationic/Anionic Collectors on Muscovite (001) Surface in Aqueous Solution

Jiang

Huang

et al. 2022

Materials

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In this study, the adsorption mechanisms of dodecylamine hydrochloride(DDAHC), sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulfonate(SDBS), and their mixed anionic/cationic collectors at ten different molar ratios on a muscovite (Mcv) surface in neutral aqueous solution were assessed by molecular dynamics simulations (MDS). According to the snapshot, interaction energy, radial distribution function (RDF), and density profile between the Mcv surface and collector molecules, the individual DDAHC collector was an effective collector for the flotation of Mcv. The molar ratio of anionic/cationic collectors was determined to be an essential factor in the flotation recovery of Mcv. The DDAHC collector was involved in the adsorption of the mixed anionic/cationic collectors on the Mcv (001) surface, whereas SDS and SDBS collectors were co-adsorbed with DDAHC. The mixed cationic/anionic collector showed the best adsorption on the Mcv surface in a molar ratio of 2. Additionally, SDBS, which has one more benzene ring than SDS, was more likely to form spherical micelles with DDAHC, thus resulting in better adsorption on the Mcv surface. The results of micro-flotation experiments indicated that the DDAHC collector could improve the flotation recovery of Mcv in neutral aqueous solution, which was in agreement with MDS-derived findings. In conclusion, DDAHC alone is the optimum collector for Mcv flotation under the neutral aqueous conditions, while the mixture of DDAHC and SDBS collectors (molar ratio = 2:1) exhibits the similar flotation performance.

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Section: Introductionsupporting

confidence: 63%

Section: Resultsmentioning

confidence: 99%

Molecular Dynamics Simulation Study on the Interactions of Mixed Cationic/Anionic Collectors on Muscovite (001) Surface in Aqueous Solution

Jiang

Huang

et al. 2022

Materials

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“…While both head groups bond ionically to the surface, NH3 can form additional N-H…O-Si hydrogen bonds to the surface. [124][125][126] In contrast, because N(CH3)3 is larger in size the O…H and N…O distances would become too large to allow hydrogen bonds to bridge oxygen atoms of the surface. 124,125 According to Monte Carlo simulation the C16TA + ions penetrate the first adsorbed water layer, desorb the doubly hydrogen-bonded water molecules from the mineral surface, and ultimately adsorb above ditrigonal cavities with the methyl group closest to the surface positioned directly above the cavity center (see Fig.…”

Section: Thermodynamic Equilibriummentioning

confidence: 99%

Cationic-Surfactant-Coated Mica Surfaces below the Critical Micellar Concentration: 1. Patchy Structures As Revealed by Peak Force Tapping AFM Mode

Kékicheff

Contal

2019

Langmuir

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The morphology and structure of the self-assembled surfactant aggregates at the solid-liquid interface remain controversial. For the well studied system of cationic cetyltrimethylammonium bromide (C16TAB) adsorbed onto the opposite negatively charged atomically smooth mica surface, a variety of surface aggregates have been previously reported: AFM imaging pointing to cylinders and surface micelles as opposed to mono/bilayered-like structures revealed by neutron and X-ray reflectometry, NMR, spectroscopic techniques, and numerical simulations. In order to reconcile with the latter results, we revisit the morphometry of the C16TAB-coated mica surfaces using the recent Peak Force Tapping (PFT-AFM) mode that allows fragile structures to be imaged with the lowest possible applied force. The evolution of the structural organization at the mica-water interface is investigated above the Krafft boundary over a wide concentration range (from 1/1000 cmc to 2 cmc) after long-equilibration times to insure thermodynamic equilibrium. A complex but fairly complete picture has emerged: At very low concentrations the C16TAB surfactants adsorb as isolated molecules before forming small clusters. Above 1/140 cmc, monolayeredlike stripes are formed. As the concentration is increased, a connected network of these patches covers progressively the mica substrate. Above 1/80 cmc, bilayered-like patches build on top of the underlying monolayer and ultimately a complete bilayer (at about half the cmc) covers the entire mica substrate. Thanks to the less invasive PFT-AFM imaging mode, our observations agree not only with the theoretical predictions and numerical simulations, but also reconcile, at last, the direct observations by means of the AFM imaging technique with the results obtained with other techniques.

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“…and only present the surfactant arrangement at the oil/water interface, which was obtained through observation and is not completely precise. Herein, the radial distribution functions (RDF) g ( r ) between the relevant atoms of the headgroups in C 12 EO and SDS were calculated to characterize the detailed structure information using the following formula (Xu et al, ):

g_{A - B} ((), r) = \frac{1}{4 π ρ_{B} r^{2}} \frac{d N_{A - B}}{d_{r}}

…”

Section: Resultsmentioning

confidence: 99%

Effects of Surfactant Headgroups on Oil‐in‐Water Emulsion Droplet Formation: An Experimental and Simulation Study

Zhang

Liu

et al. 2018

J Surfact & Detergents

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Nonpolar oils such as kerosene and diesel oil are common collectors in coal flotation. Surfactants are usually added to the pulp to emulsify the oil collectors. The present study used dodecane as the oil collector and anionic sodium dodecyl sulfonate (SDS) and nonionic tetraethylene glycol monododecyl ether (C12EO) with different headgroups and identical chain alkyls to investigate the effect of the surfactant headgroups on oil‐in‐water emulsion droplet formation. The morphology and stability of dodecane emulsions were determined experimentally. Density functional theory (DFT) and molecular dynamics (MD) simulations were used to explain the microscopic mechanism. The results of DFT indicated a larger interaction between SDS and the water molecules than that between C12EO and water molecules. The results obtained by MD suggested that the SDS headgroup exhibited a loose arrangement and a relatively large gap size, thereby weakening the interaction between SDS and water molecules at the dodecane/water interface. In contrast, the headgroups of C12EO were bent and interwoven with others to form a tight reticulation at the interface. According to the simulation results, the ability of the surfactant to form dodecane‐in‐water emulsion droplets depends on the arrangement of the surfactants at the oil–water interface rather than on the interaction strength between the headgroups of the surfactants and water molecules. The presented microscopic mechanism of the surfactant headgroup formation of oil‐in‐water emulsion droplets offers surfactant selection and design references.

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Molecular dynamics simulation of primary ammonium ions with different alkyl chains on the muscovite (001) surface

Cited by 35 publications

References 40 publications

Molecular Dynamics Simulation Study on the Interactions of Mixed Cationic/Anionic Collectors on Muscovite (001) Surface in Aqueous Solution

Molecular Dynamics Simulation Study on the Interactions of Mixed Cationic/Anionic Collectors on Muscovite (001) Surface in Aqueous Solution

Cationic-Surfactant-Coated Mica Surfaces below the Critical Micellar Concentration: 1. Patchy Structures As Revealed by Peak Force Tapping AFM Mode

Effects of Surfactant Headgroups on Oil‐in‐Water Emulsion Droplet Formation: An Experimental and Simulation Study

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