Crystallisation of sodium dodecyl sulfate–water micellar solutions with structurally similar additives: counterion variation
File(s)
Published version
Author(s)
Miller, Ruhina M
Cabral, Joao
Robles, Eric
Brooks, Nicholas
Ces, Oscar
Type
Journal Article
Abstract
The effects of a series of structurally similar sodium dodecyl sulfate (SDS) additives on the crystallisation of SDS–water micellar solutions were investigated using a combination of differential scanning calorimetry, dynamic light scattering, optical microscopy and inductively coupled plasma optical emission spectroscopy. Seven different counterions were chosen from groups 1 and 2 of the periodic table to replace the sodium on SDS: LDS, (SDS), KDS, RbDS, CsDS, Mg(DS)2, Ca(DS)2 and Sr(DS)2. Two representative temperature profiles
were employed – linear cooling ramps at rate of 0.5 °C min−1 to determine near-equilibrium kinetics and transitions and isothermal holds at 6 °C to elucidate morphological changes. Crystallisation of the reference solution 20% SDS–H2O with 0.25, 1.0 and 2.5% additive was generally promoted or inhibited even at the lowest concentrations. Melting points however remained largely unchanged, suggesting that the additives predominantly had a kinetic rather than thermodynamic effect. ICP-OES measurements for the solutions containing 1% additive indicated that most of the additives were integrated into the SDS crystals which was reflected by morphological changes, including the formation of hexagonal and oval shaped crystals. Our results both quantify and provide a morphological insight into the effect of a series of additives on the crystallisation of micellar SDS solutions, which can readily form due to preferential Na exchange.
were employed – linear cooling ramps at rate of 0.5 °C min−1 to determine near-equilibrium kinetics and transitions and isothermal holds at 6 °C to elucidate morphological changes. Crystallisation of the reference solution 20% SDS–H2O with 0.25, 1.0 and 2.5% additive was generally promoted or inhibited even at the lowest concentrations. Melting points however remained largely unchanged, suggesting that the additives predominantly had a kinetic rather than thermodynamic effect. ICP-OES measurements for the solutions containing 1% additive indicated that most of the additives were integrated into the SDS crystals which was reflected by morphological changes, including the formation of hexagonal and oval shaped crystals. Our results both quantify and provide a morphological insight into the effect of a series of additives on the crystallisation of micellar SDS solutions, which can readily form due to preferential Na exchange.
Date Issued
2018-11-14
Date Acceptance
2018-08-01
Citation
CrystEngComm, 2018, 20 (42), pp.6834-6843
ISSN
1466-8033
Publisher
Royal Society of Chemistry
Start Page
6834
End Page
6843
Journal / Book Title
CrystEngComm
Volume
20
Issue
42
Copyright Statement
© The Royal Society of Chemistry 2018. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence (https://creativecommons.org/licenses/by/3.0/)
Subjects
Science & Technology
Physical Sciences
Chemistry, Multidisciplinary
Crystallography
Chemistry
AQUEOUS-SOLUTIONS
CRYSTAL PHASES
SURFACE-TENSION
ALKYL SULFATES
NUCLEATION
DIHYDRATE
SYSTEM
STABILIZATION
DISSOLUTION
HYDROLYSIS
0306 Physical Chemistry (Incl. Structural)
0912 Materials Engineering
0302 Inorganic Chemistry
Inorganic & Nuclear Chemistry
Publication Status
Accepted
Date Publish Online
2018-10-15