Dodecyl Sulfate Ions Research Articles

Elucidating the interaction between polar alkoxysilane-modified silicate glass and ionic surfactant in the obtainment of hydrophobic transparent film

Soda-lime-silicate glass is a widely used material in industry and everyday life. For some applications, it is important to have hydrophobic properties of its surface and at the same time retain the transparency in the visible spectrum. This can be achieved using fluoroalkyl silanes as surface modifiers. However, fluorine shows severe health effects and the nowadays tendency is to use more appropriate substances for surface modification. In this work, we show the possibility of obtaining a hydrophobic and transparent film on silicate glass using alkoxysilanes with alkyl groups possessing terminal -NH2 and subsequent modification of such silanized glass using an anionic surfactant. The possible mechanism of the interaction between the chemisorbed silyl group and the dodecyl sulfate ion was discussed.

Dodecyl sulfate ions co-intercalated nickel cobalt carbonate hydroxide with multiwall carbon nanotube: An advanced catalyst for the electrochemical detection of nilutamide

Nilutamide (NLD) serves as a crucial anti-androgen drug for prostate cancer treatment; however, its elevated presence poses ecological risks. Monitoring NLD in environmental and biological samples is imperative. Layered double hydroxide (LDH) stands out as an intriguing electrocatalyst material, and this study focuses on enhancing its properties by hydrothermally preparing a hydrophobic LDH through co-intercalation of dodecyl sulfate anion in nickel cobalt carbonate hydroxide (NCCH). The catalytic performance is further improved by incorporating multiwall carbon nanotubes (MWCNT) to achieve precision and sensitivity in the electrochemical detection of NLD. The resulting NCCH/MWCNT-based electrochemical sensor demonstrates excellent structural, functional, and morphological characteristics verified by various spectroscopic techniques. Electrochemical analyses reveal impressive results, including a low detection limit (0.001 μM), quantification limit (0.0036 μM), two linear ranges (0.01–59.19 μM and 59.19–537.19 μM), and high sensitivity (3.957 μA μM−1cm−2). The practical utility is confirmed through successful monitoring of NLD in environmental and biological samples with satisfactory recoveries. In conclusion, NCCH/MWCNT emerges as a superior electrode material for the selective detection of NLD, showcasing its potential in environmental monitoring and clinical applications.

Counter-ion adsorption and electrostatic potential in sodium and choline dodecyl sulfate micelles - a molecular dynamics simulation study.

Choline-based surfactants are interesting both from the practical point of view to obtaining environmental-friendly surfactants as well as from the theoretical side since the interactions between the choline and surfactants can help to understand self-assembly phenomena in deep eutectic solvents. Although no significant change was noticed in the micelle size and shape due to the exchange of the sodium counter-ion by choline in our simulations, the adsorption of the choline cation over the micelle surface is stronger than the adsorption of the sodium, which leads to a reduction of the exposed surface area of the micelle and remarkable effects over the electrostatic potential. The choline neutralizes the surface charge of the surfactant better than sodium; however, this is partially compensated by a stronger water orientation around the SDS micelle. The balance between the contributions from the surfactant, the counter-ion, and water to the electrostatic potential leads to a complex pattern with alternate regions of positive and negative potential at the micelle/water interface which can be important to the incorporation of other charged species at the micelle surface as well as for the interaction between micelles in solution. To evaluate the effects of the counter-ion substitution, micelles of sodium dodecyl sulfate (SDS) and choline dodecyl sulfate (ChDS) were studied and compared by means of molecular dynamics simulations in aqueous solution. In both cases, the simulations started from pre-assembled micelles with 60 dodecyl sulfate ions and 240-ns simulations were performed at NPT ensemble at T = 323.15K and P = 1bar using the Gromacs software with the OPLS-AA force field to describe dodecyl sulfate and choline, Åqvist parameters for sodium, and SPC model for water molecules.

Ni foam-supported Cu0.33Co0.67Se2 and modified NiCo-layered double hydroxide nanoarray composites for high-energy-density hybrid supercapacitors

High-performance supercapacitors, valued for their extended operational lifespan and remarkable power density, have garnered significant attention as potential energy storage solutions. Nevertheless, their practical application has been impeded by the limited energy density and unsatisfied rate capability of conventional electrode materials. To address these challenges, we developed an effective approach for crafting a composite material, featuring a core-shell nanostructure comprised of dodecyl sulfate (DS) ions intercalated Cu0.33Co0.67Se2/NiCo-DS-LDH nanostructures. The synergistic inter-component effect between copious active sites of Cu–Co–Se and DS-modified NiCo-LDH readily boosts the high specific capacity as ∼488 mAh g−1 at 1 A g−1 with an enhanced capacity retention of ∼36.3%. In this material system, the Cu0.33Co0.67Se2/NiCo-DS-LDH cathode-integrated hybrid supercapacitor device, with the N, S co-doped porous carbon anode achieves an energy density of ∼54.4 Wh kg−1 at a power density of ∼801 W kg−1. These exceptional electrochemical performances can be attributed to the combinatorial effect of the high conductivity of the Ni network, the high activity of the bimetallic selenide, and the expanded interlayer spacing of the NiCo-LDH. The current work presents a newly developed strategy for the design of promising transition metal-based composites with a rational architecture, offering significant potential for next-generation energy storage systems.

Studying the Effect of Cross-Linking and Sulfonation on the Calcium-Binding Ability of Polystyrene Sulfonate in the Presence of Dodecyl Sulfate

Calcium ions in hard water deteriorate the cleaning performance of detergents by interacting with the anionic surfactants and inducing their precipitation. Polystyrene sulfonate is a common component of cation-exchange resins that adsorb hard ions such as Ca+2 and Mg+2, which adhere to the sulfonate groups. Therefore, understanding the calcium-binding ability of polystyrene sulfonate in the presence of dodecyl sulfate can help in designing novel water-softening agents for applications related to detergency. Studying the association between polystyrene sulfonate and dodecyl sulfate via calcium ion bridges is also important. Since resins contain cross-linked polystyrene sulfonate, degrees of cross-linking and sulfonation are two important parameters. We use molecular dynamics simulations to study the effect of the above parameters on the calcium-binding ability of isotactic polystyrene sulfonate in the presence of dodecyl sulfate. We observe negligible dependence of calcium-ion binding of polystyrene sulfonate on the degrees of cross-linking and sulfonation. The formation of calcium ion bridges between cross-linked polystyrene sulfonate and dodecyl sulfate is strongly affected by the degree of sulfonation. Such bridges are observed more for the intermediate degrees of sulfonation. This is because, at a very low degree of sulfonation, dodecyl sulfate ions align closer to the cross-linking aromatic groups than the sulfonated ones. On the other hand, at high degrees of sulfonation, stronger electrostatic repulsion disfavors the proximity between dodecyl sulfate and polystyrene sulfonate.

Pseudomonas cepacia lipase immobilized on Zn2Al layered double hydroxides: Evaluation of different methods of immobilization for the kinetic resolution of (R,S)-1-phenylethanol

The present work deals with the preparation and characterization of Zn2Al layered double hydroxides (LDHs) intercalated with chloride and dodecyl sulfate ions and their use as supports for the immobilization of Pseudomonas cepacia lipase (LipPS). LipPS was immobilized on LDH by adsorption, in situ entrapment and delamination entrapment methods. The performance of free and immobilized LipPS in the transesterification of (R,S)-1-phenylethanol was compared. The immobilized derivatives prepared by adsorption gave the highest conversions (c = 50%), with an enantiomeric excess of the product (eep ) greater than 99% and a high enantiomeric ratio (E > 200). For immobilization by in situ entrapment (coprecipitation), a conversion of 31.5% and E > 200 were obtained. For immobilization by delamination entrapment, a conversion of 36% and E= 155 were obtained. Although the best results were obtained by adsorption, these results show that the delamination entrapment method can also be used to prepare bioinorganic-enzyme materials based on LDH. Our work therefore increases the range of methods that can be used to immobilize lipases for use in the production of optically pure secondary alcohols.

Renaturation of Myoglobin Denatured by Sodium Dodecyl Sulfate by Removal of Dodecyl Sulfate Ions Bound to the Protein Using Sodium Cholate.

The secondary and tertiary structures of myoglobin were disrupted by sodium dodecyl sulfate (SDS) but were hardly affected by the bile salt, sodium cholate (NaCho). This disruption was induced by the binding of dodecyl sulfate (DS) ions to the protein. In this study, the removal of DS ions bound to the protein was attempted using NaCho. The extent of removal of DS ions was estimated by the restoration of the secondary and tertiary structures of the protein disrupted by SDS. The secondary structural change was followed by monitoring mean residue ellipticity at 222 nm, [θ]222, which was frequently used as a measure of α-helical content. The tertiary structural change was followed by examining the Soret band absorbance of the protein. Evidently, the magnitude of [θ]222 of myoglobin in the SDS solution initially decreased and then increased back to almost its original value as the NaCho concentration increased. The initial decrease in [θ]222 indicated the cooperation of NaCho and SDS in disrupting the secondary structure at low concentrations of both surfactants. This cooperation was also observed in the tertiary structural change as a shift of the Soret band maximum wavelength, λmax, and a decrease in the molar absorption coefficient, εmax, at λmax. Above a certain NaCho concentration, the position of λmax and the magnitude of εmax were also restored to their original states. The secondary and tertiary structures were simultaneously restored by adding NaCho. These recoveries were attributed to removal of the DS ions bound to the protein. This removal might be due to the ability of cholate anions to strip DS ions bound to the protein. The stripped DS ions are more likely to form SDS-NaCho mixed micelles in bulk than SDS-NaCho mixed aggregates on the protein.

Effect of SDS modified coal microstructure on wettability and methane adsorption

Adding ionic solution can improve the microstructure of coal, inhibit the gas absorption capacity and effectively reduce the outburst risk. In this paper, the high-quality anthracite in Jincheng, Shanxi Province is selected as the research object, and sodium dodecyl sulfate (SDS) ion solutions with different concentrations are configured. Combined with infrared spectroscopy, mercury intrusion test, the change features of coal microstructure after soak by SDS solutions with different concentrations are studied, and the variations of the contact angle and adsorption constant of samples before and after modification are tested. The paper further discusses the influence of changing coal microstructure on the wettability and gas adsorption. The experimental results show that SDS can modify the microstructure of coal to some extent: –OH, -CO, and COC increase obviously, macropores and mesopores increase, micropores and ascospores decrease. After SDS modification, the contact angle and the maximum gas adsorption a decrease linearly as oxygen groups and vtotal increase. In addition, the hydrophilic groups in the coal body increase significantly, which makes it easier to attract water molecules, and strengthen the pore connectivity and coal wettability. The polar oxygen-containing functional group molecules of coal also increase, occupying the adsorption site of non-polar molecular methane, and the adsorption site (micropore) decreases. The conclusion of this paper establishes theoretical foundation for the exploitation of coal seam gas resources. Adding SDS can directionally ameliorate coal microstructure, and then regulate the coal wettability and its ability to adsorb methane, to utilize coal resources safely and efficiently.

Application of Fixed-Length Ultrasonic Interferometry to Determine the Kinetics of Light-/Heat-Induced Damage to Biological Membranes and Protein Complexes

This manuscript describes the application of a fixed-length ultrasonic spectrometer to determine the kinetics of heat- and photo-induced damage to biological membranes and protein complexes and provides examples of the test measurements. We implemented a measurement scheme using the digital analysis of harmonic signals. To conduct the research, the fixed-length ultrasonic spectrometer was modernized: the speed was increased; lighting was supplied to the sample cells; the possibility of changing the gas atmosphere and mixing the sample was given. Using solutions containing natural concentrations of deuterium oxide, a high sensitivity of the spectrometer was shown. The spectrometer performed well in the measurement of phase state of dimyristoylphosphatidylcholine liposomes, both in the absence and in the presence of additions, which are capable of changing the lipid properties (sodium dodecyl sulfate, palmitic acid, and calcium ions). The heat- and photo-induced changes in the state of photosystem II core complexes were demonstrated using a fixed-length ultrasonic spectrometer. Transitions at 35.5 °C, 43.5 °C, 56.5 °C, and 66.7 °C were revealed. It is proposed that the transitions reflect the disassembly of the complexes and protein denaturation. Thus, the present study demonstrates that a fixed-length ultrasonic spectrometer can be applied to determine the kinetics of heat- and photo-induced damage to biological membranes and protein complexes.

Effect of Tacticity and Degree of Sulfonation of Polystyrene Sulfonate on Calcium-Binding Behavior in the Presence of Dodecyl Sulfate

The hardness-causing ions like calcium are detrimental to the performance of anionic surfactants like dodecyl sulfate. Polystyrene sulfonate is an essential component of ion exchange resins that are used to adsorb such ions. Therefore, understanding the binding behavior of calcium ions to polystyrene sulfonate in the presence of dodecyl sulfate is of industrial relevance. Two important structural parameters of polystyrene sulfonate are known to influence its behavior: (i) The arrangement of aromatic groups around the carbon backbone (tacticity) and (ii) the degree of sulfonation. We use molecular dynamics simulations to study the effect of the above two parameters on the calcium-binding to polystyrene sulfonate in the presence of dodecyl sulfate. We observe that the calcium-binding ability and its response to the dodecyl sulfate are highly sensitive to the arrangement of aromatic groups around the backbone. We identify one atactic structure of 100% sulfonated polystyrene sulfonate and another of 20% sulfonated polystyrene sulfonate that shows a significant increase in calcium ion binding upon the addition of dodecyl sulfate ions. The increase in the 100% sulfonated structure is due to the formation of calcium ion bridges between the sulfonate groups located on one side of the backbone. The increase in the 20% sulfonated structure is due to the increase in the sulfonate-Ca-Cl type of ion bridges. We also observe a stronger association between dodecyl sulfate and low sulfonated polystyrene sulfonate because of the hydrophobic interaction between polystyrene sulfonate’s backbone and the hydrocarbon tail of dodecyl sulfate. However, aligning all the aromatic groups on the same side of the backbone (isotactic structure) sharply weakens the association between the two species. Our results can aid in achieving the desired water softening capacity of ion exchange resins in the presence of anionic surfactants via altering the tacticity and degree of sulfonation.

Enhanced removal of Sb(V) from aqueous solutions using layered double hydroxide modified with sodium dodecyl sulfate

In this study, surfactant-modified layered double hydroxides (LDHs) were prepared via a hydrothermal method using sodium dodecyl sulfate (SDS). The synthesized sorbent (DS-LDH) was utilized for the removal of Sb(V) from aqueous solutions. The results demonstrated that DS4-LDH with a SDS/(Mg2++Al3+) molar ratio of 0.35 exhibited excellent Sb(V) sorption ability (136 mg g−1), which was 11 times that of pure LDH (12 mg g−1), for an initial Sb(V) concentration of 40 mg L−1. Acidic and alkalescent aqueous solutions and ionic strength hardly affected Sb(V) sorption by DS4-LDH, whereas strong alkalinity inhibited Sb(V) sorption. Under neutral conditions, coexisting anions, including sulfate and phosphate, exhibited a significant influence on Sb(V) removal, whereas chloride, acetate, and carbonate had negligible effects. Ion exchange and the formation of brandholzite-like structures primarily contributed to the Sb(V) sorption by DS4-LDH. The intercalation of dodecyl sulfate ions in LDH increased the interlayer spacing, which enhanced anion exchange between the original interlayer ions of LDH and Sb(OH)6-, and facilitated contact between the interlayer functional sites and Sb(OH)6-, leading to an improved removal of Sb(V). This study proposes a new concept for the development of high-performance LDH sorbents modified by organic surfactants, which could be promising remediating substances for the efficient removal of Sb(V).

NiS2 nanodots on N,S-doped graphene synthesized via interlayer confinement for enhanced lithium-/sodium-ion storage

Rational design of high-capacity nanosized composites as anode nanomaterials is crucial to boosting electrochemical performances towards large-scale application for lithium- and sodium-ion batteries (LIBs and SIBs). The small sizes and homogeneous dimensional size distributions are achieved typically by either the surface confinement on the underlying supports, or the encapsulation confinement within the precursors (such as metal-organic frameworks). Herein, we report the ultrasmall NiS2 nanodots on reduced graphene oxide (NiS2/N,S-rGO) synthesized via interlayer confinement as anode nanomaterials for LIBs and SIBs. The composite is synthesized by pyrolyzing a host/guest precursor of sodium dodecyl sulfate ion/[NiEDTA]2− anions co-intercalated MgAl-layered double hydroxide LDH host, without additional sulfur source. The host/guest-derived interlayer nanoconfinement enables the composite to integrate the advantageous features: low-content active NiS2 nanodots (11.0 wt%) with a mean size of 3.8 ± 0.5 nm, high-content N,S-rGO (89.0 wt%), as well as a large specific surface area and mesopore size distribution. The composite used as anode nanomaterial exhibits reversible capacities of 801.2 mAh g−1 after 100 cycles at 100 mA g−1 for LIBs, and 207.7 mAh g−1 after 200 cycles at 0.1 A g−1 for SIBs, which are greatly higher than those of the pristine N,S-rGO without NiS2 nanodots. The enhancement is experimentally supported by the low charge transfer resistance, high capacitive-controlled contribution, and good structural stability. Our guest/host-based interlayer nanoconfinement can promise an effective synthesis strategy for designing various nanosized anodes for electrochemical energy storage.

Functionalized dodecyl sulfate ions on Co/Ni hydroxides: synergistic effect on supercapacitor electrode performance

Functionalized dodecyl sulfate ions on Co/Ni hydroxides: synergistic effect on supercapacitor electrode performance

LIBERAÇÃO LENTA DO ÓLEO DE COPAÍBA ADSOLUBILIZADO EM HIDRÓXIDOS DUPLOS LAMELARES: UM MATERIAL PROMISSOR PARA POMADAS CUTÂNEAS

SLOW-RELEASE OF COPAIBA OIL ADSOLUBILIZED INTO LAYERED DOUBLE HYDROXIDES: A PROMISING MATERIAL FOR SKIN OINTMENTS. In this work, Zn/Al layered double hydroxides intercalated with dodecyl sulfate ion (DS) in molar ratios (Zn2+/Al3+) 2:1, 3:1 and 4:1 were synthesized by co-precipitation method and then they were adsolubilized with essential oil of copaiba in the concentrations of 3, 5, 10, 13 and 15% wt/wt to be used as carriers in therapeutic ointments for skin injury treatments. The XRD results showed a diffraction pattern corresponding to the structure of LDHs with the presence of diffraction peaks referring to the basal reflection planes. Typical stretching and vibration bands of copaiba essential oil in FTIR spectra confirmed the adsolubilization process. The oil release plateau in the ointment was above 80% at normalized values in a time of approximately 20 h, the time required for dissolution and release of molecules adsorbed in the layered structure of the material for molar ratios 2:1 and 3:1 and the release of the solubilized molecules in the interlayer space. In contrast, LDH with a 4:1 molar ratio showed slower release and did not reach the plateau in 48 h, as this material has the ability to retain oil molecules in the LDH for longer, causing a slower release in relation to other molar ratios. The analysis for the non-intercalated copaiba oil showed a gradual increase in the concentration of the oil in the ointment, indicating a different curve profile.

Structural Study and Antibacterial Activity of Cetylpyridinium Dodecyl Sulfate Ion Pair

A bactericidal and structural study on the cetylpyridinium dodecyl sulfate ion pair has been taken. The ion pair was a subject of numerous investigations, and its properties are widely discussed in different works. However, systematic studies on the specific interionic interactions in this ion pair are absent in the literature. To fill the gap in knowledge on the structure of cetylpyridinium dodecyl sulfate, we have synthesized this ion pair and characterized it with XRD, NMR, and DFT techniques. Moreover, antibacterial activity against various bacteria strains was analyzed.

Using Molecular Simulations to Understand the Effect of Dodecyl Sulfate on the Calcium-Binding Ability of Polystyrene Sulfonate

We demonstrate the potential to tune the binding of calcium ions with polystyrene sulfonate (PSS) in the presence of dodecyl sulfate (DS). This can aid the design of surfactant-responsive water-softening agents for applications in detergency. We use molecular dynamics simulations to study the effect of the concentration of DS ions and the degree of sulfonation on the propensity of calcium ions toward PSS. We observe that the presence of DS ions increases the propensity of calcium ions toward 100% sulfonated PSS. The above phenomenon is due to the hydrophobic attraction between PSS and DS at low DS concentrations and the formation of calcium ion bridges between sulfonate and sulfate groups at moderate to high DS concentrations. We also observe the formation of calcium ion bridges between the sulfonate groups at high DS concentrations. The presence of DS ions also increases the propensity of calcium ions toward 20% sulfonated PSS. This is mainly due to the hydrophobic attraction between PSS and DS ions. The calcium ion bridges between sulfonate and sulfate groups are less prevalent than those of 100% sulfonated PSS. We do not observe calcium ion bridges between sulfonate groups of 20% sulfonated PSS. We use the above-mentioned insights to suggest potential strategies for designing an anionic polyelectrolyte having a suitable calcium-binding ability at a given concentration of the anionic surfactant. Finally, strong PSS-DS affinity is detrimental to the activity of surfactants because less surfactant ions are available for detergency. Our results also indicate the possibility of altering the PSS-DS affinity by changing the degree of sulfonation.

Low-Density Polyethylene Nanocomposite Containing Zn/Ti Layered Double Hydroxide

The presented work shows the synthesis and characterization of Zn/Ti layered double hydroxide (LDH) intercalated with carbonate and dodecyl sulfate ions following its application as a functional filler in LDPE in order to improve the thermal properties and resistance degradation in UV-Vis radiation. X-ray diffractogram patterns of Zn/Ti LDH-CO3 and Zn/Ti LDH-DDS present basal spacing value in the order of 6.81 Å and 38.09 Å, respectively, indicating success in layered compound synthesis. LDPE nanocomposite containing hydrophobic and hydrophilic LDH presented a very well dispersed nanocomposite, as demonstrated in XRD and DSC results. The addition of only 1 % of LDH as filler into LDPE causes an increase of 5.43 oC in the thermal property. Zn/Ti LDH-DDS absorbs more light compared to the Zn/Ti LDH-CO3 due to the enhanced interlayer distance in the presence of DDS in the basal space of LDH, which further the intercalation process of polymer chains within the interlayer regions of LDH.

PEDOT-supported Pd nanocatalysts – oxidation of formic acid

Palladium (Pd) nanocatalysts are obtained by electroless deposition of Pd on pre-reduced poly(3,4-ethylenedioxythiophene) (PEDOT) layers doped with either polystyrenesulfonate (PSS) or dodecylsulfate (SDS) ions. The PEDOT-supported Pd catalysts are investigated with respect to formic acid (FA) oxidation in slightly acidic solution under voltammetric and chronoamperometric conditions. Atomic force microscopy (AFM) and Scanning electron microscopy (SEM) studies are carried out before and after exposure to FA. It is established that the dopant used for the synthesis of PEDOT does affect not only the distribution of the Pd nanoparticles on the polymer surface but also the stability of the composites upon electrochemical treatment in the presence of FA. It is found that PEDOT-PSS undergoes structural rearrangement, and significant loss of the Pd catalyst is observed. In comparison, PEDOT-SDS is more resistant to FA exposure since aggregated Pd nanoparticles are providing additional stability of the polymer structure.

Sorption of methyl orange dye by dodecyl-sulfate intercalated Mg-Al layered double hydroxides

The aim of this study is to evaluate the Mg-Al layered double hydroxides (LDHs) containing dodecyl sulfate and carbonate ions in the removal of methyl orange (MO) from aqueous solution. The prepared materials (Mg-Al-CO3 and Mg-Al-Ds) were characterized by XRD, TEM and FT-IR methods. XRD patterns of the two materialsshow the interlayer type structure with (00 l) reflections. TEM analysis showed that the LDH samples have nanoscale structures. FTIR spectroscopy confirmed the presence of the desired anions in the interlayer space. The results of the adsorption experiences for MO were performed as a function of solution pH and contact time. The adsorption ability of MO onto Mg-Al-CO3was practically influenced by pH solution. However, the adsorption capacity of MO by Mg-Al-Ds appears stable at the different values of solution pH. The maximum adsorption capacities were 185.06 and 97.5 mg/g for Mg-Al-Ds MB and Mg-Al-CO3, respectively. The adsorption tests recommend the use of organic LDHs as potential adsorbents for azo dye treatment in a wide range of pH.

Capillary Electrophoretic Characterization of Carbon Nanodots Prepared from Glutamic Acid in an Electric Furnace

Carbon nanodots (CNDs) prepared from glutamic acid or glutathione in an electric furnace were characterized by capillary electrophoresis. Two major peaks were detected in the electropherograms by capillary zone electrophoresis, corresponding to anionic and less-charged CNDs. The effective electrophoretic mobility of the anionic CND formed from glutamic acid was almost identical over neutral to weakly alkaline pH range, and the CND would not contain significant amount of amino group. On the other hand, the effective electrophoretic mobility tended to decrease with decreasing pH at weakly acidic pH conditions, suggesting the functional groups of carboxylate moiety on the anionic CNDs. Dodecyl sulfate ion was added in the separation buffer to give anionic charge to the less-charged CND by adsorption. However, the anionic charge induced was little, and the dodecyl sulfate ion was not likely adsorbed on the less-charged CND and the CND would be hydrophilic.