Authors:D. Chen, J. Zhu, P. Yuan, S. Yang, T. Chen, and H. He
A series of anion-cation surfactants modified organoclays are prepared by incorporating both cationic surfactant, hexadecyltrimethylammonium
bromide (HDTMAB), and anionic surfactant, sodiumdodecyl sulfonate (SDS), to montmorillonite. The added amounts of surfactant
varied from 0.2 to 4.0 CEC of the used montmorillonite, similar to those reported in literature. A combination of elemental
analysis, X-ray diffraction and thermogravimetric analysis is used in the characterization of the resulting organoclays. The
experimental results show that anionic surfactants can not be intercalated into the montmorillonite whereas they can be loaded
onto cationic modified montmorillonite, resulting in a further increase of organic carbon content of the resulting organoclays.
This study demonstrates that SDS can be intercalated into montmorillonite interlayer space through the interaction with HDTMAB
rather than by ion exchange. The intercalation of SDS results in an increase of the basal spacing of the resulting organoclays
when comparing with HDTMAB modified montmorillonite and higher decomposition temperature of the intercalated surfactants when
comparing with them in bulk state. These new insights are of high importance in the application of organoclays in the fields
of remediation of polluted water and synthesis of clay based nanocomposites.
Authors:W. Wang, Y. Yang, H. Zhao, Q. Guo, W. Lu, and Y. Lu
The extraction of europium to a W/O microemulsion with an anionic surfactant was studied. In the sodium oleate (NaOL)/pentanol/heptane/NaCl
system, the influence of aqueous-microemulsion ratio, concentration of NaOL, extraction temperature, concentration of cosurfactant,
pH and salting-out agent on the extraction yield were investigated. Europium was probably extracted into the microemulsion
phase in the form of Eu(OL)2Cl, and the extraction yield (E%) was above 99% when R = 8. The enthalpy and entropy of Eu(III) extraction were calculated to be −12.18 kJ/mol and −61.41 J/(mol K), respectively.
The back-extraction is conducted by hydrochloric acid (0.8 mol/L), which provided better back-extraction yields (95.15%).
The ultrafiltration preconcentration of Cd2+ using micellar extraction with 8-hydroxyquinoline (8-HQ), solubilized in anionic micelles of sodium dodecylsulphate (SDS))
were studied. The n-butanol was used as a co-surfactant. Ultrafiltration yields (R, %) on cellulose acetate membranes (wet, 20000 MW-CO) under 400 kPa pressure were determined. Distribution ratios (D) of cadmium between bulk liquid phase and micellar pseudophase were estimated. The constants (app.) for the cadmium-sodium
exchange on SDS micelles surface at pH values of 4.8 and 5.3 (3.36 and 3.86, respectively) were determined. It was found,
that the values of ultrafiltration yields of the cadmium (at constant concentration of 8-HQ) are influenced not only by the
pH and by the concentration values, but also by the ratio of the concentrations of the metal and the anionic surfactant.
Authors:K. Shang, Y. Yang, J. Guo, W. Lu, F. Liu, and W. Wang
The extraction of cobalt by Winsor II microemulsion system was studied. In the bis (2-ethylhexyl) sulfosuccinate sodium salt
(AOT)/n-pentanol/n-heptane/NaCl system, AOT was used as a anionic surfactant to form microemulsion in n-heptane, n-pentanol was injected in the microemulsion as a cosurfactant. Co(II) was found to be extracted into the microemulsion phase
due to ion pair formation such as Co2+(R–SO3−)Cl. The influence of different parameters such as the volume ratio of aqueous phase to microemulsion, surfactant concentration,
pH of the feed solutions, cosurfactant concentration as well as temperature on the extraction yield (E%) were investigated. The results showed that it was possible to extract 95% of cobalt by the AOT Winsor II microemulsion.
Isothermal titration calorimetry (ITC) and batch calorimetry techniques have been used to evaluate the effect of added antioxidant
(Quercetin, QN) on the binding between a polymer/surfactant complex, namely the sodium salt of polystyrene sulfonate (PSS)
and typical anionic surfactant sodium dodecylsulfate (SDS). An indirect isotherm approximation method and the Satake–Yang
model have been used to evaluate the binding parameter (Ku), adsorption cooperativity (u), and the Gibbs free energy of cooperative and non-cooperative binding (ΔGC and ΔGN) from the ITC data. The enthalpy of dissolution of QN into various PSS/water and PSS/SDS/water solutions has been evaluated
from batch calorimetry to study the energetics of the polymer/surfactant binding in the presence of QN.
Ion, precipitate and adsorbing colloid flotation of cobalt(II) have been investigated at different pH values, using N-dodecylpyridinium chloride (DPCl), A strong cationic surfactant, and sodium lauryl sulfate (NaLS), a strong anionic surfactant, as collectors. In case of adsorbing colloid flotation, hydrous manganese dioxide was used as an adsorbent. The precipitate flotation curves experimentally obtained with the two tested collectors were compared with the corresponding theoretical one calculated from the data published for Co(II) hydrolysis. The effects of the collector concentration, ageing of the water-MnO2–Co(II) system, bubbling time period, cobalt(II) concentration and foreign salts on the percent removal of Co(II) by adsorbing colloid flotation using DPCl as collector were determined. Removals approaching 100% could be achieved under the optimum conditions.
Ion, precipitate and adsorbing colloid flotations of zinc(II) from dilute aqueous solutions have been investigated over a wide pH range using the anionic surfactant Aerosol OT or the cationic collector cetyl pyridinium chloride. In case of adsorbing colloid flotation (ACF) iron oxyhydroxide and aluminium hydroxide were used, either separately or together, as coprecipitants. The precipitate flotation curves were compared with the corresponding theoretical one calculated from the data published for Zn(II) hydrolysis. In addition to the effect of pH on the percent removal the effects of collector concentration, ionic strength, bubbling time and metal ion concentration were investigated and the optimum conditions were established. High removals could be achieved especially with ACF. The results obtained are discussed with respect to the chemical state of zinc, the ionization behaviour of the collectors and properties of the coprecipitants. The developed ACF process was applied to the removal of65Zn from radioactive process wastewater.
Authors:C. del Hoyo, C. Dorado, M. Rodríguez-Cruz, and M. Sánchez-Martín
A physicochemical study of the systems formed by the clay minerals, montmorillonite and kaolinite (layered) and sepiolite
(non-layered) and the surfactants Triton X-100 (TX100, non-ionic), dodecyl sodium sulfate (SDS, anionic) and trimethyloctadecyl-ammonium
bromide (ODTMA, cationic), with different chemical structure, was carried out by X-ray diffraction (XRD), infrared spectroscopy
(FTIR) and thermogravimetric and differential thermal analysis (TG/DTA). TG/DTA results indicated an increase in the thermal
stabilization of non-ionic (TX100) and cationic (ODTMA) surfactants adsorbed by all clay minerals in relation to pure compounds.
This effect was greater in montmorillonite and sepiolite than in kaolinite owing to these minerals must allow the establishment
of a stronger bond with the surfactants as indicated by XRD and FTIR results. Differences in decomposition of anionic surfactant
SDS are not emphasized due to the low adsorbed amount of this surfactant by all systems. The results obtained indicate the
interest of taking into account the structure of surfactant and the clay mineral type when preparing customized surfactant-clay
mineral systems which contribute to establish more efficient soil and water remediation strategies based in the use of these
Chromatography of some metal cations has been performed on silica gel layers with micellar mobile phases containing sodium dodecyl sulfate (SDS), an anionic surfactant. The effects on the mobility of metal ions of SDS concentration, mobile phase pH, and the presence of amino acids (l-arginine, dl-phenylalanine, l-tryptophan, and l-histidine) in the mobile phase were examined. Although amino acids caused diffusion (or tailing) of the metal ion spots, use of l-histidine or l-tryptophan facilitates the analytically important separation of a mixture of Au
, and Ag
ions. The TLC system comprising silica gel G as stationary phase and 0.01 m SDS (pH 2.3)-0.01 m
l-tryptophan or l-histidine, 1 + 9, as mobile phase was identified as the most suitable for the separation of mixtures of Au
, and Ag
. The interference of impurities such as amines, phenols, and inorganic anions on the mobility and separation of a mixture of Au
, and Ag
ions was also examined. The lower limit of detection of some metal ions, viz. Fe
, and Hg
was determined. The proposed method has been used for identification and separation of Au
, and Ag
in a variety of spiked samples.
In the present study, Mg–Al layered double hydroxide intercalated with nitrate anions (LDH-NO3) was synthesized, modified with the anionic surfactant, sodium lauryl sulfate, and applied for the removal of 152+154Eu from aqueous solutions. Modification of the as-synthesized Mg–Al layered double hydroxide was carried out at surfactant
concentration of 0.01 M (the organo-LDH produced denoted LDH-NaLS). The as-synthesized and surfactant-intercalated LDHs were
characterized by FT-IR and energy-dispersive X-ray spectroscopy techniques. The effect of some variables such as solution
pH, contact time and sorbate concentration on removal of 152+154Eu was investigated. The kinetic data obtained were well fitted by the pseudo-second-order kinetic model rather than the pseudo-first-order
model. Intraparticle diffusion model showed that sorption of 152+154Eu proceed by intraparticle diffusion together with boundary layer diffusion. Experimental isotherm data were well described
by Langmuir model. Organo-LDH was found to have higher capacity (156.45 mg g−1) for europium than the as-synthesized LDH-NO3 (119.56 mg g−1). Comparing LDHs capacities obtained for Eu(III) in the present work with other sorbents reported in literature indicated
that LDHs have the highest capacities. Application of the developed process for removal of 152+154Eu(III) from radioactive process wastewaters was also studied and the obtained results revealed that these LDHs are promising
materials for treatment of radioactive wastewaters.