Octadecyl Dimethyl Benzyl Ammonium Chloride Research Articles

Comparison of aqueous and non-aqueous capillary electrophoresis for the determination of four benzalkonium chloride homologues in compound chemical disinfectants

A new method was established for the simultaneous analysis of four homologous benzalkonium chlorides (dodecyldimethylbenzyl ammonium chloride, tetradecyldimethylbenzyl ammonium chloride, hexadecyldimethylbenzyl ammonium chloride, and octadecyldimethylbenzyl ammonium chloride) in compound chemical disinfectants using non-aqueous capillary electrophoresis (CE) based on a micellar electrokinetic chromatography mode with direct ultraviolet detection. The separation was performed on an uncoated fused quartz capillary with a total length of 60.2 cm and a diameter of 25 μm. The separation buffer consisted of a mixture of methanol/acetonitrile (60:40, v/v) containing 70 mmol/L sodium acetate, 60 mmol/L trifluoroacetic acid and 20 mmol/L sodium dodecyl sulfate. The sample buffer was a methanol solution containing only 2 mmol/L trifluoroacetic acid. The separation voltage was set at 8 kV with a working current of approximately 2.3 μA. The detection wavelength was 214 nm. Under optimal conditions, the limit of detection and limit of quantification for these four benzalkonium chlorides (BACs) were 1.0 mg/L and 5.0 mg/L, respectively. Good linearities were observed in the concentration ranges from 5.0 to 100.0 mg/L, with correlation coefficients above 0.999 for all compounds. The recoveries of these four BACs ranged from 92.5 % to 109.1 % with relative standard deviations below 4.7 %. With the new method, all four BACs could be analyzed in a single injection. In contrast, the aqueous CE method in the National Standard GB/T 26369-2020 only allowed for the simultaneous analysis of the first three homologous. The new method demonstrated the improved peak shape compared to the aqueous CE method and then was successfully applied to the analysis of 19 commercially available samples, such as object table disinfectants, hand sanitizers, and disinfectant wipes, which claimed to contain quaternary ammonium compound. The results obtained using the new method were compared with those of the aqueous CE of the National Standard Method, and no statistically significant differences were observed. The new method is simple in pre-treatment and provides accurate results, making it highly suitable for routine analysis.

Bentonite Modified with Surfactants—Efficient Adsorbents for the Removal of Non-Steroidal Anti-Inflammatory Drugs

Organobentonites have been applied for the removal of two common non-steroidal anti-inflammatory drugs, ibuprofen (IBU) and diclofenac sodium (DS), from aqueous solutions. Two surfactants, one with and the other without benzyl group (octadecyldimethylbenzylammonium chloride, ODMBA, and hexadecyltrimethylammonium bromide, HDTMA), in amounts equivalent to 50, 75, and 100% of the cation exchange capacity of bentonite were used for the preparation of organobentonites. Successful modification of bentonite was confirmed by several methods: X-ray powder diffraction (XRPD), point of the zero charge (pHPZC), determination of exchanged inorganic cations in bentonite, determination of textural properties, and scanning electron microscopy (SEM). Kinetic and thermodynamic data on the adsorption of IBU and DS showed that drug adsorption was controlled by the type and the amount of surfactant incorporated into the bentonite and by their arrangement in the interlayer space and at the surface of organobentonites. The adsorption of both drugs increased with an increase in the amount of both surfactants in organobentonites. The presence of the benzyl group in organobentonites enhanced the adsorption of IBU and DS and was more pronounced for IBU. Drug adsorption fits the pseudo-second-order kinetic model the best. The thermodynamic data revealed that the adsorption process was endothermic in nature and with increase of the amount of both surfactants drug adsorption processes were more spontaneous. The results obtained from this study revealed that adsorbents based on surfactants modified bentonite are promising candidates for IBU and DS removal from contaminated water.

Effect of synchronous surface grafting and intercalation bentonite on properties of SBS modified bitumen

To better enhance the improvement effect of natural bentonite on the comprehensive performance of styrene-butadiene-styrene thermoplastic elastomer modified bitumen (SMB), in this study, 3-(trimethoxysilopropyl) dimethyl octadecyl ammonium chloride (DC5700) was used for synchronous surface grafting and intercalation of bentonite (DC5700-Bentonite). Meanwhile, γ-(2,3-epoxypropoxy)propytrimethoxysilane (KH560) surface grafting bentonite (KH560-Bentonite) and octadecyldimethylbenzylammonium chloride (ODBA) intercalation bentonite (ODBA-Bentonite) were used as comparison samples. The structure and properties of the bentonite and organic bentonites (DC5700-Bentonite, KH560-Bentonite and ODBA-Bentonite) were tested by X-ray diffractometer (XRD), Fourier transform infrared spectrometer (FTIR), ultraviolet-visible spectrometer and contact angle measurement. The effects of bentonite and organic bentonites on physical, rheological and aging properties of SMB were investigated. FTIR and XRD results showed that KH560 was chemically grafted onto the surface of bentonite, ODBA was organically intercalated into the bentonite, while DC5700 achieved synchronous surface grafting and intercalation on the bentonite. Compared with KH560-Bentonite and ODBA-Bentonite, DC5700-Bentonite had the best lipophilicity and ultraviolet shielding ability. When the bentonite content was 4 wt%, KH560-Bentonite, ODBA-Bentonite and DC5700-Bentonite could increase the rutting factor of SMB by 2.9 ℃, 4.9 ℃ and 6.5 ℃, respectively, and reduce the ductility of SMB by 6.5 cm, 4.2 cm and 3.1 cm. Meanwhile, compared to SMBs containing KH560-Bentonite or ODBA-Bentonite, the SMB containing DC5700-Bentonite had the smallest creep stiffness at − 12 ℃, − 18 ℃, and − 24 ℃. The results indicated that DC5700-Bentonite was more conducive to increasing high-temperature performance of SMB than KH560-Bentonite and ODBA-Bentonite, and its adverse effects on low-temperature ductility and low-temperature cracking resistance of SMB were also significantly reduced. After thermal and ultraviolet aging, the deterioration extent of physical and rheological properties of SMB containing DC5700-Bentonite was significantly smaller than that of SMB containing KH560-Bentonite and ODBA-Bentonite. FTIR revealed that DC5700-Bentonite was more beneficial than KH560-Bentonite and ODBA-Bentonite in inhibiting the increase of carbonyl index and the decrease of butadiene index in SMB during aging. The comprehensive results revealed that compared to KH560 surface grafting bentonite and ODBA intercalation bentonite, DC5700 synchronous surface grafting and intercalation bentonite were more conducive to improving the physical and rheological properties, and aging resistance of SMB.

Efficient and stable perovskite solar cells: The effect of octadecyl ammonium compound side-chain

The extreme vulnerability of hybrid perovskite solar cells (PSCs) to moisture greatly limits the realization of their full potential. Here, we propose an efficient strategy to reinforce the efficiency and the ambient stability of PSCs via employing a series of octadecyl ammonium salts (OASs): octadecyl trimethyl ammonium chloride (OTAC), octadecyl dimethyl benzyl ammonium chloride (ODBAC), and 3-(trimethoxysilyl)propyl octadecyldimethyl ammonium chloride (TOAC), as passivating agents. Among these OASs, TOAC bearing a trimethoxysilane (Si-O-CH3) side chain group most efficiently promoted the efficiency along with the high-humidity stability of PSC devices. TOAC significantly passivated the defects, assisted better energy-level alignment and facilitated charge carrier transport in the devices. The TOAC-passivated PSCs exhibited an increase in the average PCE from 16.62 ± 0.56 % to 20.06 ± 0.68 % with a substantially enhanced fill factor of 80.10 ± 1.82 %. Furthermore, the unencapsulated TOAC-passivated PSCs preserved 90 % of their performance after storage in ambient conditions (25–30 ℃, 50–70 % relative humidity) for 300 h. When no OAS passivator was introduced, the devices were losing more than 74 % of their starting PCE after 150 h. The Si-O-CH3 groups side-chained to the OAS molecules were capable of supporting superior protection to the PSC devices against the permeation of high-moisture. Thereupon, the application of multifunctional octadecyl ammonium salt molecules to passivate defects and tailor the interface energy-level alignment in PSCs offers an encouraging staging to upgrade the PV performance of PSCs.

Treating waste with waste: Adsorption of anionic dyes in wastewater with surfactant-modified phosphogypsum

Phosphogypsum (PG) is a solid waste generated during the wet process of phosphoric acid production. The environmental-friendly disposal and recycling of PG is vital in the field of environmental solid waste treatment. In this study, PG is used for adsorbent of dyes in wastewater to achieve the goal of recycling waste with waste. Surfactant-modified phosphogypsum (ODBAC@PG) was prepared using octadecyl dimethyl benzyl ammonium chloride (ODBAC) as modifier. ODBAC@PG exhibits high adsorption capability for anionic dyes (methyl blue (MeB) and indocyanine carmine (IC)). The pseudo-second-order kinetic model fits the kinetic experimental data for the adsorption of two organic anionic dyes. Langmuir adsorption isotherm fits the adsorption characteristics of MeB and IC on ODBAC@PG, exhibiting a monolayer adsorption pattern. Thermodynamic parameters indicate the spontaneous and exothermic properties of MeB and IC on ODBAC@PG. MeB and IC have antagonistic effects on each other in binary adsorption system. High adsorption capacity after six cycles of experiments demonstrates the high reusability of ODBAC@PG. The nature for the adsorption includes electrostatic interaction, hydrogen bond and hydrophobic interaction. Using ODBAC@PG for dyes wastewater treatment can accomplish the goal of treating waste with waste and turning waste into treasure.

Influence of the Type and the Amount of Surfactant in Phillipsite on Adsorption of Diclofenac Sodium

Modified phillipsite samples were prepared with two different amounts (monolayer and bilayer coverage) of surfactants octadecyldimethylbenzylammonium chloride (O) and dodecylamine (D). Composites were characterized by Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR–ATR), thermal analysis and determination of zeta potential, and subsequently tested for removal of diclofenac sodium (DCF). Drug adsorption experiments were performed under different initial DCF concentrations and different contact times. In order to investigate the influence of the chemical structure of surfactants used for modification of phillipsite on the preparation and properties of composites and DCF adsorption, experimental data were compared with previously published results on DCF adsorption by composites containing phillipsite and the same amounts of surfactants cetylpyridinium chloride (C) and Arquad®2HT-75 (A). DCF adsorption isotherms for O and D composites showed a better fit with the Langmuir model with maximum adsorption capacities between 12.3 and 38.4 mg/g and are similar to those for C and A composites, while kinetics run followed a pseudo-second-order model. Composites containing either benzyl or pyridine functional groups showed higher adsorption of DCF, implying that surfactant structure has a significant impact on drug adsorption. Drug adsorption onto O, D, C and A composites was also confirmed by FTIR–ATR spectroscopy and zeta potential measurements.

Balance the rapid release of insecticide microcapsules using double-layer shielding effect when the foliar application

The development of microencapsulation is currently blocked by the mismatch between the release rate and pest-control demand in terms of improving the photostability of pesticides. Achieving both long-term stability and quick release of pesticides through the use of microcapsules (MCs) is an effective way to increase pesticide efficiency. Sodium lignosulfonate and four types of polyalkyl quaternary ammonium salts (PQAS) were used as shell materials in the fabrication of four types of microcapsules by electrostatic self-assembly. The effects of the PQAS alkyl chain length on the morphology, zeta potential, molecular electrostatic potential, particle size distribution, encapsulation efficiency, release behaviour, anti-photolysis performance, and field application effects of the MCs were investigated. The four types of MCs were spherical and 0.5–3 μm in size, and they had an encapsulation efficiency of more than 75 %. The X-ray diffraction results showed that the longer the alkyl chain of PQAS was, the looser the material formed by electrostatic attraction was. With the increase of the alkyl chain length of PQAS, the MCs shell was looser and easier to deform, leading to rapid nuclear release. Therefore, the MCs shells were looser and more prone to deformation with increasing PQAS alkyl chain length, resulting in the quick release of the core. This quick release of the core to the bottom of the microcapsules and the loose shell formed a double-layer structure, which effectively prevented ultraviolet degradation. Therefore, abamectin MCs with quick-release and favourable anti-photolysis performances showed advantages in controlling Plutella. xylostella and Pieris. rapae insect pests. Octadecyl dimethyl benzyl ammonium chloride can be used to fabricate loose MCs by electrostatic self-assembly, which achieves both rapid and long-term pest control.

Ibuprofen and diclofenac sodium adsorption onto functionalized minerals: Equilibrium, kinetic and thermodynamic studies

Cationic surfactant - octadecyldimethylbenzyl ammonium chloride (ODMBA) was used for modification of the three natural raw materials – bentonite, kaolin and zeolite. Adsorption of ODMBA by minerals occurred via ion exchange of inorganic cations on minerals with surfactant. Organomodified minerals – organobentonite (OB), organokaolin (OK) and organozeolite (OZ) were studied as adsorbents for removal of two non-steroidal anti-inflammatory drugs - ibuprofen (IBU) and diclofenac sodium (DS) at pH 7. For all systems, the pseudo-second order model showed the best correlation to kinetic experimental data. In all cases, the positive values of ΔH° indicated that the adsorption of both IBU and DS by organomodified minerals was endothermic in nature. Equilibrium data were better described by the Freundlich isotherm model, pointing to adsorbent heterogeneous active sites for adsorption. Under applied experimental conditions, the highest adsorption of both drugs was achieved by OB, while much lower capacities were observed for OK and OZ. Nonlinear isotherms and physicochemical characterization of organomodified minerals after drugs adsorption suggested complex mechanism consisting of hydrophobic interactions between hydrophobic part of the drugs and surfactants alkyl chains, electrostatic interactions of anionic forms of IBU and DS with the cationic “head” of ODMBA, as well as anion exchange of counterion ions from ODMBA micelle and anionic forms of both drugs. Adsorption of both IBU and DS was strongly dependent on the amount of ODMBA ions in the minerals.

Study on properties and mechanism of organic montmorillonite modified bitumens: View from the selection of organic reagents

Organic reagents, as modifiers of montmorillonite (MMT), have great effects on bitumen properties. In this respect, octadecyl dimethyl benzyl ammonium chloride (1827), stearyl trimethyl ammonium chloride (1831) and dodecyl trimethyl ammonium chloride (1231) were selected to modify MMT. The MMT and three kinds of organic montmorillonite (OMMT) were then used to modify base bitumen. Structures of MMT and OMMTs were tested by scanning electron microscope (SEM) and X-ray Diffraction (XRD). Results show that organic treatments contribute to the expansion of MMT interlayer space and make lamellar edges of OMMTs more regular without obvious curls. Properties of modifiers and modified bitumens were studied mainly by hydrophilicity test, physical tests, dynamic shear rheometer (DSR) and bending beam rheometer (BBR). It is found that introduction of MMT and OMMTs improves high temperature property but weakens low temperature property of bitumen. 1827-OMMT modified bitumen exhibits the best high temperature property, followed by 1831-OMMT modified bitumen, while there is better low temperature property for 1831-OMMT modified bitumen than 1827-OMMT modified bitumen. Moreover, 1827-OMMT modified bitumen and 1831-OMMT modified bitumen all show excellent storage stability. Modification mechanism and micro-morphologies were tested by XRD, Fourier transform infrared spectroscopy (FTIR) and atomic force microscope (AFM). Results show that bitumen molecules can intercalate into interlayer spaces through reacting with exchangeable cations in interlayers. Only 1831-OMMT and 1827-OMMT modified bitumens form the exfoliated nanostructures.

Zearalenone and ochratoxin A: adsorption by kaolin modified with surfactant

Octadecyldimethylbenzyl ammonium chloride (OA) was used as a surfactant for the preparation of organokaolin. The natural kaolin (from a plant for production of quartz sand in Rgotina, Serbia) was modified with a surfactant in amount equal to 90% of the kaolin cation exchange capacity (CEC). FTIR spectroscopy was used for characterization of the new product. FTIR spectra confirmed the presence of OA ions at the kaolin surface. Adsorption of mycotoxins – zearalenone (ZEN) and ochratoxin A (OCHRA) was studied by organokaolin at different amounts of adsorbent and pHs. Results showed that the presence of organic cations in the kaolin structure increased adsorption of both ZEN and OCHRA. Adsorption of the mycotoxins by organokaolin increased with increasing amounts of adsorbent and, at the lowest amount of solids in suspension, adsorption of ZEN and OCHRA was slightly higher at pH 7 and 9.

Enhanced adsorption and Fenton oxidation of 2,4-dichlorophenol in aqueous solution using organobentonite supported nZVI

Abstract The removal of organic persistent contaminants in the environment is a challenge due to their hydrophobic nature. In this work, the removal of 2,4-DCP based on the adsorption and Fenton oxidation was reported, where organobentonite (OB)-supported zero-valent iron nanoparticles (nZVI) generated a hydrophobic environment to enhance adsorption, as well as to reduce the aggregation of nZVI. Adsorption efficiencies of 2,4-DCP by organobentonites which modified with hexadecyl trimethyl ammonium chloride (DK1), octadecyl dimethyl benzyl ammonium chloride (DK3) and aminocaproic acid (DK5), were found to be 27.8, 25.3, 1.0 and 1.0%, while the degradation efficiencies of 2,4-DCP using nZVI/DK1, nZVI/DK3, nZVI/DK5 and nZVI/B were 73.5, 46.1, 27.1 and 25.7%, respectively. Characterization of nZVI/DK1 by SEM, EDS and XRD revealed that nZVI effectively supported the interlayer and did not change the layer structure of DK1, and no peaks of 2,4-DCP was observed by FTIR and GC–MS due to degradation. The degradation of 2,4-DCP fitted well to the Langmuir-Hinshelwood model, and about 80.24% of chemical oxygen demand (COD) was removed using nZVI/DK1, suggesting that enhanced removal was attributed to the synergetic effect between adsorption by DK1 and Fenton oxidation by nZVI as the catalyst. The high number of recycling times proves that nZVI/DK1 could be a potential material to degrade halogenated organic pollutants.

Effect of modification extent of montmorillonite on the performance of starch nanocomposite films

The mechanism of the influence of organically modified montmorillonites (OMts) with different modification extents on starch/OMt nanocomposites was investigated. The nanostructures of OMts and their dispersion in starch films were analyzed using X‐ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. The modifier content in the OMts increased with an increase in the added amount and molecular weight of the modifiers. The highest d‐spacing of 3.71 nm was achieved for the OMt modified with 30% dioctadecyl dimethyl ammonium chloride (DDAC). Intercalated nanostructures were formed between starch and the OMts modified with DDAC, whereas exfoliated nanostructures were formed between starch and the OMts modified with octadecyltrimethyl ammonium chloride (OAC) and octadecyl dimethyl benzyl ammonium chloride (ODBAC). The films with the OMt modified with 50% DDAC exhibited the highest tensile strength of 6.22 MPa. The water vapor permeability (WVP) of the film with the OMt modified with 30% DDAC exhibited a minimum value of 1.63 × 10−10 g · m/m2 · s · Pa. The amount and types of the modifiers in the OMts significantly influenced the structure and properties of the starch/clay nanocomposites. For a given polymer, the modification extent of Mt should be optimized to achieve high‐performance nanocomposites.

Cationic superfine pigment dyeing for wool using exhaust process by pH adjustment

The cationic superfine pigment is prepared using octadecyl dimethyl benzyl ammonium chloride as dispersing agent in order to enable the pigment to dye wool through an exhaust process. Pigment uptake, color strength (K/S value), fastness properties, and penetration were measured. The results show that cationic superfine pigment can be adsorbed on wool under different pHs. Not only dyebath pH but also dyeing time and pigment dosage are found to be closely related to K/S value. The increase of pH results in high pigment uptake and K/S value which increases rapidly beyond or at isoelectric point (PI) of wool. Dry and wet rubbing fastness are improved with the increase of binder dosage, achieving 3 and 3–4 grade respectively as binder amount increases up to 40 % o.w.f. Wool yarns dyed by cationic superfine pigment present better light fastness over 5 grade than those treated with acid dyes. According to micrographs of cross-sections, the distribution of pigment particles on wool fibers shows loop dyeing. It has been demonstrated that it is feasible for cationic superfine pigment to dye wool by pH adjustment.

Effect of Rectorite and Its Organic Modification on Properties of Bitumen

Two organic rectorites (ORECs) were prepared by using cetyltrimethyl ammonium bromide (CTAB) and octadecyl dimethyl benzyl ammonium chloride (ODBA) as organic modifiers to modify the rectorites. Rectorite and OREC modified bitumens were prepared by melt blending. Microstructures of the modified bitumens were characterized by X-ray diffraction (XRD). The effect of rectorite (REC) and its organic modification on the physical and aging properties of bitumen was investigated. X-ray diffraction results show that REC and ODBA-REC modified bitumens form the intercalated nanostructure, whereas CTAB-REC modified bitumen forms an exfoliated nanostructure. Compared with RECs, ORECs show the better compatibility with the bitumen as well as the higher improvement in softening point, viscosity, and aging resistance of the bitumen. The CTAB-REC modified bitumen shows lower viscosity aging index values and softening point increment in comparison with the ODBA-REC modified bitumen, indicating its good aging resistance.

An improvement of color electrophoretic paint via ultrafine modified pigment paste

The ultrafine paste used in electrophoretic paint was prepared via ultrasonic method with pigment yellow 83 (P.Y.83), octadecyl dimethyl benzyl ammonium chloride, and deionized water. The average particle size of the ultrafine paste was only 196 nm and zeta potential was 30 mV with ultrasound for 30 min and 2 wt.% cationic dispersant. The conductivity of the paint was improved as the cationic dispersant increased. Centrifugal stability of the paint with ultrafine paste reached the maximum at 2 wt.% cationic dispersant. Compared with the performances of cathodic electrophoretic paint with the ultrafine yellow paste, the anodic film was smooth, uniform, and neat with 0.5 wt.% cationic dispersant in the ultrafine yellow paste. Deposited amount of the anodic film was 27 g/m2, which was higher than the cathodic film. The curing property, adhesion, and chemical resistance of the cathodic film were better than the anodic film. Properties of five color cathodic paints (blue, yellow, red, black, and green) were discussed and were compared with the film of electrophoretic paint containing commercial pastes. Except the green film, the blue, yellow, red, and black films were smooth, fine, and uniform, and also provided good L-effect. The deposited amount of these films with excellent adhesive force was about 14–19 g/m2. The electrophoretic paints containing modified pigment pastes and commercial pigment pastes present good adhesion and chemical resistance.

Microstructures and thermal aging mechanism of expanded vermiculite modified bitumen

This work evaluates a novel bitumen modification through the use of expanded vermiculite (EVMt) which has been traditionally used as thermal insulation material. In order to improve the compatibility between EVMt and bitumen, EVMt was modified by octadecyl dimethyl benzyl ammonium chloride and marked as organo-expanded vermiculite (OEVMt). A new approach to determine the microstructures of OEVMt modified bitumen was reported by combining the results from X-ray diffraction analysis of OEVMt modified bitumen and the dissolving–filtrating procedure. Aging mechanism of the binders was revealed by using atomic force microscopy (AFM). The results show that OEVMt modified bitumen forms a semi-exfoliated nanostructure. As a result of thin film oven test (TFOT) and situ thermal aging, mass change rate and viscosity aging index are increased, while retained penetration and ductility are decreased of binders. However, these physical changes can be effectively prevented by OEVMt. Aging influences bitumen morphology significantly. TFOT leads to the association of the dispersed domains and the single phase trend of bitumen. These changes are accelerated by situ thermal aging. However, these morphology changes of bitumen are inhibited obviously with the introduction of OEVMt, indicating the good thermal aging resistance of OEVMt modified bitumen with semi-exfoliated nanostructure.

Effect of expanded vermiculite on microstructures and aging properties of styrene–butadiene–styrene copolymer modified bitumen

Organic expanded vermiculites (OEVMTs) were prepared using cetyltrimethyl ammonium bromide (CTAB) and octadecyl dimethyl benzyl ammonium chloride (ODBA) as intercalation agents. Effect of EVMT organic modification on physical and aging properties of styrene–butadiene–styrene (SBS) modified bitumen was investigated. The microstructures of the binders were characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM), respectively. EVMT/SBS modified bitumen forms a phase-separated structure, while OEVMT/SBS modified bitumens form the exfoliated nanostructures according to XRD analysis. OEVMTs show the more obvious influence on physical properties of SBS modified bitumen in comparison with EVMT. The compatibility between the EVMT and SBS modified bitumen is also improved after organic modification of EVMT. AFM analysis indicates that the contrast between the dispersed phase and the matrix phase in SBS modified bitumen increases with the addition of ODBA-EVMT. As a result of thin film oven test (TFOT), the viscosity aging index of SBS modified bitumen decreases, while the retained ductility and penetration increase obviously with the introduction of EVMT and OEVMTs. ODBA-EVMT/SBS modified bitumen has more pronounced improvements in aging resistance of SBS modified bitumen in comparison with CTAB-EVMT/SBS modified bitumen by preventing the phase-separated trend of the SBS modified bitumen during TFOT.

The adsorption of salicylic acid, acetylsalicylic acid and atenolol from aqueous solutions onto natural zeolites and clays: Clinoptilolite, bentonite and kaolin

In this study, adsorption of salicylic acid, acetylsalicylic acid and atenolol from aqueous solutions onto clinoptilolite modified with sorbed metallic cations (Cu(II), Zn(II), Ni(II) or Mn(II)) have been probed. Natural clays (kaolin and bentonite, pure or ion-exchanged by octadecyl dimethyl benzyl ammonium chloride) have been also probed as adsorbents. The adsorption was studied at 30°C by titration microcalorimetry, employed to obtain the heats evolved as a result of adsorption. Adsorption experiments were performed under the same conditions, the equilibrium adsorbate concentrations were determined by fluorescence spectrophotometry. The maximal adsorption capacities of investigated solids against target pharmaceuticals lie in the range of 10−5–10−6mol/g. Modified minerals have shown different capacities in comparison with natural ones. The adsorption capacities are dependent on the characteristics of pharmaceutically active compound. The results obtained in this work show that natural materials can be used effectively in the removal of investigated pharmaceuticals by adsorption.

Effect of expanded vermiculite on aging properties of bitumen

Expanded vermiculite (EVMT) clays modified bitumen was prepared by using EVMT, cetyltrimethyl ammonium bromide (CTAB)–EVMT and octadecyl dimethyl benzyl ammonium chloride (ODBA)–EVMT as modifiers. The morphology characteristic of the modified bitumen was investigated by X-ray diffraction (XRD). The binders were aged by pressure aging vessel (PAV), situ thermal aging and ultraviolet (UV) radiation. The phase-separated structure is observed in EVMT modified bitumen, while CTAB–EVMT and ODBA–EVMT modified bitumen form the intercalated and exfoliated nanostructure, respectively. The mass change rate, viscosity aging index and softening point increment of the binders can be effectively decreased after PAV simulation and situ thermal aging. The improved aging resistance of the binders after thermo-oxidative aging (PAV simulation and situ thermal aging) is more obvious than that after UV aging. Compared with EVMT, organic expanded vermiculites (OEVMTs) have more pronounced improvements in aging resistance of bitumen. In addition, the morphology and aging resistance of OEVMTs modified bitumen depend on the nature of the organic modifiers in OEVMTs.

Adsorptive Removal of 2,6-Dichlorophenol from Aqueous Solution by Surfactant-Modified Palygorskite Sorbents: Equilibrium, Kinetics and Thermodynamics

Raw palygorskite was modified by the addition of selected surfactants, viz. hexadecyltrimethylammonium bromide (CTAB), cetylpyridinium bromide (CPB) and octadecyldimethylbenzyl ammonium chloride (ODBAC). These modified clays were used as sorbents for the adsorptive removal of 2,6-dichlorophenol (2,6-DCP) from aqueous solution. Characterization of the sorbents was achieved by Fourier-transform infrared (FT-IR) analysis, nitrogen adsorption/desorption measurements and particle-size analysis. The adsorptive performance of the modified palygorskites towards the removal of 2,6-DCP from aqueous solution was studied by batch methods. In addition, the influence of contact time, pH and temperature on the adsorption process was investigated in detail.The equilibrium data for the three modified sorbents were well fitted by the Langmuir model. It was found that the monolayer adsorption capacity increased with increasing contact time and solution temperature, respectively. Application of the pseudo-first-order and pse...