Adsolubilization Of 2-naphthol Research Articles

Adsolubilization by a photo-responsive surfactant

We have characterized the adsolubilization of 2-naphthol into the adsorbed layer of a photo-responsive surfactant. The surfactant used in this study was 1′(6-trimethylammoniohexyl)-3′,3′-dimethyl-6-nitrospiro-(2H-1-benzopyran-2,2′-indoline) bromide (SP-Me-6). Visible light incident to the aqueous solution of SP-Me-6 results in the isomerization from the merocyanine (MC) form to the spiro (SP) form, whereas the isomerized SP form reverts to the MC form when the surfactant solution is stored in the dark. In our previous paper, we reported that the photo-isomerization occurs even after the surfactant adsorption on silica. In our current study, the amounts of adsorbed SP-Me-6 and adsolubilized 2-naphthol were measured through a depletion method in a colloidal silica system. The adsolubilized amount of 2-naphthol is observed to be greater for the MC form than for the SP form. It seems likely that the planar and zwitterionic MC structure facilitates the adsolubilization of 2-naphthol. We also performed quartz crystal microbalance with dissipation monitoring (QCM-D) measurements to assess conformational information about the SP-Me-6 layer formed at the silica/aqueous solution interface. One of the key findings in these QCM-D studies is the fact that the adsolubilization induces swelling of the adsorbed aggregates, and this swelling occurs more significantly for the MC form than for the SP form.

Electrochemically Assisted Visible Light Photocatalysis in a Heterosupramolecular System Consisting of α-Fe2O3 and Surfactant Molecular Assembly

The synergy of an anodic-biased alpha-Fe2O3 film and a cationic surfactant molecular assembly leads to a high visible light induced activity for 2-naphthol oxidation and high stability. An abrupt increase in the photocatalytic activity at a surfactant concentration of ca. 0.2 mmol dm(-3) results from the adsolubilization of 2-naphthol into the hydrophobic nanospace of the surfactant bilayer formed on the alpha-Fe2O3 surface. Also, the surfactant bilayer provides sustainable photocurrent during the reaction.

Adsolubilization of 2-naphthol into adsorbed layers of triblock PEO–PPO–PEO copolymers on hydrophobic silica particles

Adsolubilization of 2-naphthol into an adsorbed layer of triblock poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) (PEO–PPO–PEO, Pluronics) copolymers on hydrophobically modified silica particles has been investigated. Four kinds of Pluronics (P103, P105, P123, and F108) were employed in order to understand the effect of the hydrophobicity of the surfactants on the adsolubilization. The amount of the Pluronics adsorbed of the maximum/saturation adsorption level was increased with a decrease in the HLB value, suggesting that the more hydrophobic Pluronics (P103 and P123) adsorb preferentially onto the hydrophobic silica surface over the more hydrophilic Pluronics (P105 and F108). The greater adsorbed amount of the more hydrophobic surfactants resulted in a greater amount of 2-naphthol adsolubilized into the adsorbed Pluronics layers. In the case of simultaneous addition of the Pluronics and 2-naphthol, the amount adsolubilized into the adsorbed P123 and P103 layers increased in their low-surfactant-concentration regime, reached a maximum, and then decreased with a further increase in the Pluronics concentration. On the other hand, for both the P105 and F108 copolymers, a decrease in the adsolubilized amount was not observed over the whole range of copolymer concentration investigated. This difference is attributed to a difference in the hydrophobicity of the micellar aggregates in solution and of the adsorbed layers on the hydrophobic surface. When 2-naphthol was added after replacement of the Pluronics supernatant by a surfactant-free solution, the final decrease in the adsolubilization was insignificant for all the Pluronics. Indeed, the maximum amount of adsolubilization was comparable to the corresponding amount obtained in the case of simultaneous addition.

Adsolubilization of 2-naphthol into adsorbed layer of PEO–PPO–PEO triblock copolymers on hydrophilic silica

Adsolubilization of 2-naphthol into an adsorbed layer of poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) (PEO–PPO–PEO) triblock copolymers (Pluronics) on hydrophilic silica has been investigated. Four kinds of Pluronics (P103, P105, P123, and F108) were used in order to understand the effect of the hydrophobicity of surfactant on the adsolubilization. The order of the adsorption in the saturation level was found to be P123 ≈ P103 > P105 ≫ F108, meaning that Pluronics with higher hydrophobicity can adsorb preferentially to the silica surface. Indeed, this order was parallel to the order of the adsolubilization amount of 2-naphthol. In the case of co-addition of the Pluronics and 2-naphthol, the adsolubilization amount increased gradually at lower surfactant concentration regions, reached a maximum, and then decreased with increasing concentration of the Pluronics. The maximum amount appeared at critical polymolecular micelle concentration of each Pluronics. On the other hand, the final decrement was not observed when 2-naphthol was added after replacement of the Pluronics supernatant by the Pluronics free solution. These results suggest that adsolubilization behavior is influenced by the existence of the polymolecular micellar aggregates in the solution phase.

二酸化チタンに形成されたフッ化炭素界面活性剤吸着層への二種類の有機化合物の吸着可溶化

The binary adsolubilization behaviors of 2-naphthol+biphenyl and 2-naphthol+1,3-dichlorobenzene in a cationic fluorocarbon surfactant adsorbed layer formed on TiO 2 have been investigated as a function of pH. In the binary adsolubilization of 2-naphthol+biphenyl, the adsolubilized amount of 2-naphthol increases gradually until pH 7 and then sharply with a further increase of pH, whereas the adsolubilization of biphenyl is not observed in the wide pH region. In the binary adsolubilization of 2-naphthol +1,3-dichlorobenzene, the adsolubilization behavior of 2-naphthol shows a similar trend as that of 2-naphthol+biphenyl system, while the adsolubilized amount of 1,3-dichlorobenzene increases gradually with pH from 3 to 10. The enhancement in the adsolubilization of 2-naphthol at high pH is attributed to the interaction between deprotonated 2-naphthol and the cationic surfactant as well as the increase of interaction between negatively charged TiO 2 and the surfactant. The adsolubilized sites for binary adsolubilization of 2-naphthol+1,3-dichlorobenzene are also discussed from the admicellar partitioning coefficients.

シリカ/水界面での陽イオン性多鎖型界面活性剤による2-ナフトールの吸着可溶化

Adsolubilization of 2-naphthol by cationic multi-chained surfactants such as gemini (m-2-m, m=alkyl chain length ; 10-2-10, 12-2-12) and trimeric surfactants (m-2-m-2-m ; 10-2-10-2-10, 12-2-12-2-12) on silica has been investigated. For comparison, a similar experiment has been performed using a cationic single-chained surfactant, dodecyltrimethylammonium bromide (DTAB). Adsorption of the surfactants increases with an increase of the concentration and reaches a saturation, while adsolubilization of 2-naphthol increases and shows a maximum and then decreases with the surfactant concentration for all the surfactant systems. The ratio of maximum amount of 2 -naphthol adsolubilized to the adsorbed amount of surfactant on silica is decreased as in the order, 10-2-10-2-10> 12-2-12-2-12>12-2-12=DTAB>10-2-10. In addition, the order of the ratio per one-hydrocarbon chain is 10-2-10-2-10 =12-2-12>12-2-12-2-12 =10-2-10, where the ratio of DTAB is considerably large compared to those of the multi -chained surfactants. These results can be interpreted by the compactness of surfactant adsorbed layer. The effect of the surfactant structure on the adsolubilization is also discussed using admicellar partitioning coefficients of 2-naphthol.

陰イオン性と非イオン性界面活性剤混合系を用いたアルミナ粒子上での2-ナフトールの高効率な吸着可溶化

The adsolubilization of 2-naphthol by mixtures of an anionic surfactant, sodium dodecyl sulfate (SDS), and nonionic surfactants, hexaoxyethylenedecyl ether (C 1 0 E 6 ), and hexaoxyethylenedodecyl ether (C 1 2 E 6 ) on alumina was investigated. Adsorption and adsolubilization were performed using a feed concentration of SDS under various fixed concentrations of the nonionic surfactants. The adsolubilization of 2-naphthol increased with an increase of the fixed nonionic surfactant concentration, showed a maximum and then decreased with a further increase of nonionic surfactant concentration for both SDS/C 1 0 E 6 and SDS/C 1 2 E 6 systems. The adsolubilization of 2-naphthol was greater for SDS/C 1 0 E 6 and SDS/C 1 2 E 6 systems than that for SDS single system. Furthermore, the adsolubilization efficiency defined by ratio of 2-naphthol adsolubilized to total surfactant adsorbed amount was higher for SDS/C 1 2 E 6 system than that for SDS/C 1 0 E 6 system at the maximum adsolubilization. This difference in the efficiency between SDS/C 1 0 E 6 and SDS/C 1 2 E 6 systems is attributed to the properties of the mixed-surfactant adsorbed layer which are affected by the hydrocarbon chain lengths of nonionic surfactants.

Adsolubilization of 2-Naphthol by Binary Mixtures of Cationic and Nonionic Surfactants on Silica

The adsolubilization of 2-naphthol by binary mixtures of cationic and nonionic surfactants on silica was investigated. Two cationic surfactants used were hexadecyltrimethylammonium bromide (HTAB) and 1,2-bis(dodecyldimethylammonio)ethane dibromides (2RenQ), and a nonionic surfactant used was hexaoxyethylenedecyl ether (C10E6). In the single surfactant systems, adsolubilization of 2-naphthol for HTAB and 2RenQ was very similar and was greater than that for C10E6. In the HTAB/C10E6 system the adsolubilization of 2-naphthol was enhanced by surfactant mixtures of HTAB and C10E6 compared to those of single systems. However, in the 2RenQ/C10E6 system the adsolubilization of 2-naphthol by surfactant mixtures of 2RenQ and C10E6 was rather smaller than that of 2RenQ alone but still larger than that of C10E6. It is found that the adsorbed layers of surfactant mixtures formed from different surfactant structures exhibit different adsolubilization behaviors of 2-naphthol, and the alkyl chain length of the surfactants is an important factor to correlate with the adsolubilization of 2-naphthol.

Mixed Surfactant Adsolubilization of 2-Naphthol on Alumina

The adsolubilization of 2-naphthol by surfactant mixtures of an anionic surfactant, sodium dodecyl sulfate, and a nonionic surfactant, hexaoxyethylenedodecyl ether on alumina was investigated. In a single-surfactant system, only the anionic surfactant was found to show an appreciable adsolubilization. In the mixed-surfactant system, the adsolubilization grew with an increase in the total amount of adsorbed surfactant, whereas the adsolubilization became greater with an increase in the anionic surfactant content in the initial mixtures. On the other hand, the ratios of adsolubilized amount to surfactant adsorbed amount became smaller when the anionic surfactant content in the initial mixtures increased. This behavior is attributed to the properties of the mixed-surfactant adsorbed layer at the alumina−water interface.

Adsorption and adsolubilization of surfactants on titanium dioxides with functional groups

Adsorption of ionic surfactants on titanium dioxide with dodecyl chain groups or quaternary ammonium groups (XN m, where m is the carbon number of the alkyl chain, 4–16) was investigated. The adsorbed amount of cationic surfactants (dodecyltrimethylammonium bromide, DTAB; 1,2-bis(dodecyldimethylammonio)ethane dibromide, 2RenQ) on titanium dioxide with dodecyl chain groups increased with increasing concentration of the dodecyl chain due to hydrophobic interaction, where the adsorbed amounts of DTAB at saturation was considerably greater than those of 2RenQ. Adsorption of an anionic surfactant (sodium dodecyl sulfate, SDS) on XN m occurred mainly due to both electrostatic attraction force and hydrophobic interaction, depending on the alkyl chain length on XN m. On the other hand, adsorption of cationic surfactants, DTAC and 2RenQCl (their counter ions are chloride ions), on XN m was quite smaller compared with that of SDS due to electrostatic repulsion force. Adsolubilization of 2-naphthol in the surfactant-adsorbed layer on the titanium dioxides with the functional groups was also studied. The adsolubilized amounts of 2-naphthol on titanium dioxide with dodecyl chain groups were enhanced by adsorption of DTAB, but no distinct increase in the adsolubilization was observed by adsorption of 2RenQ. In the case of XN m, the amount of 2-naphthol adsorbed in the absence of surfactants increased with increasing alkyl chain length on XN m. Further, an appreciable increase in the adsolubilization of 2-naphthol on XN m with adsorption of 2RenQCl was observed. It was found from the admicellar partitioning coefficients that the adsolubilization of 2-naphthol preferably occurs on XN m by adsorption of SDS or 2RenQCl compared with that by DTAC. These differences in the adsolubilization were discussed by microproperties of the surfactant-adsorbed layers estimated using a spin probe.

Reexamination of 2-Naphthol Adsolubilization on Alumina with Sodium Dodecyl Sulfate Adsorption

Adsolubilization behavior of 2-naphthol on alumina with adsorption of sodium dodecyl sulfate (SDS) at pH 3.5 in the presence of 10 mmol dm−3 NaCl was reexamined. The adsolubilized amount of 2-naphthol increased sharply and reached a maximum, then decreased with SDS concentration. The decrement of the adsolubilized amount began below the critical micelle concentration of SDS. From the dispersion state of the alumina suspension and the SDS adsorption isotherm, it is demonstrated that the decrement of adsolubilization of 2-naphthol is not due to the partition of 2-naphthol between the SDS adsorbed layer and SDS micelles, but is due to the difference of SDS adsorption states such as monolayers and admicelles.

Adsorption and Adsolubilization Behaviors of Cationic Surfactant and Hydrophobically Modified Polymer Mixtures on Na−Kaolinite

The adsolubilization of 2-naphthol by tetradecyltrimethylammonium bromide (TTAB) and by mixtures of TTAB and hydrophobically modified polyacrylamide (HMPAM) on Na-kaolinite was investigated. At concentrations of TTAB in the region of the CMC, only small differences were found in the amounts of 2-naphthol adsolubilized in the presence and in the absence of HMPAM. However, at much lower TTAB concentrations, adsolubilization of 2-naphthol onto the Na-kaolinite surface was greatly enhanced in the presence of HMPAM. The stability of the clay dispersion was found to be strongly diminished by the addition of HMPAM.

Adsorption of sodium dodecyl sulfate on hydrotalcite and adsolubilization of 2-naphthol

Adsorption behavior of sodium dodecyl sulfate (SDS) on hydrotalcite was investigated by measuring the amount of SDS adsorbed, ζ potential and pyrene fluorescence spectra of suspensions. The amount of SDS adsorbed increased sharply and then reached a plateau with SDS concentration, accompanying the change of ζ potential from positive to negative. The X-ray diffraction and fluorescence measurements show that the interlayer separation of hydrotalcite increases, while the microenvironment of SDS adsorbed layer becomes hydrophobic with SDS concentration. The amount of 2-naphthol adsolubilized increased considerably at low SDS concentration and then decreased gradually with SDS concentration. In addition, the amount of 2-naphthol adsolubilized increased proportionally with increasing feed concentration of 2-naphthol.

Adsorption Characteristics of Cationic Surfactants on Titanium Dioxide with Quaternary Ammonium Groups and Their Adsolubilization

Adsorption of cationic surfactants on titanium dioxide with quaternary ammonium groups (XNm, where m is the carbon number of the alkyl chain, 4–16) was investigated by measuring the amount of adsorbed surfactants, ζ potential, and dispersion stability. The cationic surfactants used were dodecyltrimethylammonium chloride (DTAC) and 1,2-bis(dodecyltrimethyl ammonio) ethane dichloride (2RenQCl). The amount of surfactants adsorbed increased with increasing chain length of XNm, accompanying a gradual increase of ζ potential. The dispersion stability of XNm was very high in a whole surfactant concentration region except that of untreated titanium dioxide. The electron spin resonance measurements using a spin probe methyl 12-doxylstearate show that the order parameters are very similar for XN4-12, but the order parameter for XN16 is higher than that for XN4-12. Adsolubilization of 2-naphthol on XNm by adsorption of surfactants was also carried out: the amount of 2-naphthol adsolubilized increased with increasing surfactant concentration where the amount adsolubilized increased with increasing chain length of XNm. Further, the adsorption of 2RenQCl enhanced the amount adsolubilized greater than by the adsorption of DTAC.

Adsorption of Sodium Dodecyl Sulfate and 2-Naphthol Adsolubilization on Titanium Dioxide with Quaternary Ammonium Groups

The adsorption behavior of sodium dodecyl sulfate (SDS) was investigated on titanium dioxide with quaternary ammonium groups (XNm, m is the carbon number of the alkyl chain, 4-16) by measuring amount adsorbed, ζ potential, and dispersion stability. The amount of SDS adsorbed increased sharply at low SDS concentration, reached a constant level on XN4, XN8, and XN12, and gradually increased on XN16. However, the amount of SDS adsorbed on untreated titanium dioxide was significantly low compared with that on XNm. The suspensions of XNm created by adsorption of SDS showed a dispersion-flocculation-redispersion sequence, accompanying a change in the ζ potential from positive to negative for all XNm. The flocs formed could be transferred to a toluene phase by adding toluene to the XNm suspensions, indicating that the flocs of all XNm are hydrophobic regardless of different alkyl chain lengths. The order parameter of methyl 12-doxylstearate located in the SDS adsorbed layer estimated by electron spin resonance shows that the mobilities of the probe are not restricted in the SDS adsorbed layer for all XNm. Adsolubilization behavior of 2-naphthol in the SDS adsorbed layer on XNm was peculiar; the amount of 2-naphthol adsolubilized was insensitive to the SDS concentration and was almost the same as the amount of 2-naphthol adsorbed on XNm in the absence of SDS, where the amount of 2-naphthol adsorbed increased with increasing alkyl chain length of XNm. In the case of untreated titanium dioxide, the amount of 2-naphthol adsolubilized increased with the SDS concentration, reached a maximum, and then decreased. Thus, the adsolubilization behavior of 2-naphthol for XNm was significantly different from that for untreated titanium dioxide.

Cationic Surfactant Adsolubilization of 2-Naphthol and Naphthalene with Titanium Dioxide Having Dodecyl Chain

Adsolubilization of 2-naphthol and naphthalene by cationic surfactant-adsorbed layers formed on titanium dioxides with or without a dodecyl chain was investigated. The cationic surfactants used were dodecyltrimethylammonium bromide and 1,2-bis(dodecyldimethylammonio) ethane dibromide (2RenQ). It was found that the adsolubilized amounts of 2-naphthol and naphthalene increase and reach a maximum and then decrease for both surfactants and titanium dioxides with or without the dodecyl chain, where in the absence of surfactants the incorporated amount of naphthalene on the titanium dioxide with the dodecyl chain is markedly large. The adsolubilized amounts of 2-naphthol and naphthalene were enhanced with the titanium dioxide with the dodecyl chain by adsorption of surfactants, in particular 2RenQ. The admicellar partitioning coefficients also showed that naphthalene is adsolubilized preferentially rather than 2-naphthol and the surface treatment with the dodecyl chain enhances the adsolubilization for two adsolubilizates.

シリカ上の第四級アンモニウム陽イオン性界面活性剤吸着層への2-ナフトールの吸着可溶化

シリカ上の第四級アンモニウム陽イオン性界面活性剤吸着層への2-ナフトールの吸着可溶化

Adsolubilization Behavior of 2-Naphthol into Adsorbed Anionic Surfactant and Poly(vinylpyrrolidone) at an Alumina/Water Interface

Adsolubilization of 2-naphthol in a polymer-surfactant layer on alumina has been studied. Two systems are explored: poly(vinylpyrrolidone) (PVP-sodium dodecyl sulfate (SDS) and PVP-sodium bis(2-ethylhexyl) sulfosuccinate (Aerosol OT). Under a constant feed concentration of PVP, the adsolubilized amounts of 2-naphthol increase sharply at low surfactant concentration, reach a maximum, and then decrease with the surfactant concentration. This sharp increment is attributed to a formation of complex between PVP and surfactant on alumina. The subsequent decrease in the adsolubilization is caused by the decrement of PVP adsorption and by partitioning 2-naphthol into a bulk complex of PVP-surfactants and surfactant micelles. Compared with two systems, although the adsorbed amount of SDS becomes considerably smaller with increasing feed concentration of PVP than that of Aerosol OT, the maximum adsolubilized amounts of 2-naphthol are not so different with the feed concentration of PVP. From fluorescence measurements, it is found that the polarity of SDS adsorbed layer on alumina upon addition of PVP is significantly decreased, whereas that of Aerosol OT is hardly changed upon addition of PVP. In the PVP-SDS system, the increment in the adsolubilization of 2-naphthol is correlated with the polarity change of the adsorbed layer, while in the PVP-Aerosol OT system it is attributed to the increase of the hydrophobic capacity by adsorption of PVP-Aerosol OT

Adsolubilization of 2-Naphthol into Polymer-Surfactant Adsorbed Layer on Alumina

Adsolubilization of 2-Naphthol into Polymer-Surfactant Adsorbed Layer on Alumina