Effects of pulsed ultrasound on the adsorption of n-alkyl anionic surfactants at the gas/solution interface of cavitation bubbles

Sonolysis of argon-saturated aqueous solutions of the nonvolatile surfactants sodium dodecyl sulfate (SDS) and sodium 1-pentanesulfonate (SPSo) was investigated at three ultrasonic frequencies under both continuous wave (CW) and pulsed ultrasound. Secondary carbon-centered radicals were detected by spin trapping using 3,5-dibromo-4-nitrosobenzenesulfonic acid (DBNBS) and electron paramagnetic resonance (EPR) spectroscopy. Following sonolysis, -*CH- radicals were observed for both surfactants under both sonication modes. Under CW at 354 kHz, the maximum plateau -*CH- radical yield was higher for SPSo than for SDS, indicating that SDS, which is more surface active under equilibrium conditions, accumulates at the gas/solution interface of cavitation bubbles to a lesser degree, compared with the less surface active surfactant, SPSo. However, after sonolysis (354 kHz) under pulsed ultrasound with a pulse length of 100 ms and an interval of 500 ms, the -*CH- radical yield at the plateau concentrations was higher for SDS than for SPSo due to increased amounts of SDS accumulation on the bubble surfaces. In contrast to the findings following sonolysis at 354 kHz, sonolysis of aqueous surfactant solutions at 620 kHz and 803 kHz showed a higher -*CH- radical yield for SDS compared with SPSo under CW but lower -*CH- radical yield with increasing pulsing interval, indicating a frequency dependence on accumulation. Results indicate that pulsing the ultrasonic wave has a significant effect on the relative adsorption ability of n-alkyl surfactants at the gas/solution surface of cavitation bubbles.     

Protein adsorption to organosiloxane surfaces studied by acoustic wave sensor

Surfaces of the two organosiloxanes, polymercaptopropylmethylsiloxane and octaphenylcyclotetrasiloxane, were prepared on the gold electrodes of thickness-shear mode acoustic wave sensors. Compounds containing the siloxane bond are important in the fabrication of medical implants. The flow-through adsorption of the proteins: human serum albumin, alpha-chymotripsinogen A, cytochrome c, fibrinogen, hemoglobin, immunoglobulin G and apo-transferrin to the two siloxane surfaces and a gold electrode were detected by acoustic network analysis. With the exception of minor wash-off by buffer flow, the adsorption of all proteins to the three surfaces is irreversible. Differences observed for the magnitudes of adsorption for the various cases are ascribed to the role played by molecular interactions at the liquid/solid interface. The results confirm that changes in series resonant frequencies caused by macromolecular adsorption differ significantly from the widely accepted "mass based" model usually employed to characterize the response of this type of acoustic wave device.     

Surface adsorption of zwitterionic surfactants: n-alkyl phosphocholines characterised by surface tensiometry and neutron reflection

The surface adsorption of n-dodecyl phosphocholine (C12PC) has been characterised by a combined measurement of surface tension and neutron reflectivity. The critical micellar concentration (CMC) was found to be 0.91 mM at 25 degrees C in pure water. At the CMC, the limiting area per molecule (A(cmc)) was found to be 52+/-3 A2 and the surface tension (gamma(cmc)) to be ca. 40.0+/-0.5 mN/m. The parallel study of chain isomer n-hexadecyl phosphocholine (C16PC) showed a decrease of the CMC to 0.012 mM and a drop of gamma(cmc) to 38.1+/-0.5 mN/m. However, A(cmc) for C16PC was found to be 54+/-3 A2, showing that increase in alkyl chain length by four methylene groups has little effect on A(cmc). The almost constant A(cmc) suggested that the limiting area per molecule was determined by the bulky PC head group. It was further found that the surface tension and related key physical parameters did not vary much with temperature, salt addition, solution pH or any combination of these, thus showing that surface adsorption and solution aggregation from PC surfactants is largely similar to the zwitterionic betaine surfactants and is distinctly different from ionic and non-ionic surfactants. The thickness of the adsorbed monolayers measured from both dC12hPC and dC16hPC was found to be 20-22 A at the CMC from neutron reflectivity. Neither A(cmc) nor layer thickness varied with alkyl chain length, indicating that as the alkyl chain length became longer it was further tilted away from the surface normal direction and the layer packing density increased. It was also observed that the thickness of the layer varied little with surfactant concentration, indicating that the average conformational orientation of the alkyl chain remained unchanged against varying surface coverage.     

Efficient synthesis of alkyl 2,3-unsaturated glucopyranosides from glycals mediated by ytterbium(III) triflate-trialkyl aluminum

Treatment of glycals with trialkylaluminum in the presence of a catalytic amount of Yb(OTf)₃ leads to the corresponding alkyl 2,3-unsaturated glycosides in good to excellent yields. Reactions of protected glycals are achieved under very mild conditions.     

Evaluating adsorption ability of granite to radioselenium by chemical sequential extraction

A good understanding of the migration of selenite, Se(IV), through deep granitic layers depends on a good understanding of the geochemistry of these layers. Chemical sequential extraction is applied herein to evaluate the ability of granite to adsorb Se(IV) in DW, GW and SW systems. The experimental results indicate that the removal of crystalline Fe oxides reduces the adsorption of Se(IV), suggesting its importance in granite. The normalized concentrations of Se(IV) adsorbed onto crystalline Fe oxides is approximately 0.0301, 0.0330 and 0.0335 mole Se(IV) adsorbed/mole of Fe in DW, GW and SW systems. Kinetic adsorption experiments are conducted to elucidate the results of the chemical sequential extraction. Both the treated and the untreated granite take the same time to reach their equilibrium, suggesting that crystalline Fe oxides dominate the adsorption of Se(IV). Meanwhile, the one-site model suffices to simulate the kinetics of adsorption.     

Synthesis of novel heptaplatin derivatives and evaluation of their ability to inhibit proliferation of cancer cell lines

A series of novel heptaplatin derivatives were synthesized and evaluated for their ability to inhibit growth of two cancer cell lines: human colon carcinoma cell line HCT-8 and human hepatocarcinoma cell line Bel-7402. Majority of the synthesized compounds demonstrated superior activity against cancer cell lines compared to heptaplatin. Specifically, compounds 5a and 5b (5 µg/mL) had more pronounced efficacy against the HCT-8 cell line while 6b and 6c (0.5 µg/mL) had higher efficacy against Bel-7402 cell line.     

Dynamic adsorption properties of Kr and Xe isotopes in charcoal

Some batches of²³³U oxide product obtained from the reprocessing treatment of irradiated thorium rods, called J-rods in our plant, have been found to contain thorium as much as 85% and iron above 5% as impurities. This product has to be purified before sending for fabrication of the fuel. The present purification method consists of the following three steps: (1) preferential dissolution of U₃O₈ as compared to thoria, (2) a novel solvent extraction process, and (3) preferential precipitation of Th as oxalate leaving behind the entire U in the filtrate. Development and application of the present purification method to the above²³³U oxide proxduct are presented in this paper.     

Binary solvent mixture adsorption as a characterisation tool to determine the hydrophilic/hydrophobic properties of multiwall carbon nanotubes

A simple method is offered to quantitatively characterise the hydrophobic/hydrophilic properties of carbon nanotubes by measuring binary solvent mixture adsorption.     

Correlation between acoustic cavitation noise and yield enhancement of sonochemical reaction by particle addition

The mechanism of the effect of particle addition on sonochemical reaction is studied through the measurements of frequency spectrum of sound intensity for evaluating the cavitation noise and the absorbance for the liberation of iodine from an aqueous solution of KI as an index of oxidation reaction by ultrasonic irradiation in the presence or absence of alumina particles. As it is expected that both the acoustic noise and a rise in temperature in the liquid irradiated by intense ultrasound will increase with the number of collapsing bubbles, these are supposed to be the best tools for evaluating the relative number of bubbles. In the present investigation, it has been shown that the addition of particles with appropriate amount and size results in an increase in the absorbance when both the acoustic noise and the rise in the liquid temperature due to cavitation bubbles also increase. This suggests that the enhancement in the yield of sonochemical reaction by appropriate particle addition comes from an increase in the number of cavitation bubbles. The existence of particle in liquid provides a nucleation site for cavitation bubble due to its surface roughness, leading to the decrease in the cavitation threshold responsible for the increase in the number of bubbles when the liquid is irradiated by ultrasound. Thus, from the present investigation, it is clarified that the particle addition has a potential to enhance the yield in the sonochemical reaction.     

Effect of lipophilicity of C60 fullerene derivatives on their ability to inhibit peroxide oxidation of lipids in aqueous medium

The aqueous solutions of C₆₀ fullerene derivatives were studied by means of dynamic light scattering, their effect on the peroxide oxidation of lipids (POL) in aqueous solutions was investigated via chemiluminescence method. It was shown that the colloidal solubility in water, which defines the antioxidant activity of C₆₀ fullerene derivatives during POL, is controlled by the chemical structure of the addend added to C₆₀ fullerene. For the studied derivatives, the direct dependence of the efficiency of POL inhibition on the lipophilicity was established.     

The adsorption of dyestuffs from aqueous solutions using the activated carbon adsorption model to determine breakthrough curves

A series of breakthrough curves for the adsorption of Deorlene Yellow and Telon Blue on carbon have been used to test a kinetic model. The model is based on the unreacted core theory and assumes resistances due to external mass transfer and pore diffusion, and irreversible adsorption. The experimental and theoretical data are well correlated by the model at low dye flow rates, but the model was modified at high dye flow rates. The effective diffusivities are 4.0 × 10⁻¹⁰ m² s⁻¹ and 3.0 × 10⁻¹⁰ m² s⁻¹ for Deorlene Yellow and Telon Blue respectively.     

Preparation of dithiocarbamatecellulose derivatives and their adsorption properties for trace elements

Tosylcellulose was treated separately with aniline, benzylamine, n-butylamine and piperazine to give four different aminocelluloses which were further treated with carbon disulfide to furnish four dithiocarbamatecelluloses (AND, BZD, BUD and PID). A comparative study was made of their performance as adsorbents for several kinds of metal ions. PID, which has the highest degree of substitution of the dithiocarbamate group of the four derivatives obtained, was investigated for its adsorption behavior towards Ag⁺, As⁵⁺, Cd²⁺, Co²⁺, Cr³⁺, Cr⁶⁺, Cu²⁺, Fe³⁺, Hg²⁺, Mn²⁺, Pb²⁺, Sb⁵⁺; Se⁴⁺, Te⁴⁺ and Zn²⁺. PID showed good adsorption characteristics with relatively large capacities for Ag⁺, Cr⁶⁺, Cu²⁺, Hg²⁺, Pb²⁺ and Se⁴⁺ ranging from 9.5 to 370 mg g^-1 of resin.     

Preparation of surface-charged CNF aerogels and investigation of their ion adsorption properties

Cross-linked cellulose nanofibril (CNF) aerogel with positive and negative surface charge was prepared. For the surface charge modification of CNF from its intrinsic negative charge to positive charge, glycidyltrimethylammonium chloride was used. To stabilize the network structure of CNF aerogel in aqueous condition, maleic acid and sodium hypophosphite cross-linking treatment was applied. The ion adsorption properties of positive and negative charged cross-linked CNF aerogels were evaluated using the Langmuir adsorption model, and it was affected by pH of the ion solution. The maximum ion adsorption capacity of negatively charged cross-linked CNF aerogel was 0.79 mmol/g for the nickel cation while that of the positively charged cross-linked aerogel was 0.62 mmol/g for the permanganate anion.     

MgO/Al_2O_3吸附剂对CO_2动态吸附性能的研究

以γ-Al2O3为载体,采用等体积浸渍法制取MgO/Al2O3吸附剂,利用BET、XRD等表征手段对吸附剂进行表征;并通过固定床测量穿透曲线的方法研究其对CO2动态吸附性能的影响,考察了MgO负载量、吸附温度、气体流量等因素对吸附剂吸附CO2性能的影响,同时还通过多次吸脱附实验考察MgO/Al2O3吸附剂的稳定性和再生能力。结果表明,MgO负载量为10%的吸附剂,吸附温度在50℃左右,流量为45 mL/min动态吸附量最大;经数次循环后材料的结构性质和吸附性能未见明显变化,可再生性能比较优异,是一种潜在的可工业化应用的CO2吸附剂。     

p-Phenylene sulfide oligomers and their properties. Ar-S couplings mediated by copper or by fluorine substitutions

A series of monodisperse p-phenylene sulfide oligomers were efficiently synthesized by using a bidirectional growth. A strategy combining Cu-catalyzed Ar-S couplings for small oligomers and fluorine aromatic substitutions by aryl thiolates for longer ones was put forward. The latter method is superior to Cu-catalyzed reactions for longer oligomers. Fluorine chemistry brings some new advantages such as solubility and reactivity. Qualitative crystallinity studies were reported according to the oligomer size and the functional series, by using a microscope equipped with a heating stage and a camera.     

Controlling the shifting degree of interpenetrated metal-organic frameworks by modulator and temperature and their hydrogen adsorption properties

For the first time, the shifting degree of pcu-type interpenetrated framework was well controlled by employing a modulator and changing the temperature, in which their evacuated samples are almost non-crystalline products with different meso- and microstructures, resulting in different hydrogen adsorption properties.     

The properties of anions which determine the extractability of their associates with triarylmethane dyes

Conclusions Some properties of anions which affect the extraction of their ionic associates with organic cations have been studied in the present paper. A comparison of these properties is exceedingly difficult even for ions of a single type. Almost any change in the composition of the ion (for example, the substitution of one ligand for another with similar properties: Cl and Br) involves the simultaneous change of the size and effective charge of the ion, the metal-ligand bond stability, and so on. It is not always possible to isolate the factor which has the main influence on the properties of the associate. Besides, the maximum activity of various ions is observed at various acidities in the aqueous phase, and the acidity strongly affects the activity of the dye and its tendency toward association [5]. Nevertheless, the relationships developed herein allow us to interpret the experimental material in several cases and do not exclude the possibility of making predictions for the trends studied.Ural Scientific Research Chemical Institute, Sverdlovsk; Institute of Inorganic Chemistry, Siberian Division, Academy of Sciences, USSR, Novosibirsk. Translated from Zhurnal Strukturnoi Khimii, Vol. 8, No. 2, pp. 216–220, March–April, 1967.     

Synthesis of MPTS-modified cobalt ferrite nanoparticles and their adsorption properties in relation to Au(III)

Cobalt ferrite magnetic nanoparticles (Co-MNP) were prepared by a co-precipitation method and subsequently coated with (3-mercaptopropyl)trimethoxysilane (MPTS) for the extraction and recovery of Au(III) from aqueous chloride solutions. Physical characterization of the MPTS-modified particles (Co-MPTS) was performed using FT-IR, TGA, and SEM. Results from FT-IR confirmed that MPTS was present on the surface of the magnetic nanoparticles. The amount of MPTS was 0.36 mmol g⁻¹ of Co-MPTS, obtained by elemental analysis. SEM images revealed aggregates composed of nanocrystalline Co-MPTS particles. The extraction efficiency as a function of the pH, contact time, and initial Au(III) concentration was evaluated. The modified particles showed maximum adsorption in the pH range from 1.0 to 4.0. The adsorption behavior of Co-MPTS toward Au(III) followed a Langmuir isotherm and the maximum adsorption capacity was found to be 120.5 mg g⁻¹. The stability of the modified materials was improved as compared to that of bare Co-MNP. The subsequent desorption of gold could be achieved by using acidified thiourea solution; the highest gold recovery reached 85%.