Fast and Efficient Removal of Cationic Dye Using Graphite Oxide,Adsorption, and Kinetics Studies

Dye adsorption on graphite oxides, which were prepared by different methods, was compared for the first time. The adsorption process was followed using ultraviolet-visible spectroscopy, while the adsorbents before and after adsorption were characterized using physicochemical and spectroscopic techniques. Surprisingly, we found that higher oxidation degree of graphite oxide resulted in higher adsorption efficiency for methylene blue (MB), while the ultrasonic exfoliation of graphite oxide impaired the adsorption efficiency. Among all samples investigated, graphite oxide prepared by modified Hummers' method (HmGO) before ultrasonic exfoliation exhibited the best adsorption capacity of MB. It is pretty high compared with other reported absorbents for MB. The experiment conditions such as pH, adsorbent dosage, stirring speed and adsorption time on adsorption of MB on graphite oxide, as well as adsorption kinetics and isotherms, were also investigated. The maximum adsorption capacity of graphite oxide is 751.9 mg · g^?1 based on the Langmuir model. [Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Dispersion Science and Technology to view the free supplemental file.]     

Adsorption and Aggregation Behavior of n-Undecyl Ammonium Acetate Ionic Liquid in Aqueous Solution

A surface active ionic liquid (IL), [CH₃(CH₂)₁₀NH₃][OOCCH₃], was synthesized and characterized by FTIR, ¹H NMR, and ¹³C NMR. Its surface activity and aggregation behavior in aqueous solution were investigated using surface tension measurements, conductivity measurements, transmission electron microscopy (TEM), and dynamic light scattering (DLS). The results reveal that the CAC and γ_cac of this IL are 15.3 mM and 23.1 mN/m, respectively. We observed a strong interaction between the counter-ions, leading to ion pairs that self-assemble into spherical vesicles in aqueous solution, with an average diameter in the range of 120 to 130nm.     

Surface Activity of Novel Polymerizable Anionic Polyoxyethylene 4-Nonyl-2-Prpylene-Phenyl Ether Ammonium Sulfate Succinate Surfactants

Novel polymerizable surface-active monomers were synthesized by successive treatment of polyoxyethylene 4-nonyl-2-prpylene-phenyl ether ammonium sulfate with maleic anhydride in the presence of hydroquinone at temperature of 180°C. The molecular structures of the polymerizable surfactants were confirmed by ¹H and ¹³C NMR spectroscopy. The surface tension isotherms on the air-water solution interface were obtained. The critical micelle concentrations (cmc) as well as the surface tension at the cmc were determined for these substances. The micellization and adsorption of the prepared anionic surfactants have been investigated by surface tension, and cloud point measurements. Surface parameters such as surface excess concentration (Γ _max), the area per molecule at interface (A _min) and the effectiveness of surface tension reduction (π_CMC) were determined from the adsorption isotherms of the prepared surfactants.      

Stability of Nanoporous Silica Aerogel Dispersion as Wettability Alteration Agent

This work studies the stability of silica aerogel aqueous dispersion for wettability alteration in enhanced oil recovery (EOR) processes. Modified silica aerogel is synthesized with cheap water glass as the precursor, and ambient pressure drying method. Brine composition, brine concentration and temperature of oil reservoirs are the most important parameters for success of wettability alteration processes in EOR. Stability of Silica aerogel aqueous dispersions in NaCl, MgCl₂ and combinations of them are surveyed. Brines at different concentrations, 10000, 20000, 40000 ppm, are used to determine stability conditions. Stability at 30°C and 75°C are surveyed, and the results are reported. DLVO and non-DLVO theories are used for modeling the stability of nanodispersion.     

Adsorption of Cd(II) Ions onto Activated Carbon Prepared from Hazelnut Husks

In this study, a batch adsorption of Cd(II) ions onto activated carbon (AC) produced from hazelnut husks were investigated. The factors controlling the adsorption process such as initial pH, agitation time, dosage and initial concentration have been examined. The AC was showed a high affinity to Cd(II) ions at pH values between 5.0 and 7.0. The equilibrium time was found to be 300 minutes. Cd(II) adsorption equilibrium was analyzed with both Langmuir and Freundlich isotherm equations and it was found that Langmuir equations fitted well with the experimental data. Maximum Cd(II) adsorption capacity of AC was calculated to be 20.9 mg g^?1. Cd(II) adsorption kinetics described well with the pseudo second order model. The activated carbon prepared from hazelnut husks is efficient sorbent material for the removal of Cd(II) ions from aqueous solutions.     

Interfacial Tension Measurements Between Oil Fractions of a Crude Oil and Aqueous Solutions with Different Ionic Composition and pH

Dynamic and equilibrium interfacial tensions between crude oil fractions and aqueous solutions of various compositions and pH were measured. The basic oil components seemed to determine the interfacial tensions at pH 2, while the non-dissociated and dissociated acidic components governed the interfacial tension at the natural pH and pH 9, respectively. The ionic composition of the aqueous phase influenced the degree of dissociation of the acidic components at pH 9: Na⁺ ions in the aqueous phase promoted dissociation of the interfacial acidic components (compared to pure water), while Ca²⁺ ions resulted in complexation with the dissociated acids and most likely formation of stable interfacial films. The amount of Ca²⁺ determined which of these phenomena that dominated when both ions were present in sea water solutions. Generally, the interfacial tensions of the oil fractions were lower when measured against the high salinity aqueous solutions than against the corresponding low salinity solutions.      

Photocatalytic Degradation of Styrene in Aqueous Solution: Central Composite Design Optimization

In this study, the response surface methodology was first applied to optimize the photocatalytic degradation of styrene in aqueous phase under UV/TiO₂ system. Twenty experiments were done by adjusting three parameters (styrene concentration, TiO₂ dose, and pH) at five levels. Optimal experimental conditions for arbitrary aqueous styrene concentration (115 mg L^?1) were found: initial pH 7 and TiO₂ loading 2 g L^?1 with photocatalytic degradation efficiency of 79.2%. Furthermore, the main degradation intermediate produced was identified by GC/MS. The total organic carbon results revealed that the photocatalysis process could be effectively mineralized. Kinetics of the photocatalytic reaction followed a pseudo-first-order model.     

Dried Biomass of Activated Sludge for Cu2+ Adsorption: Behaviors and Mechanisms

Activated sludge was tested for its ability to remove Cu²⁺ from aqueous solution. The effects of various experimental parameters (initial pH, initial Cu²⁺ concentration, adsorbent dosage, and temperature) on Cu²⁺ adsorption were evaluated. The Langmuir isotherm model well described the adsorption of Cu²⁺ onto activated sludge. The pseudo-second-order kinetic equation was appropriate for describing the kinetic performance of the sorption. Furthermore, Webber–Morris models indicated that the sorption of Cu²⁺ was generally found to involve with the intraparticle diffusion process. Parameters of adsorption thermodynamic suggested that the interaction of Cu²⁺ adsorbed by sludge was spontaneous and exothermic. Activated sludge was characterized by Fourier transform infrared spectroscopy analysis and results showed that active groups such as –OH, –COOH, –NH₂ were involved in Cu²⁺ adsorption. Zeta potential analysis demonstrated inner-sphere adsorption for Cu²⁺ adsorption on sludge.     

Preparation and Characterization of Cubosomal KIOM-C Suspension and Investigation on In Vitro Small Intestinal Absorption of Baicalin

KIOM-C suspension and cubosome/KIOM-C suspension were prepared in various buffer solution of different pHs by a sonication method. KIOM-C particles were unstable in terms of time-dependent change in the size and the zeta potential. The fluctuation in the size and the zeta potential of KIOM-C particles was effectively damped by cubosome. The shape of KIOM-C particles was irregular and the size was hundreds to thousands of nm. Cubosome/KIOM-C particles exhibited stripes on their surfaces and the size was hundreds of nm. Regardless of the pH values (pH 2.0–10.0) of media, baicalin, a major component of KIOM-C, was chemically stable for 48 hours at a room temperature. Cubosome markedly enhanced the stability of baicalin particles against sedimentation. EDTA significantly enhanced the in vitro small intestinal absorption of baicalin, but MO cubosome hardly promoted.