The influence of acid demineralization on surface characteristics of black carbon and its sorption for pentachlorophenol

Acid treatment is a routine demineralization process to obtain black carbon (BC), but there has been little systematic research about its influence on BC's characteristics. In this study, elemental analysis, SEM, FTIR, and Boehm titration were used to investigate that effect. Our results showed that the acid treatment had little influence on the sorption of fly ash and soot to pentachlorophenol (PCP), but it greatly increased the sorption of rice chars to PCP. There were two competing effects of acid demineralization on the adsorption capacity of BC. On one hand, it increased the amount of the acidic functional groups, which decreased the adsorption capacity. On the other hand, it increased the surface and pore volume of BC and caused the emergence of hidden carbon enclosed by minerals, which in turn increased the sorptivity significantly. Especially for rice chars (600°C), after acid treatment, their surface area increased from 3.52 to 235 m(2) g(-1) and the sorption capacity coefficient increased from 2.12 to 4.10.     

Low-cost and effective phenol and basic dyes trapper derived from the porous silica coated with hydrotalcite gel

Novel low-cost and effective adsorbents of phenol and basic dyes were made by coating amorphous silica with hydrotalcite (HT) gel followed by soaking in alkaline solution, and the surface basic-acidic properties of resulting composites were evaluated by CO(2)-TPD, Hammett indicator method and NH(3)-TPD, respectively. Both BET surface area and microporous surface area of the composites were increased after they were soaked with alkaline solution; meanwhile the center of pore size distribution was changed from 9 to 3-4 nm. These composites efficiently captured phenol in gaseous and liquid phases, superior to mesoporous silica such as MCM-48 or SBA-15 and zeolite NaY, and the equilibrium data of gaseous adsorption could be well fitted to Freundlich model. These modified silicas also exhibited high adsorption capacity forward basic dyes such as crystal violet (CV) and leuco-crystal violet (LCV), reaching the adsorption equilibrium within 1 h and offering a new material for environment protection.     

Controlling the primary particle evolution process towards silica monoliths with tunable hierarchical structure

In order to establish the hierarchical structure in multiple levels on mesoporous silica, this article reports a new strategy to prepare the monolith with the pore configuration in nanometer scale, micro-morphology in micrometer level and macroscopic shape in millimeter or larger grade. These hierarchical monoliths are synthesized in a weak acidic condition by using triblock copolymer P123, hydroxyl carboxylic acid and tetramethyl orthosilicate (TMOS), and the textural properties of the mesostructure can be facilely adjusted by simply controlling the synthesis condition without any additive. During the synthesis, the primary particles can be selectively synthesized as monodispersed sphere, noodle, prism, straight rods with different size or irregular bars, and their connection plus arrangement in 3D directions can be also regulated. Therefore, various textural properties of mesopore are able to be altered including pore size (5.5-10.6 nm), total pore volume (0.48-1.2 cm(3) g(-1)), micropore surface area (47-334 m(2) g(-1)), and pore shape (from 2D or 3D straight channel to plugged channel). Moreover, these monoliths exhibit a considerable mechanical strength; they are also applied in eliminating particulate matters and tobacco special nitrosamines (TSNA) in tobacco smoke, exhibiting various morphology-assisted functions.     

Effect of pH, ionic strength, and temperature on the phosphate adsorption onto lanthanum-doped activated carbon fiber

Phosphate removal from polluted water is crucial to preventing eutrophication. Herein, we present the investigation on phosphate adsorption in aqueous solutions by using lanthanum-doped activated carbon fiber (ACF-La). Various batch sorption conditions, e.g., pH, ionic strength, and temperature were tested, and the adsorption mechanisms were discussed. The sorption capacity of ACF-La was higher in acidic solutions than that in basic ones, suggesting that the Lewis acid-base interaction gradually dominated the adsorption process with the increase in pH values. The degree of phosphate removal decreased with the enhancement of the ionic strength of the solution, meaning that the adsorption of phosphate on ACF-La was strongly dependent on ionic strength. Employing the pseudo first- and second-order, and intra-particle diffusion models to evaluate the adsorption kinetics of phosphate onto ACF-La indicated that the second-order model best fits the experimental data. The presence of chloride ion in solutions increased the effect of intra-particle diffusion on the adsorption of phosphate onto ACF-La but reduced the overall rate of the adsorption. The thermodynamic parameters were determined which revealed the feasibility, spontaneity, and endothermic nature of adsorption.     

Unique fusiform alumina nanotubes fabricated by combined anodization

Alumina nanotubes (ANTs) with unique fusiform morphologies were synthesized via a simple electrochemical route; the fluctuation of the electronic current density during the anodization process is considered to be the main reason for the formation of such new alumina nanostructures.     

Fast and facile fabrication of a graphene oxide/titania nanocomposite and its electro-responsive characteristics

A graphene oxide/titania (GO/TiO(2)) nanocomposite was fabricated by a facile electrostatic attraction method. With high polarization of GO particles and a relatively high dielectric constant of TiO(2) nanoparticles, the GO/TiO(2) nanocomposite is observed to be a potential electro-responsive electrorheological material under an applied electric field.     

Interaction of the main components from the traditional Chinese drug pair Chaihu-Shaoyao based on rat intestinal absorption

The Chaihu-Shaoyao drug pair (Bupleuri Radix and Paeoniae Radix Alba) which is a traditional Chinese drug pair, has been widely used for anti-inflammatory purposes. Saikosaponin a (SSA), saikosaponin d (SSD) and paeoniflorin are identified as the main components in the pair. The present study focused on the interaction of the main components based on investigating their intestinal absorption using a four-site perfused rat intestinal model in order to clarify the mechanism of the compatibility of Chaihu-Shaoyao. The concentrations of SSA, SSD and paeoniflorin in the intestinal perfusate were determined by LC/MS or UPLC (Ultra Performance Liquid Chromatography) methods, followed by P*(eff) (effective permeability) and 10% ABS (the percent absorption of 10 cm of intestine) calculations. The results showed that all of the three main components displayed very low permeabilities (P*(eff) < 0.4), which implied their poor absorption in the rat intestine. The absorption levels of SSA and SSD were similar in intestine and higher in ileum than those in other intestinal regions in the decreasing order: colon, jejunum and duodenum. However, there is no significant difference in the absorption of paeoniflorin in the four segments (P < 0.05). The P*(eff) values of paeoniflorin exhibited an almost 2.11-fold or 1.90-fold increase in ileum when it was co-administrated with SSA and SSD, as well as 2.42-, 2.18-fold increase in colon, respectively, whereas the absorptions of SSA and SSD were not influenced by paeoniflorin. In conclusion, SSA and SSD could promote the absorption of paeoniflorin. To some extent this might explain the nature of the compatibility mechanisms of composite formulae in TCMs.     

Electrochemical preparation and magnetic properties of submicron Co x Pb1−x dendrites

Magnetic dendrites of Co _x Pb_1−x were fabricated through potentiostatic electrochemical deposition on Cu substrates in boric acid solution at room temperature. The as-deposited dendrites were determined by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), electrodeposition (ED), and energy dispersive X-ray spectroscopy (EDS). SEM results indicate that the Co _x Pb_1−x dendrites are highly symmetrical in structures. The diameters of the branches are about 50 ~ 200 nm, and the backbones are continuous with lengths up to about 10 μm. XRD patterns show that the as-deposited dendrites are solid solutions. The annealing treatment can result in the recrystallization of these metastable alloys into two separate phases. TEM, ED, and EDS results also reveal that the backbones and the branches of the dendrites are composed of different amounts of cobalt. Magnetic measurements confirm that the as-deposited Co _x Pb_1−x dendrites have a softly ferromagnetic behavior, and a small coercive force (about 80 Oe). Also the saturation magnetizations of the Co _x Pb_1−x dendrites decrease rapidly with the temperature increasing.     

The kinetics of CO pathway in methanol oxidation at Pt electrodes, a quantitative study by ATR-FTIR spectroscopy

Methanol (MeOH) oxidation reaction (MOR) at Pt electrodes under potentiostatic conditions has been investigated by electrochemical in situ FTIR spectroscopy (FTIRS) in attenuated-total-reflection configuration under controlled flow conditions in 0.1 M HClO(4) with 2 M MeOH, where the mass transport effects are largely eliminated using a flow cell. Our results reveal that (i) at constant potentials, the methanol dehydrogenation rate decreases while the CO(ad) oxidation rate increases with the accumulation of CO(ad) until the maximum CO(ad) coverage (ca. 0.5 ML i.e., the steady state) is reached; (ii) at fixed CO(ad) coverage, the rates for MeOH decomposition to CO(ad) and CO(ad) oxidation increases with potential from 0.3 to 0.7 V (vs. RHE), with Tafel slopes for MeOH dehydrogenation of ca. 440 ± 30 mV/dec, which is independent of CO(ad) coverage; (iii) the current efficiency of the CO pathway in MOR at 0.6 and 0.7 V is below 20% and it decreases toward higher potentials. The mechanisms as well as the potential induced change in the kinetics of different pathways involved in MOR are briefly discussed.     

Reactions of Ruthenium–Allenylidene Complexes Tethering a Cyclopropyl Group

Two cyclopropyl allenylidene complexes [Ru]=CCC(R)(C₃H₅) ([Ru]=[RuCp(PPh₃)₂], Cp=Cyclopentadienyl; R=thiophene ( 2a ) and R=Ph ( 2b )) are prepared from the reactions of [Ru]Cl with the corresponding 1‐cyclopropyl‐2‐propyn‐1‐ol in the presence of KPF₆. Thermal treatment, halide‐anion addition, and palladium‐catalyzed reactions of 2a and 2b all lead to a ring expansion of the cyclopropyl group, giving the vinylidene complexes 4a and 4b , respectively, each with a five‐membered ring. This ring expansion proceeds by C C bond formation between Cβ of the cumulative double bond and a methylene group of the cyclopropyl ring. In the reaction of 2a with pyrrole, consecutive formation of two C C bonds, one between C‐2 of pyrrole and Cγ of 2a and the other between C‐3 of pyrrole and Cα, results in the formation of 6a . The reaction proceeds by addition of pyrrole and 1,3‐proton shifts. The hydrogenation of 2a by NaBH₄ is carried out in different solvents. The cumulative double bonds are reduced regioselectively to give a mixture of 7a and 8a . Interestingly, use of different solvents leads to different ratios of 7a and 8a . Presence of a protic solvent like methanol in dichloromethane or chloroform solution increases the yield of 8a , thus revealing that both the rates of hydroboration and deboronation increase. The structures of two new complexes 4a and 6a have been firmly established by X‐ray diffraction analysis.