Biodiesel is an environmentally friendly fuel which can be economically produced by the use of waste culinary oil as raw material and NaOH as catalyst. However, the moisture in waste culinary oil or solid NaOH can affect the distribution of final products. In this paper, the water content of solid NaOH and waste culinary oil were determined to be 4.7 and 1.0 % respectively. A simulated transesterification system of methyl butyrate and n-butanol was catalyzed by anhydrous NaOH which was sintered at 800 °C for 2 h. The moistures in reaction system were imitated by contrived addition of water. Experimental results show that when the water content is 0.25 %, the yield of transesterification achieves the highest, simultaneously, saponification remains at the minimum level. The soybean oil and methanol were investigated as exemplary biodiesel system. The results show that when the water content is 1 %, the yield of biodiesel reaches 98.81 %, which is the highest.

As a solid foam stabilizer, spherical silica particles with diameters ranging from 150 to 190 nm were prepared via an improved Stöber method and were subsequently modified using three different silane coupling agents to attain the optimum surface hydrophobicity of the particles. Fourier transform infrared (FTIR) spectra and the measured contact angles were used to characterize the surface properties of the prepared particles. The foam stability was investigated by the foam drainage half-life and the expansion viscoelastic modulus of the liquid film. The results demonstrate that all of the modified silica nanoparticles effectively improve the foam stability. The surface hydrophobicity of the modified particles is found to be a key factor influencing the foam stability. The optimum contact angle of the particles lies in the approximate range from 50° to 55°. The modifier molecular structure used can also influence the stabilizing foam property of the solid particles. The foam system stabilized by (CH3)2SiCl2-modified silica particles exhibits the highest stability; its drainage half-life at maximum increases by 27% compared to that of the blank foam system and is substantially greater than those of the foam systems stabilized by KH570- and KH550-modified particles.

•The high hydrophobicity of FTAP was reflected through data of multi light scattering, which brings about the ultra-low solubility in aqueous phase.•The extraction capability of FTAP is optimized through adjusting O/A phase ratio, whose one-step extraction efficiency is 85.1%.•The hydrophobicity and extraction capability of FTAP and TAP were theoretically analyzed via the DFT calculation.Extractant residual in water phase is a destined and disgusted consequence after solvent extraction operation. In order to reduce extractant residual in aqueous phase, extractants modified by fluorination were probed. In this paper, tri-n-amylphosphate (TAP) was selected as model extractant along with its fluorinated analogue, tris (2,2,3,3,4,4,5,5-octafluoropentyl) phosphate (FTAP), to extract the salicylic acid from its aqueous solution to investigate residual and extraction behaviors by both experimental and computational methods. The experimental results obtained from multiple light scattering revealed that FTAP barely interacted with water and possessed high hydrophobicity. The solubility of FTAP in aqueous phase was less than 6.0×10−5 (w/w), and declined with increase of temperature, which was similar to the nature of nonionic surfactant. In acid solution with high concentration, the solubility of FTAP remained quite low. The one-step extraction efficiency of FTAP on salicylic acid was approximately 85%. The cycling experimental results showed that the durability of FTAP was overwhelmingly excellent compared with that of TAP, especially after the cycles more than 10 times. DFT calculation demonstrated the hydrophobicity and extraction behavior at molecular level. All results implied that fluorinated modification of extractant was a possible way to reduce its loss in aqueous phase.

•The possible aggregation structures of amide–sulfuric acid–water are proposed.•The major forms of water change from H2O⋯HN+ to SO⋯HOH⋯OS.•N+ forms ion-pair complex through attracting sulfate radical.Fourier transform infrared spectrum (FT-IR) combined with Gaussian function linear fitting is applied to analyze the aggregation structure in the system of oleamide mixed with sulfuric acid aqueous solution. The possible aggregation structure is proposed according to the shifts of hydroxyl peaks and the changes of their percentage areas. Results show that the interaction modes between sulfuric acid and oleamide vary with the different proportions of two ingredients. When the molar ratio of sulfuric acid to oleamide is low, the major forms of water existing in the system are bulk-like water and the water combining with N+H as N+H⋯OH2. With the increase of the molar ratio of sulfuric acid to oleamide, N+ forms ion-pair complex through attracting sulfate radical. That may be responsible to the scum-like aggregation.

•A model fluorinated extractant, 1H,1H,2H,2H-perfluoro-1-octanol, is described.•The extraction capacity of 1H,1H,2H,2H-perfluoro-1-octanol is acceptable.•1H,1H,2H,2H-perfluoro-1-octanol can avoid losing in the raffinate.•Recycling 1H,1H,2H,2H-perfluoro-1-octanol was demonstrated to be feasible.1H,1H,2H,2H-Perfluoro-1-octanol, octanol and benzoic acid were selected as model extractant and target acid to investigate extraction behaviors of fluorinated n-alcohol. According to experimental results, the extraction capacity of 1H,1H,2H,2H-perfluoro-1-octanol is acceptable with distribution ratio (D) of 13. The extraction efficiency reaches 98.0% after three stage continuous countercurrent extraction under the conditions of pH 2.55–3.16 and temperature 20–25 °C at oil to water (Vo/Vw) ratio of 1. The residual of 1H,1H,2H,2H-perfluoro-1-octanol in aqueous phase was quite low, which was less than 2 ppm. The back-extraction of 1H,1H,2H,2H-perfluoro-1-octanol by NaOH was demonstrated to be feasible, which is up to 100% with single stage.The perflouorinated octanol, 1H,1H,2H,2H-perfluoro-1-octanol, is selected as a model extractant to compare the extract behaviors with traditional n-octanol. Experimental results show that the 1H,1H,2H,2H-perfluoro-1-octanol is sufficiently hydrophobic to avoid its own losing in the feed solution of less than 2 ppm.

The catalytic removal of NOx technologies must pay attention to waste selective catalytic reduction (SCR) catalysts, which are the traditional commercial V2O5–WO3/TiO2 catalysts. Our work focuses on the progress in green reclamation and green chemistry for dealing with the spent SCR catalysts with sustainability perspectives. The problem outlined deals largely with the study of a feasible preparation way for visible-light-sensitive BiVO4/Bi2WO6 heterojunction photocatalyst, which was synthesized via a hydrothermal process through waste SCR catalysts. In this paper, the simulated waste SCR catalyst dissolved by sodium hydroxide (NaOH) solution was proposed. V2O5 and WO3 were dissolved heavily while TiO2 was rarely dissolved by sodium hydroxide. Afterword, the dissolved vanadium and tungsten in leaching solution were used to produce BiVO4/Bi2WO6 heterojunction through a hydrothermal process at 160 °C, which can be used as photocatalyst. The photocatalytic performance of the BiVO4/Bi2WO6 sample was evaluated by degradation of methylene blue in aqueous solution under visible light irradiation, which attributed to the improved separation efficiency of photogenerated hole-electron pairs generated by the heterojunction between Bi2WO6 and BiVO4.

In the paper, Fourier transform infrared spectroscopy combined with Gaussian function linear fitting is used to analyze the structure of the viscoelastic scum formed during solvent extraction of sulfuric acid with trioctylamine (TOA). The results show that when the molar ratio of sulfuric acid to TOA is low in the system, it would form N⋯HO through TOA coupling with sulfuric acid or TOA coupling with water. The N⋯H stretching vibration is around 3400 cm−1. With the increase of molar ratio of sulfuric acid to TOA, three peaks, near 2660 cm−1, 2610 cm−1, and 2535 cm−1, appear in the infrared spectrum and they are assigned to NH+ combining with water, NH+ combining with OS, NH+ combining with water and OS in the extraction system. The wave-number of CN stretching vibration increases with the increase of molar ratio of sulfuric acid to TOA.Highlights► There are two kinds of reactions in the TOA extraction of sulfuric acid system. ► There are three peaks during 2750–2450 cm−1 and assigned to three kinds of NH+. ► They may be NH+ combining with water, sulfuric acid and water. ► The possible molecular structures are proposed.

In the paper, Fourier transform infrared spectroscopy (FTIR) is employed to investigate the formation of viscoelastic scum during solvent extraction of sulfuric acid with trioctylamine (TOA) as extractant. The spectra are deconvolved and peak-fitted to study the change of wave-number and the peak area of O–H stretching vibration. Results suggest that the water plays an important role in viscoelastic scum formation. The water, sulfuric acid and TOA can combined as SO…HOH…N or HOH…OS or NH…OS. With the increase of the molar ratio of sulfuric acid to TOA, the combination of the water, sulfuric acid and TOA would transform to SO…HOH…OS or N+…HOH, which may be form macro-molecules in the extraction system.Highlights► Water is considered in viscoelastic molecule formation of sulfuric acid and amine. ► Water can be bridge of H2SO4 and TOA leading to the viscoelastic molecules. ► It changes from SO…HOH…N, HOH…OS to NH…OS with H2SO4 addition. ► The possible molecular structures are proposed.

Two types of metal-loaded visible-light-driven photocatalysts, Mo-BiVO4 and Ag-BiVO4, were synthesized by wet impregnation method. Material poperties were characterized by UV-vis diffuse reflectance spectroscopy, X-ray diffraction, field emission scanning electron microscopy, X-ray photoelectron spectroscopy and low temperature nitrogen adsorption-desorption. Photocatalytic activity of the obtained materials was investigated through degrading methylene blue (MB) solution under visible-light irradiation. The results reveal that both metal loaded-BiVO4 catalysts have monoclinic scheelite structure. Mo and Ag exist as oxides on the surface of the particles. The changes of absorption in visible-light region, band gap (Eg) and specific surface area (ABET) caused by loading Ag are more obvious than those caused by loading Mo. But the isoelectric point of Ag-BiVO4 decreases less than that of Mo-BiVO4 does. Both catalysts show higher photocatalytic activity than pure BiVO4, resulting in the significantly improved efficiency of degradation of MB. And the degradation efficiency of these two metal-loaded BiVO4 photocatalysts is similar to each other. However, mechanisms of such enhancement are different. The decrease of isoelectric point helps Mo-BiVO4 improve the degradation efficiency. As for Ag-BiVO4, the augmentation of absorption in visible-light region as well as the abatement of Eg plays more important roles.

Surface dilational rheological behavior and foam stability of starch/surfactant mixed solutions were studied at different starch concentrations and constant surfactant concentration. The results show that dilational viscoelasticity modulus, dilational elasticity modulus and dilational viscosity modulus increase with the concentration of starch particles. Foam stability increases with dilational viscoelasticity. Foam strength also increases with starch concentration. Starch particles play a positive effect on foam stability and dilational viscoelasticity and the effect becomes more significant as drainage proceeds. Film pictures indicate that the film with 20% (by mass) starch particles is thicker than that without starch. Starch particles gather in Plateau border and resist drainage, making the foam more stable.With the addition of starch particles in a solution, a typical dilatant fluid is obtained, improving foam stability. The film without starch particles is much thinner than that with 20 wt.% starch particles added. The addition of starch particles could maintain film thickness, slow liquid drainage and make foam more stable. The film in panel (a) is transparent, while that in panel (b) is different. This suggests that in the drainage process, starch particles aggregate in Plateau border and the solution becomes dilatant fluid, which increases the viscosity of film solution and makes film and foam more stable.Download full-size image

One-dimensional strontium hydroxyapatite (Sr-HAp) nanorods were successfully synthesized by a simple solvothermal method. The products were characterized via X-ray diffraction (XRD), Fourier transform infrared (FT-IR), cold field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), photoluminescence (PL) excitation and emission spectra. The experimental results indicated that oleic acid as a surfactant played a key role in confining the growth of the Sr-HAp powders. A possible formation mechanism of the one-dimensional nanorod was proposed and elaborated. Moreover, the as-obtained Sr-HAp samples showed an intense and bright emission band centered at 460 nm under long-wavelength UV light excitation and the contents of NaOH used in the synthetic process had an obvious impact on the optical performance of Sr-HAp powders. The possible luminescent mechanism of the Sr-HAp samples was discussed.