Concentration Of Impregnation Solution Research Articles

Effect of Impregnation Solution Concentration on Vacuum Impregnation Efficiency of Potato Tuber

Effect of Impregnation Solution Concentration on Vacuum Impregnation Efficiency of Potato Tuber

Study on impregnation process optimization for regenerating the spent V2O5-WO3/TiO2 catalysts

It is of great economic value and environmental significance to extend the service life of commercial SCR catalysts. Water and acid wash as well as thermal regeneration were often used to remove toxic substances (such as dust, metal sulfates and metal chlorides) residual on catalyst surface so as to reduce the replacement frequency of catalyst, but easily lead to the loss of active components. In this paper, impregnation method was used to supplement the lost active components of the spent honeycombed V2O5-WO3/TiO2 (labeled as VW/Ti) catalyst, and the effects of drying duration and impregnation solution concentration on NH3-SCR performance of catalyst were studied. The results showed that the catalyst dried for 6 h at 110 °C exhibited the best deNOx activity and sulfur/water resistance. Further prolonging or shortening drying duration reduced the catalytic activity instead. It can be attributed that proper drying duration constructs abundant pore channels inside catalyst, optimizes active components dispersion, reduces diffusion resistance of reactants into the inner surface and provides more effective active sites on catalyst surface for adsorption and oxidation of reactants. With rise of V content in impregnation solution from 1.06 wt.% to 3.61 wt.%, deNOx activity as well as SO2/H2O resistance of catalyst improves at 150–300 °C. Besides, key influence factors are also discussed based on reaction kinetics analysis.

Wave absorption properties of Cu/C hollow fibers derived from ceiba-fiber templates

Absorbing materials with a hollow structure are lightweight and possess excellent wave absorbing properties. In this study, natural ceiba fiber with hollow structure is used as a bio-template to prepare Cu/C absorbing fibers through impregnating and sintering processes. These hollow composite fibers exhibit excellent absorbing performance. Compared with the Cu-based absorbing materials with a solid structure, the Cu/C hollow fiber has a reflection loss of −51.34 dB. The strong absorption over a wideband can be attributed to the hollow structure that improves the impedance matching and enables multiple reflections and scattering of electromagnetic waves in the internal cavity to weaken the waves. In addition, the influence of the sintering temperature and impregnation-solution concentration on the hollow structures of Cu/C fibers is investigated. As a result, 1000 ℃ is identified as the optimal sintering temperature to achieve good absorption performance of Cu/C fibers prepared with different impregnation-solution concentrations.

Effect of activation conditions and iron loading content on the catalytic cracking of toluene by biochar

Biochar (BC) is a catalyst carrier with a porous structure and low production cost. Herein, a Fe-loaded BC catalyst was prepared by impregnation and calcination, and use toluene to determine the removal efficiency of the catalyst. When the Fe impregnation solution mass fraction was 4%, the removal efficiency for the Fe-loaded BC catalyst was 94.1%. The amount of H2 produced by toluene catalysis is 963.22 ml, which is about three times the total amount of H2 produced by toluene self-pyrolysis and catalyst self-gasification. The effects of steam activation conditions and Fe impregnation mass fraction on the microstructure of BC were studied. The results show that the activation temperature and time can increase the BET surface area. A high concentration of steam volume and impregnation solution decreases the BET surface area. The characterizations of the catalyst before and after the toluene removal experiment shows that C–O bond plays a vital role in the removal process and micropores of BC preferentially adsorb toluene. The adsorption mechanism on BC mainly depends on n–π interaction and pore filling. The electrostatic attraction and π–π interaction on Fe-loaded BC were enhanced. Loading treatment introduces lattice oxygen and leads to increased oxygen vacancies.

The Effect of Vacuum Impregnation Pretreatment on Air-Drying Kinetics of Pears

The aim of this study was to examine the drying kinetics of pears (Pyrus communis L.) with and without vacuum impregnation and under the different temperature by using tray dryer. Vacuum impregnation were applied to the the pears (15 mm thickness, 65 mm outer and 20 mm inner dimensions respectively) with the conditions of 50⁰ Brix impregnation solution concentration, 225 mbar vacuum pressure and 45 min vacuum time. Drying process was carried out at temperatures of 55, 65 and 75°C. Drying time of non-vacuum impregnated pears was determined 640, 500 and 340 min and vacuum impregnated pears was determined 700, 540 and 560 min respectively. Page, Exponential, Henderson and Pabis, Diffusion Approach were examined for testing the drying kinetics. Experimental values are in accordance with the expected values resulted Page and Difussion models of with and without vacuum impregnated pears. Effective diffusion coefficient (Deff) was varying 2.74×10-11 to 7.31×10-11 m2/s. m2/s with respect to the drying temperatures. The activation energy for the non-vacuum impregnated and vacuum impregnated pears was 32.93 kJ / mol and 24.25 kJ / mol, respectively.

Catalytic Oxidation of NO on N-doped Carbon Materials at Low Temperature

By hetero atom doping, a nitrogen-doped porous carbon was synthesized and applied to catalytic oxidation removal of NO. The synthesis conditions and NO removal process conditions of the modified carbon material were investigated, including calcination temperatures, impregnation amount, NO inlet concentration (100–500 ppm) and catalytic reaction temperature. The results showed that the dicyandiamide impregnation solution concentration of 0.5 M, and the calcination temperature of 600 °C performed the best in the preparation of structurally stable nitrogen-modified carbon. Due to the formation of a large number active centers of pyridine nitrogen (N-6) groups and graphitic nitrogen (N-Q) groups, the optimal conversion rate of NO could reach 67.2%.

Accumulation of 2-Acetylamino-5-mercapto-1,3,4-thiadiazole in chitosan coatings for improved anticorrosive effect on zinc

Chitosan (Chit) coatings were applied on zinc substrates by the dip-coating method. Subsequently, the coatings were impregnated with a corrosion inhibitor, 2-Acetylamino-5-mercapto-1,3,4-thiadiazole (AcAMT) to obtain an increased anticorrosive effect. The coating thickness and the AcAMT accumulation were determined using UV–Vis spectroscopy on glass and quartz substrates, respectively. The surface morphology and coverage were investigated with atomic force microscopy. Electrochemical impedance spectroscopy and potentiodynamic polarization techniques were used to investigate the protective properties of the impregnated coatings. The chitosan coatings facilitated the accumulation of the corrosion inhibitor inside the polymeric matrix (a multiplication of 380 times compared to the impregnating solution concentration was calculated), channeling high amounts of AcAMT to the Zn surface, which resulted in an inhibition efficiency of >90%. This effect demonstrates the applicability of chitosan coatings as carriers for corrosion inhibitors, significantly reducing the amount of inhibitor needed to achieve good anticorrosive effects.

Production of zirconia-based ceramic fibers using viscose material

The paper focuses on the technology of producing ZrO2-Y2O3 ceramic fibers by impregnating twisted viscose yarns with zirconyl nitrate solutions with the addition of yttrium nitrate and subsequent heat treatment. We determined the effect of the impregnating solution concentration on the strength characteristics of the obtained ceramic fibers. As a result, we proposed a method for determining the tensile strength of discrete ceramic fibers

Preparation of high density garnet electrolytes by impregnation sintering for lithium-ion batteries

The conductivity of solid state electrolyte is closely connected with its chemical composition, crystal structure and density. High density Ta-doped Li7La3Zr2O12 (LLZTO) plates were synthesized by impregnation sintering. The density of electrolyte plates increased when the impregnating solution concentration increased from 5 to 35%. The LLZTO electrolyte plates showed a highest ionic conductivity of 6.47 × 10−4 S/cm when the impregnating solution concentration was 35%. The LLZTO electrolyte plates presented a highest relative density of 97% when the impregnating solution concentration was 40%, meanwhile, the activation energy of this electrolyte plate was calculated to be 0.35 eV, lower than the other samples.

Surface Characterization of Sulfated Iron Oxide and Its Synthesis of Biodiesel Under Microwave Radiation

AbstractThe solid acid catalysts SO42−/Fe2O3were prepared by impregnation technique, and the preparation conditions were different in calcination temperature, concentration of impregnation solution of H2SO4and impregnation time. The characterization was performed by using Fourier transform infrared spectrometer (FTIR), X-ray diffraction (XRD), Temperature programed desorption of NH3(NH3‒TPD), N2‒BET and microwave absorbing test. As shown by FTIR spectra, the S=O functional group existed in the sample, which was essential for the strong acidity of the SO42‒/MxOytype solid acids. The XRD results indicated that when the calcination temperature exceeded 400℃, iron in SO42‒/Fe2O3transformed from amorphous to crystalline phase. The results from NH3-TPD showed that the prepared sample possessed strong acid and superacid sites. As shown by N2-BET results, the BET surface area of the samples was up to 200m2/g, and their pore size distributions essentially belonged to mesoporous characteristic distribution. The SO42−/Fe2O3solid acid catalysts were used for the transesterification of castor oil under microwave radiation to produce biodiesel. The amounts of FAME in the product were analyzed by high-performance liquid chromatography. The highest yield of product was 65.3 wt.% when the reaction temperature was 65 ℃, alcohol/oil molar ratio was 30/1, catalyst loading was 20 wt.%, the reaction time was 3 h and the power of microwave was 300 w. Furthermore, the reaction results showed that SO42‒/Fe2O3had better catalytic activity under microwave radiation than under conventional heating condition.

Preparation and characterization of proton exchange membranes with through-membrane proton conducting channels

The primary goal of this study is to develop a novel PEMs with unique surface structure utilizing the high viscosity of the impregnation solution. SiO2 nanofiber mats were prepared via the electrospinning method and introduced into sulfonated poly(ether sulfone) (SPES) matrix to prepare hybrid membrane. The effect of concentration of impregnation solution on the morphology and properties of the proton exchange membranes (PEMs), including thermal stability, water uptake, dimensional stability, proton conductivity, and methanol permeability were investigated. SEM results showed that a unique surface structure was prepared due to the high solution concentration. Moreover, the hydrophilic nanofibers on the surface constructed continuous proton pathways, which can enhance the proton conductivity of the membranes, a maximum proton conductivity of 0.125 S/cm was obtained when the SPES concentration was 40 wt% at 80 °C, and the conductivity was improved about 1.95 times compared to that of pure SPES membrane. The SiO2 nanofiber mat-supported hybrid membrane could be used as PEMs for fuel cell applications.

Characterization of SO4 2−/TiO2 and its catalytic activity in the epoxidation reaction

The solid acid catalysts SO4 2−/TiO2 were prepared by the impregnation technique under two preparation conditions which were different in calcination temperature and concentration of impregnation solution of H2SO4. The characterization was carried out by using Fourier transform infrared spectrometer (FTIR), X-ray diffraction (XRD), temperature programmed desorption of NH3 (NH3-TPD), N2-BET, X-ray fluorescence and thermal gravity (TG)–differential scanning calorimetry (DSC). The characteristic peaks in the FTIR spectrum were essentially the same within the calcination temperature range of 400–600 °C. The XRD results indicated that the sample could show partial specific peaks of the anatase phase as the calcination temperature was higher than 400 °C. The obvious strong acid and superacid sites of the prepared SO4 2−/TiO2 were conformed by the NH3-TPD results. The BET surface areas of 102–206 m2/g were measured by the N2-BET method, and the pore size distributions were essentially mesoporous. The TG–DSC results showed that SO4 2−/TiO2 would decompose at about 500 °C in the air. The solid acid SO4 2−/TiO2 were used for the epoxidation of castor oil. The lowest iodine value of the product was 52.65/100 g when the reaction temperature was 65 °C, reaction time was 10 h and catalyst loading was 15 wt.%.

Vacuum impregnation and drying of calcium-fortified pineapple snacks

Impregnation methods combined with drying (convective- or freeze-) were used for producing calcium-fortified pineapples snacks. Three impregnation alternative were evaluated: I) at atmospheric pressure for 20 min; II) applying 10 min of vacuum (13.33 kPa) to a container with pineapple samples immersed into the impregnating solution followed by 10 min of impregnation at atmospheric pressure; and III) applying vacuum impregnation followed by vacuum pulses (6.70 kPa) after removing the samples from the impregnating solution. The impregnating solution concentration was 1 g Ca2+ 100 ml−1 prepared with CaCl2. The influence of the impregnation method on the kinetics of convective-drying and on porosity, shrinkage, glass transition temperature, water sorption isotherms, texture and microstructure of convective-dried and freeze-dried pineapple samples were determined. After drying, vacuum-impregnated products presented 91% higher concentration of Ca2+ than pineapples impregnated at atmospheric pressure (equal total processing time). Calcium chloride impregnation increased the drying rates and positively influenced the physical properties of the convective-dried product. The combination of vacuum impregnation and drying is a suitable way for the production of calcium-fortified pineapples, which are porous-and-crunchy, with high glass transition temperature favouring its preservation during storage.

Plasmonic AgX nanoparticles-modified ZnO nanorod arrays and their visible-light-driven photocatalytic activity

AgX (X = I, Br) nanoparticles-surface modified ZnO nanorod arrays (AgX/ZnO) were prepared using an impregnation method. The influence of impregnating solution concentration, immersion time, and UV light illumination pretreatment on the visible light-driven photocatalytic activity of AgX/ZnO was evaluated. The morphology, phase composition, band gap, and surface characteristics of the AgX/ZnO nanorod arrays were assessed by field-emission scanning electron microscopy, X-ray diffraction, diffuse reflectance UV-Vis absorption spectroscopy, and X-ray photoelectron spectroscopy. The AgBr nanoparticles were homogeneously distributed on the top and side surfaces of the ZnO nanorods, and connected to form a porous network structure. Following UV light illumination pretreatment, Ag nanoparticles were formed on the surface of the AgBr nanoparticles producing a Ag/AgBr/ZnO nanostructure. Methyl orange photodegradation study showed that the photocatalytic activity of AgBr/ZnO was higher than that of AgI/ZnO, synthesized under similar conditions, and was highly related to the impregnating solution concentration and immersion time. Owing to the high surface area of the ZnO nanorod arrays, the visible light sensitivity of AgBr, and surface plasmon resonance of Ag/AgBr, Ag/AgBr/ZnO exhibited the highest visible light-driven photocatalytic activity.

Effect of Process Factors on TiO<sub>2</sub> Loading Rate of Wooden Activated Carbon Fibers Loaded TiO<sub>2</sub> as Packaging Sterilization Material

In order to achieve food packaging sterilization rapidly and improve packaging sterilization property, the nanoTiO2 photocatalyst loaded on wooden activated carbon fibers (WACFs) is prepared by sol-gel method. The effects of loading processes on loading rate of nanoTiO2 are studied. It is shown that the loading rate of nanoTiO2 increases with decreased deionized water and increased nanoTiO2 impregnation solution concentration; the loading rate of nanoTiO2 initially increases and then decreases with increased alcohol content and dip-coating time, but the dip-coating time only has weak influence on the loading rate of nanoTiO2. When the ratio of butyl titanate to alcohol is 1:9, the ratio of butyl titanate to water is 3:1, the dip-coating time is 20 min and the nanoTiO2 impregnation solution concentration is 2 mg/ml, the loading rate of nanoTiO2 reaches maximum, which is 33.64%.

Effect of impregnation methods on sorbents made from lignite for desulfurization at middle temperature

With lignite after vacuum drying as the raw material, a series of Zn-based sorbents were prepared by static impregnation, ultrasonic-assisted impregnation, bubbling-assisted impregnation and high-pressure impregnation. The physical properties and the desulfurization performances of Zn-based sorbents were studied systematically by XRD, BET, AAS characterization techniques and the fixed-bed desulfurization evaluation apparatus. The sorbents obtained by high-pressure impregnation method have a larger specific surface area, pore volume and pore diameter comparing with other methods, which is conducive to the sulfidation reaction of hydrogen sulfide gas in the sorbent. The effects of pressure during the high-pressure impregnation and concentration of Zn(NO3)2 precursor solution on the sorbents properties and desulfurization behavior were investigated. The higher the impregnation pressure and the concentration of impregnation solution are, the greater the amount of the active components are uploaded. However, overhigh impregnation pressure can cause collapse and blocking of the carrier pore. The optimal operating condition of high-pressure impregnation method for preparing the sorbents was the impregnation pressure of 20 atm and the solution concentration of 41%. Under that condition, the sorbent had the best desulfurization ability with a sulfur capacity of 13.94 gS/100 gsorbent and a breakthrough time of 54 h. Its desulfurization precision and efficiency of removing H2S before sorbent breakthrough from the middle temperature gases of 400 °C can reach <5 ppm and >99%, respectively. Sorbents could be regenerated under the condition of 1 vol% O2, 20 vol% H2O, 0.5 vol%NH3, and N2 balance gas. The regenerated sorbent could be used for repeated absorption of H2S with a slight decrease in desulfurization effect.

Influence of Impregnation-Vacuum Filtration Conditions on Ni Dispersion and Activity of Ni-Cordierite for Hydrogenation

The influence of the preparation conditions of the impregnation-vacuum filtration method was investigated systematically on the Ni dispersion and the activity of Ni-cordierite structured catalysts in hydrogenation of m-dinitrobenzene to m-phenylenediamine. H2-TPD measurement showed that the Ni dispersion has close relationship with the impregnation solution concentration of nickel nitrate, the impregnation time, the vacuum degree, the vacuum filtration time and the calcination temperature. The hydrogenation activity test and nitrogen physisorption investigation showed that the catalytic performance of Ni-cordierite is dependent upon the Ni dispersion and the chemisorption mode of m-dinitrobenzene on Ni particles.

Effect of Preparation Conditions on the Property Cu/AC Adsorbents for Phosphine Adsorption

Copper-based activated carbon adsorbents (Cu/AC) were prepared and used to investigate the effects of various copper precursors, impregnation solution concentration, and calcination temperature on phosphine (PH3) adsorption removal from yellow phosphorus tail gas. N2 adsorption isotherm and X-ray Diffraction (XRD) were used for characterizing the Cu/AC adsorbents. It can be seen that the Cu(N)/AC adsorbent prepared from the Cu(NO3)2 precursor has higher PH3 breakthrough adsorption capacity than other three adsorbent because the surface copper status of it is mainly CuO. Fresh activated carbon requires an optimal impregnation solution concentration (0.05 mol/L) to reach this optimal PH3 breakthrough adsorption capacity (78.62 mg/g). The result shows that the surface chemical characteristics (Cu content) of activated carbon is more important than the physical ones (specific surface or pore volume) for the PH3 adsorption performance. When the calcination temperature is 350°C, the Cu(N)/AC adsorbent has the biggest PH3 breakthrough adsorbed amount of 112.38 mg/g. The present study confirmed that the Cu/AC adsorbents would be one of the candidates for PH3 adsorption removal from yellow phosphorus tail gas.

Fungicidal values of bio-oils and their lignin-rich fractions obtained from wood/bark fast pyrolysis

Pine wood, pine bark, oak wood and oak bark were pyrolyzed in an auger reactor. A total of 16 bio-oils or pyrolytic oils were generated at different temperatures and residence times. Two additional pine bio-oils were produced at the National Renewable Energy Laboratory in a fluidized-bed reactor at different temperatures. All these bio-oils were fractionated to obtain lignin-rich fractions which consist mainly of phenols and neutrals. The pyrolytic lignin-rich fractions were obtained by liquid–liquid extraction. Whole bio-oils and their lignin-rich fractions were studied as potential environmentally benign wood preservatives to replace metal-based CCA and copper systems that have raised environmental concerns. Each bio-oil and several lignin-rich fractions were tested for antifungal properties. Soil block tests were conducted using one brown-rot fungus ( Gloeophyllum trabeum) and one white-rot fungus ( Trametes versicolor). The lignin-rich fractions showed greater fungal inhibition than whole bio-oils for a impregnation solution 10% concentration level. Water repellence tests were also performed to study wood wafer swelling behavior before and after bio-oil and lignin-rich fraction treatments. In this case, bio-oil fractions did not exhibit higher water repellency than whole bio-oils. Comparison of raw bio-oils in soil block tests, with unleached wafers, at 10% and 25% bio-oil impregnation solution concentration levels showed excellent wood preservation properties at the 25% level. The good performance of raw bio-oils at higher loading levels suggests that fractionation to generate lignin-rich fractions is unnecessary. At this more effective 25% loading level in general, the raw bio-oils performed similarly. Prevention of leaching is critically important for both raw bio-oils and their fractions to provide decay resistance. Initial tests of a polymerization chemical to prevent leaching showed some success.

Preparation of carbon supported platinum catalysts: role of π sites on carbon support surface

The role of the π sites in the adsorption of anionic platinum precursor (PtCl 6 2− ) on the carbon surface was studied. A set of carbon supports was prepared by the oxidative treatments of a commercial carbon black in liquid or thermal treatment in a nitrogen gas flow. The supports obtained had similar physical structure, but were different in their surface chemistry, e.g., the types and the amount of the surface functional groups. The Pt/C catalysts were prepared by the impregnation of the supports with an aqueous solution of hexachloroplatinic acid. N2 adsorption, acid-base titration, X-ray photoelectron spectrometry (XPS), ICP, and TEM were used to characterize the supports and the catalysts. It was found that the absence of the surface acidic groups led to a higher platinum loading amount on the supports; and platinum loading amount would decrease when the higher H2PtCl6 impregnating solution concentration was used. The π sites in the basal planes play a more important role than the surface acidic groups in PtCl 6 2− ions adsorption on the carbon surface. Upon impregnation, the delocalized π electrons form coordination bonds with the platinum precursors, and further cause the reduction of Pt(IV) complex to Pt(II) complex, which was strongly chemisorbed on the surface of the supports. PtCl 6 2− ions adsorbing at the surface acidic groups would easily desorb during the washing process. However, when the impregnating solution was used at a higher concentration, a large amount of H3O+ was firstly adsorbed in the π sites, leading to a decrease of the amount of strong PtCl 6 2− ions adsorption on the supports.