Reaction Time Of 3h Research Articles

Organic Modification and Ball Milling of Bentonite and its Retention Properties

Stearyltrimethyl ammonium bromide(STAB) was used for organic modification of bentonite and then ball milled the modified bentonite. The organically modified bentonite was analyzed by FT-IR and XRD. The results show that the stearyltrimethyl ammonium bromide has been interalated into the layers of bentonite. The layer distance of the bentonite is increased from 1.256nm to 2.694nm. The appropriate experimental conditions of interplanar spacing increasing were the dosage of STAB 40%, reaction time 4h, temperature 75°C. The ball milled organically modified bentonite was analyzed by SEM. The results show that the particle mainly reach submicron to nanometer when ball mill 2h. The particle size distribution range is from 100nm to 500nm. Ball milled organically modified bentonite/ cationic guar gum(CGG) can improve retention rate of paper-process reconstituted tobacco pulp obviously than organically modified bentonite/CGG because of smaller grains and better unigormity of ball milled bentonite.

Optimization of selenylation conditions for Chinese angelica polysaccharide based on immune-enhancing activity

Chinese angelica polysaccharide (CAP) was extracted by water decoction and ethanol precipitation, purified through eliminating protein by Sevage method and column chromatography of Sephadex G-200, then selenizingly modified by nitric acid–sodium selenite method according to L9(34) orthogonal design of three-factors, the usage amount of sodium selenite, reaction temperature and reaction time, at three level to obtain nine selenizing CAPs, sCAP1–sCAP9. Their effects on chicken peripheral lymphocytes proliferation in vitro were compared by MTT assay taking the non-modified CAP as control. The results showed that selenylation modification could significantly enhance the immune-enhancing activity of CAP, sCAP2 presented best effect and the optimal modification conditions were 200mg of sodium selenite for 500mg of CAP, the reaction temperature of 70°C and the reaction time of 6h.

Sulfation modification and anticoagulant activity of the polysaccharides obtained from persimmon (Diospyros kaki L.) fruits

The optimal conditions for sulfation of polysaccharides from persimmon fruits (PFP) with chlorosulfonic acid–pyridine (CSA–Pyr) method were determined by response surface methodology. Box–Behnken design was applied to evaluate the effects of three independent variables (volume ratio of Pyr to CSA, volume ratio of PFP to SO3Pyr and reaction time) on the degree of substitution (DS), molecular weight (MW) and activated partial thromboplastin time (APTT) of sulfated polysaccharides (PFP-S). The APTT activity of PFP-S could be improved by application of various volume ratio of Pyr to CSA, volume ratio of PFP to SO3Pyr and reaction time, which was possible due to the degradation of polysaccharides to different extent and increasing of DS. The optimal conditions to obtain the strongest APTT of PFP-S were the volume ratio of CSA to Pyr of 1:8, the volume ratio of SO3Pyr to PFP of 1:3.6 and the reaction time of 3h, respectively.

Characterization of KNO3/NaX catalyst for sunflower oil transesterification

NaX zeolite loaded with potassium nitrate was prepared, characterized and applied as heterogeneous catalyst in the transesterification of sunflower oil with methanol. The influence of the loaded amount of KNO3, the methanol/oil molar ratio and catalyst amount on the final methyl esters content was studied. The catalysts were characterized by atomic absorption spectrometry (AAS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and CO2 temperature programmed desorption (CO2-TPD). The results demonstrated that methyl esters content was highly influenced by basicity and the catalyst with the highest catalytic activity was obtained using an amount of 35wt.% KNO3. The produced biodiesel was 98.2% methyl esters when the transesterification reaction was carried out at atmospheric pressure, a reaction temperature of 60°C, a reaction time of 6h, with a 21:1M ratio of methanol to sunflower oil, and a catalyst amount of 10%. The biodiesel obtained at these conditions met the European norm EN-14214 regarding viscosity and acid value.

Synthesis of glycerol carbonate from glycerol and dimethyl carbonate catalyzed by NaOH/γ-Al2O3

The NaOH/γ-Al2O3 as catalyst for the synthesis of glycerol carbonate via transesterification of glycerol with dimethyl carbonate (DMC) has been developed in this work. It was found that NaOH/γ-Al2O3 was a highly efficient heterogeneous catalyst for the synthesis of glycerol carbonate and the catalyst can be easily recovered and recycled. Under the conditions of DMC/glycerol molar ratio of 2, catalyst/glycerol weight ratio of 3%, reaction time of 1h, and reaction temperature of 78°C, the conversion of glycerol and the selectivity to glycerol carbonate reached 97.9% and 99.0%, respectively. The catalytic performance of 80wt.% NaOH/γ-Al2O3 is much better than that of K2CO3. A plausible reaction mechanism about this catalytic reaction was also proposed.

Parametric study of reactive extraction of castor seed (Ricinus communis L.) for methyl ester production and its potential use as bio lubricant

Castor oil methyl ester (COME) was produced by reactive extraction of castor seed and the purpose of this study is to investigate the feasibility of the reaction and to find out optimum reaction conditions. Reactive extraction of castor seed was carried out at varied reaction conditions such as oil to methanol molar ratio (1:50–1:250), catalyst concentration (0.5–2%), temperature (35–65°C) and rate of mixing (200–800rpm) and the effect of above parameters on reactive extraction were investigated. The optimum reaction conditions for reactive extraction were found to be 1% KOH (wt basis of oil), reaction temperature 65°C, reaction time 3h, methanol to oil molar ratio 250:1 and mixing speed of 600rpm. The kinetics of the reaction was studied and the activation energy was found to be 38.916kJmol−1. The potential use of COME as bio lubricants is promising due to its high viscosity, low pour point, and good lubricity. Economic analysis and sensitivity study of reactive extraction has been carried out which estimated the price of COME at $3.71/gal.

Hydrothermal conversion of biomass and different model compounds

In this study, a comparison of the hydrothermal behavior of various biomasses such as phyto mass, zoo mass, phyto mass/K2CO3 and glucose K2CO3 (model system for the phyto mass) is given. The experiments have been carried out in a batch reactor at 500°C, 30MPa with a reaction time of 1h. The phenol content of the aqueous phase obtained by biomass conversion was remarkably high. Actually, phenols and furfurals are the most important intermediates formed during the hydrothermal conversion of biomass. No furfural and its derivatives were observed in this study. In order to investigate the hydrothermal biomass conversion in detail, the behavior of the phenols and furfurals, under the same experimental conditions was also studied. The differences between the feedstocks have been discussed. Likely variations of the products and intermediates formed are a consequence of differences in the composition of the feedstock, namely, salts and proteins which seem to influence the chemistry of hydrothermal conversions.

Interfacial reactions of high-temperature Zn–Sn solders with Ni substrate

The interfacial reactions of Ni substrate with various high-temperature Zn–xSn (x=20, 30, 40, and 50wt%) solders were studied through the microstructural observation and reaction kinetics analysis of interfacial products. Regarding liquid/solid reactions at temperatures of 380°C to 420°C, only one uniform intermetallic compound (IMC), γ-Ni5Zn21, was formed on the interface. In the Zn–20Sn/Ni reacted at 400°C, the Ni5Zn21 layer demonstrated an unusually porous structure that grew rapidly; the average thickness reached ∼140μm after a reaction time of 1h. Specially, the layer exhibited a linear growth correlating to the reaction time. In contrast, the specimens with the Sn content above 30wt% exhibited a considerably lower Ni5Zn21 growth rate, following a parabolic relationship. Additionally, the Ni5Zn21 microstructure was relatively denser. Microstructural variations could be responsible for the different growth kinetics among the Zn–Sn/Ni couples. The Zn–Sn/Ni solid/solid interfacial reactions were also examined at 150–170°C. The Ni5Zn21 layer revealed a linear growth relationship for all the couples. This study determines the relevant growth kinetic parameters, and then discusses the possible growth mechanisms.

Furfural production from rice husk using sulfuric acid and a solid acid catalyst through a two-stage process

This study aimed to optimize the conditions for furfural production from rice husk via a two-stage process: acid hydrolysis followed by dehydration using an orthogonal test design and response surface methodology, respectively. Orthogonal test design was utilized in the hydrolysis step; optimum conditions were as follows: 2.5% sulfuric acid (mass fraction), 110°C reaction temperature, sulfuric acid to rice husk (L/S) ratio of 8 (g/mL), and a reaction time of 3h. According to the Box–Behnken design, the temperature, amount of catalyst, extractant volume, and reaction time were chosen as four important factors with three levels for the dehydration step. Conditions were further optimized by response surface analysis. The results showed that the optimal conditions were 177°C, 120mL extractant volume, 2.1g of catalyst, and a reaction time of 4.8h. Under the optimal conditions, the furfural yield reached 8.9%, which is consistent with the estimated value, 8.97%.

Manufacture and Application of PAE as Wet Strength Agent

PAE as the wet strength agent has a long history; it not only has the wet strength performance and the retention and drainage characteristics. This paper focuses on the technological conditions of preparation of PAE wet-strength agent and the application conditions. The results showed that the well PPC was obtained under the following conditions: the mole ratio of adipic acid and diethylenetriamine were 1:1.05, the amount of catalyst (mole ratio of the total raw materials) was 1%, the temperature of heat preservation was 165°C and the reaction time was 4h. The optimum condition of preparing PAE was obtained as followings: the ratio of EPI to PPC of 1.2:1, the epoxidation temperature of 60°C and reaction time of 2h. While applied in softwood pulp, when the dosage of PAE was 1%, the wet strength agent provided the satisfactory effect.

Synthesis of Li4Ti5O12 in supercritical water for Li-ion batteries: Reaction mechanism and high-rate performance

Nanosized and highly crystalline spinel lithium titanium oxide (Li4Ti5O12, LTO) particles are synthesized in supercritical water. The effects of various synthesis conditions – feed concentration, reaction time, and calcination – on the particle properties, including particle size, surface area, particle morphology, phase purity, and crystallinity, are carefully analyzed. Phase-pure LTO particles are obtained with a long reaction time of 6h in supercritical water at 400°C and 300bar without subsequent calcination, while the anatase TiO2 impurity phase is detected at shorter reaction times of 5min to 2h. Particles synthesize in supercritical water with subsequent calcination at a relatively low temperature of 700°C exhibit the highly crystalline LTO phase. Based on the analytical results using scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), and X-ray diffraction (XRD), an LTO formation mechanism in supercritical water is proposed. LTO particles prepare in supercritical water with subsequent calcination exhibit excellent long-term cyclability and high-rate performance. The discharge capacity after 400 cycles at 1C is 117.2mAhg−1, which is approximately 80% of the initial discharge capacity (147.1mAhg−1), and the discharge capacity at 10C is 100.5mAhg−1. These electrochemical performances are significantly better than those of uncalcinated LTO synthesize in supercritical water and solid-state synthesize LTO.

Separation of niobium and tantalum from Mozambican tantalite by ammonium bifluoride digestion and octanol solvent extraction

Tantalite ore from Mozambique was digested using molten ammonium bifluoride (NH4HF2) as an alternative to hydrofluoric acid. Niobium and tantalum were extracted from the water-leached filtrate using 1- and 2-octanol as extractants. The main process variables are time, temperature and the bifluoride-to-ore mass ratio, for the bifluoride treatment step, along with the sulphuric acid concentration of the aqueous filtrate, and the solvent-extraction contact time. The optimum parameters obtained for the bifluoride treatment were a reaction time of 3h, a reaction temperature of 250°C, and a tantalite-to-bifluoride mass ratio of 1:30. Under these conditions, up to 97.24% of Nb and 98.66% of Ta were recovered. Introduction of sulphuric acid (H2SO4) into the aqueous phase increases the extraction of Nb and Ta with octanol. It is shown that a 5M to 6M sulphuric acid concentration results in good extraction of tantalum. An acid concentration higher than 5M must be used for efficient extraction of niobium. A contact time of 10min between the feed solution and the solvent is required. McCabe–Thiele equilibrium diagrams constructed from the experimental data suggest that two and three extraction stages are sufficient for almost complete extraction of Ta and Nb respectively, at optimum extraction conditions.

The optimization of sulfation modification conditions for ophiopogonpolysaccharide based on antiviral activity

Ophiopogonpolysaccharide (OPS) was extracted by water decoction and ethanol precipitation, purified through eliminating protein by trichloroacetic acid method and column chromatography of DEAE-Cellulose-52, then sulfatedly modified by chlorosulfonic acid–pyridine method according to three-factors, ratio of chlorosulfonic acid to pyridine, reaction temperature and reaction time, and three level L9(34) orthogonal designed to obtain nine sulfated OPSs, sOPS1–sOPS9. Their effects on NDV to infect chick embryo fibroblast were compared by MTT assay taking the non-modified OPS as control. The results showed that sulfation modification could significantly enhance the antiviral activity of OPS, sOPS3 presented best effect and the optimal modification conditions were the ratio of chlorosulfonic acid to pyridine of 1:4, the reaction temperature of 60°C and the reaction time of 2h.

ZnO nanoparticles: Structural, optical and photoconductivity characteristics

Zinc acetate dihydrate, Zn(CH3COO)2·2H2O has been used as a precursor to prepare zinc oxide nanoparticles (NPs) by thermal decomposition in air at 400°C. Two samples with reaction time of 3 and 12h are studied. Structural study of ZnO NPs has been analyzed by X-ray diffraction (XRD). The synthesized ZnO NPs are found to possess wurtzite structure. The average crystallite size determined by XRD is found as 29.66 and 32.68nm corresponding to reaction time of 3 and 12h, respectively. Optical properties of the ZnO NPs have been investigated by UV–visible spectroscopy and photoluminescence (PL) spectroscopy at room temperature. Blue shift in band gap is observed due to nano size. PL spectra exhibit a UV emission peak at ∼396nm (∼3.11eV), and broad visible emission peaks including violet emission at ∼418nm (∼2.96eV), blue emission at ∼441nm (∼2.79eV), blue–green emission ∼481nm (∼2.56eV) and green emission ∼522nm (∼2.37eV). Photoconductivity properties have been investigated with several parameters such as voltage dependence of photocurrent and darkcurrent, time-resolved rise and decay of photocurrent and spectral response of photocurrent. Longer reaction time of 12h manifests in improved photosensitivity as compared to that for sample with reaction time of 3h.

Synthesis of hybrid SBA-15 functionalized with molybdophosphoric acid as efficient catalyst for glycerol esterification to fuel additives

Fibrous mesoporous hybrid silica (SBAH-15) with mesopore diameter of 70Å was synthesized using pluronic P123 (EO20PO70EO20) as surfactant, with Brij S100 as nonionic co-surfactant. Series of catalysts with different molybdophosphoric acid (MPA) loading (5–25%) were synthesized by the thermal decomposition of MPA species in the lattice of SBAH-15. Catalysts calcined at 560°C undergone a thermal decomposition of MPA resulted in the formation of β-MoO3 active species. The effectiveness of the hybrid support was evaluated by comparison with analogous catalyst prepared by incorporating MPA into the framework of classical SBA-15. The catalytic performance of the prepared acid catalysts was examined during glycerol esterification with acetic acid. Mono-, di- and triacetyl glycerol (MAG, DAG and TAG, respectively) were the esterification reaction products. SBAH-15(15) catalyst, with 15wt.% MPA loading, exhibited an excellent activity during this reaction, indicated by the complete glycerol conversion (after 1h) with a corresponding combined selectivity of 86% toward both DAG and TAG. The best reaction conditions are: reaction temperature of 110°C, glycerol to acetic acid molar ratio of 1:6 and reaction time of 3h. The SBAH-15(15) catalyst demonstrated good stability in activity upon recycling for four times.

Heterogeneous Fenton-like Degradation of Orange II in Water Using FeZSM-5 Zeolite Catalyst

In this study, Fenton-like degradation of Orange II in water was investigated over an FeZSM-5 zeolite catalyst prepared by ion exchange. A color removal of 99.99 % and a COD elimination of 55.0 % were achieved after a reaction time of 2h at 266.7 mM H2O2 at 323 K for 0.05 g/dm3 of Orange II solution at a pH around 7. Initial decolorization rate was described by an equation of -rAo = 6.4x103 e-30.7/RT COII,o CH2O2,o0.3 where R is in kJ/mol. No significant decay in decolorization efficiency of the used catalyst was observed.

Ionic liquids as solvents for dissolution of corn starch and homogeneous synthesis of fatty-acid starch esters without catalysts

Ionic liquids (ILs) utilized for dispersing cellulose have gained increasing attention in recent years, but the number of the reports using ILs for starch is still limited. In this study, 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) and 1-ethyl-3-methlyimidazolium acetate ([EMIM]AC) were used to dispersing corn starch. Dimethyl sulfoxide (DMSO), a traditional organic solvent for starch, was added into [BMIM]Cl, and the mixture of [BMIM]Cl/DMSO was utilized for dispersing corn starch as well. Results showed that the starch granules dispersed in ILs was much smaller than native starch granules, and large starch aggregates were partially formed. Starch granules dispersed in [BMIM]Cl at 100°C for 60min remained less crystallinity than native starch granules, while it was disappeared when starch granules were dispersed in [EMIM]AC at 100°C for 60min. Homogenous synthesis of fatty-acid starch esters without catalysts in these ILs was also studied. The degree of substitution (DS) value of starch laurate was reached to 0.053, 0.068 and 0.100 in [BMIM]Cl, [EMIM]AC and the mixture of [BMIM]Cl/DMSO, respectively, at the reaction conditions of lauric acid/AGU molar ratio 1:5, temperature 120°C at a reaction time of 3h.

Acid-catalyzed esterification of karanja (Pongamia pinnata) oil with high free fatty acids for biodiesel production

We report the production of a biodiesel fuel by acid-catalyzed esterification of high free fatty acid (FFA) karanja oil (KO). Pretreated KO was converted to biodiesel by a process of alkaline catalyzed transesterification. Optimum acid-catalyzed esterification was achieved using 1% Sulfated Zirconia (SZ) as a solid acid catalyst with a methanol-to-oil ratio of 9:1, temperature at 60°C and reaction time of 2h. During this process, FFA were converted into fatty acid methyl esters. The acid value of karanja oil was reduced to 1.3mg KOH/g from 12.27mg KOH/g, which confirmed the conversion. Consequently, this pretreatment reduces the overall complexity of the process and reduces the cost of producing biodiesel fuel.

Experimental Researches on the Preparation of High-Efficient Active Floridin by Mixed Acids

Taking ca-bentonite as the raw material, the activation effect of active floridin prepared by mixed acids of H2SO4, HCl and C2H2O4 is studied. The research results indicate that the main factors influencing the activity and decolorization ratio of floridin include volume ratio of mixed acids, liquid-to-solid ratio, reaction temperature and reaction time. When the volume ratio of mixed acids H2SO4: HCl: C2H2O4=5:5:1, liquid-to-solid ratio =4:1, reaction temperature 80 and reaction time 4h, it is possible to prepare high-efficient active floridin.

Optimization of biocatalytic biodiesel production from pomace oil using response surface methodology

Microbial lipase from T. lanuginosus was immobilized onto polyglutaraldehyde-activated olive pomace powder. The support was used to produce biodiesel with pomace oil and methanol. Response Surface Methodology (RSM) in combination with Central Composite Design (CCD) was used to optimize the biodiesel production parameters. Reaction temperature, molar ratio of methanol to oil, biocatalyst content and reaction time were chosen as the variables and the response selected was the yield of pomace oil methyl ester in present work. A quadratic polynomial equation was obtained for pomace oil methyl ester yield by multiple regression analysis. The optimal conditions for the transesterification have been found to be: reaction temperature of 40°C, alcohol/oil molar ratio of 5.3:1, biocatalyst content of 5.8% w/w and reaction time of 24h. The predicted pomace oil methyl ester yield was 92.87% under the optimal conditions. Verification experiment (91.81%) confirmed the validity of the predicted model. Biodiesel yield reached 93.73% by adding water (1% w/w) in reaction medium under the optimal conditions. Immobilized lipase was used to determine operational stability and it indicated that immobilized lipase was stable retaining more than 80% residual activity after being used repeatedly for 10 consecutive batches of pomace oil transesterification.