Effects Of Hydrolysis Temperature Research Articles

Potential of Subcritical Water Hydrolysis to Valorize Low-Valued Ray-Finned Fish (Labeobarbus nedgia): Effects of Hydrolysis Temperature and Pressurization Agent.

Subcritical water (SCW) hydrolysis was applied to valorize the low-valued ray-finned fish (Labeobarbus nedgia) into valuable protein hydrolysates, employing N2 and CO2 as pressurization agents at varying temperatures (140, 160, 180, and 200 °C). The degree of hydrolysis (DH) and total free amino acid content increased with temperature for both pressurizing agents. The highest DH (54.5 ± 0.4%) and total free amino acid content (210 ± 1 mg/gprot) were observed at 200 °C when CO2 gas was used as the pressurizing agent. Predominantly, glycine and alanine were released for both pressurizing agents. The antioxidant activity, evaluated through three different assays, increased with temperature and was found to be the highest at 200 °C. This study illustrated the advantages of the intensified SCW technology by using CO2 as a pressurization agent in valorizing low-valued ray-finned fish (Labeobarbus nedgia), as animal residue rich in proteins, for the production of valuable protein hydrolysates with a high fraction of valuable free amino acids, which could offer potential applications as a functional ingredient in the food industry.

Kinetic model analysis of mild autohydrolysis of eucalyptus woodchips for xylose production

The autohydrolysis process of eucalyptus hemicelluloses was studied. The effect of hydrolysis temperature and soaking time on the dissolution of hemicellulose from eucalyptus chips was considered, and the process conditions were further optimized by P factor. The kinetic equations for the hemicellulose reaction were derived by studying the reaction process of hemicellulose during the pre-hydrolysis of eucalyptus chips, based on the reaction activation energy of xylose from eucalyptus chips and the investigated reaction mechanism of eucalyptus pre-hydrolysis process. The results demonstrated the feasibility of efficient extraction and utilization of hemicellulose in the process of dissolving pulp preparation from eucalyptus chips.

Optimization of the Temperature and Time for the Autolysis and Enzymolysis of Perna Viridis Protein

To determine the optimal conditions for autolysis, the autolysis of mussel (Perna viridis) protein was studied. Using P. viridis meat as the raw material and the degree of hydrolysis as the index, the effects of hydrolysis temperature and hydrolysis time, were researched. Single-factor experiments of autolysis of P. viridis were conducted, taking the degree of hydrolysis as the index. Keeping the pH, time, and solid/liquid ratio unchanged, the temperature was controlled at 30, 40, 50, 60, and 70 °C to study the effects of temperature on the autolysis of P. viridis protein. When the enzymatic hydrolysis temperature was 30 °C, the degree of protein hydrolysis was very low. The results showed that: with increasing temperature up to 50 °C, the degree of hydrolysis increased, reaching a maximum of 15.84%. Keeping the pH, temperature, and solid/liquid ratio unchanged, hydrolysis times of 2, 3, 4, 5, and 6 h were tested to determine the effect of time on the autolysis of P. viridis protein. The results showed that: hydrolysis occurred between 2 and 5 h, when the degree of hydrolysis increased from 13.62% to 15.31%, exhibiting a marked change in the extent of hydrolysis. The continuous increase in hydrolysis could be explained by the fact that P. viridis increased the amino nitrogen content in the hydrolysate via enzymatic hydrolysis and microbial degradation of endogenous enzymes. Therefore, the optimum conditions obtained in these experiments were a temperature of 50 °C, time of 5 h.

A facile urea-hydrolysis calcination process for the preparation of α -Fe2O3 nanoparticles and α -Fe2O3 nanorods and their fabrication mechanisms

A facile urea-hydrolysis calcination process for the preparation of α-Fe2O3 nanoparticles and α-Fe2O3 nanorods was introduced. The effects of hydrolysis temperature, Fe3+ concentration, and the molar ratio of urea and Fe3+ on nanorod-like precursors and α-Fe2O3 nanomaterials were investigated. The average length and diameter of the nanorod precursors increased with the increasing hydrolysis temperature, Fe3+ concentration, and molar ratio of urea and Fe3+. When the molar ratio of urea and Fe3+ was not less than 5, the α-Fe2O3 nanoparticles were produced. However, when the molar ratio was not greater than 4, the α-Fe2O3 nanorods could be obtained. In addition, the average diameter of the α-Fe2O3 nanoparticles was the largest when the hydrolysis temperature was 85 °C. With the increase in Fe3+ concentration, the average diameter of the α-Fe2O3 nanoparticles was enlarged. The average length and diameter of the α-Fe2O3 nanorods increased with the increase in hydrolysis temperature and Fe3+ concentration. All the results suggested that the rod-like structure of the precursors provided a possibility and the template for the fabrication of α-Fe2O3 nanorods, and the content of Fe3+ in the rod-like precursors played the decisive role in the morphology of the α-Fe2O3 nanomaterials.

Fabrication and properties of amorphous silica particles by fluorination of zircon using ammonium bifluoride

A method to prepare amorphous silica particles from zircon has been developed using the fluorination method through a three-step process: the fluorination of zircon using ammonium bifluoride at 230 ℃, the sublimation of (NH4)2SiF6 at 300 ℃ and the hydrolysis of (NH4)2SiF6. During above progress, the composition and phases of materials produced during fluorination of zircon were analyzed; the chemical reaction of silica with ammonium bifluoride, the sublimation behavior of (NH4)2SiF6 and its composition were determined; the effect of hydrolysis temperature (30 ℃, 45 ℃ and 60 ℃) on the hydrolysis ratio of Si and the size of silica particles were investigated. The results indicated that (NH4)3ZrF7 and (NH4)2SiF6 formed after the fluorination of zircon at 230 ℃ for 5 h. (NH4)2SiF6 started to sublimate at 175 ℃, but the sublimation dominated at 280 ℃ and ended at 300 ℃. The hydrolysis results indicated that uni-modal silica particles in micrometer size range were produced at 45 ℃, while bi-modal particles in a variety of sizes ranging from nanometer to micrometer were produced at 30 ℃ and 60 ℃. The amorphous silica particles obtained at 45 ℃ exhibited high purity above 99.96 wt.%, narrow size distribution (average: 254 ± 17 nm), high specific surface (136.8 m2/g), high dibutyl phthalate (DBP)-absorption (2.7 cm3/g), low density (0.532 g/cm2) and pH (5.7). Therefore, the amorphous silica obtained has potential application as filler in plastic and rubber compounding. After the hydrolysis process, ammonium bifluoride can be recycled through the evaporation of NH4F solution. Thus, this work provides a novel strategy for processing zircon by ammonium bifluoride to produce amorphous silica particles and recycle of ammonium bifluoride.

Catalytic Decomposition of Dichlorodifluoromethane (CFC-12) Over MgO/ZrO2 Solid Base Catalyst

MgO/ZrO2 solid base catalyst was prepared by co-precipitation method. The effects of hydrolysis temperature, water vapor concentration, total flow rate and calcination temperature of the catalyst on the decomposition rate of dichlorodifluoromethane (CFC-12) were studied. The results showed that the decomposition rate of CFC-12 could reach 98.90% by using MgO/ZrO2 solid base as the catalyst at a hydrolysis temperature of 400 °C, a water vapor concentration of 25%, a total flow rate of 5 mL/min and a calcination temperature of 700 °C. The XRD characterization of the catalyst under different calcination temperature showed that the MgO/ZrO2 catalyst was a solid solution. The products were tested by ion chromatography, SEM and EDS and finding that the decomposition products were main HCl, HF and CO2.

Subcritical Water Hydrolysis of Microalgal Biomass for Protein and Pyrolytic Bio-oil Recovery

Microalgae are a promising source of protein and biofuels. This study involved the extraction of soluble proteins from raw microalgae using subcritical water hydrolysis followed by pyrolysis of the resulting spent microalgal biomass for bio-oil production. The extraction process produced solubilized protein in amounts up to 10 wt% of the dry biomass. The effects of hydrolysis temperature (150–220 °C), process time (90–180 min), and initial pH (2–12) on the chemical compositions and reactivity of the spent biomass as biofuel intermediates were investigated. It was found that when the temperature and time increased, the protein and carbohydrate fractions of the spent biomass were reduced, while their lipid fraction increased. A low initial pH led to lower protein content in the spent biomass. Compared with the raw microalgae, the spent biomass gave a higher yield of pyrolytic bio-oil that contained much less of the N-containing compounds and higher amounts of long-chain fatty acids (C16) and C14–C20 long-chain hydrocarbons. In addition, enhanced energy recovery and a reduction in the energy consumption of the pyrolysis process were the other benefits acquired from the protein extraction. Therefore, subcritical water hydrolysis was considered to be an effective process to recover solubilized proteins, enhance the properties of the spent biomass, improve the energy balance of the subsequent pyrolysis process, and raise the quality of the bio-oil.

Comparative study on the effects of superheated water and high temperature alkaline hydrolysis on wool keratin

The purpose of this work is to understand the impact of superheated water hydrolysis treatment on the chemical properties of wool, and compare it with a conventional method of alkaline hydrolysis. The effects of hydrolysis temperature and concentration of alkali on the properties of wool were investigated. Superheated water hydrolysis was carried out at the temperatures of 140℃ and 170℃, with a material to liquor ratio of 1:3 for 1 hour. In conventional alkaline hydrolysis, the experiments were carried out in the same conditions using potassium hydroxide (KOH) and calcium oxide (CaO) with a concentration in the range of 5%–15% on the fiber weight (o.w.f.). The effects of hydrolysis temperature and alkali concentrations on wool properties were checked using optical and scanning electron microscopy. It was observed that the hydrolyzates obtained in both cases contained low molecular weight proteins and amino acids. Both the hydrolysis processes resulted in degradation of the wool fibers. However, superheated steam hydrolysis is an environmentally friendly and less expensive process, as it is performed using water as a solvent. The wool hydrolyzates produced using superheated water hydrolysis could find a potential application in agriculture, such as fertilization, soil improvement and suchlike.

Optimization of Enzymatic Hydrolysis of Freeze-Dried Sea Cucumber Powder with Response Surface Methodology and Its Antioxidant Evaluation

In this study, freeze-dried sea cucumber powder was used as raw material and the preparation processing conditions were studied for hydrolysis of sea cucumber powder with neutral protease using Response Surface Methodology (RSM) to obtain a high concentration of sea cucumber polypeptide. The effects of hydrolysis temperature, pH, enzyme dosage and hydrolysis time on the degree of hydrolysis (DH) were studied. Based on the single factor experiment, Box-Benhnken center composite experiment was carried out with three factors and three levels, including hydrolysis temperature, pH and enzyme dosage. RSM was used to determine the effect of prime factors on the DH and establish a regression model. The results showed that the optimal hydrolysis conditions were as follows: enzyme dosage of 5753 U g-1 dry matter, hydrolysis temperature of 52°C, pH of 8.3, substrate concentration of 5% and hydrolysis time of 5 h. Under the optimal conditions, the DH was up to 16.01%, which matched well with the predicted value. With VC as the positive control, the scavenging ability of the hydrolyzate on DPPH radicals, hydroxyl radicals and superoxide radicals were very powerful, which mean that the hydrolyzate of sea cucumber powder has good antioxidant activity.

Influences of Hydrolysis Temperature and Hydrolysis Time on Titanium White Pigment via Short Sulfate Process

Using low concentration TiOSO4 as titanium raw material, anatase white pigment was prepared by self seeded thermal hydrolysis route via short sulfate process. The effects of hydrolysis temperature and hydrolysis time on the structure and pigment properties of the as-prepared samples were investigated. The samples were characterized by XRD, particle size distribution and pigment properties test. The hydrolysis temperature and time had great effects on the hydrolysis rate, particle size distribution, crystal growth and particle aggregation of TiO2, eventually determined the pigment structure and its pigment properties. The optimized hydrolysis temperature was at faint boiling point, and the hydrolysis time after second boiling point was of 2.5h. Anatase white pigment was appropriate particle size, narrow particle size distribution and good pigment properties.

Electrical property and characterization of nano-SnO2/wollastonite composite materials

Nano-tin oxide was deposited on the surface of wollastonite using the mixed solution including stannic chloride pentahydrate precursor and wollastonite by a hydrolysis precipitation process. The antistatic properties of the wollastonite materials under different calcined conditions and composite materials (nano-SnO2/wollastonite, SW) were measured by rubber sheeter and four-point probe (FPP) sheet resistance measurement. Effects of hydrolysis temperature and time, calcination temperature and time, pH value and nano-SnO2 coating amount on the resistivity of SW powders were studied, and the optimum experimental conditions were obtained. The microstructure and surface properties of wollastonite, precipitate and SW were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), specific surface area analyzer (BET), thermogravimetry (TG), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and Fourier translation infrared spectroscopy (FTIR) respectively. The results showed that the nano-SnO2/wollastonite composite materials under optimum preparation conditions showed better antistatic properties, the resistivity of which was reduced from 1.068×104Ωcm to 2.533×103Ωcm. From TG and XRD analysis, the possible mechanism for coating of SnO2 nanoparticles on the surface of wollastonite was proposed. The infrared spectrum indicated that there were a large number of the hydroxyl groups on the surface of wollastonite. This is beneficial to the heterogeneous nucleation reaction. Through morphology, EDS and XPS analysis, the surface of wollastonite fiber was coated with a layer of 10–15nm thickness of tin oxide grains the distribution of which was uniform.

Preparation Technology of Hydrolysis Protein of Tilapia Meat

The preparation technology of tilapia protein hydrolysates by building single factor test and response surface methodology (RSM) were defined. The effect of hydrolysis temperature, pH, the additive quantity of Alcalase, the ratio of liquid-to-solid on degree of hydrolysis (DH), TCA-soluble nitrogen index (TCA-NSI) and yield of acid-solubility peptide (YASP) by regression model was obtained by response surface analysis. Regression model indicated that the optimal condition hydrolyzed animal protein of tilapia meat by proteinase was described as following：hydrolysis temperature 54.30°C, pH 8.77, the additive quantity of Alcalase 2.4L was 3702U/g, the ratio of liquid-to-solid was 3.06, hydrolysis time 1 hour. Under such conditions, the DH(%), TCA-NSI(%) and YASP(%) reached 33.63%, 22.10%, 64.55%, respectively. Experiment result showed that the predictive value and experimental value was small deviation and indicated that regression model was reasonable and reliable.

Anchorage of iron hydro(oxide) nanoparticles onto activated carbon to remove As(V) from water

The adsorption of arsenic (V) by granular iron hydro(oxides) has been proven to be a reliable technique. However, due to the low mechanical properties of this material, it is difficult to apply it in full scale water treatment. Hence, the aim of this research is to develop a methodology to anchor iron hydro(oxide) nanoparticles onto activated carbon, in which the iron hydro(oxide) nanoparticles will give the activated carbon an elevated active surface area for arsenic adsorption and also help avoid the blockage of the activated carbon pores. Three activated carbons were modified by employing the thermal hydrolysis of iron as the anchorage procedure. The effects of hydrolysis temperature (60–120 °C), hydrolysis time (4–16 h), and FeCl3 concentration (0.4–3 mol Fe/L) were studied by the surface response methodology. The iron content of the modified samples ranged from 0.73 to 5.27%, with the higher end of the range pertaining to the carbons with high oxygen content. The materials containing smaller iron hydro(oxide) particles exhibited an enhanced arsenic adsorption capacity. The best adsorbent material reported an arsenic adsorption capacity of 4.56 mg As/g at 1.5 ppm As at equilibrium and pH 7.

Preparation and Characterization of Light-Color Conductive Composite Based on Talc

As additive, economic and low resistivity material was useful in the fields of electrostatic prevention and electromagnetism screening. Antimony-doped tin oxide(Sb:SnO2)/talc composite was prepared for this purpose via a modified chemical deposition method using economic and natural talc as matrix. Effects of hydrolysis temperature, pH value, doping concentration of antimony, proportion of Sb:SnO2 to talc, calcination temperature and time on the resistivity of the composite powder were investigated. The construction of Sb:SnO2/talc conductive composite was characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The resistivity of Sb:SnO2/talc composite prepared at the optimum conditions decreased to 3.0×103 Ω•cm, at the same time its whiteness was greatly improved.

Preparation of transparent ultrahydrophobic silica film by sol–gel process

Transparent ultrahydrophobic films were synthesized by sol–gel process with organic silicones modified into silica sol and cured under UV irradiation. The effects of hydrolysis temperature, hydrolysis time, molar ratio of organic silicone to silica sol, and surface morphology on the hydrophobicity of the films were discussed in detail using FTIR spectroscopy, scanning electron microscopy (SEM), AFM, optical transmission, and contact angle measurement, respectively. The AFM and SEM images indicated that the surface roughness enhanced the hydrophobicity of the films. The results revealed that methyl-trimethoxysilane (MTMS)-modified silica film prepared at 50°C for 2 h with an MTMS/silica sol molar ratio of 1:10 had a very high contact angle (130°). However, the higher hydrolysis temperature and longer reaction time might have accelerated the self-condensation of silanol and decreased the contact angle of the films.

Novel technology for sewage sludge utilization: Preparation of amino acids chelated trace elements (AACTE) fertilizer

This study developed a novel technology for sewage sludge utilization. The bacteria proteins in the sewage sludge were extracted to produce the amino acid chelated trace elements (AACTE) fertilizer by virtue of several chemical processes. Firstly, the sewage sludge was hydrolyzed under hot hydrochloric acid solution to obtain protein solution. The effects of hydrolysis temperature, reaction time and pH on the extraction ratio of protein from the sewage sludge were investigated. Secondly, the protein solution was further hydrolyzed into amino acids under hot acid condition. The effects of the HCl dosage, hydrolysis temperature and reaction time on the yields of amino acids were investigated in detail. Thirdly, the raw amino acids solution was purified by activated carbon decolorization and glacial acetic acid dissolution. Finally, the purified amino acids were used to produce the AACTE fertilizer by chelating with trace elements. Results showed that, under optimum hydrolysis conditions, 78.5% of protein was extracted from the sewage sludge and the amino acids yield was 10–13 g per 100 g of dry sludge. The AACTE fertilizer produced was in accordance with China Standard for Amino Acids Foliar Fertilizer. This novel technology is more environmentally friendly compared with the conventional sludge treatments.

Use of Pressurized Hydrolytic Processes as a Pretreatment of the Wastewater from Organophosphate Pesticide Manufacturing

Wastewater from commercial manufacture of the pesticide O-methyl-O-(2-isopropyl salicylate) thiophosphoryl amide contains large amounts of pollutants, such as organophosphate, organic sulfides, COD, NH3-N. A comprehensive pretreatment process including alkaline hydrolysis, precipitation and flocculation was explored in this paper. The effects of hydrolysis temperature, initial pH values, etc., on the removal of pollutants were investigated. The experimental results showed that, with this physicochemical process, the removal of total phosphorus, organophosphate, sulfides, and NH3-N exceed 90%, and the removal of COD attains to 70%. The biodegradability (BOD5/COD) of the wastewater is greatly improved from 0.05 to 0.33. The NH3 gas generated was absorbed with water and could be reused in the manufacturing.

다시마 Laminaria iaponicus 알긴산의 분자량 분포에 미치는 가수분해 온도의 영향

To prepare oligouronic acids from high-molecular-weight alginates prepared from sea tangle (Laminaria japonica), the alginates were hydrolyzed at various temperatures for 1 hr at pH 5.0. The effects of hydrolysis temperature <TEX>$(H_{Temp})$</TEX> on the average molecular weight (AMW) and distribution ratio of MW (DR) in the hydrolyzed alginates were investigated. As <TEX>$(H_{Temp})$</TEX> increased, the AMW of the alginates decreased exponentially; in addition the DR of the alginates with MW>500 kDa decreased exponentially, while the DR of those with MW=50-100 and MW<50 kDa increased exponentially. For the alginates with MW=300-500 and MW=100-300 kDa the DR increased exponentially until <TEX>$H_{Temp}$</TEX> reached <TEX>$80^{\circ}C$</TEX>, and then decreased exponentially at above <TEX>$80^{\circ}C$</TEX>. AS <TEX>$H_{Temp}$</TEX> increased, the MW cutoff size and AMW Of the alginates fraction With the highest DR both decreased. For <TEX>$H_{Temp}<60^{\circ}C$</TEX>, the MW cutoff size with the highest DR was MW>500 kDa; the DR was 39-67% and the AMW 1,000-1,300 kDa. For <TEX>$H_{Temp}$</TEX> <TEX>$80^{\circ}C$</TEX>, the MW cutoff size with the highest DR was MW=300-500 kDa and the DR was about 33% and the AMW about 400 kDa. For <TEX>$H_{Temp}\;100-121^{\circ}C$</TEX>, the MW cutoff size with the highest DRs was MW=50-100 kDa, with a DR of 39-44% and an AMW of 70-80 kDa.

Synthesis and electrical property of antimony-doped tin oxide powders with barite matrix

Antimony-doped tin oxide (Sb-SnO2) nanoparticles were deposited on barite (BaSO4) to produce Sb-SnO2/barite (SSB) composite conductive powders via a chemical liquid deposition method. Effects of hydrolysis temperature, pH value, percentage of barite, doping concentration of antimony, calcination temperature and time on the resistivity of the SSB composite powder were primarily investigated. SSB powders with resistivity of less than 1.5×103Ωcm can be successfully obtained under the optimum experimental parameters. The samples were characterized by scanning electronic microscopy (SEM) and X-ray diffraction (XRD). The precursors of Sb-SnO2 powder were researched by means of thermogravimetric analysis (TG) and Fourier transform infrared (FTIR) spectroscopy in order to discuss the mechanism of hydrolysis reaction.

In vitro hydrolysis of poly(l-lactide) crystalline residues as extended-chain crystallites: II. Effects of hydrolysis temperature.

The effects of hydrolysis temperature on the hydrolysis behavior and mechanism of poly(l-lactide) crystalline residues or extended-chain crystallites were investigated in phosphate-buffered solution (50-97 degrees C), using gel permeation chromatography and differential scanning calorimetry (DSC). The hydrolysis of the crystalline residues proceeded from their surface composed of very short chains with a free end along the chain direction, irrespective of hydrolysis temperature, but the hydrolysis from their lateral surface could not be traced. The activation energy of hydrolysis for the crystalline residues (extended-chain crystallites) was evaluated to be 18.0 kcal mol(-1) (75.2 kJ mol(-1)). The monotonic melting temperature (T(m)) and crystallinity decreases occurred after their initial very small increases, excluding the monotonic crystallinity decrease at 97 degrees C with no initial increase. The T(m) decrease reflects the decreased thickness of the crystalline residues. The equilibrium T(m) of the crystalline residues (extended-chain crystallites) was estimated to be 464.5-464.9 K. The free energy values for the surface composed of very short chains with a free end, which are neighboring the air (or nitrogen during DSC scanning), were calculated to be 55.6-56.4 erg cm(-2) for heat of fusion per unit mass = 135 J g(-1). The obtained surface free energy values are significantly higher than that for the surface composed of folding chains, tie chains, and the chains with a free end, which are neighboring the same kind of amorphous chains (39.9 erg cm(-2)).