Pressured Microwave-assisted Hydrolysis of Crude Glycyrrhizic Acid for Preparation of Glycyrrhetinic Acid

A pressured microwave-assisted hydrolysis （PMAH） technique has been developed for hydrolyzing the crude glycyrrhizic acid （GA） extracted from licorice root to prepare glycyrrhetinic acid （GRA）. In order to optimize the efficiency of PMAH, several experimental parameters were investigated, including liquid-solid ratio, hydrolysis time, sulfuric acid concentration and hydrolysis temperature. The optimized hydrolysis conditions were as follows：pressured microwave-assisted hydrolysis of crude GA for 21 min （taking 15 min to reach 150 ℃, and holding it for 6 rain） at 150 ℃ （at a radiation power of 450 W） in 3%-5% sulfuric acid solution with the liquid-solid （ml.g-1 crude GA） ratio of 25 ： 1. As a result of the considerable saving in time and higher product yields （up to 90%）, PMAH was proved more effective than conventional methods.

Theoretical Studies on Mechanism and Rate Constant of Gas Phase Hydrolysis of Glyoxal Catalyzed by Sulfuric Acid

The gas phase hydration of glyoxal （HCOCHO） in the presence of sulfuric acid （H2SO4） were studied by the high-level quantum chemical calculations with M06-2X and CCSD（T） theoretical methods and the conventional transition state theory （CTST）. The mechanism and rate constant of the five different reaction paths are consid- ered corresponding to HCOCHO＋H2O, HCOCHO＋H2O… H2O, HCOCHO… H2O＋H2O, HCOCHO＋H2O… H2SO4 and HCOCHO… H2O＋H2SOa. Results show that H2SO4 has a strong catalytic ability, which can significantly reduce the energy barrier for the hydration reaction of glyoxal. The energy barrier of hydrolysis of glyoxal in gas phase is lowered to 7.08 kcal/mol from 37.15 kcal/mol relative to pre-reactive complexes at the CCSD（T）/6- 311＋＋G（3df, 3pd）//M06-2X/6-311＋＋G（3df, 3pd） level of theory. The rate constant of the H2SO4 catalyzed hydrolysis of glyoxal is 1.34×10-11 cm3/（molecule.s）, about 1013 higher than that involving catalysis by an equal number of water molecules, and is greater than the reaction rate of glyoxal reaction with OH radicals of 1.10×10-11 cm3/（molecule·s） at the room temperature, indicating that the gas phase hydrolysis of glyoxal of H2SO4 catalyst is feasible and could compete with the reaction glyoxal＋OH under certain atmospheric condi- tions. This study may provide useful information on understanding the mechanistic features of inorganic acid-catalyzed hydration of glyoxal for the formation of oligomer.

MICROWAVE-ASSISTED EXTRACTION OF GLYCYRRHIZIC ACID FROM LICORICE ROOT-EFFECT OF THE PROPERTY OF SOLUTION ON EXTRACTION OF GA

The property of extraction solution is an important factor influencing the extraction efficiency. In the present work, the effect of the property of solution on extraction of GA was studied, which including the concentration of ethanol, ammonia and cation (M+), pH of extraction solution, different kinds of organic solvent etc. The results show that 50%-60%(v/v) ethanol can reach high percentage extraction of GA. If 1% (v/v) ammonia solution was added into 60%(v/v) ethanol, the percentage extraction can be increased from 2.0% to 2.31%. Without ammonia, 50mmol/L [M+] (M+ = K+, NH4+) was added into 60%(v/v) ethanol, percentage extraction of GA can reach about 2.26%. If pH of solution (60% ethanol) was adjust to pH=4.0, it can reach high percentage extraction. If pH of solution (60% ethanol + 50mmol [M+], pH=6.1) was adjust tO PH=4.0, especially M+ is K+ or NH4+, it can reach almost same extraction efficiency as that of 1% ammonia solution + 60% ethanol, and the operation environment can be greatly improved.

Kinetic analysis of waste activated sludge hydrolysis and short-chain fatty acids production at pH 10

The accumulation of short-chain fatty acids （SCFAs）, a preferred carbon source for enhanced biological phosphorus removal microbes, was significantly improved when waste activated sludge （WAS） was fermented at pH 10. The kinetics of WAS hydrolysis and SCFAs production at pH 10 was investigated. It was observed that during WAS anaerobic fermentation the accumulation of SCFAs was limited by the hydrolysis process, and both the hydrolysis of WAS particulate COD and the accumulation of SCFAs followed first-order kinetics. The hydrolysis and SCFAs accumulation rate constants increased with increasing temperature from 10 to 35℃, which could be described by the Arrhenius equation. The kinetic data further indicated that SCFAs production at pH 10 was a biological process. Compared with the experiment of pH uncontrolled （blank test）, both the rate constants of WAS hydrolysis and SCFAs accumulation at 20℃ were improved significantly when WAS was fermented at pH 10.

Hydrolysis of mechanically pre-treated cellulose catalyzed by solid acid SO4^2--TiO2 in water–ethanol solvent

An efficient catalyst SO4^2--TiO2(ST) from industrial metatitanic acid has been successfully prepared to catalyze hydrolysis of ball-milling cellulose. The results show that the highest catalytic efficiency is obtained for ST calcined at 450 ℃(ST-450) with the yield of 21.8% glucose, 13.0% 5-HMF and 4.2% furfural at 200 ℃ for30 min. The ball milling of cellulose and solid acid catalyst significantly enhances the cellulose hydrolysis. The high Lewis to Bronsted acid sites ratio for ST-450 induced by bidentate ligands between SO4^2-and TiO2 benefits high organics yield, and high total acid sites contribute to the high cellulose conversion. The large pore volume of 0.29 cm^3·g^-1 and appropriate pore size of 7.35 nm of ST-450 also contribute to the high performance. High reaction temperature over 200 ℃ exhibits negative effect on glucose and 5-HMF yield due to undesired side reactions, while furfural product is stable in the reaction system. The bidentate ligands between SO4^2-and TiO2 are considered as active acid sites for cellulose hydrolysis in water–ethanol solvents.

Amino Acids Production from Fish Proteins Hydrolysis in Subcritical Water

The hydrolysis technology and reaction kinetics for amino acids production from fish proteins in subcritical water reactor without catalysts were investigated in a reactor with volume of 400 ml under the conditions of reaction temperature from 180-320℃, pressure from 5-26 MPa, and time from 5-60 rain. The quality and quantity of amino acids in hydrolysate were determined by bioLiquid chromatography, and 17 kinds of amino acids were obtained. For the important 8 amino acids, the experiments were conducted to examine the effects of reaction temperature, pressure and time on amino acids yield. The optimum conditions for high yield are obtained from the experimental results. It is found that the nitrogen and carbon dioxide atmosphere should be used for leucine, isoleucine and histidine production while the air atmosphere might be used for other amino acids. The reaction time of 30 rain and the experimental temperature of 220℃, 240℃ and 260℃ were adopted for reaction kinetic research. The total yield of amino acids versus reaction time have been examined experimentally. According to these experimental data and under the condition of water excess, the macroscopic reaction kinetic equation of fish proteins hydrolysis was obtained with the hydrolysis reaction order of 1.615 and the rate constants being 0.0017, 0.0045 and 0.0097 at 220℃, 240℃ and 260℃ respectively. The activation energy is 145.1 kJ·mol^- 1.

Effect of hydrolysis conditions on hydrous TiO_2 polymorphs precipitated from a titanyl sulfate and sulfuric acid solution

The relationship between hydrolysis conditions and hydrous titania polymorphs obtained in a titanyl sulfate and sulfmic acid solu- tion was investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and high-resolution transmission electron micros- copy （HRTEM）. The results revealed that the feeding rate of the titanyl sulfate stock solution, the concentration of sulfi.Lric acid, and the seed dosage of mtile crystal could significantly affect the hydrolysis rate, thus influencing the titania crystal phase. Hydrous TiO2 in the form of rutile, anatase, or the mixture of both could be obtained in solutions of low titanium concentrations and 2.5wt% to 15wt% sulfuric acid at 100℃. When the hydrolysis rate of titanitma expressed by TiOa was more than or equal to 0.04 g/（L.min）, the hydrolysate was almost phase-pure anatase, while the main phase state was rutile when the hydrolysis rate was less than or equal to 0.01 g/（L.min）. With the hy- drolysis rate between 0.02 and 0.03 g/（L.min）, the hydrolysate contained almost equal magnitude ofrutile and anatase. It seems that although rutile phase is thermodynamically stable in very acidic solutions, anatase is a kinetically stable phase.

Monitoring the Hydrolysis of Olive Oil Catalyzed by Lipase via Acid Value Detection

Hydrolysis of olive oil catalyzed by Candida lipolytica lipase was investigated. The relative concentration of the components in the product was determined by using high performance liquid chromatography（HPLC）. Furthermore, a novel rapid method to detect the hydrolytic process of olive oil was developed based on the relationship between the acid value and the relative concentration of the different components.

Microwave-assisted Micellar Extraction and Determination of Glycyrrhizic Acid and Liquiritin in Licorice Root by HPLC

The feasibility of emploving non-ionic surfactant （Triton X-100） as an alternative and effective solventfor the microwave-assisted extraction of glycyrrhizic acid （GA） and liquiritin （LQ） from licorice root was studied.The optimal extraction parameters based on the microwave-assisted micellar extraction technique were determined.Under the optimal conditions, i.e. 5% （by volume） Triton X-100, microwave-assisted extraction for 3--5min at 373K, the percentage extraction of active ingredients reached the highest value. The preconcentration tactor for GA and L＇Q （about 13.5） and the extraction efficiency for these two ingredients approached 100% showed the coupling of microwave-assisted extraction and cloud-point extraction could be employed as a new and. effective techniquefor the rapid extraction and preconcentration of pharrnacologically active ingredients from medicinal plants SUCh aslicorice root without disturbing chromatographic analysis.

Kinetic Studies on Wheat Straw Hydrolysis to Levulinic Acid

Levulinic acid is considered as a promising green platform chemical derived from biomass.The kinetics of levulinic acid accumulation in the hydrolysis process of wheat straw was investigated in the study.Using dilute sulfuric acid as a catalyst,the kinetic experiments were performed in a temperature range of 190-230°C and an acid concentration range of 1%-5% (by mass) .A simple model of first-order series reactions was developed,which provided a satisfactory interpretation of the experimental results.The kinetics of main intermediates including sugar and 5-hydroxymethylfurfural(5-HMF) were also established.The kinetic parameters provided useful information for understanding the hydrolysis process.

Preparation of κ-carra-Oligosaccharides with Microwave Assisted Acid Hydrolysis Method

A rapid method of microwave assisted acid hydrolysis was established to prepare κ-carra-oligosaccharides. The optimal hydrolysis condition was determined by an orthogonal test. The degree of polymerization （DP） of oligosaccharides was detected by high performance thin layer chromatography （HPTLC） and polyacrylamide gel electrophoresis （PAGE）. Considering the results of HPTLC and PAGE, the optimum condition of microwave assisted acid hydrolysis was determined. The concentration of κ-carrageenan was 5 mgmL-1; the reaction solution was adjusted to pH 3 with diluted hydrochloric acid; the solution was hydrolyzed under microwave irradiation at 100 ℃ for 15 min. Oligosaccharides were separated by a Superdex 30 column （2.6 cm × 90 em） using AKTA Purifier UPC100 and detected with an online refractive index detector. Each fraction was characterized by electrospray ioni- zation mass spectrometry （ESI-MS）. The data showed that odd-numbered κ-carra-oligosaccharides with DP ranging from 3 to 21 could be obtained with this method, and the structures of the oligosaccharides were consistent with those obtained by traditional mild acid hydrolysis. The new method was more convenient, efficient and environment-friendly than traditional mild acid hydrolysis. Our results provided a useful reference for the preparation of oligosaceharides from other polysaccharides.

An ultrasonic-ionic liquid process for the efficient acid catalyzed hydrolysis of feather keratin

A novel efficient method for hydrolyzing feather keratin using an ultrasonic-ionic liquid coupling process has been developed, with reaction conditions optimized using response surface analysis of data obtained from single factor optimization studies. Ultrasonic irradiation(225 W power) of feathers in 8.4 mol·L^(-1) hydrochloric acid containing 1-butyl-3-methylimidazolium chloride as a cosolvent at 80 °C for 1.4 h, followed by heating at 110 °C for 8.3 h, resulted in hydrolysis of their keratin component in an excellent 83.1% yield. Compared with previous methods, this new method employs reduced amounts of hydrochloric acid, shorter reaction time, and affords amino acid hydrolysis products in higher yield.

Microwave-assisted chemoselective copper-catalyzed amination of o-chloro and o-bromobenzoic acids using aromatic amines under solvent free conditions

Copper-catalyzed synthesis of N-aryl anthranilic acid derivatives using effective amination of 2-chloro and 2-bromobenzoic acid under microwave irradiation is reported. Some of the advantages of this method are high chemoselectivity, short reaction times, ease of work up procedure and elimination of the need for acid protection. 2009 Published by Elsevier B.V. on behalf of Chinese Chemical Society.

Strategies for Fermentable Sugar Production by Using Pressurized Acid Hydrolysis for Rice Husks

This study investigated the use of leftover biomass(rice husks)as the raw material for the biotechnological production of platform chemicals and biopolymers.Following the biorefinery concept,different acid hydrolysates were studied and resulted into a wide range of treatment strategies.Chemometrics were applied throughout the procedures in multivariate experimental conditions.By using the best hydrolytic conditions of 6.0%H3PO4,135oC(45 MPa)and reaction time of 62 min,21.0 g/L sugar hydrolysates were produced;by using the best hydrolytic condition of 4.5%HNO3,135oC/35 min,16.1 g/L sugar hydrolysates were produced;and with the hydrolysates use of 1.5%H2SO4 and 1.5%HCl,135oC/62 min,18.2 and 17.8 g/L sugar hydrolysates were produced,respectively.The highest productivity,in terms of fermentable sugars,reached 68%of integral cellulose/hemicellulose fraction and surpassed those found in the literature,with regard to the processing of rice husks,by considering just one step process.Sulfuric hydrolysate,detoxified with active carbon,was used to prove this proposal viability,resulting in a fermentation substrate for A.terreus(ATCC10020)and R.radiobacter(LMG196)strains(natural producers of bioproducts),which certified the feasibility of the proposal.The production of fermentable sugars from leftover biomass should encourage a search for new bioconversion routes,which can result in economic and environmental benefits and a spread of knowledge.

Hydrolysis of cellobiose catalyzed by zeolites—the role of acidity and micropore structure

The roles of acidity and micropore structure of zeolite were studied in the hydrolysis of the model oligosaccharide of cellulose–cellobiose. HZSM-5, HY, HMOR and Hβ zeolites were selected as model catalysts for the hydrolysis of cellobiose. The effect of acidity of zeolite, including the strength, type and location, on its catalytic activity was investigated. The strong Br？nsted acid sites located in micropores are the active sites for the hydrolysis of cellobiose to glucose. Meanwhile, the catalytic performance of zeolite is also dependent on the micropore size of zeolite.

Effects of Potassium Ferrate and Low-Temperature Thermal Hydrolysis Co-Pretreatment on the Hydrolysis and Anaerobic Digestion Process of Waste Activated Sludge

This study evaluated the effect of potassium ferrate(PF)and low-temperature thermal hydrolysis co-pretreatment on the promotion of sludge hydrolysis process and the impact on acid production in the subsequent anaerobic digestion process.The analytical investigations showed that co-pretreatment significantly facilitated the hydrolysis process of the sludge and contributed to the accumulation of short-chain fatty acids(SCFAs).The pretreatment conditions under the optimal leaching of organic matter from sludge were hydrothermal temperature of 75℃,hydrothermal treatment time of 12 h,and PF dosage of 0.25 g g^(−1)TSS(total suspended solids),according to the results of orthogonal experiments.By pretreatment under proper conditions,the removal rate of soluble chemical oxygen demand(SCOD)achieved 71.8%at the end of fermentation and the removal rate of total phosphorus(TP)was 69.1%.The maximum yield of SCFAs was 750.3 mg L^(−1),7.45 times greater than that of the blank group.Based on the analysis of the anaerobic digestion mechanism,it was indicated that the co-pretreatment could destroy the floc structure on the sludge surface and improve organic matter dissolving,resulting in more soluble organic substances for the acidification process.Furthermore,microbial community research revealed that the main cause of enhanced SCFAs generation was an increase in acidogenic bacteria and a reduction of methanogenic bacteria.

Honeycomb-structured solid acid catalysts fabricated via the swelling-induced self-assembly of acidic poly(ionic liquid)s for highly efficient hydrolysis reactions

The development of heterogeneous acid catalysts with higher activity than homogeneous acid catalysts is critical and still challenging.In this study,acidic poly(ionic liquid)s with swelling ability(SAPILs)were designed and synthesized via the free radical copolymerization of ionic liquid monomers,sodium p-styrenesulfonate,and crosslinkers,followed by acidification.The 31P nuclear magnetic resonance chemical shifts of adsorbed trimethylphosphine oxide indicated that the synthesized SAPILs presented moderate and single acid strength.The thermogravimetric analysis results in the temperature range of 300–345°C revealed that the synthesized SAPILs were more stable than the commercial resin Amberlite IR-120(H)(245°C).Cryogenic scanning electron microscopy testing demonstrated that SAPILs presented unique three-dimensional(3D)honeycomb structure in water,which was ascribed to the swelling-induced self-assembly of the molecules.Moreover,we used SAPILs with micron-sized honeycomb structure in water as catalysts for the hydrolysis of cyclohexyl acetate to cyclohexanol,and determined that their catalytic activity was much higher than that of homogeneous acid catalysts.The equilibrium concentrations of all reaction components inside and outside the synthesized SAPILs were quantitatively analyzed using a series of simulated reaction mixtures.Depending on the reaction mixture,the concentration of cyclohexyl acetate inside SAPIL-1 was 7.5–23.3 times higher than that outside of it,which suggested the high enrichment ability of SAPILs for cyclohexyl acetate.The excellent catalytic performance of SAPILs was attributed to their 3D honeycomb structure in water and high enrichment ability for cyclohexyl acetate,which opened up new avenues for designing highly efficient heterogeneous acid catalysts that could eventually replace conventional homogeneous acid catalysts.

Efficient hydrolysis of cellulose to glucose catalyzed by lignin-derived mesoporous carbon solid acid in water

Two kinds of mesoporous carbon solid acids(LDMCE-SO3H and LDMCS-SO3H)were successfully prepared using masson pine alkali lignin as carbon source by evaporation-induced self-assembly(EISA)and salt-induced selfassembly(SISA)followed by sulfonation,respectively.In terms of preparation process,SISA(self-assembly in water and preparation time of 2 days)is greener and simpler than EISA(self-assembly in ethanol and preparation time of 7 days).The prepared LDMCE-SO3H and LDMCS-SO3H exhibit obvious differences in structural characteristics such as pore channel structure,specific surface area,mesopore volume and the density of-SO3H groups.Furthermore,the catalytic performances of LDMCE-SO3H and LDMCS-SO3H were investigated in the hydrolysis of microcrystalline cellulose in water,and the glucose yields of 48.99%and 54.42%were obtained under the corresponding optimal reaction conditions.More importantly,the glucose yields still reached 28.85%and 30.35%after five runs,and restored to 39.02%and 45.98%through catalysts regeneration,respectively,demonstrating that LDMCE-SO3H and LDMCS-SO3H have excellent recyclability and regenerability.

Simultaneous Extraction of Carboxylated Celulose Nanocrystals and Nanofibrils via Citric Acid Hydrolysis--A Sustainable Route

In this study, cellulose nanocrystals(CNC) with surface carboxylic groups were prepared from bleached softwood pulp by hydrolysis with concentrated citric acid at concentrations of 60 wt%~80 wt%. The solid residues from acid hydrolysis were collected for producing cellulose nanofibrils(CNF) via post high-pressure homogenization. Citric acid could be easily recovered after hydrolysis reactions through crystallization due to its low water solubility or through precipitation as a calcium salt followed by acidification. Several important properties of CNC and CNF, such as dimension, crystallinity, surface chemistry, thermal stability, were evaluated. Results showed that the obtained CNC and CNF surfaces contained carboxylic acid groups that facilitated functionalization and dispersion in aqueous processing. The recyclability of citric acid and the carboxylated CNC/CNF give the renewable cellulose nanomaterial huge potential for a wide range of industrial applications. Furthermore, the resultant CNC and CNF were used as reinforcing agents to make sodium carboxymethyl cellulose(CMC) films. Both CNC and CNF showed reinforcing effects in CMC composite films. The tensile strength of CMC films increased by 54.3% and 85.7% with 10 wt% inclusion of CNC and CNF, respectively. This study provides detailed information on carboxylated nanocellulose prepared by critic acid hydrolysis; a sustainable approach for the preparation of CNC/CNF is of significant importance for their various uses.

Catalytic Hydrolysis of CFC-12 over MoO_(3)/ZrO_(2)-TiO_(2)

Solid acid MoO_(3)/ZrO_(2)-TiO_(2)catalysts were prepared by impregnation method,and catalytic hydrolysis of difluorodichloromethane(CFC-12)over the catalyst was studied.The presence of MoO_(3)/ZrO_(2)-TiO_(2)catalyst in polycrystalline state could be clearly observed by transmission electron microscopy(TEM).Mesopores were detected by N2 adsorption-desorption isotherms which further confirmed the MoO_(3)/ZrO_(2)-TiO_(2)structural characteristics of catalyst.The results of NH_(3)-TPD showed that the calcination temperatures had a great influence on the acidity of the catalyst,and the weak acidic site had a strong catalytic activity for the catalytic hydrolysis of CFC-12.Moreover,ZrO_(2)-TiO_(2)was highly dispersed in the MoO_(3)framework,suggested by powder X-ray diffraction(XRD)and N_(2)adsorption-desorption results.The effects of the catalyst calcination temperatures on the conversion rate of CFC-12 were studied.The effects of catalytic hydrolysis temperatures and water vapor concentration on the catalytic hydrolysis rate of CFC-12 were also studied.The solid acid MoO_(3)/ZrO_(2)-TiO_(2)was calcined at 500℃for 3 h at a catalytic hydrolysis temperature of 400℃and water vapor concentration of 83.18%,and catalytic hydrolysis rate of CFC-12 reached 98.65%.The hydrolysis rate of CFC-12 remained above 65.34%after 30 hours continuous reaction.