Structural sensitivity of heterogeneous catalysts for sustainable chemical synthesis of gluconic acid from glucose

Gluconic acid and its derivatives have been widely used in the food and pharmaceutical industries. Conventional processes that involve the conversion of glucose into gluconic acid via fermentation present several technological shortcomings as they involve energy-intensive wastewater treatment and complex enzyme separation. Greener oxidation processes over heterogeneous metal catalysts have attracted increasing attention worldwide. Au-, Pt-and Pd-based heterogeneous catalysts have been extensively used for the chemical oxidation of glucose to gluconic acid. Bimetallic catalysts synthesized by adding either noble or inexpensive metals have also presented excellent performance for the oxidations of glucose. In particular, particle size, which has been recognized as the most important factor that affect catalytic performances, could be rationally tuned by changing the types of support and ligand as well as the synthesis conditions. In this perspective review, we summarize and critically discuss the recent advances in the structural design of mono-and bimetallic catalysts for the oxidation of glucose in aqueous media. Furthermore, the challenges of developing catalysts for the green synthesis of gluconic acid have been highlighted. This review provides alternative insights for designing effective catalytic materials for the catalytic oxidation of bio-derived oxygenates over heterogeneous catalysts.

Steady State and Dynamic of Gluconic Acid Production by Aspergillus Niger

Batch and continuous fermentation ofgluconic acid production has been studied. The kinetic parameters of the fermentation process were determined from the batch experimental data. The continuous fermentation was modeled to be carried out in a stirred tank reactor. The effect of hydraulic retention time on the steady state continuous fermentation process of glucose by Aspergillus niger to produce gluconic acid was investigated. The result showed that increasing the hydraulic retention time caused the cell amount and gluconic acid concentration at the outlet stream increased but the glucose concentration at the outlet stream decreased. The steady state simulation result was useful for fermenter size determination. Dynamic behaviour of gluconic acid production through fermentation by Aspergillus niger was also studied for a fermenter with 24 h hydraulic retention time. Applying step change of inlet substrate concentration resulted in first order response of cell, substrate and product concentration with all having positive gain. On the other hand, applying step change of inlet cell concentration has resulted in positive gain for cell and product concentration and negative gain for substrate concentration with first order response for all those three parameters.

Compositional evolution for mixed aerosols containing gluconic acid and typical nitrate and the effect of multiply factors on hygroscopicity

The aging process of atmospheric aerosols usually leads to a mixture of inorganic salts and organic compounds of anthropogenic origin.In organic compounds,polyhydroxy organic acids are important components,however,the study on composition and hygroscopic properties of the mixture containing inorganics and polyhydroxy organic acids is scanty.In this study,gluconic acid,the proxy of polyhydroxy organic acids,is mixed with the representative nitrate(Mg(NO_(3))_(2),Ca(NO_(3))_(2))to form aerosols.ATR-FTIR and optical microscopy are employed to study the component changes and hygroscopicity as a function of relative humidity.As relative humidity fluctuates,the FTIR-ATR spectra display that the internal mixed gluconic acid(CH_(2)(CH)_(4)(OH)_(5)COOH)and nitrate can react to release acidic gases,forming relevant gluconate and further affecting the hygroscopicity.The specific presentation is particles cannot be recovered to their original size after the dehydration-hydration process and there will be some disparities in GF for mixed particles.For the gluconic acid-Ca(NO_(3))_(2)/Mg(NO_(3))_(2)mixtures with molar ratios of 1:1,higher degree of reaction resulting in the production of large amounts of gluconate should be responsible to the lower hygroscopicity compared to ZSR model.For 1:2 gluconic acid-nitrate mixed systems(with higher nitrate content),the hygroscopicity of mixtures are higher than the ZSR prediction.A possible reason could be‘salt-promoting effect’on the organic fractions of the surplus inorganic salt in the mixture.These data can improve the chemical composition list evaluation,in turn hygroscopic properties and phase state of atmospheric aerosol,and then the climate effect.

Efficient oxidation of monosaccharides to sugar acids under neutral condition in flow reactors with gold-supported activated carbon catalysts

A significant reaction in the synthesis of biomass-based chemicals is the catalyst-based and targeted oxidation of monosaccharides into valuable sugar acids.In this study,an activated carbon supported gold catalyst was used to oxidize glucose and xylose to gluconic acid and xylonic acid under neutral condition.Optimization of reaction conditions for the catalysts was performed using both a batch reactor and a flow-through reactor.In a batch reactor,the yields of gluconic and xylonic acid reached 93%and 92%,respectively,at 90℃ within 180 min.In a flow reactor,both reactions reached a similar yield at 80℃ with the weight hourly space velocity of 47.1 h^(-1).The reaction kinetics were explored in the flow reactor.The oxidation of glucose and xylose to gluconic and xylonic acid followed a first-order kinetics and the turnover frequency was 0.195 and 0.161 s^(-1),respectively.The activation energy was evaluated to be 60.58 and 59.30 kJ·mol^(-1),respectively.This study presents an environmentally friendly and feasible method for the selective oxidation of monosaccharides using an activated carbon supported gold catalyst,benefiting the high-value application of carbohydrates.

LC-MS分析葡萄糖酸钙锌口服液中葡萄糖酸和盐酸赖氨酸的含量

Establishing a method to detect the gluconate and lysine hydrochloride in calcium gluconate and zinc gluconate oral liquid by LC-MS.The mobile phase was acetonitrile and water (10:90),flow rate was 0.2 mL/min,and MS run in negative ion mode.The m/z of gluconic acid was 195,and m/z of lysine hydrochloride was 145.

Characterization of tricalcium phosphate solubilization by Stenotrophomonas maltophilia YC isolated from phosphate mines

The phosphate solubilizing characteristics of a strain YC, which was isolated from phosphate mines (Hubei, China), were studied in National Botanical Research Institute’s phosphate (NBRIP) growth medium containing tricalcium phosphate (TCP) as sole phosphorus (P) source. The strain YC is identified as Stenotrophomonas maltophilia (S. maltophilia) based upon the results of morphologic, physiological and biochemical characteristics and 16S rRNA sequences analysis. The results show that the strain S. maltophilia YC can solubilize TCP and release soluble P in NBRIP growth medium. A positive correlation between concentration of soluble P and population of the isolate and a negative correlation between concentration of soluble P and pH in the culture medium are observed from statistical analysis results. Moreover, gluconic acid is detected in the culture medium by HPLC analysis. It indicates that the isolate can release gluconic acid during the solubilizing experiment, which causes acidification of the culture medium and then TCP solubilization. S. maltophilia YC has a maximal TCP solubilizing capability when using maltose as carbon source and ammonium nitrate as nitrogen source, respectively, in NBRIP growth medium.

Fatigue and Corrosion Fatigue Properties of Mg-Zn-Zr-Nd Alloys in Glucose-Containing Simulated Body Fluids

Medical bone implant magnesium(Mg)alloys are subjected to both corrosive environments and complex loads in the human body.The increasing number of hyperglycemic and diabetic patients in recent years has brought new challenges to the fatigue performance of Mg alloys.Therefore,it is significant to study the corrosion fatigue(CF)behavior of medical Mg alloys in glucose-containing simulated body fluids for their clinical applications.Herein,the corrosion and fatigue properties of extruded Mg-Zn-Zr-Nd alloy in Hank’s balanced salt solution(HBSS)containing different concentrations(1 g/L and 3 g/L)of glucose were investigated.The average grain size of the alloy is about 5μm,which provides excellent overall mechanical properties.The conditional fatigue strength of the alloy was 127 MPa in air and 88 MPa and 70 MPa in HBSS containing 1 g/L glucose and 3 g/L glucose,respectively.Fatigue crack initiation points for alloys in air are oxide inclusions and in solution are corrosion pits.The corrosion rate of the alloy is high at the beginning,and decreases as the surface corrosion product layer thickens with the increase of immersion time.The corrosion products of the alloy are mainly Mg(OH)_(2),MgO and a small amount of Ca-P compounds.The electrochemical results indicated that the corrosion rate of the alloys gradually decreased with increasing immersion time,but the corrosion tendency of the alloy was greater in HBSS containing 3 g/L glucose.On the one hand,glucose accelerates the corrosion process by adsorbing large amounts of aggressive Cl^(-)ions.On the other hand,glucose will be oxidized to form gluconic acid,and then reacts with Mg(OH)_(2) and MgO to form Mg gluconate,which destroys the corrosion product film and leads to the aggravation of corrosion and the accumulation of fatigue damage.

Hydroxyl-and-carboxyl ligand concatenating multi-lanthanide substituted tellurotungstates and electrochemical detection of noradrenaline

Developing and exploring organic-inorganic hybrid multi-lanthanide(Ln)implanted heteropolyoxometalates(HPOMs)has bloomed into an emerging research fieId.In this article,two neoteric Dgluconic acids(H_(6)GA)concatenating multi-Ln^(Ⅲ) implanted heteropoly tungstates K_(14)H_(10)[Ln_(4)(H_(2)O)_(4)W_(6)(H_(2)-GA)_(4) O_(12)(B-α-TeW_(9)O_(33))_(4)]·60 H_(2)O(Ln=La^(3+)(1),Pr^(3+)(2))were obtained in acidic aqueous system.Attractively,in the polyanion structure of 1 and 2,six WⅥand four LnⅢcenters are connected by four flexible H_(2)GA^(4-) ligands via carboxyl and hydroxyl groups,resulting in the heterometallic[Ln_(4)(H_(2)O)_(4)W_(6)H_(2)GA)_(4)O_(12)]^(8+)cluster and then the heterometallic cluster is surrounded by four[B-α-TeW_(9)O_(33)]^(8-)segments.Electrochemical measurements for the 1@CFMCN/GCE sensor(CFMCN=carboxylfunctionalized multiwalled carbon nanotube;GCE=glass carbon electrode)demonstrate that 1@CFMCN/GCE shows benign recognition response to detecting noradrenaline(NDA).This research expands the structural diversity of Ln-implanted HPOMs and presents an electrochemical platform of recognizing NDA in the field of biosensors.

Hydrothermal fabrication of selectively doped organic assisted advanced ZnO nanomaterial for solar driven photocatalysis

Hydrothermal fabrication of selectively doped（Ag＋＋ Pd3＋） advanced ZnO nanomaterial has been carried out under mild pressure temperature conditions（autogeneous; 150°C）.Gluconic acid has been used as a surface modifier to effectively control the particle size and morphology of these ZnO nanoparticles. The experimental parameters were tuned to achieve optimum conditions for the synthesis of selectively doped ZnO nanomaterials with an experimental duration of 4 hr. These selectively doped ZnO nanoparticles were characterized using powder X-ray diffraction（XRD）, Fourier transform infrared spectroscopy（FT-IR）, UV–Vis spectroscopy and scanning electron microscopy（SEM）. The solar driven photocatalytic studies have been carried out for organic dyes, i.e., Procion MX-5B dye,Cibacron Brilliant Yellow dye, Indigo Carmine dye, separately and all three mixed, by using gluconic acid modified selectively doped advanced ZnO nanomaterial. The influence of catalyst, its concentration and initial dye concentration resulted in the photocatalytic efficiency of 89% under daylight.