Preparation, characterization and in vitro anticoagulant activity of corn stover xylan sulfates.

A new anticoagulant agent was prepared by introducing sulfate groups into corn stover xylan through homogeneous reactions. Three organic solvents, N, N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO) and formamide (FA), were adopted as reaction media, with the assistance of LiCl. Structural characterization by FT-IR and 13CNMR showed that xylan sulfate (XS) could be successfully synthesized with SO3∙Pyridine (SO3∙Py) complexes sulfation reagent in the three media. The effect of sulfation temperature, sulfation time, media type and molar ratio of -SO3/-OH on the degree of substitution (DS) and degree of the polymerization (DP) were studied. DMF/LiCl were more effective than DMSO/LiCl and FA/LiCl in preparation of xylan sulfate with high DS. The optimal conditions for sulfation were obtained when SO3∙Py complex was added to DMF/LiCl with -SO3/-OH ratio of 1.5:1 and maintained at 50 °C for 3 h. Degree of polymerization of xylan was decreased during the sulfation process and DMF/LiCl offered the least xylan degradation as compared with DMSO/LiCl or FA/LiCl. Anticoagulant activities of the resultant xylan sulfates with different DS were evaluated by using activated partial thromboplastin time (APTT), thrombin time (TT), and prothrombin time (PT). Results indicated that the introducing of sulfate groups into xylan did endow the polysaccharides with anticoagulant activity. The APTT and TT of XS with DS of 1.20 reached 141 and 45.3 s at a dosage of 20 µg/mL, while the APTT and TT values for the blank sample were only 35.5 and 15.6 s. Furthermore, coagulation time was prolonged with the increase of DS and the concentration of XS. Our findings provide new insights into the value-added utilization of agricultural biomass.

[A rapid method for the determination of hydrogen peroxide concentration].

The present paper reported a spectrophotometry for the determination of hydrogen peroxide concentration. It is based on the reaction between ceric sulfate and hydrogen peroxide in an acidic medium, in which orange tetravalent cerium is converted to colorless trivalent cerium that causeds the change in absorbance. According to the quantitative relationship between ceric sulfate and hydrogen peroxide, the hydrogen peroxide concentration can be calculated. The selected conditions were as follows: detection wavelength of 480 nm, H2SO4 concentration of 0.5 mol x L(-1), and reaction time of 3.0 min. The results showed that the method has an excellent measurement precision (RSD = 0.31%) and accuracy (RSD < or = 0.91%) for the quantification of hydrogen peroxide. The present method is simple and rapid, with high detection sensitivity and low cost. It is suitable for use in rapid industrial analyses.

[Rapid determination of silicon content in black liquor of straw fibrous material].

The present paper reports a novel method for the determination of silicon content in straw fibrous material black liquor based on alpha-Si--Mo heteropoly acid spectrophotometry. The selected conditions were as follows: detection wavelength 360 nm, pH 4.0, and reaction time 10 min. It was found that the acidic soluble lignin in the sample liquor was the major interference species in the silicon content determination. The interference of acidic soluble lignin can be eliminated by hydrogen peroxide-nitric acid digestion method. The present method is not only simple, rapid, stable and less interferential, but also of good measurement precision and accuracy, with the relative standard deviations of 0.9%, and recoveries of 99.0%-102%. It is suitable for use in high silicon content of black liquor routine rapid analyses.

[Rapid method for determination of furfural and 5-hydroxymethyl furfural in pre-extraction stream of biomass using UV spectroscopy].

The present paper reports a rapid method for the determination of furfural (F) and 5-hydroxymethyl furfural (HMF) in pre-extraction liquors of lignocellulosic biomass based on UV spectroscopy. In a concentrated acetic acid medium, F and HMF have an isosbestic point at 276 nm. It was found that the acidic soluble lignin in the pre-extraction sample is the major interference species in the F and HMF spectroscopic quantification However, only acidic soluble lignins have the absorption at the wavelengths above 325 nm. Based on the absorption of the acidic soluble lignins at 325 nm, their absorptions at either F or HMF absorbed wavelengths can be determined. Thus, with a simple triple-wavelength technique, both F and HMF in the pre-extraction liquors of lignocellulosic biomass can be quantified based on the spectroscopic measurement at the isosbestic point wavelength (276 nm), maximum absorption wavelength of F (272 nm) and the acid soluble lignin absorbed wavelength (325 nm). The present method does not require the hazardous organic compounds (such as phenolic compounds etc.) acting as a color reagent in the experiment. It is not only simple and rapid, but also has a good measurement precision and accuracy, with the relative standard deviations of 3.02% and 2.72%, and recoveries of 95%-107% and 96%-101%, respectively, in the F and HMF quantification. The present method is suitable for use in the research on pre-extraction hemicellulose of the lignocellulosic biomass in bio-refinery area in order to achieve a high selective sugar conversion.

Novel preparation and characterization of cellulose microparticles functionalized in ionic liquids.

Ionic liquid (IL)-reconstituted acrylic acid (AA)-functionalized cellulose microparticles were successfully prepared by a water-in-oil suspension technique preliminary modification with AA in homogeneous condition. Cellulose was fully dissolved in 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) IL, and subsequently was grafted homogeneously with AA and N,N'-methylenebisacrylamide (N,N'-MBA) initiated with ammonium persulfate. The grafted cellulose was spheroidized using white silicone oil as the dispersion medium and Span 80 as a dispersant and then reconstituted from [Bmim]Cl. Reaction conditions were optimized to obtain microparticles with both the highest possible grafting efficiency and most uniform bead sizes. Fourier transform infrared spectroscopy, scanning electron microscopy, and an optical microscope were employed to provide structural information for the functionalized IL-reconstituted cellulose microparticles. These microparticles were shown to behave as good sorbents for Cu(II), Ni(II), Fe(III) ions.

Adsorption/desorption behavior between a novel amphoteric granular lignin adsorbent and reactive red K-3B in aqueous solutions.

A novel amphoteric granular lignin adsorbent (AGLA) was prepared using magnesium lignosulfonate as a raw material which was provided by a straw sulfite pulp mill in Guangdong Province, China. A reactive dye (red K-3B) was used as an adsorbate to investigate the adsorption behavior by static and mobile ways. The removal of reactive red K-3B was found to be initially pH and concentration dependent. Moreover, an increase of solution temperature ranging from 5 degrees C to 60 degrees C helped to enhance the rate of intraparticle diffusion of adsorbate and changes in the size of the pores of the adsorbent and thus to reduce the adsorption time. The total breakthrough adsorption capacity was 531 mg/g, and the saturated adsorption capacity was 560 mg/g, which prevailed over the activated carbons evidently. The reactive red K-3B adsorbed on AGLA could be recovered with a mixture of alcohol, NaCl and HCl aqueous solutions. The recovery percentage could reach 92.4%.

Simultaneous anaerobic-aerobic biodegradation of halogenated phenolic compound under oxygen-limited conditions.

The successful application of co-immobilized aerobic-anaerobic biomass under limited aeration in wastewater treatment systems would eliminate the problems associated with the intermediates mono-chlorophenol (MCP) and di-chlorophenol(DCP) accumulations. With low initial pentachlorophenol (PCP) concentration, all PCP could be completely removed under oxygen-limited strict anaerobic conditions, and the removal efficiencies with different initial headspace oxygen percentage (IHOP) were not obviously different from each other. While at high initial PCP concentration, under strictly anaerobic conditions PCP and their intermediates were clearly higher than that under other conditions, and produced obvious accumulation, the highest PCP reduction was achieved by the system receiving 30 IHOP, oxygen-limited system also exhibited lower residual TOC concentration and lower concentration of metabolic intermediates MCP and DCP. These results suggested that under strictly anaerobic condition the reductive dechlorination of low chlorinated compounds became rate limiting in the reductive dechlorination pathway, less chlorinated compounds be more amenable to aerobic degradation, and the aerobes of outer layers could function under limited oxygen. The co-immobilized aerobic-anaerobic biomass for methanogenesis under limited-aeration for chlorophenol degradation might be an attractive and efficient alternative for the sequential anaerobic/aerobic system to achieve mineralization of a broad range of recalcitrance highly chlorinated organics and low final TOC concentrations.

Coupled anaerobic/aerobic biodegradation of 2,4,6 trichlorophenol.

Degradation of 2,4,6-trichlorophenol (TCP) with co-immobilizing anaerobic granular sludge and isolated aerobic bacterial species was studied in coupled anaerobic/aerobic integrated reactors. The synergism of aerobes and anaerobes within co-immobilized granule might facilitate degrading the TCP and exchange of anaerobic metabolites 4-CP, which promoted system organic removal efficiency and recovered from organic shock-loads more quickly. The biomass specific activities experiment further confirmed that strict anaerobes be not affected over the course of this experiment by the presence of an oxic environment, aerobic activity predominated in the outer co-immobilized granule layers, while the interior was characterized by anaerobic activity. The co-immobilized granule could thus enable both aerobic and anaerobic microbes function in the same reactor and thereby integrate the oxidative and reductive catabolism.