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In this investigation, softwood pulp and bleached wheat straw pulp were used as raw materials, and Calcium Sulfate Whiskers (CSW) were used as fillers. Based on the structural properties and characteristics of CSW, the printing properties of the paper with CSW, such as whiteness, opacity, pH value, uniformity, Z-direction tensile strength and surface strength, were analyzed. The results showed that CSW has low solubility, high retention and fiber-like appearance. The whiteness of the paper is the best when the filling amount of CSW is 20 %. The paper opacity of softwood pulp increases significantly, and the opacity of bleached wheat straw pulp decreases significantly when CSW is more than 30 %. The addition reduces pH and surface strength of the paper. The evenness of the paper does not change obviously. The Z-direction tensile strength of the paper decreases in the softwood paper, but increases obviously in the bleached wheat straw paper.

By combining the structural properties and characteristics of phosphogypsum whiskers, a preliminary study on the modification of phosphogypsum whiskers and their application in papermaking was carried out. The effects of reaction temperature, reaction time, and reaction concentration on the solubility and retention of modified phosphogypsum whiskers and the effects of phosphogypsum whiskers on the physical properties of paper under different modified conditions were explored. The research results show that, after the phosphogypsum whiskers are modified with calcium stearate, a coating layer will be formed on the surface of the whiskers, which effectively reduces the solubility of the phosphogypsum whiskers. The best modification conditions are: the amount of calcium stearate relative to the absolute dry mass of the phosphogypsum whisker is 2.00%; the modification time is 30 min, and the modification temperature is 60°C. The use of modified phosphogypsum whiskers for paper filling will slightly reduce the whiteness, folding resistance, burst resistance, and tensile strength of the paper, but the tearing degree and retention of the filler will be increased to some extent.

The in-situ synthesis of calcium silicate in the fiber can not only meet the requirements for high loading of paper, but also make up and improve the reduction of paper performance caused by filling. In this investigation, the effects of pulp type, beating degree, fiber ratio, reaction time, rotational speed, dosage of lime milk and dispersant on calcium silicate loading and paper properties were investigated. The results showed that when the beating degree was 40 °SR, the ratio of softwood and hardwood pulp was 1:1, the reaction time was 60 min, the rotation speed was 600 r·min−1, the dosage of lime milk was 1.33 times of the theoretical amount, and the dosage of cationic polyacrylamide was 0.3 % (absolutely dry pulp), the ash content of hand-made sheet was 41.2 %, and the loading amount of calcium silicate was 26.3 %. Under this condition, the comprehensive performance of paper was the best.

In the past, H2O2 has been used as an oxidant when Ti-based materials are used as catalysts at ambient conditions. However, H2O2 suffers from high cost and safety concerns. Therefore, replacing H2O2 with O2 has been highly desired. In this study, a Ti-based bi-MOF, MIL-125(Ti)@NH2-MIL-125(Ti) has been synthesized through the internal extended growth of MIL-125(Ti) on NH2-MIL-125(Ti). This Ti-based bi-MOF performed in sequence to synergistically catalyze the oxidative desulfurization (ODS) reaction with O2. In this bi-MOF catalyst, MIL-125(Ti) is partly embedded and well distributed on the surface of NH2-MIL-125(Ti). NH2-MIL-125(Ti) serves as a catalyst for the production of H2O2 from O2/methanol under visible light, while MIL-125(Ti) serves as an ODS catalyst. The ODS over MIL-125(Ti) is the most effective as the in situ generated H2O2 could be used fully, and the consumed H2O2 (ODS reaction) also promotes further H2O2 production through the Le Chatelier's principle. MIL-125(Ti) and NH2-MIL-125(Ti) exist in close proximity in the bi-MOF material, which leads to an increase in the catalytic efficiency by 2.5-fold in comparison to that obtained from their physical mixture.

The liquefaction and reuse of plant biomass have attracted the attention of researchers because the fossil energy is running out gradually, corn stalk waste is rich and can be converted into high quality biofuels through the liquefaction process. The effects of polyethylene glycol on the atmospheric liquefaction yield of corn stalk and the properties of biofuel products were investigated. It was found that the optimal temperature was 170 ℃, reaction time was 60 min, liquid solid ratio was 5:1, catalyst concentrated phosphoric acid dosage was10%, the maximum liquefaction rate reached 97.19%. GC-MS analysis showed that the composition of biofuels is complex, which mainly including alcohols, organic acids, esters, ketones, sugars and other compounds. Results of FT-IR demonstrated that the characteristic functional groups of cellulose, hemicellulose and lignin in liquefied corn stalk were almost completely disappeared, SEM analysis showed that the surface morphology of liquefaction residue and original corn stalk was completely different, the fiber structure could not be seen in the residue, all these phenomenons indicating that corn stalk was completely liquefied.

In this work, reduced graphene oxide (rGO) with homogeneously dispersed phosphotungstate acid (HPW), were directly fabricated by using electrochemical strategy. In this one-pot route, the reduction of graphene oxide (GO) and HPW anchoring on rGO (HPW/rGO) have been achieved simultaneously. This strategy has not toxic reductants used, and meanwhile, produces high-quality rGO with sheet structure. Sheeted rGO could provide more anchor sites for HPW and prohibited HPW agglomeration. The produced HPW/rGO hybrid material performed high activity and durability in oxidative desulfurization (ODS) reaction due to the synergism of HPW and rGO. This work provides a novel sight for preparing high-efficient and stable catalyst for oxidative desulfurization.

In recent years, the biological activity of polysaccharides and their derivatives has been widely studied. However, in addition to the natural polysaccharides directly extracted from plants and animals, there are rich polysaccharides in the pulping waste liquor that have not been fully utilized. The extracted polysaccharide from eucalyptus Alkaline Peroxide Mechanical Pulping (APMP) waste liquor was used as a raw material. For the production of carboxymethyl polysaccharide, the effects of temperature (T), the amount of alkali (NaOH) and the amount of etherifying agent (ClCH2COOH) on the degree of substitution (DS) were investigated, the optimal preparation conditions are: reaction time 2 h, temperature 75 °C, and the molar ratio of polysaccharide, NaOH and ClCH2COOH is 1:1:2, the highest DS is 1.47; FT-IR, NMR and GPC were used to characterize the structure and Molecular weight, the results show that the polysaccharide of APMP waste liquor is rich in xylan, and it was proved that the carboxymethyl substitution was successful and the positions of the substituent group were determined. The characterization and biological activity research of xylan polysaccharide (XP) and carboxymethyl xylan polysaccharide (CMXP), such as antioxidation, moisture absorption/retention, bacteriostatic action and cytotoxicity were discussed. CMXP shows better effects compared with XP.

In this investigation, a variety of innovative temperature/pH-sensitive hydrogels consisting of hemicellulose (extracted from APMP waste liquor) and acrylic acid/acrylamide monomers were synthesized via free radical polymerization for water retention agents and controlled release. The results showed that the hydrogel polymer was chemically cross-linked and entangled to form a three-dimensional network structure, and the monomer successfully grafted on the hemicellulose chain. The content of crosslinkers and monomers had obvious effects on the swelling ratio of hydrogel. The sensitivity of the hydrogel was determined according to the change of the swelling ratio of the hydrogel under different temperature and pH conditions, combined with the chemical structure analysis of the hydrogel, and explain its sensitivity mechanism. Finally, after 6 days at 25 °C and pH 6, the swelled hydrogel still retained 79.46 % of the moisture, which proved that it has high water retention ability.

Background: Hydrogel has a three-dimensional network structure that is able to absorb a large amount of water/liquid and maintain its original structure. Hemicellulose (HC) is the second most abundant polysaccharide after cellulose in plants and a heterogeneous polysaccharide consisting of various saccharide units. The unique physical and chemical properties of hemicellulose make it a promising material for hydrogels. Methods: This review first summarizes the three research hotspots on the hemicellulose-based hydrogels: intelligence, biodegradability and biocompatibility. It also overviews the progress in the fabrication and applications of hemicellulose hydrogels in the drug delivery system and tissue engineering (articular cartilage, cell immobilization, and wound dressing). Results: Hemicellulose-based hydrogels have many unique properties, such as stimuliresponsibility, biodegradability and biocompatibility. Interpenetrating networking can endow appropriate mechanical properties to hydrogels. These properties make the hemicellulose-based hydrogels promising materials in biomedical applications such as drug delivery systems and tissue engineering (articular cartilage, cell immobilization, and wound dressing). Conclusion: Hydrogels have been widely used in biomedicine and tissue engineering areas, such as tissue fillers, drug release agents, enzyme encapsulation, protein electrophoresis, contact lenses, artificial plasma, artificial skin, and tissue engineering scaffold materials. This article reviews the recent progress in the fabrication and applications of hemicellulose-based hydrogels in the biomedical field.

The hemicellulose, cellulose and lignin were directly separated from corn stalk, and their liquefaction processes were investigated via acid-catalyzed solvolysis treatment with 1,2-propylene glycol (PG) and diethylene glycol (DEG) to produce bio-oil and residues. The main components, functional groups and organics structure of bio-oil were analyzed by the FTIR, 1H-NMR, 13C-NMR, GCMS, and TGA. It was found that there had a similar tendency in the liquefaction processes of cellulose, hemicellulose and lignin. Corn stalk and its biomass components were degraded and formed plentiful low-molecular polymers by acid catalysis, prior to polymers were converted into corresponding PG/DEG-derivatives. Finally, low-molecular weight soluble substances and insoluble residues were generated by decomposition and polymerization. Additionally, more than 80% compounds' carbon number in four bio-oils was below 25. The residues were mostly stemmed from macromolecules produced by degradation products and PG/DEG or re-polymerization between degraded small molecules.

Fischer-Tropsch waste water (FTW) is with complex organic compositions, and is toxic/stinking odor. So far, FTW is very difficult to be treated in industry. In this work, Fe-based bi-MOFs heterojunctions, i.e., MIL-88A(Fe)@MIL-88B(Fe) are synthesized through internal extended growth of rod-like MIL-88A on spindle-like MIL-88B. The compositions, structure and characteristics are systematically investigated. By virtue of larger surface area, rich active sites and strong interfacial coupling, this bi-MOFs catalyst establish better h+-e− separation/transfer. As expected, this bi-MOFs hybrid materials shows remarkable photo-catalytic performance toward FTW remediation by the help of ozone. The COD removal in bi-MOFs/O3 system is 4.2 times higher than that of ozonation alone. Furthermore, h+, O2− and OH are the predominant active radicals for FTW remediation. Bi-MOFs displays acceptable stability after 5 cycles. This work provides a new way for photo-catalytic ozonation and may drive the development of MOFs-based photo-catalytic ozonation for waste water treatment, not limited in FTW.

In this study, it is first time reported that benzoic acid functionalized g-C3N4 (BF-g-C3N4) sheets assisted synthesis of (0 0 1) surface-oriented MIL-88B-Fe with rod-like structure (BF-CM-rod). Pristine g-C3N4 sheets leaded to produce (1 0 1) surface-oriented MIL-88B-Fe with diamond-like structure (CM-diamond). BF-CM-rod composite catalyst achieves covalent bond links between g-C3N4 and MIL-88B-Fe, performs better separation of h+-e− pairs, and leads to excellent photo-catalytic performance for pollutant removal under visible light irradiation, with persulfate (PS) as oxidant. Its photo-activity is almost 4.2, 2.0 and 1.3 times of g-C3N4, MIL-88B-Fe and CM-diamond, respectively. A possible mechanism is proposed to explain the improved photo-catalytic performance of the Vis/BF-CM-rod/PS system. This work provides a novel way to prepare shape controlled Fe-based metal-organic frameworks formed by covalent bonds.

Synthesis of highly efficient isotype carbon nitride/carbon nitride (CN/CN) heterojunction, is a hot topic in the photocatalysis field. In this study, isotype CN/s-doped CN heterojunction is facile constructed with mixed precursor (melamine and trithiocyanuric acid). The structures and properties of CN/s-CN samples are systematically characterized by XRD, IR, TEM, TG, UV–vis, XPS, electrochemical and photo-catalytic degradation test. The synergistic CN and s-CN can significantly overcome the intrinsic drawback of rapid h+-e− recombination of CN or s-CN only. The CN/s-CN altered electronic structure, including narrowed band gap, upshifted band edge potential and improved electronic conductivity, and achieves 2.1 times activity than that of pristine CN.

A carboxylate chitooligomer (C-COS) containing carboxyl groups attached to chitooligomer (COS) molecules has been prepared by laccase/2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) system, which is a green-chemistry method. Several experiments were designed to evaluate inhibition effects on melanin and mechanisms of C-COS. The results indicated that C-COS exhibited more distinct anti-melanogenic effects compared to COS. C-COS inhibits melanin production with tyrosine (Tyr) and DOPA as the substrate of melanin formation, and the inhibition rates are, respectively, 89.07% and 84.45%, which reach 1.4–2 times those of COS. UV–vis spectroscopy was used to elucidate the interaction mechanism between C-COS and tyrosinase (TYR). It is C-COS chelating with metal Cu ions in tyrosinase (TYR) that decreases the enzyme activity. Half-maximal inhibitory concentrations (IC50) of C-COS were calculated as 13.49 and 4.07 mg/mL for monophenolase (cresolase) and diphenolase (catecholase), respectively.

6-carboxylate chitooligosaccharides (6-CCOS), as a superabsorbent material, were prepared by way of the laccase/TEMPO oxidation system. It exhibited a higher moisture-absorption ability and stronger affinity for water. To understand the real reasons for this, the hydrogen bonding structure of 6-CCOS and the hydration mechanism of the molecule were investigated using infrared (IR), differential scanning calorimetry (DSC), and nuclear magnetic resonance (NMR). It was found that the introduction of a strongly hydrophilic carboxylate ion on the C6 site of chitooligosaccharides molecule was conducive to the enhancement of the interaction between polysaccharide polymers and water molecules. The most important was the formation of hydrogen bonds connected between carboxylate ion and residual water. In addition, the hydration mechanism of 6-CCOS molecules was presumed to be that more water molecules from outside were incorporated into the already embedded water molecules within the polymer. The whole molecule was woven into a huge water-polymer network structure through intermolecular hydrated hydrogen bonds.

Hemicelluloses present in the prehydrolysis liquor (PHL) of the hardwood kraft-based dissolving pulp production process can be utilized in the production of furfural, which is an important renewable, non-petroleum-based platform chemical. A lower furfural yield was observed from the concentrated sugars in PHL in acetic-acid-catalyzed systems. The reaction rate of sugar consumption and furfural destruction in PHL was higher than those of model xylan and xylose systems, which may be due to the side-reactions of lignin with sugars and carbonization of oligomeric sugars. In order to minimize these side-reactions, a steam-stripping method of generated furfural was adopted. The results showed that the method was effective in increasing the furfural yield (41.5%) from the concentrated PHL.

The kinetics of C-5 sugars (xylose/xylan) conversion to furfural in an industrial pre-hydrolysis liquor (PHL) in both acetic acid (HAc)-catalyzed system and sulfuric acid (H 2 SO 4 )-catalyzed system, were determined in a temperature range of 150–190 °C. The main reactions involved during the process included: 1) C-5 sugars consumption for furfural formation and side reactions; 2) furfural degradation. It was found that these reactions followed first order kinetics. A consecutive reaction model (from xylose to furfural, then to degradation products) fitted into the data obtained in the H 2 SO 4 -catalyzed system; while a consecutive/parallel model suited for the HAc-catalyzed system due to side reactions, which also consumed C-5 sugars. The activation energy for C-5 sugar disappearance, and the furfural degradation, was 151 kJ mol −1 and 115 kJ mol −1 , respectively, in the HAc-catalyzed system.

In this study, experimental viscosity results of hardwood prehydrolysis liquor (PHL) from the kraft-based dissolving pulp production process were obtained and used to develop empirical models describing the effect of temperature, solid content, the interaction between solute and solvent, and the concentration of lignin and hemicelluloses. The concentration, molar mass, and molecular weight of lignin and polysaccharide of PHL, all are the factors that affect the rheological behavior of the PHL. The results showed that, on the one side, Zaman and Fricke’s model gave better fitting when the viscosity is lower, on the other hand, a much better fitting of the Moosavifar’s model could be obtained by taking interaction between solute and solvent, solids content, concentration of lignin and hemicelluloses into account when the viscosity is higher, because of the interaction between solute lignin/hemicelluloses and solvent water, and the aggregation of lignin with itself, hemicelluloses with itself, and lignin wit...

Acid hydrolysis is an essential step in converting polysaccharides to monosaccharides for the production of fuels and chemicals. The prehydrolysis liquor (PHL) from the kraft-based dissolving pulp production process contains mainly oligosugars with a minor amount of monosugars. In this study, the influence of process conditions, including the sulfuric acid concentration, temperature, and time on the PHL hydrolysis was thoroughly investigated in order to get maximum monosugar concentration with minimal degradation of sugars. The maximum monosugar concentration was obtained at 130 °C for 20 min when the hydrolysis was carried out with 1.78% H2SO4. A high acid concentration (3.33%) increased furfural formation and decreased the monosugar concentration. Acetic acid is generated from the acetyl groups bound to the dissolved hemicelluloses, resulting in a significant increase in the acetic acid concentration in the PHL.

The yellowish color of High Yield Pulp (HYP) gives some psychological obstacles and limits its application in some paper grades. Dyes are widely used in the papermaking process to shade the yellowish color of the paper products. We proposed to add dyes into the HYP manufacturing process to minimize the yellowish hue. In this work, we substituted the dye-added HYP (dyes added in the HYP manufacturing process) for hardwood kraft pulp in the production of fine paper grades, and compared the results from those by adding dyes into the papermaking wet end. A higher dye effectiveness was obtained when we used the dye-added HYP. Also, the dye-added HYP gave more effective performance of Precipitated Calcium Carbonate (PCC) fillers and Optical Brightening Agents (OBA) in terms of CIE whiteness and b*. In addition, the dye-added HYP showed less negative effect on brightness and better compatibility with other dyes. The underlying mechanism for the above experimental observation was proposed.

This study aimed to produce furfural from waste aqueous hemicellulose solution of a hardwood kraft-based dissolving pulp production processing in a green method. The maximum furfural yield of 82.4% and the xylose conversion of 96.8% were achieved at 463 K, 1.0 g ZSM-5, 1.05 g NaCl and organic solvent-to-aqueous phase ratio of 30:15 (V/V) for 3 h. The furfural yield was just 51.5% when the same concentration of pure xylose solution was used. Under the optimized condition, furfural yield was still up to 67.1% even after the fifth reused of catalyst. Catalyst recycling study showed that ZSM-5 has a certain stability and can be efficiently reused. (C) 2014 Elsevier Ltd. All rights reserved.