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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 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.