Shouxin Liu

Synthesis of nickel-incorporated larch-based carbon membranes with controllable porous structure for gas separation

AbstractnNi-incorporated larch-based carbon membranes have been synthesized by introducing the Ni(NO3)2 into the liquefied larch using liquefied larch sawdust as precursors and F127 as the soft template. The porous structure can be tailored by the amount of Ni(NO3)2, and the Ni and NiO nanoparticles with a size of 10xa0nm incorporated in the carbon frameworks. The increase in Ni(NO3)2 content can lead to the formation of disordered porous structure and shrinkage of carbon frameworks. The Ni-incorporated carbon membranes with largest pores possess highest gas permeation for N2, CO2, and O2 of 37.5, 19.8, and 55.5xa0m3xa0cm/m2xa0hxa0kPa, which is larger than that of the pure carbon membranes, respectively. However, the poor ordered porous structure caused by adding large amount of Ni(NO3)2 can reduce the gas separation performance, which is attributed to the weaken of the molecular sieve function. The results indicate that the incorporation of few nanoparticles into larch-based carbon membranes can improve molecular sieve function.Graphical abstractNi-incorporated larch-based carbon membranes have been synthesized by introducing the Ni(NO3)2 into the liquefied larch. The porous structure can be tailored by the amount of Ni(NO3)2, and the Ni and NiO nanoparticles incorporated in the carbon frameworks. The Ni-incorporated carbon membranes with largest pores possess highest gas permeation and gas permseparation.

Enhanced thermal and mechanical properties of PVA composites formed with filamentous nanocellulose fibrils

Long filamentous nanocellulose fibrils (NCFs) were prepared from chemical-thermomechanical pulps (CTMP) using ultrasonication. Their contribution to enhancements in thermal stability and mechanical properties of poly(vinyl alcohol) films were investigated. The unique chemical pretreatment and mechanical effects of CTMP loosen and unfold fibers during the pulping process, which enables further chemical purification and subsequent ultrasound treatment for formation of NCFs. The NCFs exhibited higher crystallinity (72.9%) compared with that of CTMP (61.5%), and had diameters ranging from 50 to 120 nm. A NCF content of 6 wt% was found to yield the best thermal stability, light transmittance, and mechanical properties in the PVA/NCF composites. The composites also exhibited a visible light transmittance of 73.7%, and the tensile strength and Youngs modulus were significantly improved, with values 2.8 and 2.4 times larger, respectively, than that of neat PVA.

A novel biodegradable β-cyclodextrin-based hydrogel for the removal of heavy metal ions

A novel biodegradable β-cyclodextrin-based gel (CAM) was prepared and applied to the removal of Cd(2+), Pb(2+) and Cu(2+) ions from aqueous solutions. CAM hydrogel has a typical three-dimensional network structure, and showed excellent capability for the removal of heavy metal ions. The effect of different experimental parameters, such as initial pH, adsorbent dosage and initial metal ion concentration, were investigated. The adsorption isotherm data fitted well to the Freundlich model. The adsorption capacity was in the order Pb(2+)>Cu(2+)>Cd(2+) under the same experimental conditions. The maximum adsorption capacities for the metal ions in terms of mg/g of dry gel were 210.6 for Pb(2+), 116.41 for Cu(2+), and 98.88 for Cd(2+). The biodegradation efficiency of the resin reached 79.4% for Gloeophyllum trabeum. The high adsorption capacity and kinetics results indicate that CAM can be used as an alternative adsorbent to remove heavy metals from aqueous solution.

Nanocellulose fibrils isolated from BHKP using ultrasonication and their reinforcing properties in transparent poly (vinyl alcohol) films

Nanocellulose fibrils (NCFs) were isolated from bleached hard kraft pulp (BHKP) using high-intensity ultrasonication, and their reinforcement capabilities for poly (vinyl alcohol) films were investigated. Scanning electron microscopy (SEM), thermogravimetric analysis (TG), and X-ray diffraction (XRD) were used to characterize the fibrils and films. The results revealed that the prepared NCFs were long filaments with a cellulose I crystal structure. The filaments were 50–150xa0nm in diameter, and had lengths longer than 500xa0μm. The crystallinity and thermal stability of the NCFs were increased compared with BHKP because of the removal of hemicellulose. A NCFs content of 4xa0wt% was found to give the best light transmittance and mechanical properties in the PVA composites. The PVA composites exhibited a visible light transmittance of 75xa0%, and the tensile strength and Young’s modulus were significantly improved, with values 1.86 and 1.63 times larger than that of neat PVA.

Preparation of entangled nanocellulose fibers from APMP and its magnetic functional property as matrix.

Nanocellulose fibers (NCFs) aerogels were prepared from poplar alkaline peroxide mechanical pulp (APMP) using physical ultrasonication method. As raw materials, the unique mechanical effects of APMP cause the fiber folding and loose during the pulping process, which was beneficial to further chemical purification and subsequent treatment for long and entangled NCFs. The obtained NCFs exhibited higher crystallinity (77.8%) compared with that of APMP (72.6%) together with diameters range from 20 to 90 nm and self-assembled to network. The primary thermal degradation of NCFs occurred at 331.5°C. The prepared NCFs network aerogels acted as matrix which can prevent the growth and aggregation of ferromagnetic CoFe2O4 nanoparticles. The ratio of the CoFe2O4 of magnetic composites increased from 34 wt% to 75 wt%, and the magnetic properties were all increased with increasing the reaction concentration of FeSO4/CoCl2 salt.

Synthesis and swelling properties of β-cyclodextrin-based superabsorbent resin with network structure

A biodegradable, β-cyclodextrin-based superabsorbent resin was synthesized by the inverse suspension method. The microstructure, chemical structure, and thermal performance of the resin were characterized by scanning electron microscopy, Fourier transform-infrared spectroscopy, and differential scanning calorimetry. The effects of the synthesis conditions (dosage of cross-linking agent, mass ratios of acrylic acid to acrylamide, mass ratios of β-cyclodextrin to total monomer, neutralization degree, initiator dosage, and reaction time) were optimized to achieve a resin with a maximum swelling capacity. The water absorbency of the optimized resin in distilled water was 1544.76 g/g and that in 0.9 wt.% NaCl was 144.52 g/g. The resin, which is thermoplastic as well as pH-sensitive, had good salt resistance and underwent a maximum in swelling with time in CaCl(2) and AlCl(3) solutions. The fracture surface of the dry resin contained many pores. After swelling, the internal hydrogel showed a typical three-dimensional network structure. The biodegradation of the resin reached 71.2% after 18 days treatment at 30 °C with Lentinus edodes.

Preparation and swelling behavior of a novel self-assembled β-cyclodextrin/acrylic acid/sodium alginate hydrogel

A novel biodegradable β-cyclodextrin/acrylic acid/sodium alginate (CSA) hydrogel with a three-dimensional network structure was self-assembled by inverse suspension copolymerization. The CSA resin was pH sensitive and had good water absorption properties in pH 6-8 buffer solutions. At a β-CD:AA:SA mass ratio of 1:9:3 the CSA water absorbency was found to be 1403 g/g and the CSA hydrogel strength was 4.968 N. In 0.005-0.1 mol/L chloride salt and sulfate salt solutions the CSA water absorbencies increased as follows: NaCl>KCl>MgCl2>CaCl2>FeCl3, and Na2SO4>K2SO4>FeSO4>Al2(SO4)3, respectively. The release of water from the CSA hydrogel occurred slowly over 120 h. The biodegradation efficiency of the resin reached 85.3% for Lentinula edodes. The super water absorbency, good salt resistance and excellent water retention properties of CSA make it suitable for application as an agricultural water retention agent in saline soils.

Effect of reaction temperature on properties of carbon nanodots and their visible-light photocatalytic degradation of tetracyline

Water-soluble carbon nanodots (CNDt) with diverse sizes, crystal structures, surface properties, and characteristic fluorescence spectra were synthesized by the hydrothermal carbonization of larch at different temperatures. The effects of reaction temperature on the diameter distribution, structural components, and fluorescence properties of the CNDt were investigated systematically. The synthesized CNDt were found to be monodispersed spherical polymer nanodots with a low degree of aromatization and abundant oxygen-containing groups on their surface. Increasing the reaction temperature decreased the average size of the nanodots from 20.35 to 6.48 nm, while their quantum yield increased from 13% to 18%. Broader and weaker UV characteristic peaks were detected when the reaction temperature was increased from 200 to 260 °C. All the CNDt samples exhibited excitation and emission-independent properties, and obvious blue shift of the excitation and emission peaks occurred at higher reaction temperatures owing to the smaller size and different surface properties obtained. The CNDt were used as a photosensitizer in a CND/TiO2 system to effectively degrade tetracycline hydrochloride (TCH) under visible-light irradiation. The obvious blue shift exhibited by the smaller CNDt allowed the light to be fully used by the TiO2, resulting in nearly 100% TCH degradation for CND260/TiO2.

Carbon spheres obtained via citric acid catalysed hydrothermal carbonisation of cellulose

Abstract Well dispersed micrometre sized carbon spheres were prepared by citric acid catalysed hydrothermal carbonisation (200–240°C) of cellulose. The obtained product was characterised using scanning electron microscopy, field emission scanning electron microscopy, X-ray diffraction, and Fourier transform infrared and X-ray photoelectron spectroscopy. The results showed that the shape and size of the obtained carbons were highly dependent on the concentration of catalyst, hydrothermal temperature and reaction time. The optimal citric acid concentration, temperature and reaction time for the synthesis of carbon with smooth and regular sphere morphology were 2·5 wt-%, 240°C and 12 h respectively. The formation of the carbon spheres from cellulose followed the paths of hydrolysis, dehydration, polymerisation and aromatisation. The obtained carbon spheres consisted of aliphatic and aromatic structures and rich in oxygen containing functional groups on the surface.

Preparation and adsorption behaviors of sodium alginate-based adsorbent-immobilized β-cyclodextrin and graphene oxide

Highly water soluble graphene oxide (GO) was synthesized via a modified Hummers method. A sodium alginate (SA)-based adsorbent-immobilized β-cyclodextrin (β-CD) and GO gel (SCGG) with excellent regeneration ability were prepared. The adsorptive properties of methylene blue (MB) on the SCGG adsorbent were studied. The results showed that when the dosage of the adsorbent was 1.0 g, pH of the solution was 7, temperature was 35 °C, initial concentration of MB was 50 mg L−1, and adsorption time was 180 min, the removal rate of MB was 84.98% and the adsorption capacity was 133.24 mg g−1. The isotherms and kinetics of adsorption were investigated to reveal that the equilibrium adsorption and kinetics were well-described by the Freundlich model and pseudo-second-order kinetics, respectively. The thermodynamic parameters showed that the adsorption process was spontaneous and endothermic in nature. The mechanical property of the SCGG was improved by the addition of GO. The regeneration removal rate of MB was more than 82% after six recycles.