Qiu-Feng Lü

Liquefaction of lignin by polyethyleneglycol and glycerol.

Enzymatic hydrolysis lignin (EHL), isolated from the enzymatic hydrolysis residues of the biomass, was liquefied using the mixed solvents of polyethyleneglycol (PEG) and glycerol at the temperature of 130-170°C with sulfuric acid as a catalyst. The influences of liquefaction parameters, such as the molecular weight of PEG, mass ratio of sulfuric acid to EHL, liquefaction temperature and time, and mass ratio of liquid (liquefying cosolvent) to solid (EHL) on the residue content and hydroxyl number were discussed. The FT-IR spectrum result showed that the liquefaction product of EHL was polyether polyol. The hydroxyl number of the liquefaction product was 80-120 mgKOH/g higher than that of PEG.

Preparation and heavy metal ions biosorption of graft copolymers from enzymatic hydrolysis lignin and amino acids

Novel biosorbents, graft copolymers, were prepared via Mannich reaction from enzymatic hydrolysis lignin with glycine and cystine, respectively. The element content, FT-IR and fluorescence spectra, relative viscosity, and particle size of the copolymers were systematically investigated. Furthermore, effects of initial pH, ionic strength, temperature, contact time and initial metal ion concentration on the biosorption capacities of Cu(II) and Co(II) ions onto the copolymers were studied using batch sorption technique. It was found that the copolymers exhibited excellent biosorption characteristics for Cu(II) and Co(II) ions. The sorption kinetic data can be described well with a pseudo-second-order model, and the equilibrium data can be fitted well to the Langmuir and Freundlich isotherm for Cu(II) and Co(II) biosorption process, respectively. Surface complexation and ion-exchange modeling were performed to elucidate the biosorption mechanism involved because surfaces of the copolymers contained three main types of acid/base sites from the amino acid grafted copolymer units.

Facile Preparation of Hierarchical Polyaniline-Lignin Composite with a Reactive Silver-Ion Adsorbability

A hierarchical polyaniline-lignin (PANI-EHL) composite was facilely prepared from aniline and enzymatic hydrolysis lignin in an aqueous solution of ammonia. The morphology, FTIR, UV-vis spectra, thermogravimetric analysis, and wide-angle X-ray diffraction analyses of the composite were systematically investigated. Furthermore, the sorption property of the PANI-EHL composite for silver ions in aqueous solution was studied via a static sorption technique. The result demonstrated that the PANI-EHL composite possessed a strongly reactive sorption characteristic for silver ions. Serrated silver threads with length up to 10 mm were obtained by using the PANI-EHL composite as a low-cost adsorbent. Moreover, the role of EHL and polyaniline in the PANI-EHL composite for silver ions sorption was investigated. The investigation indicated that the EHL unit could play a vital role in the chelation of silver ions, whereas the polyaniline unit played a leading role in redox sorption.

Preparation and application of porous nitrogen-doped graphene obtained by co-pyrolysis of lignosulfonate and graphene oxide.

Nitrogen-doped graphene with in-plane porous structure was fabricated by simple co-pyrolysis of lignosulfonate and graphene oxide in the presence of urea. Lignosulfonate first performs as a dispersant adsorbed on the surface of graphene oxide to prevent the aggregation of graphene oxide sheets for preparing homogeneous nitrogen-containing precursor, and then acts as a porogen to render graphene sheets with nanopores in the pyrolysis process of the nitrogen-containing precursor. Urea was used as a nitrogen source to incorporate nitrogen atoms into graphene basal plane. The special nanoporous structure combined with nitrogen content of 7.41at.% endows the nitrogen-doped graphene electrode material with super capacitance up to 170Fg(-1), high rate performance, and excellent cycling stability.

Nanocomposites of Sulfonic Polyaniline Nanoarrays on Graphene Nanosheets with an Improved Supercapacitor Performance

A new nanocomposite, poly(aniline-co-diphenylamine-4-sulfonic acid)/graphene (PANISP/rGO), was prepared by means of an in situ oxidation copolymerization of aniline (ANI) with diphenylamine-4-sulfonic acid (SP) in the presence of graphene oxide, followed by the chemical reduction of graphene oxide using hydrazine hydrate as a reductant. The morphology and structure of PANISP/rGO were characterized by field-emission (FE) SEM, TEM, X-ray photoelectron spectroscopy (XPS), Raman, FTIR, and UV/Vis spectra. The electrochemical performance was evaluated by cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. The PANISP/rGO nanocomposite showed a nanosized structure, with sulfonic polyaniline nanoarrays coated homogeneously on the surface of graphene nanosheets. This special structure of the nanocomposite also facilitates the enhancement of the electrochemical performance of the electrodes. The PANISP/rGO nanocomposite exhibits a specific supercapacitance up to 1170 F g(-1) at the current density of 0.5 A g(-1) . The as-prepared electrodes show excellent supercapacitive performance because of the synergistic effects between graphene and the sulfonic polyaniline copolymer chains.

Fabrication, characterization and application of nitrogen-containing carbon nanospheres obtained by pyrolysis of lignosulfonate/poly(2-ethylaniline).

Lignosulfonate/poly(2-ethylaniline) (LS-PEA) composite nanospheres were prepared via in situ polymerization of 2-ethylaniline (EA) with lignosulfonate (LS) as a dispersant. LS-PEA nanospheres with an average diameter of 155 nm were obtained at an optimal LS concentration of 20 wt.%. Subsequently, nitrogen-containing carbon nanospheres were fabricated via direct pyrolysis of the LS-PEA composite nanospheres at 600-800 °C. The carbon nanospheres prepared by pyrolysis were used as anodes of lithium-ion batteries. The first charge and discharge capacity of carbon nanospheres prepared at 700 °C at current densities of 60 and 100 mA g(-1) were 980 and 432 mAh g(-1), and 764 and 342 mAh g(-1), respectively. The batteries still owned a high capacity of 353 and 296 mAh g(-1) after 20 cycles. The results indicated that these nitrogen-containing carbon nanospheres could be used as a promising candidate for electrode materials of lithium-ion batteries.

Controlled Preparation and Reactive Silver‐Ion Sorption of Electrically Conductive Poly(N‐butylaniline)–Lignosulfonate Composite Nanospheres

Electroconductive poly(N-butylaniline)-lignosulfonate (PBA-LS) composite nanospheres were prepared in a facile way by in situ, unstirred polymerization of N-butylaniline with lignosulfonate (LS) as a dispersant and dopant. The LS content was used to optimize the size, structure, electroconductivity, solubility, and silver ion adsorptive capacity of the PBA-LS nanospheres. Uniform PBA-LS10 nanospheres with a minimal mean diameter of 375 nm and high stability were obtained when the LS content was 10 wt %. The PBA-LS10 nanospheres possess an increased electroconductivity of 0.109 S cm(-1) compared with that of poly(N-butylaniline) (0.0751 S cm(-1)). Furthermore, the PBA-LS10 nanospheres have a maximal silver-ion sorption capacity of 815.0 mg  g(-1) at an initial silver ion concentration of 50 mmol  L(-1) (25 °C for 48 h), an enhancement of 70.4% compared with PBA. Moreover, a sorption mechanism of silver ions on the PBA-LS10 nanospheres is proposed. TEM and wide-angle X-ray diffraction results showed that silver nanoparticles with a diameter size range of 6.8-55 nm was achieved after sorption, indicating that the PBA-LS10 nanospheres had high reductibility for silver ions.

Fabrication of poly(N-ethylaniline)/lignosulfonate composites and their carbon microspheres

Novel poly(N-ethylaniline)/lignosulfonate (PNA-LS) composites were prepared via an in situ polymerization of N-ethylaniline (NA) with lignosulfonate (LS) as a dispersant. Nitrogen-containing carbon materials were obtained by direct pyrolysis of the PNA-LS composites at the pyrolytic temperatures ranging from 300°C to 1200°C. The as-prepared PNA-LS composites and their carbon materials were investigated by TGA, SEM, TEM, FTIR and UV-vis spectra, XRD and elemental analysis. The results showed that the morphology, structure and properties of the PNA-LS composites were depended on the LS:NA mass ratio. PNA-LS microspheres with an average diameter of 1300 nm could be fabricated when the LS:NA mass ratio was 2.5:97.5, while regular hexagon sheets of PNA-LS composite were obtained with the LS:NA mass ratio above 5:95. Furthermore, nitrogen-containing carbon nanospheres with an average diameter of 820 nm were achieved at the carbonization temperature of 800°C.

Biosorption of methylene blue by chemically modified cellulose waste

Citric acid modified cellulose waste (CMCW) was prepared via esterification and used as a low-cost biosorbent for the removal of methylene blue (MB) from aqueous solutions. The effects of biosorbent concentration, initial pH of MB solution, biosorption temperature, contact time, and initial MB concentration on the biosorption of MB were investigated using batch biosorption technique under static conditions. The experimental results showed that CMCW exhibited excellent biosorption characteristics for MB. The maximum biosorption capacity of MB was up to 214.5 mg/g at an adsorption temperature of 293 K. The removal rate of MB onto CMCW reached the maximum at pH>4 and the biosorption reached an equilibrium at about 50 min. The kinetic data can be described well with the pseudo-second-order model and the isotherm data was found to fit the Langmuir isotherm with a monolayer adsorption capacity of 211.42 mg/g. The biosorption appears to be controlled by chemisorption and may be involved in surface adsorption and pore diffusion during the whole biosorption process.