Enzymatic hydrolysis lignin functionalized Ti3C2Tx nanosheets for effective removal of MB and Cu2+ ions.

Functionalized two-dimensional Ti3C2Tx (TN-EHL) was prepared as an effective adsorbent for removal of methylene blue dye (MB) and copper ions (Cu2+). Enzymatic hydrolysis lignin (EHL), a reproducible natural resource, was used to functionalize the Ti3C2Tx nanosheets. EHL can not only introduce active functional groups into TN-EHL but also prevent the oxidation of Ti3C2Tx, thus promoting the adsorption performance of TN-EHL. The maximum adsorption capacities of TN-EHL50 (in which the EHL content is 50 wt%) for MB and Cu2+ were 293.7 mg g-1 and 49.96 mg g-1, respectively. The higher correlation coefficients (R2) of MB (0.9996) and Cu2+ (0.9995) indicating that their adsorption processes can be described by the pseudo-second-order kinetic model. The MB adsorption data fit the Freundlich isotherm with R2 of 0.9953, whereas the Cu2+ ions adsorption data fit the Langmuir isotherm with R2 of 0.9998. The thermodynamic analysis indicates that the adsorption process of MB and Cu2+ on TN-EHL50 is spontaneous and endothermic. Significantly, the Cu2+ ions were reduced to Cu2O and CuO particles during the adsorption process. Therefore, TN-EHL has a great potential as an environmentally friendly adsorbent for MB removal and recovery of Cu2+ ions from wastewater.

A low-pass filter of 300 Hz improved the detection of pacemaker spike on remote and bedside electrocardiogram.

BACKGROUND: The current upper-frequency cutoff of 150 Hz sometimes causes loss of pacemaker spike and misdiagnosis. We hypothesized that low-pass filter (LPF) other than 150 Hz could improve the detection of pacemaker spike. This study aimed to examine the effect of different LPF on pacemaker spike detection in remote and bedside electrocardiogram (ECG). METHODS: Patients with permanent pacemaker implantation were included during routine follow-up. Standard 12-lead ECGs at 6 different upper-frequency cutoff (40, 100, 150, 200, 300, and 400 Hz) were collected. All ECGs were then transmitted to the remote clinic center. Ventricular and atrial pacing were analyzed by 2 independent medical practitioners. RESULTS: A total of 88 patients' ECGs were analyzed (mean age 73.8 ±â€Š10.2 years and 85 with dual-chamber pacemakers). About 75.3% (64/85) of patients were diagnosed as atrial pacing by pacemaker programming. Among 6 different upper-frequency cutoff, the 300 Hz turned out to perform best in detecting atrial-paced spike (area under the curve [AUC] = 0.73, 95% confidence interval [CI]: 0.61-0.84 vs. 0.56, 95% CI: 0.61-0.84 at 150 Hz; P = 0.002) on bedside ECGs. Using programming as the golden standard, the 300 Hz LPF has a sensitivity of 59.4%, specificity of 85.7%, positive predictive value of 92.7% and negative predictive value of 40.9% on bedside ECGs. As for the ventricular pacing, the 300 Hz LPF also had a higher accuracy (AUC = 0.93; 95% CI = 0.84-1.00) than that at 150 Hz (AUC = 0.86; 95% CI: 0.77-0.94; P < 0.001) in detecting ventricular-paced spike on bedside ECGs. The results of remote ECGs were similar with bedside ECGs. CONCLUSIONS: A filter of 300 Hz cutoff may be recommended for ECG spike detection. With the recommended parameter, remote ECG can perform as well as bedside ECG.

Efficient adsorption of methylene blue and lead ions in aqueous solutions by 5-sulfosalicylic acid modified lignin.

As a kind of biomass that exists widely in plants, lignin shows much diversity as a functional material. In order to improve the adsorption ability, lignin was chemically modified by 5-sulfosalicylic acid and then used to adsorb methylene blue (MB) and Pb2+ from aqueous solutions. The results showed that the 5-sulfosalicylic acid modified lignin exhibited a high adsorption ability for dyes or heavy metals. The maximum adsorption capacity of the adsorbent approached 83.2 mg/g for MB and 39.3 mg/g for Pb2+ with the adsorbent dosage of 5 g/L at pH 5.85 or 5.35 (corresponding to MB or Pb2+, respectively), initial adsorbate concentration of 200 mg/L, temperature of 318 K and contact time of 12 h. The adsorption kinetics and isotherm studies indicated that both the adsorption of MB and Pb2+ onto SSAL followed the pseudo-second-order model and Langmuir isotherm model. It means that the adsorption process fits the model of mono-layer adsorption and it was mainly chemical process and accompanied with surface adsorption. The proposed SSAL is low-cost, eco-friendly and highly efficient therefore a promising material for adsorptive removal of MB and Pb2+ from wastewater.

Fabrication of Low-Cost and Ecofriendly Porous Biocarbon Using Konjaku Flour as the Raw Material for High-Performance Supercapacitor Application.

Low-cost and ecofriendly porous biocarbons were fabricated from konjaku flour via precarbonization and potassium hydroxide (KOH) activation. The obtained biocarbon ACK-5 derived from a precarbonized carbon/potassium hydroxide (KOH) mass ratio of 1:5 possessed an ultrahigh specific surface area of 1403 m2 g-1 and hierarchical porous structures with the existence of micro- to macropores. When ACK-5 was employed as a supercapacitor electrode in 6 M KOH, it showed a high specific capacitance of 216 F g-1 and excellent cycling stability with capacitance retention remaining 93.7% after 5000 cycles. Moreover, the ACK-5 sample acquired a supramaximal specific capacitance of 609 F g-1, and the high energy density of ACK-5//ACK-5 symmetrical cells reached up to 9.2 Wh kg-1 when p-phenylenediamine serving as a redox electrolyte was added into KOH electrolyte. The reported simple fabrication strategy would leverage a green biomass precursor for the preparation of supercapacitors.

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.

Self-assembled poly(N-methylaniline)-lignosulfonate spheres: from silver-ion adsorbent to antimicrobial material.

Self-assembled poly(N-methylaniline)-lignosulfonate (PNMA-LS) composite spheres with reactive silver-ion adsorbability were prepared from N-methylaniline by using lignosulfonate (LS) as a dispersant. The results show that the PNMA-LS composite consisted of spheres with good size distribution and an average diameter of 1.03-1.27 µm, and the spheres were assembled by their final nanofibers with an average diameter of 19-34 nm. The PNMA-LS composite spheres exhibit excellent silver-ion adsorption; the maximum adsorption capacity of silver ions is up to 2.16 g g(-1) at an adsorption temperature of 308 K. TEM and wide-angle X-ray results of the PNMA-LS composite spheres after absorption of silver ions show that silver ions are reduced to silver nanoparticles with a mean diameter of about 11.2 nm through a redox reaction between the PNMA-LS composite and the silver ions. The main adsorption mechanism between the PNMA-LS composite and the silver ions is chelation and redox adsorption. In particular, a ternary PNMA-LS-Ag composite achieved by using the reducing reaction between PNMA-LS composite spheres and silver ions can be used as an antibacterial material with high bactericidal rate of 99.95 and 99.99% for Escherichia coli and Staphylococcus aureus cells, respectively.

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.

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.

Self-stabilized nanoparticles of intrinsically conducting copolymers from 5-sulfonic-2-anisidine.

Novel copolymer nanoparticles with inherent self-stability, narrow size distribution, and high electrical conductivity are facilely and productively synthesized by the oxidative precipitation polymerization of 5-sulfonic-2-anisidine and aniline in acidic medium without any external stabilizer. The structures of the copolymer particles are systematically characterized by IR and UV/Vis spectroscopy, X-ray diffraction, laser particle-size analysis, atomic force microscopy, field-emission scanning electron microscopy, and high-resolution transmission electron microscopy. The comonomer ratio, oxidant/monomer ratio, and polymerization temperature and medium can be used to optimize the size and conductivity of the nanoparticles. It is found that the nanoparticles exhibit a minimal size and polydispersity index of around 53 nm and 1.045, respectively. Nanocomposite films of the nanoparticles with diacetyl and ethyl celluloses show good thermostability and a low percolation threshold of 0.08 wt%, at which the films retain 89% of the transparency, 96-98% of the strength, and 10(8) times the conductivity of the matrix film. The synthesis of sulfoanisidine copolymer nanoparticles is thus achieved without the use of external stabilizer, which opens up a simple and general route to the fabrication of nanostructured polymer materials with controllable size, narrow size distribution, intrinsic self-stability, strong dispersibility, high purity, and optimizable electroconductivity.

Synthesis and heavy-metal-ion sorption of pure sulfophenylenediamine copolymer nanoparticles with intrinsic conductivity and stability.

Novel copolymer nanoparticles were easily synthesized with a polymerization yield of 59.3 % by an oxidative precipitation polymerization of aniline (AN) and m-sulfophenylenediamine (SP) in HCl without any external stabilizer. The polymerization yield, size, morphology, electroconductivity, solubility, solvatochromism, lead and mercury ion adsorbability of the HCl-doped copolymer salt particles were studied by changing the AN/SP ratio. The AN/SP (80:20) copolymer particles are found to have the minimal number-average diameter(84.4 nm), minimal size polydispersity index (1.149), high stability, good long-term stability, powerful redispersibility in water, high purity, and clean surface because of a complete elimination of the contamination from external stabilizer. The copolymer salts possess a remarkably enhanced solubility, interesting solvatochromism, and widely adjustable electroconductivity moving across nine orders of magnitudes from 10(-9) to 10(0) S cm(-1). The AN/SP (70:30) copolymer particles have the highest Hg2+ adsorbance and adsorptivity of 497.7 mg g(-1) and 98.8 %, respectively, which are much higher values than those of other materials. The sorption mechanism of lead and mercury ions on the particles is proposed. The copolymer bases with 5-10 mol % SP unit show excellent film formability, flexibility, and smooth appearance. The copolymer should be very useful in the fabrication of cost-effective conductive nanocomposite with low percolation threshold and in removal of toxic metallic ions from waste water.

Facile synthesis and optimization of conductive copolymer nanoparticles and nanocomposite films from aniline with sulfodiphenylamine.

A new series of electrically conductive pure copolymer nanoparticles was facilely synthesized by using oxidative polymerization of aniline (AN) and sodium diphenylamine-4-sulfonate (SDP) in acidic media in the absence of stabilizer. The variation of the structure of the copolymer particles was comprehensively studied by carefully choosing several important parameters, such as the comonomer ratio, oxidant/monomer ratio, polymerization time and temperature, monomer concentration, acidic medium, and oxidant species. Analytical techniques used include IR and UV-visible spectroscopy, X-ray diffraction, laser particle analysis, atomic force microscopy, and transmission electron microscopy. It was found that the particle size varied significantly with the above-mentioned polymerization parameters, only changes in the salt concentration in the aqueous testing solution had no noticeable effect. The polymerization conditions were optimized for the formation of copolymer nanoparticles with sought-after properties. The doped copolymer particles of AN/SDP (50:50) at an oxidant/monomer molar ratio of 0.5 exhibit a minimum length of 50 nm and a minimum diameter of 44 nm. The bulk electrical conductivity of the copolymer particles increases greatly from 5.90x10(-4) to 1.15x10(-2) S cm(-1) with increasing AN content. Compared with barely soluble polyaniline, the copolymers exhibit a remarkably enhanced solubility in most solvents, including NH4OH and even water, due to the presence of the hydrophilic sulfonic groups. Nanocomposite films of the nanoparticles and cellulose diacetate exhibit a percolation threshold of down to 0.1 wt %, at which the film retains 98% of the transparency, 94% of the strength, and 5x10(7) times the conductivity of a pure cellulose diacetate film.