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.     

Preparation of activated carbons by microwave heating KOH activation

Activated carbons with high surface areas were prepared via KOH activation process by microwave (MW) heating. As a comparison, activated carbons were also prepared by conventional heating (EF) method. The influences of KOH/Mesocarbon microbeads (MCMB) weight ratio and activation time on the pore properties of the activated carbons were investigated. For both MW and EF heating methods, the surface area and pore volume increase to a maximum and then decrease with the KOH/MCMB ratio increasing. The effects of activation time on the pore properties depend on the KOH/MCMB ratio. The activated carbons prepared by MW heating have higher surface area and larger pore volume than those by EF heating when KOH/MCMB ratio is the same. The MW heating method shortens the activation time considerably. Activated carbons prepared by MW heating show low content of oxygen containing groups.     

Preparation and properties of graphene oxide nanosheets/cyanate ester resin composites

Graphene oxide nanosheets (GONSs)/cyanate ester (CE) resin composites were prepared via a solution intercalation method. The structures of the GONSs and the composites were studied using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The mechanical and tribological properties of the composites were investigated. In addition, the thermal behavior of the composites was characterized by thermogravimetric analysis (TGA). Results show that the GONSs/CE resin composites were successfully prepared. The addition of GONSs is beneficial to improve the mechanical and tribological properties of the composites. Moreover, the composites exhibit better thermal stability in comparison with the CE resin matrix.     

Preparation and properties of nitrogen-containing hollow carbon nanospheres by pyrolysis of polyaniline-lignosulfonate composites

Polyaniline-lignosulfonate composite hollow spheres were synthesized by using one-step unstirred polymerization of aniline in the presence of lignosulfonate. Novel nitrogen-containing hollow carbon nanospheres were prepared by direct pyrolysis of the polyaniline-lignosulfonate composite spheres at different temperatures under a nitrogen atmosphere. Thermal behavior of the polyaniline-lignosulfonate composite spheres was studied by TG-DTG, FTIR and element analyze instruments. The resultant carbon spheres were characterized by SEM, XRD and nitrogen adsorption-desorption measurement. It was found that the pyrolysis products of the polyaniline-lignosulfonate composite spheres were made up of uniform hollow carbon nanospheres with an average diameter of 135 nm. Furthermore, the hollow carbon nanospheres exhibit high BET surface area range from 381.6 m² g⁻¹ to 700.2 m² g⁻¹. The hollow carbon nanospheres could be used as adsorbents of papain. The papain adsorption capacity for the carbon spheres prepared at 1200 °C was up to 1161 mg g⁻¹ at an initial papain concentration of 10 mg mL⁻¹ at 25 °C.     

Effect of rosin to coal-tar pitch on carbonization behavior and optical texture of resultant semi-cokes

Coal-tar pitch was modified with rosin, and carbonization behavior of the modified pitches and optical texture of resultant semi-cokes were studied in this paper. The carbonization behavior was studied by thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy techniques, respectively. The optical texture of resultant semi-cokes was characterized by polarized-light microscopy. The results show that there are marked differences in the carbonization behavior of coal-tar pitch and the modified pitches. The modification results in a small decrease in carbonization yield by 1.2–3.2% when rosin content is kept at 5–15 wt.% of coal-tar pitch. The modified pitches have functional groups of cycloparaffin, double bonds, and carboxyl group, which gradually disappear and aromatization degree increases with increasing heat treatment temperature. Moreover, the modification contributes to a notable improvement in the optical texture of resultant semi-cokes which varies from coarse-grained mosaics to domains.     

Selectivity enhancement of quaternized poly(arylene ether ketone) membranes by ion segregation for vanadium redox flow batteries

Quaternary ammonium densely functionalized octa-benzylmethyl-containing poly(arylene ether ketone)s(QA-OMPAEKs) with ion exchange capacities(IECs) ranging from 1.23 to 2.21 mmol g~(-1) were synthesized from:(1) Ullmann coupling extension of tetra-benzylmethyl-containing bisphenol A;(2) condensation polymerization with activated dihalide in the presence of K_2CO_3;(3) selective bromination using N-bromosuccinimide; and(4) quantitative quaternization using trimethylamine. Both smallangle X-ray scattering(SAXS) and transmission electron microscope(TEM) characterizations revealed distinct nano-phase separation in QA-OMPAEKs as a result of the dense quaternization. The QA-OMPAEK-20 with an IEC of 1.98 mmol g~(-1) exhibited a high SO_4~(2-) conductivity of 11.4 mS cm~(-1) and a low VO~(2+) permeability of 0.06×10~(-12) m~2 s~(-1) at room temperature,leading to a dramatically higher ion selectivity than Nafion N212. Consequently, the vanadium redox flow battery(VRFB)assembled with QA-OMPAEK-20 achieved a Coulombic efficiency of 96.9% and an energy efficiency of 84.8% at a current density of 50 mA cm~(-2), which were much higher than those of the batteries assembled with Nafion N212 and a home-made control membrane without distinct nano-phase separation. Therefore, ion segregation is demonstrated to be a strategical route for the design of high performance anion exchange membranes(AEMs) for VRFBs.     

Construction of ion-conductive dual-channels by P(EA-co-AALi)-based gel electrolytes for high-performance lithium metal batteries

Journal of Solid State Electrochemistry - As people possess more safety conscious, the issue of electrolytes is attracting concern. The gel polymer electrolyte offers high ionic conductivity,...