Wanting Yu

Controllable synthesis of hierarchical porous Fe3O4 particles mediated by poly(diallyldimethylammonium chloride) and their application in arsenic removal.

Hierarchical porous Fe3O4 particles with tunable grain size were synthesized based on a facile poly (diallyldimethylammonium chloride) (PDDA)-modulated solvothermal method. The products were characterized with scanning electron microscopy (SEM) and transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), N2 adsorption-desorption technique, vibrating sample magnetometer (VSM), and dynamic light scattering (DLS). The results show that increasing the PDDA dosage decrease the grain size and particle size, which increased the particle porosity and enhanced the surface area from 7.05 to 32.75 m(2) g(-1). Possible mechanism can be ascribed to the PDDA function on capping the crystal surface and promoting the viscosity of reaction medium to mediate the growth and assembly of grain. Furthermore, the arsenic adsorption application of the as-obtained Fe3O4 samples was investigated and the adsorption mechanism was proposed. High magnetic Fe3O4 particles with increased surface area display improved arsenic adsorption performance, superior efficiency in low-level arsenic removal, high desorption efficiency, and satisfactory magnetic recyclability, which are very promising compared with commercial Fe3O4 particles.

Preparation of a macroscopic, robust carbon-fiber monolith from filamentous fungi and its application in Li–S batteries

A new sustainable microorganism-based route is reported for the synthesis of carbon-fiber monolith through using filamentous fungi as feedstock. The fungi are cultured in solution within three days with biomass as nutrient, and fungi concentration reaches as high as 11 mg mL−1 on an average. Based on the rational control of fungi filtration and drying, fungi membrane or aerogel was obtained. Through pyrolysis in an inert atmosphere, intact carbon-fiber monolith (membrane or aerogel) was formed and its conductivity was more than 1 S cm−1. The carbon-fiber aerogel and membrane synthesized at 800 °C was doped by N (∼2.4 at%) and O (∼1.3 at%) and displayed a BET surface area of ∼305 and ∼20 m2 g−1, respectively. Mesopores and macropores were detected in the carbon materials. The carbon-fiber monolith showed promising capability to improve the cyclability and capacity of lithium–sulphur (Li–S) batteries, and are expected to be used as versatile electrode in energy storage.

Adsorption of Cr(VI) using synthetic poly(m-phenylenediamine).

Poly(m-phenylenediamine) (PmPD) with different oxidation state was successfully synthesized by the improved chemically oxidative polymerization. The function of oxidation state on Cr(VI) adsorption was systematically examined through adsorption experiments. Results showed that the Cr(VI) adsorptivity of all PmPD increased with decreasing the initial pH. When the oxidation state of PmPD was dropped, the equilibrium time for Cr(VI) adsorption was obviously shortened and its Cr(VI) removal and adsorption selectivity were profoundly obviously increased. Typically, PmPD with the lowest oxidation state in this research possesses the highest Cr(VI) removal of 500 mg g(-1). Moreover, PmPD with lower oxidation state displays a potentially superior prospect in Cr(VI) treatment through preliminary experiments on 5 cycles of adsorption, column adsorption and practical wastewater treatment. The possible adsorption mechanism was discussed mainly according to characterizations (FTIR, XPS) and experiments, which together suggests that the Cr(VI) adsorption most possibly involve redox reaction, chelation and doping adsorption.

pH manipulation: a facile method for lowering oxidation state and keeping good yield of poly(m-phenylenediamine) and its powerful Ag+ adsorption ability.

A method of pH manipulation has been used to improve chemically oxidative polymerization of m-phenylenediamine (mPD) through concurrent addition of NaOH when adding oxidant (NH(4))(2)S(2)O(8). pH detection and open-circuit potential technique were adopted to monitor the polymerization process of mPD and to explain the oxidation state-pH and yield-pH relationships. Results from Fourier transformed infrared (FTIR) and X-ray photoelectron (XPS) spectroscopies indicate that a low oxidation state is under control by regulating NaOH concentration. At 2.5 M NaOH, the oxidation state of poly(m-phenylenediamine) (PmPD) is 64.7 mol % (measured by molar content of quinoid imine from XPS), while the yield is 84%. The synthesized PmPD possesses better Ag(+) adsorption performance when lowering its oxidation state. Moreover, the Ag(+) adsorbance of PmPD can reach 1693 mg g(-1). Meanwhile, Ag(+) adsorption mechanism was studied by pH tracking, X-ray diffraction (XRD) patterns, and X-ray photoelectron spectroscopy. The adsorption process includes redox reaction, chelation, and physical adsorption.

Facile and large-scale synthesis of functional poly(m-phenylenediamine) nanoparticles by Cu2+-assisted method with superior ability for dye adsorption

Traditional chemical oxidative polymerization, with the procedure of gradually adding the oxidant, generally produces amine-containing conjugated polymer (NCP) microparticles. In this paper, an improved method has been developed through using a small amount of Cu2+ prior to the polymerization for large-scale synthesis of poly(m-phenylenediamine) (PmPD, one typical NCP) nanoparticles. The Cu-monomer/oligomer complex nanoparticle structures formed before the polymerization are suitable intermediates to activate the polymerization and induce the morphology evolution of the PmPD nanostructures. A possible mechanism is that Cu ions at the centre of the complex mediate the electron transfer from ligand to persulfate oxidant, as analyzed by comparative experiments; Fourier transform infrared spectrometry (FTIR) and open-circuit potential of the polymerization. During the growth of macromolecular chains, the Cu ions are gradually released into the bulk solution from the complex. The nano-sized PmPD was used to adsorb a dye (Orange G) and showed high adsorbance of 387.6 mg g−1, which is on average 200 mg g−1 more than that of the microparticles.

Methanol-induced formation of 1D poly(m-phenylenediamine) by conventional chemical oxidative polymerization exhibiting superior Ag+ adsorption ability

Morphology and size of poly(m-phenylenediamine) (PmPD) can be tuned readily with conventional chemical oxidation by introducing methanol (MeOH). Increasing MeOH content facilitates the formation of one-dimensional (1D) PmPD microstructures. Typically, when the MeOH content is up to 100%, 1D nanorods were formed, displaying the Ag+ absorbability of 2073 mg g−1.

Facile and large-scale synthesis of poly(m-phenylenediamine) nanobelts with high surface area and superior dye adsorption ability

Uniform poly(m-phenylenediamine) (PmPD) nanobelts have been synthesized through chemical oxidative polymerization of m-phenylenediamine by using white cetyl trimethyl ammonium persulfate (CTAP) powders as oxidants. Results from the Brunauer–Emmett–Teller (BET) method indicated that the surface area of PmPD reached as high as 284.5 m2 g−1. The influence of high surface area on Orange G adsorption was examined. The Orange G adsorbance of PmPD can reach 469.5 mg g−1. The adsorption process can be better described by the Langmuir and pseudo-second-order kinetic model. The acid doping of PmPD nanobelts could produce better adsorption performance for Orange G The superior performance of PmPD nanobelts makes them hopeful functional materials for dye removal.

High-yield synthesis of poly(m-phenylenediamine) hollow nanostructures by a diethanolamine-assisted method and their enhanced ability for Ag+ adsorption

A diethanolamine-assisted (DEA-assisted) conventional oxidation method was explored to synthesize the hollow nanostructures of poly(m-phenylenediamine) (PmPD) with a high specific surface area. The DEA concentration has a significant influence on the PmPD morphology and a possible formation mechanism has been proposed. The obtained hollow nanostructures show an excellent Ag+ adsorption ability with an adsorbance of 2359.3 mg g−1, much higher than other reported materials.