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The present study aimed to investigate biodegradation mechanisms of black carbon (BC)-bound contaminants in BC-amended sediment when BC was applied to control organic pollution. The single-point Tenax desorption technique was applied to track the species changes of nonylphenol (NP) during biodegradation process in the rice straw carbon (RC)-amended sediment. And the correlation between the biodegradation and desorption of NP was analyzed. Results showed that microorganisms firstly degraded the rapid-desorbing NP (6 h Tenax desorption) in RC-amended sediment. The biodegradation facilitated the desorption of slow-desorbing NP, which was subsequently degraded as well (192 h Tenax desorption). Notably, the final amount of NP degradation was greater than that of NP desorption, indicating that absorbed NP by RC amendment can be degraded by microorganisms. Finally, the residual NP amount in RC-amended sediment was decided by RC content and its physicochemical property. Moreover, the presence of the biofilm was observed by the confocal laser scanning microscope (CLSM) and scanning electron microscope (SEM) so that microorganisms were able to overcome the mass transfer resistance and directly utilized the absorbed NP. Therefore, single-point Tenax desorption alone may not be an adequate basis for the prediction of the bioaccessibility of contaminants to microorganisms or bioremediation potential in BC-amended sediment. [ABSTRACT FROM AUTHOR]

A novel, stable and sensitive non-enzymatic glucose biosensor based on bimetallic hollow Ag/Pt nanoparticles and the reduced graphene oxide (rGO) was obtained. The hybrid of bimetallic hollow Ag/Pt nanoparticles-reduced graphene oxide (HAg/PtNPs-rGO) was prepared by a galvanic replacement reaction and the thermal reduction of graphene oxide. Thermal reduction has been highly effective in producing graphene-like films which can render a stable substrate for hollow Ag/Pt nanoparticles. The morphology and composition of the prepared samples were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy-dispersive X-ray spectrometry and Fourier transform infrared spectra. Cyclic voltammetry measurements demonstrated that the biosensor decorated by HAg/PtNPs-rGO can directly detect glucose and show a superior electro catalytic activity. The results of amperometric method showed a desirable amperometric response with a sensitivity of 129.32 μA mM cm, a linear range of 0.003-7.72 mM (R = 0.9943), a fast response time (less than 3 s) and a low detection limit of 1.8 μM (S/N = 3). In addition, the fabricated sensor also had good selectivity, reproducibility and long-term stability. The sensor modified by HAg/PtNPs-rGO could make a promising application in glucose determination. [ABSTRACT FROM AUTHOR]

The transient state of the phase morphology of polypropylene with poly(ethylene-co-1-octene) blends during melt mixing are investigated by the pattern analysis of scanning electron microscope (SEM). The results show that morphology develops mainly at the initial stages of mixing. During the intermediate mixing stage, a dynamic equilibrium is established between breakup and coalescence of domains. The mixing time required for reaching equilibrium stage reduces as shear rate increases. The fractal analysis indicates that the development of the dispersed phase during melt mixing process evolves with dynamical self-similarity partly through the competitions of break-up and coalescence of dispersed phase. [ABSTRACT FROM AUTHOR]

Abstract: Zinc sulfide (ZnS) semiconductor nanocrystal films have been prepared on indium tin oxide coated glass substrates by sulfosalicylic acid (C7H6O6S)-assisted galvanostatic deposition with subsequent annealing. The deposition was performed at 10mAcm−2 in acidic electrolytes containing 15–30mM Zn(CH3COO)2, 20mM Na2S2O3, 200mM LiCl, 0.375mM Na2SO3, and 0 or 0.2mM C7H6O6S. Results show that the presence of C7H6O6S can suppress the precipitation of Zn and S impurity phases during the ZnS deposition process. As the [C7H6O6S]=0.2mM and [Zn2+]=20mM, the deposited ZnS film exhibits only hexagonal structure with an ideal Zn/S atomic ratio of 1.03 and a close-packed granular morphology. But its band gap about 2.86eV is narrower than the common value of ZnS, probably due to the existence of some spurious acetate species and defect states. By annealing the film at 400°C for 60min, its band gap increased up to 3.70eV, despite that its crystalline phase transformed into cubic structure which usually shows the narrower band gap than hexagonal ZnS. The significant band gap widening could be ascribed to the degradation of spurious acetate species and the reduction of various possible defect states in the annealing process. [Copyright &y& Elsevier]

Binary blends based on polypropylene and poly(ethylene- co-octene) were prepared in a co-rotating twin-screw extruder. A stretching process was carried out afterwards in the melt state at the extruder's exit to study the effect of stretching on morphological structures and mechanical properties. The morphological structures of the blends were investigated by scanning electron microscopy and small-angle X-ray scattering. The structure parameters, the correlation distance, the average chord lengths, and the Porod's index, obtained by the Debye-Bueche statistical theory of scattering were used to characterize the morphological structures. In addition, the relationship of mechanical properties with the structure parameters was also studied and some results were acquired. [ABSTRACT FROM AUTHOR]

Abstract: The morphological evolution during extrusion and rheological properties of polypropylene (PP) and ethylene–octene copolymer (EOC) blends were studied. The phase morphology of the blends at different locations along the extruder length was investigated by scanning electron microscopy (SEM). The PP/EOC (70/30) blends has already formed a well-established droplet/matrix morphology at Valve 3, and an elongation of particles was observed from Valve 3 to extruder die. The phase-separated PP/EOC blends within the linear viscoelastic regime display higher than expected values of storage modulus at low frequencies. The effect of the deformation of phase domain on the rheological properties of the blends, the small constant strain amplitude within the linear viscoelastic regime does not substantially alter the droplet shape of the dispersed phase and yields a linear viscoelastic response, but the large strain amplitude destroys the dispersed phase domains, and eventually results in shear-induced mixing or homogenization. [Copyright &y& Elsevier]

Abstract: Hemp (Cannabis sativa L.) bast was used to prepare activated carbon fibers by phosphoric acid activation at 400–600°C. The pyrolysis process, textural and chemical properties for the samples were investigated by means of TG/DTA, SEM, cryogenic N2 adsorption, FTIR and XPS. Dye adsorption on the resultant sample was also measured. The textural properties of the activated carbon fibers were found to be strongly dependent on the activation temperature. Activated carbon fibers exhibited narrow pore size distributions with maxima in the micropore and small mesopore regions. BET surface area, total pore volume, micropore volume and mesopore volume increased with the increase of activation temperature up to 450°C and then decreased with further heating, and a sample with maximum surface area of 1142m2 g−1 and total pore volume of 0.67cm3 g−1 was obtained. Phosphoric acid facilitated the conservation of porous structure, led to the creation of tremendous porosity, and resulted in various P-containing functional structures on the surface and in the bulk phase of the resultant samples. The adsorption of acid blue 9 on the sample could be favorably described by Langmuir isotherm, and the adsorption kinetics was found to be well fitted by the intraparticle diffusion model. [ABSTRACT FROM AUTHOR]

Abstract: Water pollution caused by ammonia nitrogen has attracted a great attention as its toxicity affects both the environment and human health. The objective of this paper was to investigate the adsorption behavior of NH4 +-N from aqueous solution by activated carbons prepared from rice husk. The physico-chemical properties of the activated carbon were characterized by Brunauer-Emmett-Teller (BET) test, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). It was found that the NH4 +-N adsorption on the rice husk derived carbons was dependent on adsorbent dosage and solution pH. The adsorption kinetics and isotherms of NH4 +-N by rice husk carbon were also investigated, and good correlation coefficients were obtained for the pseudo-second order kinetic equation. Dubinin-Radushkevitch (D-R) adsorption isotherm model could better describe the adsorption behavior of NH4 +-N on the rice husk carbon. Calculated by D-R model, the adsorption course of NH4 +-N on the rice husk carbon was favored chemical ion-exchange mechanism. Moreover, the activated carbon adsorbed NH4 +-N was highly fertilizer conservation especially for the nitrogen element. It was proposed that the amount of removed NH4 +-N from aqueous solutions would increase evidently treated by rice husk carbon if combined with biological method. [Copyright &y& Elsevier]

Abstract: The electroless nickel plating/poly(dl-lactide-co-glycolide) composite coating (EN-plating/PLGA composite coating) was fabricated on the surface of the micro-arc oxidation (MAO) film of the magnesium alloy AZ81 to double control the corrosion and drug release in the hanks'' solution. The EN-plating was fabricated on the MAO coating to improve the corrosion resistance by overlaying most pores and micro-cracks on the surface of the MAO film. Meanwhile, a double layered organic poly(dl-lactide-co-glycolide)/paclitaxel (PLGA/PTX) drug releasing coating with a top layered PLGA drug controlled releasing coating on EN plating was prepared to control the drug release rate by adjusting the different lactide: glycolide (LA:GA) ratio of PLGA. Scanning electron microscopy (SEM) and the X-ray powder diffraction (XRD) were used to analyze the morphology and the composition of the EN-plating. The corrosion behavior of the magnesium alloy substrate and the status of the drug in the PLGA matrix were respectively evaluated by Potentiodynamic polarization and Differential scanning calorimetry (DSC). The drug release was determined by ultraviolet–visible (UV–visible) spectrophotometer. EN-plating coating which was composed of compact cauliflower nodules was uniform in size and defect free with no pores or cracks. EN-plating could seal the microcracks and microholes on the outer layer of the MAO coating effectively. The corrosion resistance was improved by preventing the corrosive ions from diffusing to the magnesium alloy substrate. The drug release rate of PTX exhibited a nearly linear sustained-release profile with no significant burst releases. [Copyright &y& Elsevier]

Abstract: The objective of this study was to enhance the activity and stability of the chemi-deposited palladium/nickel foam (Pd/Ni foam) electrode used in the electrochemical dechlorination process. The electrochemical deposition of silver onto a nickel foam substrate (Ag/Ni foam) was applied before the chemical deposition of palladium. The physicochemical properties of the resultant material (Pd/Ag/Ni foam) were characterized by X-ray diffraction and scanning electron microscopy. The results showed that the silver coating was in the form of spherical apophyses, and the palladium was dispersed finely on the surface of the Ag/Ni foam. Dichloroacetic acid was selected as an indicator to evaluate the activity and stability of the palladium catalyst. Pd/Ag/Ni foam electrode consistently had relatively higher dechlorination rate and current efficiency (CE) in the current density range of 1.5–10.5mAcm−2 compared to the Pd/Ni foam electrode. Quantitative analysis of the main intermediates and final products involving monochloroacetic acid, acetic acid and the chloride ion further demonstrated the enhancement of electrochemical dechlorination by the presence of silver. Moreover, after five cycles of dechlorination, the CE for the Pd/Ni foam electrode decreased dramatically from 67% to 13%, whereas that for the Pd/Ag/Ni foam electrode was decreased by much less, from 78% to 62%, and the palladium loss was clearly reduced by the addition of a silver coating between the Ni foam and the Pd outer layer. [Copyright &y& Elsevier]

Abstract: The adsorption of Cu(II) from aqueous solution by carbons prepared from rice husk through pyrolysis and steam activation was studied. The rice husk carbon was characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), and its pore structure was also examined. After comparing different characteristics of the carbons prepared under different conditions and their adsorption abilities of Cu(II), the optimum temperature for pyrolysis and steam activation was chosen as 700 and 750°C, respectively, using 3% (V/V) steam as the best activation gas. It was found that the Cu(II) adsorption on the rice husk derived carbons was pH and temperature dependent with an optimum pH value of 5.0, and an equilibrium time of 24h. The adsorption kinetics and isotherms of Cu(II) by the rice husk derived carbons were also investigated under four different temperatures, and good correlation coefficients were obtained for the pseudo-second-order kinetic models, and the Langmuir isotherm model fitted very well with the experimental data. The mean free energy E (kJmol−1) obtained in the Dubinin-Radushkevitch (D-R) adsorption isortherm equation indicated a chemical ion-exchange mechanism. Several thermodynamic parameters were also caculated to predict the nature of adsorption process. [ABSTRACT FROM AUTHOR]