Porosity enhancement of activated carbon by hydrolyzed lignin from black liquor

Clean Technologies and Environmental Policy - In this work, the porosity enhancement of activated carbon by hydrolyzed lignin extracted from black liquor was studied. Lignin was treated before...     

Effect of ferrocene moieties on the copper‐based atom transfer radical polymerization of methyl methacrylate

The atom transfer radical polymerization (ATRP) of methyl methacrylate catalyzed by copper–tripodal complexes with ferrocene moieties (CuX/TRENFcImine, where X is Br or Cl, and TRENFcImine is tris‐[2‐(ferrocenylmethyleneimino)ethyl]amine) was investigated to understand the effect of redox active moieties on the performance of ATRP catalysts. The CuBr/TRENFcImine system was highly active, with 82% conversion in 2 h. However, the polymerization became slower at higher molar ratios of monomer to catalyst. The polydispersity index was broad, and the initiation efficiency was relatively low. On the basis of the conformational analysis, the highly active and less controlled polymerization was probably caused by the electronic effect rather than the steric effect on the ferrocene moieties, which led to the higher and lower values in the activation and deactivation steps, respectively. The polydispersity index was improved by the addition of CuBr₂, but this led to slower rates of polymerization. The effect of halide groups on ATRP caused a faster rate in the CuBr/TRENFcImine polymerization system than in the CuCl/TRENFcImine system. The higher molar ratio of monomer to catalyst had no significant effect on the CuCl/TRENFcImine system. Nonetheless, the trace of water in the CuCl₂·2H₂O system accelerated the rate of propagation, which led to a higher molecular weight. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effects of superheated steam treatment on moisture adsorption and mechanical properties of pre-dried rubberwood

Abstract

Rubberwood (Hevea brasiliensis) was treated with superheated steam (140–160?°C) for 1–3?h and then its adsorption ability, mechanical properties, and color changes were investigated. The results of adsorption show decreased equilibrium moisture content (EMC) for all heat-treated cases throughout the hygroscopic range. The Hailwood–Horrobin model was used to analyze the sorption isotherms and determine the monolayer and polylayer moisture contents for untreated and heat-treated rubberwood. The monolayer moisture content clearly decreased with treatment temperature and duration, whereas the reduction in polylayer moisture was relatively smaller. Moreover, the least density of water adsorption sites was found in wood after treatment at 160?°C for 3?h, indicating this as the cause for reduced equilibrium adsorption. All treatment conditions had improved mechanical properties, including compression parallel-to-grain, hardness, and tensile strength. The total color difference of the wood surface increased with increasing temperature and treatment duration.     

Morphology-controlled magnetite nanoclusters via polyethyleneimine-mediated solvothermal process

A facile one-pot synthesis of polyethyleneimine (PEI)-functionalized magnetic nanoclusters (MNPs) through the solvothermal method was reported for various applications. The morphology of the MNPs can be systematically tuned from loose flower-like to porous nanoclusters by controlling the pH of the PEI stabilizer. At low pH, the intense electrostatic repulsion according to the large amount of protonated amine groups of PEI would play a key role on self-assembly process to generate the loose nanostructure. Due to the presence of amine functional groups on the surface, these nanoclusters provide high degree of dispersibility in water and abundant anchoring groups for further attachment of biomolecules. Magnetization study of the MNPs indicated that they had saturated magnetization upto 80 emu g⁻¹.     

Isolation and characterisation of a novel Podoviridae-phage infecting Weissella cibaria N 22 from Nham, a Thai fermented pork sausage

A novel Podoviridae lactic acid bacteria (LAB) phage from Nham, a Thai fermented pork sausage, is reported. From a total of 36 samples, 41 isolates of LAB were obtained and employed as hosts for the isolation of phages. From these LAB, only one phage, designated Φ 22, was isolated. The lactic acid bacterial isolate named N 22, sensitive to phage Φ 22 infection was identified by an API 50 CHL kit and N 22’s complete sequence of the 16S rDNA sequence. BLASTN analysis of the 16S rDNA sequence revealed a 99% similarity to the 16S rDNA sequence of Weissella cibaria in the GenBank database. Electron micrographs indicated that the phage head was icosahedral with head size and tail length of 92 × 50 nm and 27 nm, respectively. On the basis of the morphology, this phage belongs to the family Podoviridae. Host-range determination revealed that the phage Φ 22 was not capable of infecting the other 40 isolates of LAB and referenced Weissella strains used. A one-step growth experiment showed that the latent period and burst size were estimated at 110 min and 55 phage particles/infected cell, respectively. Furthermore, the phage was infective over a wide range of pH (pH 5.0-8.0) and the D time of Φ 22 was calculated as 88 s at 70 °C and 15 s at 80 °C. Phage titers decreased below the detection limit (20 PFU/ml) after heating for more than 60 s at 80 °C, or 20 s at 90 °C or less than 10 s at 100 °C. The results from the study of Nham revealed that Φ 22 was active against the potential starter culture (W. cibaria N 22) for Nham fermentation. Phage infection could adversely affect the fermentation process of Nham by delaying acidification when using W. cibaria N 22 as a starter. However, the results from a sensory test revealed that the panelists did not detect any defects in the final products. This is the first report on the isolation of W. cibaria phage.     

Core/shell polymethyl methacrylate/polyethyleneimine particles incorporating large amounts of iron oxide nanoparticles prepared by emulsifier-free emulsion polymerization

A facile synthetic route for the preparation of magnetic poly(methyl methacrylate) (PMMA) core/polyethyleneimine (PEI) shell colloidal particles, possessing high saturation magnetization is reported. Bilayer oleic acid-stabilized iron oxide nanoparticles (bIOs) were designed to have both favorable encapsulation of iron oxide nanoparticles and interaction with protonated amine groups of PEI. The prepared particles had diameter ranging from 180 to 207 nm with narrow size distribution and displayed highly positive surface charges up to +47 mV. TEM revealed that the well-defined bIOs were successfully encapsulated inside the polymer core–shell colloids. Thermogravimetric analysis and magnetization study indicated that these colloidal particles had the magnetic material up to 80 wt % loading and exhibited superparamagnetic property with high saturation magnetization. Thus, they could be potentially useful in various applications, including magnetic separation, medical diagnostics, or drug delivery.     

Hydrogen Production by Steam Reforming of Fusel Oil Using a CeCoOx Mixed-Oxide Catalyst

Various CeCoO_x mixed-oxide catalysts with different Ce/Co ratios were prepared by surfactant-assisted template precipitation of CeO₂ and Ce₃O₄. The obtained catalysts were characterized by X-ray diffraction, X-ray photoelectron spectra, hydrogen temperature-programmed reduction, nitrogen physisorption, and transmission electron microscopy. In general, the mixed-oxide CeCoO_x catalysts showed well-dispersed CeO₂ and Co₃O₄ and good catalytic characteristics including a high specific surface area and porous structure. The effectiveness of the prepared catalysts on the hydrogen (H₂) production from steam reforming of fusel oil was studied in a packed-bed reactor. Co played an important role in C–C scission to break down the large C_2–5 molecules into smaller species resulting in H₂ formation. Ce could provide supplementary active oxygen to prevent coke formation on Co, resulting in a more stable activity of the mixed-oxide catalyst throughout the reaction course.     

Preparation of zinc oxide-montmorillonite hybrids

The new hybrid materials of zinc oxide with montmorillonite were synthesized by a reaction between the aqueous solutions of the reactants of zinc oxide (zinc chloride and sodium hydroxide solutions) and montmorillonite or hexadecyltrimetylammonium-montmorillonite. The hybrids were characterized by powder X-ray diffraction, Fourier transform-infrared, UV-visible and photoluminescence spectroscopies. The diffuse reflectance absorption spectra of the hybrids exhibited the absorption onsets at 375 nm for zinc oxide-montmorillonite and at 378 nm for zinc oxide-hexadecyltrimetylammonium-montmorillonite, respectively, confirming the formation of zinc oxide in the hybrid materials. The photoluminescence bands of both hybrids, which can be attributed to singly ionized oxygen vacancy in zinc oxide, were observed at 548 nm. The enhancement in emission intensity of the zinc oxide hybrids may be probably due to increase in oxygen vacancies defect arose by the surrounding environment of montmorillonite.     

In vitro efficacy and toxicology evaluation of silver nanoparticle‐loaded gelatin hydrogel pads as antibacterial wound dressings

The silver nanoparticle (nAg)‐loaded gelatin hydrogel pads were prepared from 10 wt % gelatin aqueous solution containing silver nitrate (AgNO₃) at 0.75, 1.0, 1.5, 2.0, or 2.5 wt % by solvent‐casting technique. These AgNO₃‐containing gelatin solutions, that had been aged for 15, 12, 8, 8, and 8 h, respectively, showed noticeable amounts of the as‐formed nAgs, the size of which increased with an increase in the AgNO₃ concentration (i.e., from 7.7 to 10.8 nm, on average). The hydrogels were crosslinked with a glutaraldehyde aqueous solution (50 wt %, at 1 μL mL^?1). At 24 h of submersion in phosphate buffer saline (PBS) or simulated body fluid buffer (SBF) solution, about 40.5–56.4% or 44.4–79.6% of the as‐loaded amounts of silver was released. Based on the colony count method, these nAg‐loaded hydrogels were effective against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, with at least about 99.7% of bacterial growth inhibition. Unless they had been treated with a sodium metabisulfite aqueous solution, these hydrogels were proven, based on the indirect cytotoxicity evaluation, to be toxic to human's normal skin fibroblasts. Lastly, only the hydrogels that contained AgNO₃ at 0.75 and 1.0 wt % were not detrimental to the skin cells that had been cultured directly on them. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012