Effects of acid treatment on adhesive performance of encapsulated aluminium pigments on plastic sheets

In this study, aluminium pigments were encapsulated with hydroxyl group‐containing acrylic resin after surface acid treatment to enhance their adhesive performance in the paint film. The removal efficiency of fatty acid on surface of aluminium particles was studied by means of thermogravimetric analysis and the effect of acid treatment on adhesive performance of aluminium pigments encapsulated with hydroxyl group‐containing acrylic resin in the paint film was investigated by pulling‐off tests. It was found that fatty acid on surface of aluminium particles was removed efficiently by acid ethanol solution, and then hydroxyl group‐containing acrylic resin can be encapsulated onto the surface of the aluminium particles by chemisorptions. The encapsulated aluminium pigments have excellent adhesive performance in the paint film. © 2011 Canadian Society for Chemical Engineering     

TIO2/Nanoclay nanocomposite for phenol degradation in sonophotocatalytic reactor

A TiO₂–nanoclay nanocomposite was used as a photocatalyst for the degradation of phenol in presence of acoustic cavitation. TiO₂–nanoclay nanocomposite was synthesised in benzyl alcohol medium wherein TiO₂ nanoparticles were formed between the nanoclay platelets. The synthesised product was characterised by using FTIR, XRD and TEM techniques. TEM image shows that TiO₂–nanoclay nanocomposite particles were in the range of 30–40 nm. XRD gram confirms the formation of nanocomposite of TiO₂ nanoclay. The effect of cavitation and TiO₂–nanoclay nanocomposite photocatalyst on phenol removal was investigated. The effects of various parameters such as nanocomposite loading, initial concentration, etc., have been studied. On comparing the results obtained with that of nanocomposite without UV, it was found for an initial concentration of 500 mg/L of phenol, the TiO₂–nanoclay nanocomposite exhibited higher percentage of pollutant removal (59%) and for nanoclay it was 47%. © 2011 Canadian Society for Chemical Engineering     

PH sensitive structural uniformity of rice husk ash‐derived MCM‐41 silica

In this study, highly uniform MCM‐41 mesoporous silica was synthesised from rice husk ash‐derived sodium silicate using cetyltrimethyl ammonium chloride (CTAC) as a template. The chemical composition of the gel mixture was based on a SiO₂:CTAC:H₂O molar ratio of 1:0.5:75. When the pH value was initially controlled at ranges of 5.0–10.5 for 5 h and then immediately adjusted to 11.25 for the next 1 h, the structural uniformity of MCM‐41 was abruptly increased by 3.3–7.5 times of the single pH value at 11.25, respectively. Moreover, thermal and hydrothermal stabilities at 900 and 250°C were clearly observed. © 2012 Canadian Society for Chemical Engineering     

Simultaneous nitrification and denitrification with electricity generation in dual‐cathode microbial fuel cells

BACKGROUND: Nitrogen removal using microbial fuel cells (MFCs) is of great interest owing to the potential benefits of bioenergy production. In this study, simultaneous nitrification and denitrification in dual‐cathode MFCs was investigated. RESULTS: The dual‐cathode MFCs investigated were capable of generating electricity and removing nitrogen, influenced by operating methods, nitrogen loading rates and external resistance. Depending on the ammonium concentration in the anode chamber, 84–97% of the ammonium nitrogen was removed via nitrification in the aerobic cathode. The removals of nitrate and total nitrogen were relatively low (～50%) at the influent ammonium concentration of 80 mg NH₄⁺‐N L^?1, but were significantly improved to more than 90% at a lower ammonium input (40 and 20 mg NH₄⁺‐N L^?1). When the electrode couples were electrically connected for different purposes, with high power output from the anode/aerobic cathode and high current generation from the anode/anoxic cathode, nitrogen removal was also improved. An investigation of aeration suggested that factors other than carbon supply, possibly inefficient reactor configuration, also limited the performance of the developed MFC. CONCLUSION: The experimental results demonstrated that the proposed pathway was feasible with effective nitrogen and organic removal. This study provided valuable information for the further development of a continuously operated dual‐cathode MFC system. Copyright © 2011 Society of Chemical Industry     

Decrement of cellulose recalcitrance by treatment with ionic liquid (1‐ethyl‐3‐methylimidazolium acetate) as a strategy to enhance enzymatic hydrolysis

BACKGROUND: The high crystallinity of cellulose underlies the recalcitrance that this polymer presents in enzymatic degradation. Thus, a pre‐treatment step is applied in most bioconversion processes. Treatments with ionic liquids are considered an emerging pre‐treatment technology, owing to their high efficiency in solvating cellulose, over molecular solvent systems. RESULTS: Crystalline cellulose with and without ionic liquid (1‐ethyl‐3‐methylimidazolium acetate) treatment, both commercially available, were used as substrates in enzymatic hydrolysis reactions using the earlier evaluated cellulolytic system of Fusarium oxysporum. The in situ removal of the hydrolysate during reactions enhanced the reaction rate as well as the overall glucose production. Ionic liquid treatment significantly decreased cellulose crystallinity and enhanced bioconversion yields and rates. The effects of cellulose structural changes during treatment on hydrolysis rate were investigated and the recalcitrance constants were determined. CONCLUSION: The study showed that ionic liquid‐treated cellulose became more homogeneous and more easily degradable than the untreated cellulose, a conclusion that was expressed mathematically by the difference in the recalcitrance constants for the two substrates. It was concluded that glucose production from ionic liquid‐treated cellulose could achieve very high conversion yields in consolidated bioprocesses or during simultaneous saccharification and fermentation. Copyright © 2012 Society of Chemical Industry     

Graphene‐supported nickel ferrite: A magnetically separable photocatalyst with high activity under visible light

A straightforward strategy is designed for the fabrication of a magnetically separable NiFe₂O₄‐graphene photocatalyst with different graphene content. It is very interesting that the combination of NiFe₂O₄ nanoparticles with graphene sheets results in a dramatic conversion of the inert NiFe₂O₄ into a highly active catalyst for the degradation of methylene blue (MB) under visible light irradiation. The significant enhancement in photoactivity under visible light irradiation can be ascribed to the reduction of GO, because the photogenerated electrons of NiFe₂O₄ can transfer easily from the conduction band to the reduced GO, effectively preventing a direct recombination of electrons and holes. The results of the kinetic study indicated that the rate‐determining stage is the adsorption process of MB molecules. NiFe₂O₄ nanoparticles themselves have a strong magnetic property, which can be used for magnetic separation in a suspension system, and, therefore, the introduction of additional magnetic supports is no longer necessary. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

Chemical modification of hemp fibers by silane coupling agents

Natural hemp fibers were chemically modified using silane coupling agents to reduce their hydrophilic character. The existence of a chemical bond between coupling agents and hemp fibers was confirmed by ATR‐FTIR spectroscopy, ²⁹Si Nuclear Magnetic Resonance (NMR), thermogravimetric analysis (TGA), energy dispersive spectroscopy (EDS), and BET surface area measurements. It was shown that the initial concentration and the chemical structure of the organosilane coupling agent have an effect on the grafted quantity on the hemp fiber surfaces. The grafted quantity increased proportionally to the initial concentration of silane molecules. The presence of polar amino end group (NH₂) in silane structure can cause an increase in the grafted quantity, compared with results obtained in the case of silane molecules containing methacryloxy groups. This effect is attributed to the formation of hydrogen bonds between NH₂ and unreacted hydroxyl groups of hemp fibers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Gel Permeation Chromatography with High Loads

Abstract

High loads on GPC columns usually lead to poor efficiency because of steep viscosity gradients. A great difference in density between solution and solvent can also cause excessive band broadening. However, under certain conditions good separations are achieved with loads of 150 mg/100 cc column volume and higher. Two mechanisms are proposed to explain this phenomenon. Secondary exclusion is caused by obstruction of pores to larger molecules by the more rapidly diffusing small molecules. It takes place predominantly with molecules of less than 2000 molecular weight in small pore gels. Incompatibility is caused by repulsive interaction between solute molecules and the polystyrene gel. It is observed with solutes which are chemically quite different from polystyrene, e.g., with polyvinyl acetate, and in a low to intermediate molecular weight range.     

Chemilumunescence of Isotactic Polypropylene Induced by UV Irradiation

Abstract

The kinetics of the weak Chemilumunescence (CL) and peroxyl radical decay after UV irradiation of isotactic polypropylene (PP) have been studied. The correlation has been found between CL and the reaction of chain termination under the PP post-oxidation at room temperature in air. Kinetics of CL decay, its compliance with kinetics of peroxyl radical decay, relative quantum yield of CL per one act of radical termination and effects of the plasticizer, accelerating both radical termination and CL decay, have been determined. Kinetic features of CL decay indicates the distributions of peroxyl radicals on both rate constants of termination and quantum yields of CL in the acts of the disproportionation of two peroxyl radicals. In terms of these distributions it is possible to describe quantitatively observed kinetics of CL decay under the post oxidation of PP after the UV irradiation in air.     

Effect of the Quenching Temperature on the Fields of Thermal Stresses and on the Mechanical and Thermal Properties of PMMA

This study explores the photoelasticimetry as a means to investigate factors affecting the residual stresses, particularly the thermal stresses, in polymethyl methacrylate (PMMA). The aim was to study the effect of quenching temperature in three different media: air, water, and ethylene glycol, on the impact strength and thermal properties of PMMA. These temperatures varied from a fixed value of 120°C to various values below Tg and the fields of distribution of cooling stresses have been obtained using a charge-coupled device (CCD) camera. It was observed that the quenching in water at 20°C gives rise to an important density of tensile stresses. However, in the ethylene glycol at 110°C this density has a tendency to disappear. An approximate evaluation of these stresses in a point near the specimen center has been assessed, and it was found that the distribution profile of the fields of tensile stresses was much closer to a parabolic form. Notched Izod impact strength and heat deflection temperature (HDT) were measured, and were found to be particularly sensitive to thermal stresses.