Studies on Silicon Containing Nano-hybrid Epoxy Coatings for the Protection of Corrosion and Bio-Fouling on Mild Steel

An epoxy nano-composite coating was developed using amine functionalized nZnO (in the amount of 2.5 %, 5.0 % and 7.5 wt %) as the dispersed phase and a commercially available epoxy resin as the matrix phase. The structural features of these materials were ascertained by FT-IR spectral studies. The anti-corrosive properties of the epoxy/nZnO hybrid coatings in comparison with a virgin coating were investigated by a salt spray test and electrochemical impedance spectroscopy technique. The surface morphology determined by SEM, indicates that nZnO particles were dispersed homogenously through the epoxy polymer matrix. The results showed improved antifouling and anticorrosive properties for epoxy-nZnO hybrid coatings.     

Uptake of arsenic by New Zealand watercress (Lepidium sativum)

Watercress (Lepidium sativum) is consumed as a vegetable, especially by the indigenous community in New Zealand. An investigation was carried out on the accumulation of arsenic by watercress, following earlier reports of inordinate arsenic concentrations in some aquatic macrophytes collected from the Waikato River, North Island, New Zealand. The Waikato River and some other aquatic systems in Taupo Volcanic Zone, New Zealand have elevated arsenic concentrations due to geothermal activity. Watercress, river water and sediment samples were collected from 27 sites along the Waikato river and analysed for arsenic. Greenhouse trials with watercress grown in beakers containing added arsenic were conducted to confirm the ability of this species to accumulate arsenic. At a number of sites, the concentration of arsenic in both the water and the watercress samples exceeded the World Health Organisation (WHO) limit for drinking water (0.01 mg l(-1)) and foodstuffs (2 mg kg(-1) on a fresh weight basis). The average leaf and stem arsenic concentrations were, respectively, 29.0 and 15.9 mg kg(-1) on a fresh weight basis. Plants grown in solutions of >0.4 mg l(-1) arsenic concentration had fresh weight arsenic concentrations above the WHO limit. Despite these higher concentrations, arsenic levels in plants grown under greenhouse conditions were approximately fivefold lower than in plants growing in the Waikato River, possibly because under natural conditions, the watercress is rooted in sediment containing on average approximately 35 mg kg(-1) arsenic. It is recommended that watercress from the Waikato River, or other areas with elevated water arsenic concentrations, should not be consumed.     

Experimental investigation of compression ignition engine fuelled by a catalytic fuel reformer

Waste engine oil (WEO) as an alternative fuel for compression ignition (CI) engine is investigated in this study. WEO was thermally cracked with alumina catalyst in the catalytic fuel reformer (CFR). The gas obtained from the CFR was condensed using a water-cooled condenser for analytical purposes. The output of the condenser was named as WEOA (reformulated WEO with alumina catalyst). The different chemical properties of WEOA were analysed. The compositional analysis for diesel and WEOA was made using Fourier transform infra-red (FT-IR) and gas chromatography–mass spectrometer (GC–MS). The experimental investigation was conducted in a single-cylinder diesel engine and the performance and emissions were compared with those of diesel fuel. Experimental results concluded that the performance and emission level are better than those of diesel fuel. This study concludes that environmentally hazardous waste material such as WEO is recycled and converted into a useful resource and serves as an alternative source of fuel for CI engine.     

Partition of tannery wastewater proteins in aqueous two-phase poly (ethylene glycol)-magnesium sulfate systems: Effects of molecular weights and pH

The partitioning behavior of soluble proteins from tannery wastewater using aqueous two-phase system (ATPS) was investigated. An ATPS polyethylene glycol (PEG)/MgSO₄ was examined with regard to the effects of PEG molecular weight (MW) and concentration, MgSO₄ concentration, pH and NaCl concentration on protein partition and extraction. The partition coefficients measured for soluble proteins were proportional to the difference in PEG concentration between the phases. The MW and concentration of PEG were found to have significant effects on protein partition and extraction with low MW PEG4000 showing the best conditions for the partitioning of protein in PEG+MgSO₄+water system. Sulfate salt was chosen as the phase-forming salt because of its ability to promote hydrophobic difference between the phases. This system was operated at room temperature . Increase in pH of the system increases the partition coefficient of proteins from tannery wastewater. The addition of sodium chloride showed significant influence on the partition coefficient. ATPS comprising PEG4000-magnesium sulfate provided a means for the recovery of proteins from tannery wastewater. The maximum percentage yield of protein extracted is 82.68%.     

Effect of Processing Conditions on Flexural Strength Properties of Chicken Feather Fibre (CFF) and Its Hybrid Composites with Polypropylene Resin

ABSTRACT

This study discusses the effect of molding temperature, pressure and time on the final compression-molded hybrid composites with polypropylene resin for its flexural strength. The results of tests conducted to characterize the hybrid composites developed with different proportion of fibers and processing conditions are discussed in this study. When comparing the overall results on the flexural strength of the composites, 25:75 Chicken Feather Fiber (CFF)/Jute composite showed highest flexural strength by keeping minimum temperature, maximum pressure and medium time. The influence of pressure on flexural strength is significant compared to temperature and time. As time increases the flexural strength decreases.     

Transparent anti-stain coatings with good thermal and mechanical properties based on polyimide-silica nanohybrids

In this work, we synthesized polyimide/silica hybrid materials via sol-gel method using a fluorinated poly(amic acid) silane precursor and a variety of perfluorosilane contents. We studied the influence of a hybrid coating film with the following characteristics; hydrophobicity, oleophobicity, optical transparency, and surface hardness of the coating films. The hybrid coatings with the fluorosilane contents up to 10 wt% are optically transparent and present good thermal stability with a degradation temperature of > 500 degrees C as well as a glass transition of > 300 degrees C. Both water contact angle and oil contact angle increase rapidly with introducing small amount of the fluorosilane in the hybrids and reaches the maximum of 115 degrees and 61 degrees, respectively. The hardness of the hybrid coatings increases up to 5H with an increase of the FTES content in the hybrids. These colorless, transparent, and thermally stable hybrid materials could be suitable for applications as anti-stain coatings.     

Synthesis, characterization, and antimicrobial activity of nano-hydroxyapatite-zinc for bone tissue engineering applications

The bone implants used in tissue repair are susceptible to infections caused by staphylococci, specifically Staphylococcus aureus. Hence, the development of better biological materials that provide antimicrobial activity in bone tissue engineering is required. The nanoparticles of hydroxyapatite (nHAp) and nHAp dopped with Zn (nHAp-Zn) were prepared by the wet chemical method and the ion exchange method, respectively. They were characterized using SEM, AFM, FTIR and XRD. The antibacterial activity of nHAp and nHAp-Zn was determined with Gram-negative and Gram-positive bacterial strains. The results indicated that nHAp alone was acting as an inert matrix and when substituted with Zn, it showed better antibacterial activity. The nHAp-Zn was found to be non-toxic to osteoprogenitor cells. Thus, due to the antimicrobial property of nHAp-Zn nanoparticles, we suggest that they would have potential applications towards bone tissue engineering.     

Combustion characteristics of a stationary diesel engine fuelled with a blend of crude rice bran oil methyl ester and diesel

The objective of the present work is to analyze the combustion characteristics of crude rice bran oil methyl ester (CRBME) blend (20% of CRBME with 80% no.2 diesel on volume basis) as a fuel in a stationary small duty direct injection (DI) compression ignition (CI) engine. When operating with CRBME blend the cylinder pressure was comparable to that of diesel. It was observed that the delay period and the maximum rate of pressure rise for CRBME blend were lower than those of diesel. The occurrence of maximum heat release rate advanced for CRBME blend with lesser magnitude when compared to diesel. CRBME blend requires more crank angle duration to release 50% & 90% of heat when compared with diesel. The brake specific fuel consumption of CRBME blend was found to be only marginally different from that of the diesel and its hourly fuel cost was higher than that of diesel. CRBME blend has lower smoke intensity and higher NOx emission than those of diesel. Since the measured parameters for CRBME blend differs only by a smaller magnitude, when compared with diesel, this investigation ensures the suitability of CRBME blend as fuel for CI engines with higher fuel cost.     

Formation of silver nanorod arrays in an anodised aluminium oxide membrane

A highly ordered silver nanorod array (AgNRs) with a diameter of 90?nm has been prepared by chemical reduction from silver nitrate in a porous anodic aluminium oxide (AAO) membrane. The AAO membrane was fabricated electrochemically in an oxalic acid solution via a one-step anodisation process, followed by the growth of silver NR in the long-range ordered nanochannels of the AAO membrane via chemical reduction. The morphologies of AAO membrane and AgNRs with periodic rows of air-pockets encapsulated in the AAO membrane have been investigated using TEM. The crystalline structure and chemical composition have been confirmed by XRD, TEM and EDX techniques. The process, which has three stages, namely, (1) anodising of aluminium foil to form a mesoporous membrane, (2) adsorption of metal ions, then (3) chemical reduction of the adsorbed metal ions to form the nanorod array of AgNRs in the pores of AAO membrane, has not, to the authors’ knowledge, been reported to date.     

Nutrient content,in vitro ruminal fermentation characteristics and methane reduction potential of tropical tannin‐containing leaves

BACKGROUND: Plant tannins as rumen modifiers are better than chemicals or antibiotic‐based modifiers since these compounds are natural products which are environmentally friendly and therefore have a better acceptance with regard to feed safety issues. Tropical plants containing phenols such as tannins were found to suppress or eliminate protozoa from the rumen and reduce methane and ammonia production. The screening of these plants is an important step in the identification of new compounds and feed additives which might contribute to mitigate rumen methanogenesis. The present study was carried out to determine the efficacy of tannins from tropical tree leaves for their methane reduction properties. RESULTS: Activity of tannins, as represented by the increase in gas volume with the addition of polyethylene glycol (PEG)‐6000 as a tannin binder (tannin bioassay) was highest in Ficus bengalensis (555%), followed by Azardirachta indica (78.5%). PEG addition did not alter (P > 0.05) methane percentage in Ficus racemosa, Glyricidia maculata, Leucena leucocephala, Morus alba and Semaroba glauca, confirming that tannins in these samples did not affect methanogenesis. The increase (P < 0.05) in protozoa population with PEG was maximal in Ficus religiosa (50), followed by Moringa oleifera (31.2), Azardirachta indica (29.9) and Semaroba glauca (27.5). There was no change (P > 0.05) in the protozoa population in Autocarpus integrifolia, Ficus bengalensis, Jatropha curcus, Morus alba and Sesbania grandiflora, demonstrating that methane reduction observed in these samples per se was not due to defaunation effect of the tannin. The increase in total volatile fatty acid concentration in samples with PEG ranged from 0.6% to > 70%. The highest increase (%) in NH₃‐N was recorded in Azardirachta indica (67.4), followed by Ficus mysoriensis (35.7) and Semaroba glauca (32.6) leaves, reflecting strong protein binding properties of tannin. CONCLUSION: The results of our study established that in vitro methanogenesis was not essentially related to the density of protozoa population. Tropical tree leaves containing tannins such as Autocarpus integrifolia, Jatropha curcus and Sesbania grandiflora have the potential to suppress methanogenesis. Therefore tannins contained in these plants could be of interest in the development of new additives in ruminant nutrition. Copyright © 2012 Society of Chemical Industry