Thermal properties of high density polyethylene-kenaf cellulose composites.

Biocomposites of high density polyethylene (HDPE) and kenaf cellulose (KC) with polyethylene glycol (PEG) have been prepared by melt blending and compression moulding. The optimum temperature and reaction period for blending KC with HDPE were 145 C and 12 minutes with rotation speed of 30 rpm, respectively. The effects of composition on the thermal properties of HDPE-KC biocomposites were investigated using TGA and DSC. Each sample of HDPE-KC biocomposites was subjected to heating programs between 35-600 C for TGA, and the DSC analysis was determined under heating cycles of 25-600 C. The results from TGA and DSC indicated that by increasing the KC content, the thermal stability was slightly improved. The melting temperature for all the composites was less than the melting point of KC (148.70 C), and almost the same as that of HDPE (130.38 C). Therefore no significant change in the melting temperature resulted from adding KC to the HDPE matrix. However, HDPE's presence surrounding the KC fibres, prevented water from reaching the cellulose fibre particles, thus reducing the water content in the composite; hence a significant advantage of forming KC composites with hydrophobic HDPE is that it helps to make the cellulose hydrophobic instead of hydrophilic

Case study: comparison of air dispersion from solid waste incinerator emission using AERMOD and ISCST3

Combustion of municipal solid waste in a solid waste incinerator will generates flue gas emission consist of pollutants that may detrimental to human health. It was intended to observe the dispersion of the pollutants from the chimney of solid waste incinerator of Cameron Highlands using two air dispersion models, AERMOD and ISCST3. This study involves usage of 1 year hourly meteorological data, terrain data, chimney specification and pollutant emission rate as input in both models to predict the pollutants incremental concentration to the surrounding environment. It was found that AERMOD model simulates in a way similar to the real meteorological condition as compared to ISCST3. Higher concentration was predicted nearer to the pollutant source and at sensitive receptors in AERMOD as compared to ISCST3 prediction

Effect of stirring time on synthesis of ultra fine x-Al2O3 powder by a simple sol-gel method.

The present paper tends to explore the effect of stirring time on the synthesis of nano α-Al2O3 particles. In this study, alumina nanoparticles were synthesized through an alkoxide route implementing sol-gel method in which aqueous solutions of aluminum isopropoxide and 0.5M aluminum nitrate nanohydrate were used to prepare an alumina sol. Sodium dodecylbenzen sulfonate was used as the surfactant stabilizing agent. The prepared solution was stirred for different times (24, 36, 48 and 60 hours) at 60 oC. The samples were, then, characterized by Brunauer-Emmet-Teller method, X-ray diffraction, thermogravimetry analysis, differential scanning calorimetry, Fourier transform infrared spectrometry, scanning electron microscopy and transmission electron microscopy. The introduction of different stirring times affected the particle size and shape and the degree of aggregation. By increasing the stirring time (starting from 24 to 48 hours), the particle size decreased, but there was a harder agglomeration for the samples with 60 hours stirring time. The finest particle size (20-30 nm) was obtained at 48 hours stirring time

Rigid ceramic filters: numerical simulation of the pressure & velocity distributions

Tightened environmental legislation enacted as a result of government policy has compelled the industry to pay serious attention to air pollution issues. Gas cleaning with ceramic filters has proven to be a major technology for removal of particulate emissions at high temperatures. Filters, after a certain period of filtration time, must be cleaned for maximum efficiency. This can be done by applying a pulsed reverse cleaning flow into the filters. The cleaning mechanisms by which the deposited cake is removed from the filter surface are still not fully understood. Varied mathematical models were thus developed to investigate the flow dynamics of the filtration and reverse pulse flow cleaning in a ceramic filter. These include a Computational Fluid Dynamics (CFD) model, a Simple Excel Reverse Pulse Flow Model and a time-dependent filter cake model. The simulation results were validated using the results of previously reported experiments carried out for filtration and reverse flow cleaning using the filter elements

Physical and antimicrobial characterization of self assembled silver nanoparticle/chitosan onto low density polyethylene film as active packaging polymer

Colloidal Silver nanoparticles with a size of 5 nm produced by chemical reduction using poly ethylene glycol (PEG 200). Layers of silver nanoparticles and chitosan were deposited onto low density polyethylene (LDPE) substrate by layer by layer (LBL) self-assembly technique. Silver nanocomposite films were built by sequential dipping of LDPE film in either anionic silver nanoparticles or cationic chitosan. Silver nanoparticles and chitosan led to the formation of nanocomposite films possessing antimicrobial properties with the thickness of 2, 4, 8, 12 and 20 layers. Silver nanocomposite films were characterized by atomic force microscopy (AFM). Thermal, mechanical and barrier properties of LBL deposited nanocomposite films were investigated. Results showed that the LBL deposition of silver nanoparticles and chitosan increased the crystallinity of the composites and also improved mechanical and barrier properties of LDPE film significantly (p<0.05). Antimicrobial activity of silver nanocomposites against Escherichia coli and Staphylococcus aureus was evaluated. Growth kinetic parameters of E.coli and S.aureus affected by silver nanocomposites were calculated by modeling of absorbance data according to Gomperz equation. LDPE-silver nanocomposite affected bacterial growth parameters significantly (p<0.05). The specific growth rate reduced from 0.30 to 0.11 h-1 for E. coli and decreased 0.27 to 0.06 h-1 for S. aureus

Effect of temperature and concentration on rheological properties pomelo juice concentrates

Rheology is the science of deformation and flow behavior of fluid. Knowledge of rheological properties of fluid foods and their variation with temperature and concentration have been globally important for industrialization of food technology for quality, understanding the texture, process engineering application, correlation with sensory evaluation, designing of transport system, equipment design (heat exchanger and evaporator), deciding pump capacity and power requirement for mixing. The aim of this study was to determine the rheological behavior of pomelo juice at different concentrations (20-60.4%) and temperatures (23-60°C) by using a rotational rotational Haake Rheostress 600 rheometer. Pomelo juice was found to exhibit both Newtonian and Non-Newtonian behavior. For lower concentration the Newtonian behavior is observed while at higher concentration Non-Newtonian behavior was observed. Standard error (SE) method was selected on the basis to carry out the error analysis due to the best fit model. For the four models the values of SE show that the Herschel-Bulkley and Power Law models perform better than the Bingham and Casson models but Herschel-Bulkley model is true at higher concentration. The rheological model of pomelo juice, incorporating the effects of concentration and temperature was developed. The master-curve was investigated for comparing data from different products at a reference temperature of 40°C. Multiple regression analysis indicated Master-Curve presents good agreement for pomelo juice at all concentrations studied with R 2>0.8

Transesterification reaction optimization and evaluation of biodiesel produced from seed oil of Colocynthis citrullus L.

This work presents Colocynthis citrullus L. (egusi) seed oil as a potential feedstock for biodiesel production. The transesterification process was optimized using response surface methodology (RSM) with three-level-three-factors face-centered central composite design employed. Catalyst (NaOH) amount (0.25-1.8％ (w/w), reaction temperature (45-65 °C) and oil-methanol molar ratio (4-10) were studied as important factors influencing the reaction. The optimum values (1:6.54 oil/methanol molar ratio, 1.22％ (w/w) catalyst amount, and 65 ºC reaction temperature) predicted by the mathematical model generated using RSM gave ester yield of 84.46％, under experimental conditions. The fuel properties of egusi oil methyl ester (EOME) measured satisfied both ASTM D6751 and EN 14214 biodiesel standards with a kinematic viscosity of 3.87 mm2/s. Fatty acid profile and fuel properties of EOME were found similar to those of soybean, safflower and sunflower biodiesel

Equilibrium, kinetics and thermodynamic studies: adsorption of Remazol Black 5 on the palm kernel shell activated carbon (PKS-AC)

The removal of Remazol Black 5 from the synthetic wastewater using palm kernel shell activated carbon was investigated in terms of initial pH, initial concentration, contact time and temperature. The optimum pH was found at acidic range, pH 2. For equilibrium studies, two isotherm models were used in this study, which is Freundlich and Langmuir, for different temperatures and it is found that Freundlich fitted experimental data very well. In the kinetics study, pseudo-first order and pseudo-second order were tested; the latter equation showed the best represent the experimental data. The change in entropy and enthalpy for an adsorption of the dye were estimated -24.26j/mol K and -9.246kJ/mol respectively

Fuel properties and rheological behavior of biodiesel from egusi (Colocynthis citrullus L.) seed kernel oil

In this study, egusi (Colocynthis citrullus L.) seed kernel oil has been evaluated as a feedstock for biodiesel production. The transesterification of the crude egusi seed kernel oil (CESKO) via methanol in the presence of sodium methoxide was performed and the resulting egusi oil methyl ester (EOME) was tested for its fatty ester composition, fuel properties and rheological behavior (at 25 °C, 40 °C and 55 °C). The fuel properties of EOME measured met both the ASTM D6751 and EN 14214 biodiesel standards, with the exception of lower oxidative stability. The fatty ester composition and fuel properties of EOME were found comparable to those of conventional biodiesels from soybean, sunflower and safflower oils. The viscosity behavior of EOME and its blends with diesel fuel (at 25 °C, 40 °C and 55 °C) was found to be pseudoplastic and Newtonian in nature and this agrees with those of other biodiesels reported in literature. From this study, the kinematic viscosity of EOME (3.91 mm2/s) was found to be slightly lower than that of most biodiesels (≥ 4.0 mm2/s) reported in literature

Preparation of meteorological input for AERMOD using Malaysian meteorological data

Gaussian plume dispersion model - AMS/EPA Regulatory Model (AERMOD) has been recognised as the preferred regulatory air dispersion model and has been proven to perform better than other available models. However, Malaysian meteorological data has limited parameters and the data recorded is inadequate to be used in AERMOD. Currently, processed meteorological data has to be bought from meteorological data service providers located overseas. The processed data does not represent the real conditions experienced at the site accurately. The study involves the identification of missing data in 4 meteorological stations located in Peninsular Malaysia (Cameron Highlands, Subang, Sepang KLIA, and Kuantan), replacement of the missing data and preparation of the data in accordance with the format that AERMOD requires. The study result in a methodology to replace missing data and calculation using bulk formulae which is developed based on certain assumptions that are practical and scientific