Carbon nanotube growth via chemical vapour decomposition method.

This paper illustrates a short review in the carbon nanotubes structure and other carbon forms and explains different forms of carbon nanotubes. The various attractive and unique properties of carbon nanotubes are also discussed. There are several methods for carbon nanotubes production but the best sufficient method for mass production with lower cost is the chemical vapour decomposition method, which is the main subject of present article. Furthermore, the various effective factors on the carbon nanotubes growth in the chemical vapour decomposition process like temperature, inert gas flow rate, carbon source, catalyst and the reaction time are discussed here

Application of supercritical antisolvent method in drug encapsulation: a review

The review focuses on the application of supercritical fluids as antisolvents in the pharmaceutical field and demonstrates the supercritical antisolvent method in the use of drug encapsulation. The main factors for choosing the solvent and biodegradable polymer to produce fine particles to ensure effective drug delivery are emphasized and the effect of polymer structure on drug encapsulation is illustrated. The review also demonstrates the drug release mechanism and polymeric controlled release system, and discusses the effects of the various conditions in the process, such as pressure, temperature, concentration, chemical compositions (organic solvents, drug, and biodegradable polymer), nozzle geometry, CO2 flow rate, and the liquid phase flow rate on particle size and its distribution

Effect of supercritical fluid density on nanoencapsulated drug particle size using the supercritical antisolvent method

The reported work demonstrates and discusses the effect of supercritical fluid density (pressure and temperature of supercritical fluid carbon dioxide) on particle size and distribution using the supercritical antisolvent (SAS) method in the purpose of drug encapsulation. In this study, paracetamol was encapsulated inside L-polylactic acid, a semicrystalline polymer, with different process parameters, including pressure and temperature, using the SAS process. The morphology and particle size of the prepared nanoparticles were determined by scanning electron microscopy and transmission electron microscopy. The results revealed that increasing temperature enhanced mean particle size due to the plasticizing effect. Furthermore, increasing pressure enhanced molecular interaction and solubility; thus, particle size was reduced. Transmission electron microscopy images defined the internal structure of nanoparticles. Thermal characteristics of nanoparticles were also investigated via differential scanning calorimetry. Furthermore, X-ray diffraction pattern revealed the changes in crystallinity structure during the SAS process. In vitro drug release analysis determined the sustained release of paracetamol in over 4 weeks

Kinetics of the transesterification of Jatropha curcas triglyceride with an alcohol in the presence of an alkaline catalyst.

The jatropha curcas methyl ester can be produced through a transesterification reaction by using an alkaline catalyst with an alcohol as the excess reactant. The reaction was carried out in a batch mixed reactor under various operating condition. The kinetics study on the transesterification of jatropha curcas-based triglycerides with methanol was carried out under various temperatures (323, 328, 333 and 338 K). The conversion of triglycerides into methyl esters follows the first-order mechanism for the forward reaction. The reaction rate constants were determined and finally the rate constants were plotted against temperatures for calculating the activation energies. The values of kTG ranges from 0.11 to 0.17 and the values of kDG are from 0.07 to 0.20 respectively. The activation energies for stepwise reactions for transesterification of jatropha curcas-based triglycerides and diglycerides with methanol are 27.38 and 46.72 kJ mol-1. Future work should examine the real step-wise reaction kinetics in jatropha curcas biodiesel production under acid catalyst

Biobased lubricants: harnessing the richness of agriculture resources

In Malaysia, the availability of diversified biomass feedstocks such as sugars, oils, protein, lignocellulosics, combined with numerous biochemical, thermo and chemical conversion technologies, offers a wealth of products that are useful in many applications. Target applications include polymer, lubricant, solvent, adhesive, herbicide, and pharmaceutical industries. Many of these industrial biobased products have already penetrated the markets, but improved technologies promise new products that can compete with fossil-based products in both cost and performance aspects. Among these markets, the biolubricant market represents an enormous potential for biobased products. Despite the increased popularity of the biobased or green products, the development of these products is a challenge because the sustainability aspect of these biobased chemicals is still being dispute. The possibility of achieving the environmental sustainability is questioned—considering the environmental degradation, climate change, overconsumption, and the pursuit of economic balance within the closed system. To tackle these issues effectively requires reverting to fundamental principles that govern the technologies that produce these chemicals. Are these technologies efficient and effective? (Developing technology that uses less energy produces less waste, and safer to environment). This is the paradigm shift of the early 21st century; innovating technologies for sustainable development. Ways of reducing negative impacts on human are also paramount which entails environmental-friendly engineering, environmental resources management and environmental protection.Lubricants which are both readily biodegradable and non-toxic to humans and environments are known as biobased lubricant or biolubricant. A biolubricant can be any plant oil or synthetic esters, which are derived from plant oils. In pursuit of environmentally friendly chemical engineering, various biolubricants from synthetic esters derived from agriculture resources have been developed using low-pressure technology. The technology enables product synthesis to take place at low temperature and pressure. In addition, the reaction time was markedly reduced and the product conversion was improved. Using the pulsed loop reactor, the methyl ester (biodiesel) can be produced in 10 minutes at 60°C and the polyol ester in 30 minutes. Similar loop reactor under vacuum condition was also used to produce various esters for biolubricants. Hydraulic fluid, metal working fluid, tapping oil, oven chain oil, and drilling fluid are among the biolubricants that are currently being developed for commercial purposes. Changing the starting materials for the synthesis allows us to tailor make the final ester for selected applications. Ester-based oil drilling fluid (or mud) has also been developed to address the increasing concern of the environmental consequences of using oil based mud (OBM) using the low-pressure technology. The ester-based mud is superior to the commercial ester, and the production cost is much lower due to the efficient technology. Incorporating graphene in the ester-based mud has further improved its performance. The ester-based mud enhanced with graphene has potential to be used for high temperature application above 450°F. Green transformer oil is another environmentally friendly product that is developed driven by the desire for a safer, non-flammable and environmentally acceptable insulating liquid for use in power equipment

CFD analysis chlorine gas dispersion in indoor storage: temperatures with wind velocities effect studies

Most of the industrial chemical products encounter natural environmental risk in the process. The indoor release of hazardous dense gases is especial topic for discussion nowadays because the clouds of heavier gases have a tendency to stay near the ground level, causing fatal and injuries the people. In this article a computational fluid dynamics (CFD) code FLUENT was employed in order to model the accidental indoor dispersion of chlorine from a small undetected leak in an indoor industrial space. The results of simulation represented that the chlorine gas spread would behave like liquid and flows on the floor, also the concentration of chlorine increased to above the ground level slowly. The effects of various temperatures and wind velocities on dispersion of heavier gas will help to better identify the potential risks. In this paper, the effects of the environmental situations with the release and spread of chlorine in the indoor space were meticulously examined

Optimizing supercritical antisolvent process parameters to minimize the particle size of paracetamol nanoencapsulated in L-polylactide

Background: The aim of this study was to optimize the different process parameters including pressure, temperature, and polymer concentration, to produce fine small spherical particles with a narrow particle size distribution using a supercritical antisolvent method for drug encapsulation. The interaction between different process parameters was also investigated. Methods and results: The optimized process parameters resulted in production of nanoencapsulated paracetamol in L-polylactide with a mean diameter of approximately 300 nm at 120 bar, 30°C, and a polymer concentration of 16 ppm. Thermogravimetric analysis illustrated the thermal characteristics of the nanoparticles. The high electrical charge on the surface of the nanoparticles caused the particles to repel each other, with the high negative zeta potential preventing flocculation. Conclusion: Our results illustrate the effect of different process parameters on particle size and morphology, and validate results obtained via RSM statistical software. Furthermore, the in vitro drug-release profile is consistent with a Korsmeyer–Peppas kinetic model

Effect of fiber length on thermomechanical properties of short carbon fiber reinforced polypropylene composites

Carbon fiber reinforced composites have all the ideal properties, leading to their rapid development and successful use for many applications over the last decade. In this paper, short carbon fiber reinforced polypropylene (SCF/PP) composite were prepared with melt blending and hot-pressing techniques. The thermomechanical properties of this composite were investigated taking into account the combined effect of mean fiber length. Thermal stability of the composite was studied via the thermal gravimetric analysis (TGA) and dynamic mechanical analysis (DMA) was used to measure the damping properties of the composites. Finally it can be shown that an increase in fiber length can enhance the thermal stability of SCF/PP composites and improve the damping properties as well

Effect of chopping oil palm fruit spikelets on the free fatty acid content release rate and its mechanical properties

Crushed oil palm fruit bunches from the continuous sterilization system cause damages and bruising of the fruits, yielding high lipase enzyme reaction if no heating pre-treatment was carried out immediately. Thus, this study was proposed to acquire the free fatty acid content (FFA) release rate and to determine the mechanical properties of chopped oil palm fruit spikelets. The fruit spikelets were chopped by using two different methods, which were manually chopping using a knife blade and utilizing a fabricated chopper blade. Damages obtained from the manually chopped using the knife blade were classified into two categories, which were minor and major damage. The chopper blade was fixed on the Instron Machine to obtain its mechanical properties, such as rupture force, deformation at rupture, hardness and energy at the break of the fruit spikelets. The chopped fruit spikelets were stored at different storage periods ranging between 0hr to 2hr at room temperature. Extraction of palm oil was extracted using the Soxhlet extractor and the FFA content of the palm oil was determined through titration method. Results showed that the mean rupture force, deformation at rupture, hardness and energy at break required when chopping the fruit spikelets were 2781N, 45.53mm, 61.02 N/mm and 36.71J respectively. The development of FFA content was highly influenced by the damaged area of the fruits and the length of storage periods. This is due to the development of lipase enzyme activity that occurred in the damaged cells, therefore simultaneously increasing the rate of FFA content released