Teong Guan Chuah

Biomass as the Renewable Energy Sources in Malaysia: An Overview

Past and current economic growths of Malaysia have been primarily energized by fossil fuels. Malaysia has very substantial potential for biomass energy utilization given its equatorial climate that is ideal for dense tropical forest growth and agricultural vegetation. There are five major sectors contributing wastes to biomass energy in Malaysia: forestry (wood products), rubber cultivation, cocoa cultivation, sugar cane cultivation and oil palm cultivation. Biomass in Malaysia contributes about 14% of the approximately 340 million barrel of oil equivalent (boe) of energy used every year. This paper provides an overview on the types of biomass being used, the research works on biomass conversion into energy and the present biomass energy projects in Malaysia.

Drying of Betel Leaves (Piper betle L.): Quality and Drying Kinetics

This work studied the effects of drying temperature on the quality and drying kinetics of betel leaves (Piper betle L.). As the drying process applies heat on the product, this might lead to the degradation and decomposition of valuable phytochemicals within the herbs. In this study, the effect of drying temperature on the quality of dried leaves was studied by analyzing the change of major phytochemicals found in the leaves, which are hydroxychavicol and eugenol. The results indicate that the content of major compounds increased with temperature from 40 to 70°C but underwent decomposition when the leaves dried at 80°C. Besides that, the drying kinetics for different drying temperatures also studied. The kinetics results show that the increase of drying temperature shortened the total drying time. Five thin-layer models were selected in describing the drying process of betel leaves. The logarithmic model was found to be the most suitable one.

Optimisation of reactive dye removal by sequential electrocoagulation-flocculation method: comparing ANN and RSM prediction

The removal of Reactive Black 5 dye in an aqueous solution by electrocoagulation (EC) as well as addition of flocculant was investigated. The effect of operational parameters, i.e. current density, treatment time, solution conductivity and polymer dosage, was investigated. Two models, namely the artificial neural network (ANN) and the response surface method (RSM), were used to model the effect of independent variables on percentage of dye removal. The findings of this work showed that current density, treatment time and dosage of polymer had the most significant effect on percentage of dye removal (p<0.001). In addition, interaction between time and current density, time and dosage of polymer, current density and dosage of polymer also significantly affected the percentage of dye removal (p=0.034, 0.003 and 0.024, respectively). It was shown that both the ANN and RSM models were able to predict well the experimental results (R(2)>0.8).

Effects of Temperatures on Rheological Behavior of Dragon Fruit (Hylocereus sp.) Juice

In Malaysia, the dragon fruit is widely commercialized. It is extensively used in the food industry. Their use as constituents of juices, jellies, marmalades, jams, wine, beverages, etc. generates a consumer market with an increasing demand. This work aims to obtain rheological data of dragon fruit juice which is essential in optimizing equipment design, process control, and consumer acceptability of a product. In the present study, dragon fruit juice with concentrates of (10 and 12oBrix) was prepared. The rheological behavior of these concentrates was studied in the temperature range of 5, 10, 15, and 40oC. Dragon fruit juice was found to exhibit non-Newtonian, pseudoplastic behavior. Samples on both concentrations were adequately described by the rheological model. The effect of temperature on dragon fruit juice is best described by the applicability of the Arrhenius model related to apparent viscosity, ?a.

Rheological Properties of Diluted Pummelo Juice as Affected by Three Different Concentrations

Pummelo is a popular fruit that has great potential to be commercialized. The physico-chemical characterization of pummelo juice such as proximate analysis, pH, moisture content, protein, fat, carbohydrate, ash and fibre contents are investigated. The rheological characterization of pummelo juice was modeled by several models, such as Bingham, Power Law and Casson models. Regression analysis shows good agreements for all three models applied in this study. Pummelo juice exhibits pseudoplastic behaviour under the conditions tested, as indicated by flow behaviour indices (n) ranging from 0.1 to 0.9 from power law model, indicating strong shear-thinning behaviour.

Modeling biodegradation and kinetics of glyphosate by artificial neural network

An artificial neural network (ANN) model was developed to simulate the biodegradation of herbicide glyphosate [2-(Phosphonomethylamino) acetic acid] in a solution with varying parameters pH, inoculum size and initial glyphosate concentration. The predictive ability of ANN model was also compared with Monod model. The result showed that ANN model was able to accurately predict the experimental results. A low ratio of self-inhibition and half saturation constants of Haldane equations (< 8) exhibited the inhibitory effect of glyphosate on bacteria growth. The value of Ki/Ks increased when the mixed inoculum size was increased from 104 to 106 bacteria/mL. It was found that the percentage of glyphosate degradation reached a maximum value of 99% at an optimum pH 6-7 while for pH values higher than 9 or lower than 4, no degradation was observed.

Glyphosate Utilization as the Source of Carbon: Isolation and Identification of new Bacteria

Mixed bacteria from oil palm plantation soil (OPS) were isolated to investigate their ability to utilize glyphosate as carbon source. Results showed that approximately all of the glyphosate was converted to aminomethyl-phosphonic acid (AMPA) (99.5%). It is worthy to note that mixed bacteria were able to degrade only 2% of AMPA to further metabolites. Two bacterial strains i.e. Stenotrophomonas maltophilia and Providencia alcalifaciens were obtained from enrichment culture. Bacterial isolates were cultured individually on glyphosate as a sole carbon source. It was observed that both isolates were able to convert glyphosate to AMPA.

Green nanocomposites from cellulose nanowhiskers and Jatropha oil–based polyurethane

A green nanocomposite film from cellulose nanowhiskers (CNWs) and Jatropha oil-based polyurethane (JOPU) was prepared. A commercial grade of microcrystalline cellulose derived from wood pulp was purchased and isolated to CNW via acid hydrolysis using 65% (w/w) sulfuric acid. JOPU was produced using in-house synthesis of Jatropha-oil polyol and 4,4′-diphenyl-methane diisocyanate (MDI). Dimethylformamide (DMF) was used as a polar organic solvent to disperse CNWs incorporated with JOPU at different ratios. Green nanocomposite films were prepared by casting in Teflon petri dish and thermal curing of the stable suspensions under vacuum conditions. Both CNW and composite films were characterized. The morphology of CNW was examined by using transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM). Chemical structures of JOPU and JOPU/CNW films were analyzed using Fourier transform infrared spectroscopy (FTIR). Thermal stability tests of the films were carried out using thermogravimetric analysis (TGA). Mechanical properties, such as tensile strength, Young modulus, and elongation at break, were investigated. Other properties such as density and water uptake were also determined. It can be concluded that composite films made from JOPU with CNW as filler showed an improved performance over JOPU films.