Jo-Han Ng

Pyrolysis production of fruit peel biochar for potential use in treatment of palm oil mill effluent

Fruit peel, an abundant waste, represents a potential bio-resource to be converted into useful materials instead of being dumped in landfill sites. Palm oil mill effluent (POME) is a harmful waste that should also be treated before it can safely be released to the environment. In this study, pyrolysis of banana and orange peels was performed under different temperatures to produce biochar that was then examined as adsorbent in POME treatment. The pyrolysis generated 30.7-47.7 wt% yield of a dark biochar over a temperature ranging between 400 and 500 °C. The biochar contained no sulphur and possessed a hard texture, low volatile content (≤34 wt%), and high amounts of fixed carbon (≥72 wt%), showing durability in terms of high resistance to chemical reactions such as oxidation. The biochar showed a surface area of 105 m2/g and a porous structure containing mesopores, indicating its potential to provide many adsorption sites for use as an adsorbent. The use of the biochar as adsorbent to treat the POME showed a removal efficiency of up to 57% in reducing the concentration of biochemical oxygen demand (BOD), chemical oxygen demand COD, total suspended solid (TSS) and oil and grease (O&G) of POME to an acceptable level below the discharge standard. Our results indicate that pyrolysis shows promise as a technique to transform banana and orange peel into value-added biochar for use as adsorbent to treat POME. The recovery of biochar from fruit waste also shows advantage over traditional landfill approaches in disposing this waste.

Microwave pyrolysis with KOH/NaOH mixture activation: A new approach to produce micro-mesoporous activated carbon for textile dye adsorption

A micro-mesoporous activated carbon (AC) was produced via an innovative approach combining microwave pyrolysis and chemical activation using NaOH/KOH mixture. The pyrolysis was examined over different chemical impregnation ratio, microwave power, microwave irradiation time and types of activating agents for the yield, chemical composition, and porous characteristic of the AC obtained. The AC was then tested for its feasibility as textile dye adsorbent. About 29 wt% yield of AC was obtained from the banana peel with low ash and moisture (<5 wt%), and showed a micro-mesoporous structure with high BET surface area (≤1038 m2/g) and pore volume (≤0.80 cm3/g), indicating that it can be utilized as adsorbent to remove dye. Up to 90% adsorption of malachite green dye was achieved by the AC. Our results indicate that the microwave-activation approach represents a promising attempt to produce good quality AC for dye adsorption.

A NOVEL STEADY-STATE TEST CYCLE FOR EMISSIONS CHARACTERISATION OF A LIGHT-DUTY DIESEL ENGINE FUELLED WITH BIODIESEL

The environmental impacts of diesel emissions coupled with the imminent depletion of petroleum, has led to extensive research efforts on alternative fuels. Biodiesel has emerged as the favoured alternative fuel for diesel engine. With this in mind, comprehensive emissions mapping would be required to ascertain the effectiveness of biodiesel in emissions reduction. In this experimental study, a modified steady-state heavy-duty diesel engine test cycle was used. Test point reduction was proposed to reduce the time required within an acceptable reduction in accuracy of the test data. Using the reduced test cycle, the effects of biodiesel from palm, soybean and coconut on tailpipe emissions were compared against that of conventional diesel.

Experimental and numerical studies of swirl combustion characteristics of syngas

Synthesis gas (syngas) is a potential clean fuel for gas turbine. Experiments and numerical simulations were conducted to study the combustion characteristics of syngases in premixed swirl mode using a model gas turbine swirl burner. Four different types of syngases, covering low to high H2-content were tested. Experimental work was conducted to study the emission performance of lean swirl flame. Obtained results were used as validation targets for numerical simulation using flamelet generated manifold (FGM) and chemical equilibrium (CE) approaches. The former method shows better agreement with experimental result, hence FGM method was adopted to model flame structure and predict emission species in the reaction zones for different syngas types. Result shows that syngas with high concentration of H2 produces lower peak flame temperature and height. Furthermore, high H2-rich syngas also produces low level of NO species in the reaction zone.

Integrated 1D-chemical kinetics model of a diesel and biodiesel fuelled light-duty diesel engine

In recent years, advances in numerical modelling of engines have led to the integration of 3-dimensional computational fluid dynamics with chemistry to calculate both the physical flow field and complex chemical reactions. However, it is only feasible to simulate the combustion chamber, but not the entire engine due to simulation runtime limitations. Onedimensional (1D) simulations of an entire engine are rapid yet comprehensive, but focus only on the applied thermodynamics with rudimentary global reaction chemistry. In this study, a compact combined biodiesel-diesel chemical kinetics reaction mechanism is integrated into the 1D modelling of a complete engine. Entire engine cycle from air intake to exhaust product is simulated using commercial software, AVL Boost. This allows for rapid system-level simulation which takes into account applied thermodynamics with complex chemical kinetics to account for combustion and pollutant formation. The integrated 1D-chemical kinetics model is successfully validated against experimental data with both the diesel and palm biodiesel fuel for key combustion parameters. The model would be able to simulate any dieselbiodiesel mixture of any blend levels and also biodiesel produced from different feedstock. This is due to the reaction mechanism comprising of n-Heptane, methyl butanoate and methyl crotonate which are the surrogate fuel models of straight chain hydrocarbon, saturated fatty acid methyl ester (FAME) and unsaturated FAME, respectively. Thus, CME, PME, and SME, are selected for blending due to their innate FAME proportions to represent the high, medium, and low saturated:unsaturated biodiesel, respectively. In all, through 100 simulated cases, this study demonstrated the feasibility of integrating chemical kinetics into 1D numerical model for a complete engine. Ultimately, the use of an integrated 1D-chemical kinetics model for engine simulations can greatly reduce optimisation time for emissions reduction.