Search

Nowadays, fragrance molecules have become a focal point in formulated products, aimed at attracting customers. However, there have been notable clinical cases involving allergies caused by these fragrance molecules in various products. Thus, the purpose of this study is to design a fragrance molecule that not only offers a pleasant and long-lasting scent but is also safe for users. A computer-aided molecular design (CAMD) model is employed to achieve this. The desirable attributes of fragrance molecules are identified and then translate these attributes into their corresponding properties. Machine learning is applied to develop prediction models for odor properties, while property prediction models are used to identify for other target properties. A CAMD model is developed using LINGO which encompasses the constraints and rules generated. Fuzzy optimization involved to address the multi-objective scenario. Upon the implementation of CAMD approach, the molecules generated all met the technical requirements. The molecules generated undergo safety and health assessment to eliminate the hazard fragrance molecule. Among these molecules, 2-methoxyethyl acetate emerges as the optimal fragrance molecule. It exhibits a higher diffusion coefficient and poses minimum hazards, ensuring both a pleasing fragrance and user safety.

Hydrogen can be one of the alternative energy carriers to replace those produced from fossil fuels. Steam methane reforming is a low-cost, high-yielding hydrogen production technique. However, there are other technologies available to produce hydrogen and they can vary in terms of safety, reliability and cost. The variation in technologies has made it challenging to design a safe, reliable and low-cost system. A system with high reliability results in higher capital costs due to added technologies. Therefore, an optimization model addresses all aspects simultaneously. A fuzzy optimization model is used to determine an optimal reformer-based hydrogen production network considering reliability, cost and safety. To illustrate the model framework, a case study with three different scenarios was presented. An inherent safety assessment was carried out to evaluate the inherent safety hazards for each scenario. Based on the results obtained from the case study, an optimal reformer-based hydrogen production network with a trade-off between cost and reliability was developed. The optimized reformer-based hydrogen production network in scenario 3 met all the objectives, with a degree of satisfaction with cost and reliability of 0.58 and 0.66, respectively, and a lower level of inherent safety hazard with a total capital cost of 49,631,850 USD.

As climate change escalates, there is a need for proper planning of future use of water resources. The occurrence of prolonged droughts and fluctuation of weather patterns can lead to serious water scarcity issues. Process integrationtechniques have been widely used for water management in the process plants. This paper extends the insight-based and mathematical programming techniques of process integration to incorporate health aspects in water management. In particular, health quality index is used as a quality metric in considering water recovery in a system of processes. The consideration of health aspects is important for cases involving direct contact of human body with water, such as in water recreational activities. In addition, multi-period planning (MPP) is also considered in this work, where water recovery takes place across different periods. A representative water park case study is used to illustrate the applicability of the proposed method.

Sector-specific strategies are needed to transition toward a low-carbon economy. Palm oil is a large-scale agriculture commodity in Malaysia, with a considerable carbon footprint. Therefore, decarbonization of the palm oil sector is crucial, accounting for emissions and mitigation opportunities along the entire value chain. Though several of the previous works have optimized the palm oil value chain (POVC), there exists a significant gap in the comprehensive evaluation of strategies to decarbonize the POVC. To address this gap, this work proposes a systematic approach to design an optimal POVC with minimum GHG emissions. This study considers integrated oil palm plantations (OPPs), integrated palm oil mills (POMs), and palm oil refineries (PORs) within the POVC boundary. An integrated OPP refers to plantation with an onsite biorefinery, while an integrated POM includes the milling process, biorefinery, palm oil mill effluent (POME) treatment, and biogas upgradation. A mathematical optimization (mixed integer nonlinear programming, MINLP) model was developed to determine the optimal process design and pathway selection along the POVC. The proposed model is illustrated with a case study of POVC in Johor, Malaysia that includes 15 OPPs, 5 POMs, and 1 POR. The optimization was performed under two scenarios─maximizing economic performance (S1) and maximizing GHG savings (S2). The results of this study show a significant improvement in the annual economic performance from USD 85 million in the existing baseline scenario to USD 167 million in S1. Furthermore, the study demonstrates that optimal technology and pathway selection can result in significant GHG savings up to 6.04 tCO2/ha at OPPs and 0.62 tCO2/t FFB at POMs, respectively.

The sustainability level of a chemical production pathway is an important element that requires to be assessed when developing a new process. Note that the typical sustainability assessment is normally emphasised on economic and technological development. In order to ensure more comprehensive level of sustainability, the protection on human health and preservation of the environment should be considered. This paper presents a systematic framework for assessment of chemical production pathway based on multi-sustainability criteria, i.e., inherent safety, health and environment (SHE) and economic performance (EP). In order to generate an optimal design solution, uncertainty analysis is also incorporated in this framework. Two optimisation approaches are adapted into this framework, i.e. fuzzy optimisation is used for multi-objective analysis, while multi-period optimisation is applied to address the multiple operational periods with presence of uncertainty. To illustrate the proposed framework, assessment on biodiesel production pathway based on enzymatic transesterification using waste oil is conducted. In the case study, three periods (low, medium and high demand period) of demand for biodiesel are considered, whereby each period is subjected to uncertainties, i.e. waste oil flow rate, waste oil price and enzyme price. To accommodate the uncertainties, sensitivity analysis is performed to determine the feasible operating condition, i.e. tert-butanol concentration and reactor residence time, as well as the appropriate sizing of the process modules (or known as unit operations).

The determination of volatile organic compounds (VOCs) at selected pump stations in Skudai, Johor Bahru was investigated. About 27 chemicals substances in petrol and 24 chemicals substances in diesel with different concentration have been identified in each pump station. Benzene, toluene, ethylbenzene and xylene (BTEX) and MTBE have been chosen as VOCs of interests because of their toxicity properties that can gives hazardous to human health. The exposures of benzene at all three pump stations during refuelling the liquid fuel have potential to cause cancer riskwhile, ethylbenzene stated as acceptable risk to the people health.As for non-carcinogenic substances, the exposure of toluene, xylene and MTBE were recorded as acceptable risk to the people health at all the studied pump stations. Besides, there is a great correlation between physical environment factors; temperature, relative humidity and wind speed typically with total volatile organic compounds that evaporate into the ambient air during refuelling activities.

The Proposed New Environmental Quality (Clean Air) Regulation 201X (Draft), which replaces the Malaysia Environmental Quality (Clean Air) 1978, specifies limits to additional pollutants from power generation using fossil fuel. The new pollutants include Hg, HCl, and HF with limits of 0.03, 100, and 15 mg/N-m3at 6% O2, respectively. These pollutants are normally present in very small concentrations (known as trace elements [TEs]), and hence are often neglected in environmental air quality monitoring in Malaysia. Following the enactment of the new regulation, it is now imperative to understand the TEs behavior and to assess the capability of the existing abatement technologies to comply with the new emission limits. This paper presents the comparison of TEs behavior of the most volatile (Hg, Cl, F) and less volatile (As, Be, Cd, Cr, Ni, Se, Pb) elements in subbituminous and bituminous coal and coal combustion products (CCP) (i.e., fly ash and bottom ash) from separate firing of subbituminous and bituminous coal in a coal-fired power plant in Malaysia. The effect of air pollution control devices configuration in removal of TEs was also investigated to evaluate the effectiveness of abatement technologies used in the plant. This study showed that subbituminous and bituminous coals and their CCPs have different TEs behavior. It is speculated that ash content could be a factor for such diverse behavior. In addition, the type of coal and the concentrations of TEs in feed coal were to some extent influenced by the emission of TEs in flue gas. The electrostatic precipitator (ESP) and seawater flue gas desulfurization (FGD) used in the studied coal-fired power plant were found effective in removing TEs in particulate and vapor form, respectively, as well as complying with the new specified emission limits.Implications:Coals used by power plants in Peninsular Malaysia come from the same supplier (Tenaga Nasional Berhad Fuel Services), which is a subsidiary of the Malaysia electricity provider (Tenaga Nasional Berhad). Therefore, this study on trace elements behavior in a coal-fired power plant in Malaysia could represent emission from other plants in Peninsular Malaysia. By adhering to the current coal specifications and installation of electrostatic precipitator (ESP) and flue gas desulfurization, the plants could comply with the limits specified in the Malaysian Department of Environment (DOE) Scheduled Waste Guideline for bottom ash and fly ash and the Proposed New Environmental Quality (Clean Air) Regulation 201X (Draft).