Search

Multi‐objective optimization (MOO) to produce low‐density polyethylene (LDPE) in a tubular reactor is performed for three different purposes, namely, maximizing the monomer exchange rate, lowering operational costs, and increasing the productivity. The ASPEN simulator is used to resolve optimization problems. Here, MOO of particle swamp optimization (MOPSO), non‐dominated sorting genetic algorithm (NSGA‐II), and a hybrid strategy of NSGA II‐MOPSO are employed as a model‐based optimization for LDPE production in a tubular reactor. The results demonstrated that the hybrid strategy of NSGA II‐MOPSO is the most effective MOO strategy. Using the hybrid strategy, the discovered solution set provides the utmost precision and diversity along the Pareto front. [ABSTRACT FROM AUTHOR]

Fed‐batch fermentation has the potential to increase the production of docosahexaenoic acid (DHA) in Schizochytrium sp. which can provide additional nutrients. The feeding strategy in fed‐batch fermentation is one of the important aspects that could help in improving the DHA yield. An enhanced scatter search (eSS) method and the control vector parametrization (CVP) approach were applied to generate the optimal feeding trajectory numerically. Three objective functions were considered, namely, maximizing the DHA concentration, minimizing the final time, and maximizing the economic function. The shortest time and maximum DHA could be determined simultaneously from the optimal feeding trajectory in maximizing the economic function. [ABSTRACT FROM AUTHOR]

The catalytic esterification of ‐butyl propionate in a semi‐batch reactor is examined using dynamic, nonlinear programming‐based optimization. To solve the conflicting bi‐objective of minimizing the final time tf and maximizing the conversion Xc, the ε‐constraint, weighted sum, and NSGA‐II (non‐dominated sorting genetic algorithm II) techniques were implemented. By computing performance measurements like hypervolume, pure diversity, and spacing, these multi‐objective optimization techniques were compared to the characteristics of the Pareto solution. Each Pareto solution point comprises a unique combination of optimal feed flow rate and temperature trajectories. These solutions provide various options for evaluating trade‐offs while establishing the best operating strategy. [ABSTRACT FROM AUTHOR]

Multi‐objective optimization of dimethyl oxalate (DMO) hydrogenation to produce ethylene glycol (EG) is performed for three problems with four different objectives: maximization of DMO conversion and minimization of energy cost for problem 1; maximization of productivity and minimization of energy cost for problem 2; maximization of productivity and minimization of side product for problem 3; minimization of bare module and energy cost for problem 4; maximization of productivity and minimization of bare module for problem 5, and maximization of productivity and minimization of bare module and energy cost for problem 6. Multi‐objective differential evolution with ranking‐based mutation operator is applied to tackle the optimization problem with ASPEN simulator as model‐based optimization for EG production. The plots of decision variables denote that the optimal solution is strongly dependent on temperature. [ABSTRACT FROM AUTHOR]

In this study, microbial cellulose production by Acetobacter xylinum 0416 using standardized liquid pineapple waste was carried out in a 4-L rotary disc reactor (RDR). The objective of this study was to optimize the process parameters for production of microbial cellulose in the RDR. The effects of the disc rotation speed (5 to 12 rpm), pH (3.5 to 7.5), fermentation period (3 to 6 days), and inoculum concentration (3 to 20% v/v) on the microbial cellulose production were investigated. The optimum microbial cellulose yield was obtained using 10% (v/v) of inoculum concentration, whereby four days' duration gave the most productive yield. In addition, the highest production of microbial cellulose was obtained at a low disc rotation speed of 7 rpm and a pH of 5.0. Analysis of data performed a high coefficient of determination value (R²=0.875) represented by a mathematical model of optimized microbial cellulose production, Y = -200.437 + 7.180X1 + 69.869X2 + 4.369X3 + 1.867X4 - 0.512X1² - 6.766X2² - 0.585X3² - 0.079X4². From the results, it can be concluded that the foremost factors that affect the production of microbial cellulose in RDR were pH followed by inoculum concentration, disc rotation speed (rpm), and fermentation period. [ABSTRACT FROM AUTHOR]

The sustainability of petroleum-based fuel supply has gained broad attention from the global community due to the increase of usage in various sectors, depletion of petroleum resources, and uncertain around crude oil market prices. Additionally, environmental problems have also arisen from the increasing emissions of harmful pollutants and greenhouse gases. Therefore, the use of clean energy sources including biodiesel is crucial. Biodiesel is mainly produced from unlimited natural resources through a transesterification process. It presents various advantages over petro-diesel; for instance, it is non-toxic, biodegradable, and contains less air pollutant per net energy produced with low sulphur and aromatic content, apart from being safe. Considering the importance of this topic, this paper focuses on the use of palm oil, its by-products, and mill effluent for biodiesel production. Palm oil is known as an excellent raw material because biodiesel has similar properties to the regular petro-diesel. Due to the debate on the usage of palm oil as food versus fuel, extensive studies have been conducted to utilise its by-products and mill effluent as raw materials. This paper also discusses the properties of biodiesel, the difference between palm-biodiesel and other biodiesel sources, and the feasibility of using palm oil as a primary source for future alternative and sustainable energy sources. [ABSTRACT FROM AUTHOR]

Transmission of pathogenic microorganisms on textile in the hospital settings may contribute to nosocomial infection. This study was aimed to develop a natural antimicrobial finishing on textile that can prevent transmission of pathogenic microorganisms that meets American Association of Textiles Chemists and Colorists (AATCC) standard. Punica granatum L ethanolic extract was shown to have broad spectrum antimicrobial efficacy with bis(6-methylheptyl)-benzene-1,2-dicarboxylate and ethyl-pentadecanoate as the main bioactive constituents. Textile samples developed with the extract finishing exhibited excellent antimicrobial efficacy with a growth reduction of 99.9% on Hoheinstein Challenge Test. The wash durability of the finished textile was found good even after 30 washes with commercial detergent. [ABSTRACT FROM AUTHOR]

Natural pigments produced as metabolites of the microorganisms are a crucial alternative to potentially harmful synthetic dyes. Unlike the traditional pigments extracted from plants and animal skin, microbial pigments are more prevalent for its availability, low-cost extraction and effectiveness. Penicillium minioluteum ED24 is an endophytic fungi previously isolated from Orthosiphon stamineus Benth and was found to produce a red pigment, monascorubin. In the present study, we investigated the feasibility of monascorubin production in P. minioluteum ED24 via solid-state fermentation (SSF). Using brown rice powder with the optimized process parameters, including 60% initial moisture content, 10%v/w K2HPO4 and 10%v/w trace ion solution, a pigment yield of 4.89 mg/g of dry fermented substrate was obtained. Pigment yield using 1% of soluble starch and mycological peptone as additional carbon and nitrogen, respectively, significantly exceeded those of other carbon and nitrogen sources. Our result indicates the viability of brown rice in combination with P. minioluteum ED24 for industrial application through solid-state fermentation. [ABSTRACT FROM AUTHOR]