Nor Asrina Sairi

A review of ionic liquids as catalysts for transesterification reactions of biodiesel and glycerol carbonate production

ABSTRACT Biodiesel production has been rapidly increasing due to the strong governmental policies and incentives provided leading to an oversupply of its by-product, glycerol. Therefore, finding ways of utilizing glycerol is essential to increase the net energy and sustainability of biodiesel. Ionic liquids have been used successfully as catalyst for both the production of biodiesel and the conversion of glycerol to glycerol carbonate. These catalysts are relatively environmentally friendly as they have the potential to enable sustainable processes. Herein, the prospect of using ionic liquids to catalyze transesterification triglycerides for the production of biodiesel and the conversion of glycerol to glycerol carbonate will be discussed. Elucidation of the reaction mechanism is expected to provide an in-depth understanding of the process with respect to the effects of cation and anion based on the reactions of interest.

Synthesis and characterization of protic ionic liquids as thermoelectrochemical materials

This unique work reports on the thermoelectrochemical potential of protic ionic liquid (PIL)-based electrolytes coupled with the I−/I3− redox couple. Two series of protic ionic liquids based on secondary and/or tertiary ammonium cations with the trifluoroacetate, methanesulfonate, trifluoromethanesulfonate and tosylate anions were synthesized for thermoelectrochemical cells. The complete study on PILs was carried out to determine the nature and efficiency for the generation of voltage through the electrochemical effect. The investigation was executed in a temperature range between room temperature and 90 °C. PILs show lower thermal conductivity and good ionic conductivity which leads to the success of good thermoelectric materials. The outcome was positive as our proposed PILs showed higher Se values of 420 μV K−1 obtained for TEHA TFMS than the reported values of the same I−/I3− redox couple. The most favorable thermoelectric figure of merit value (949.46 × 10−6) was achieved by BEHA TFMS. The power and the current output of the studied PILs are higher than those of some aprotic ionic liquids (AILs) reported.

Structure-electronics relations of discotic liquid crystals from a molecular modelling perspective

ABSTRACT Discotic liquid crystals (DLCs) have been researched for their potential in electronics applications, such as organic field-effect transistors, organic light-emitting diodes and organic photovoltaics. These molecules generally comprise a rigid planar core surrounded by aliphatic chains, and self-organise into columnar phases. Charge transfer is enabled along these columns, as the spatial overlap of the stacked π orbitals within the columns lead to a quasi-one-dimensional conductivity. An understanding of charge transfer and electronics orbitals in the field of DLCs is valuable for rational design of future DLC molecules in electronics applications. This paper provides a perspective that a range of molecular modelling tools may bring into our understanding on the structure, dynamics and electronics properties of DLCs. Whilst the description of charge transfer of DLCs has been substantially investigated, the understanding on the molecular orbitals had been relatively less explored. We introduce a multiscale molecular mechanics and quantum mechanics approach to understanding the relationship between the bandgap and density of states (DOS) and the structural parameters of a DLC. This investigation is expected to be the starting point for situations where knowledge of DOS for DLCs are of the essence, in applications such as current rectification and thermoelectricity. GRAPHICAL ABSTRACT

Enhance protection of electronic appliances through multivariate modelling and optimization of ceramic core materials in varistor devices

E-waste comprises discarded low quality protected electronic appliances that annually accumulate million tons of hazardous materials in the environment. Protection is provided to control unwanted voltages that usually generate in associated electrical circuits by a multi-junction ceramic in a voltage dependent varistor. The ceramics microstructure consists of ZnO grains that are surrounded by the narrow boundaries of melted specific additives such as Bi2O3, TiO2 and Sb2O3. In fact, the boundaries manage the quality of protection through a certain volume of intrinsic oxygen vacancies transformation which depends on the amounts of the additives. Since these amounts are the ceramic fabrications initial input variables, the optimization process is capable of improving the quality of the protection (non-linear coefficient) as an output of the varistor devices. In this work, the fabrication was designed and then experimentally performed to calculate the non-linear coefficients of the produced varistors as actual responses. The responses were used to obtain an appropriate model for the fabrication by different semi-empirical methods. Afterward, the models predicted the optimized amounts of the additives which maximized the quality of the varistors. The predicted condition was fabricated as final varistors that were electrically characterized to compare their nonlinear coefficients as the quality indicator. The comparison demonstrated that the optimized amounts of Bi2O3 (0.5), TiO2 (0.47) and Sb2O3 (0.21) in mol% provided the very high protective varistor with nonlinear coefficients of 28.1. In conclusion, the optimization, which has industrial scale-up potential, warranties the electronic protection that controls global e-waste.

Microstructures, interactions and dynamics properties studies of N-methyldiethanolamine + guanidinium triflate ionic liquid + water tertiary system at the standard temperature

Abstract Molecular dynamics simulations with an all-atom force field have been carried out in order to understand the phase equilibrium behaviour of ternary aqueous mixtures containing guanidinium triflate ionic liquid [gua][OTf] and water mixed with N-methyldiethanolamine (MDEA) in different function composition at the standard temperature of 298.15 K. A very good numerical agreement has been obtained for the prediction of the mixture densities. The analysis of structural and dynamic properties showed that the molecular level of ternary mixtures is slightly affected by the presence of MDEA and [gua][OTf] molar fractions. For MDEA–water interactions in [gua][OTf] media, we found that MDEA prefers to be surrounded by water molecules rather than by MDEA molecules even at a high MDEA molar fraction. While for [gua][OTf]–water interaction in MDEA media, as [gua][OTf] molar fraction increases, water molecules replace counterions in the coordination shell of both ions, thus weakening their interaction. On the other hand, for MDEA–[gua][OTf] interactions in water media, we have found that as the molar fraction of [gua][OTf] increases, a sulfonate group from anion appears to have a stronger association by making hydrogen bonding with MDEA molecules. The chemical process using ionic liquids (ILs) as solvents is commonly limited by their high viscosity. Based on their physical properties such as viscosities, these ternary solvents can be applied in natural gas industry, such as removing carbon dioxide using aqueous MDEA and IL at high pressure.

A new achievement in green degradation of aqueous organic pollutants under visible-light irradiation

The global attention has been focused on degradation of the environmental organic pollutants through green methods such as advanced oxidation processes (AOPs) under sunlight. However, AOPs have not yet been efficient in function of the photocatalyst that has been used. In this work, firstly, CaCu3Ti4O12 nanocomposite was simultaneously synthesized and decorated in different amounts of graphene oxide to enhance photodegradation of the organics. The result of the photocatalyst characterization showed that the sample with 8% graphene presented optimum photo-electrical properties such as low band gap energy and a great surface area. Secondly, the photocatalyst was applied for photodegradation of an organic model in a batch photoreactor. Thirdly, to scale up the process and optimize the efficiency, the photodegradation was modeled by multivariate semi-empirical methods. As the optimized condition showed, 45 mg/L of the methyl-orange has been removed at pH 5.8 by 0.96 g/L of the photocatalyst during 288 min of the light irradiation. Moreover, the photodegradation has been scaled up for industrial applications by determining the importance of the input effective variables according to the following organics order > photocatalyst > pH > irradiation time.

Density and molar volumes of imidazolium-based ionic liquid mixtures and prediction by the Jouyban-Acree model

The density of imidazolium-based ionic liquid, 1-ethyl-3-methylimidazolium diethylphosphate with sulfolane were measured at atmospheric pressure. The experiments were performed at T= (293 – 343) K over the complete mole fractions. Physical and thermodynamic properties such as molar volumes, V0, and excess molar volumes, VE for this binary mixtures were derived from the experimental density data. The Jouyban-Acree model was exploited to correlate the physicochemical properties (PCPs) of binary mixtures at various mole fractions and temperatures.

Modeling of photodegradation process to remove the higher concentration of environmental pollution

Environmental organic pollutants are mineralized to harmless final-products such H2O and CO2 by photocatalytic advanced oxidation processes (AOPs). In photocatalytic-AOPs, an appropriate concentration of p-Cresol was mixed with certain amount of ZnO in 500 mL deionized water according to an experimental-design. Then the mixture was irradiated by UV-A lamp at different pH for 6 h. At specific time intervals, the sampling was carried out to calculate the efficiency of the photodegradation. Therefore, the photodegradation as a system consists of four input variables such irradiation time, pH, amount of ZnO and p-Cresol’s concentration while the only output was the efficiency. In this work, the system was modeled and optimized by semi-empirical response surface methodology. To obtain the empirical responses, the design was performed in laboratory. Then observed responses were fitted with several well-known models by regression process to suggest a provisional model. The suggested model which was validated by several statistical evidence, predicted the desirable condition with higher efficiency. The predicted condition consisted of irradiation time (280 min), pH (7.9), photocatalyst (1.5 g L−1), p-Cresol (95 mg L−1) and efficiency (95%) which confirmed by further experiments. The closed confirmation results has presented the removal (efficiency = 94.7%) of higher p-Cresol concentration (95 mg L−1) at shorter irradiation time in comparison with the normal photodegradation efficiency (97%) which included irradiation time (300 min), pH (7.5), photocatalyst amount (1.5 g L−1) and p-Cresol (75 mg L−1). As a conclusion, the modeling which is able to industrial scale up succeeded to remove higher concentration of environmental organic pollutants with ignorable reduction of efficiency.