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A benign separation of sulfur-containing compounds (SCC) from fuel oil is crucial to produce ultra-low sulfur fuels for a cleaner environment. To achieve this, extractive desulfurization could be implemented with deep-eutectic solvent (DES) as extractor. 2 DES were synthesized from choline chloride and dihydric alcohols, which were 1, 2-ethanediol and 1, 4-butanediol. It was found that shorther alkyl chain DES has higher density and low viscosity compared to longer alkyl chain DES. Freezing point depression to form melt compound at room temperature was observed for both DES. In optimized conditions, ethanediol produce higher desulfurization efficiency (60.27%), suggesting a new opportunity for DES to be used in alternative desulfurization technology.

Presence of functional group in monomer chain is significantly affect the properties of finished coating. Thus, this study reports the copolymerization and behaviors of PVA and MMA with three different monomers with different functional group namely AAm, AAc and EG. Four type of hydrogel coating were synthesized via semi batch emulsion polymerization namely HAAC, HEG, HAAM and PVA-MMA. The functional groups of all coating were confirmed by FTIR spectra analysis and collapsed microgels with size less than 0.5 µm were observed grafted on the surface of hydrogel using FESEM. HAAM shows the highest water absorbency of up to 81% of its weight. Thermal decomposition showed rapid degradation rate of HEG at the initial curve compared to other coating samples. Nevertheless, due to strong bonding of carbonyl group and the carbon steel, HAAC has the highest adhesion strength of 4.0 MPa. Among HAAM, HAAC and HEG, amide has greatly improved the water absorbency, carboxyl aided the adhesion strength and hydroxyl has led to denser matrices of hydrogel coating.

The biggest challenge faced in oil refineries is the removal of sulfur compounds in fuel oil. The sulfur compounds which are found in fuel oil such as gasoline and diesel, react with oxygen in the atmosphere to produce sulfur oxide (SOx) gases when combusted. These sulfur compounds produced from the reaction with oxygen in the atmosphere may result in various health problems and environmental effects. Hydrodesulfurization (HDS) is the conventional process used to remove sulfur compounds from fuel oil. However, the high operating conditions required for this process and its inefficiency in removing the organosulfur compounds turn to be the major drawbacks of this system. Researchers have also studied several alternatives to remove sulfur from fuel oil. The use of ionic liquids (ILs) has also drawn the interest of researchers to incorporate them in the desulfurization process. The environmental effects resulting from the use of these ILs can be eliminated using eutectic-based ionic liquids (EILs), which are known as greener solvents. In this research, a combination of extractive desulfurization (EDS) and oxidative desulfurization (ODS) using a photocatalyst and EIL was studied. The photocatalyst used is a pre-reported catalyst, Cu-Fe/TiO2 and the EIL were synthesized by mixing choline chloride (ChCl) with organic acids. The acids used for the EILs were propionic acid (PA) and p-toluenesulfonic acid (TSA). The EILs synthesized were characterized using thermogravimetry analyser (TGA) differential scanning calorimetry (DSC) analysis to determine the physical properties of the EILs. Based on the TGA analysis, ChCl (1): PA (3) obtained the highest thermal stability whereas, as for the DSC analysis, all synthesized EILs have a lower melting point than its pure component. Further evaluation on the best EIL for the desulfurization process was carried out in a photo-reactor under UV light in the presence of Cu-Fe/TiO2 photocatalyst and hydrogen peroxide (H2O2). Once the oxidation and extraction process were completed, the oil phase of the mixture was analyzed using high performance liquid chromatography (HPLC) to measure the sulfur removal efficiency. In terms of the desulfurization efficiency, the EIL of ChCl (1): TSA (2) showed a removal efficiency of about 99.07%.

Extractive catalytic oxidative desulfurization (ECODS) is the one of the recent methods used in fuel desulfurization which involved the use of catalyst in the oxidative desulfurization of diesel fuel. This study is aimed to test the effectiveness of synthesized choline chloride (ChCl) based deep eutectic solvent (DES) in fuel desulfurization via ECODS method, with the presence of graphene oxide (GO) as catalyst and hydrogen peroxide (H2O2) as oxidant. In this study, 16 DESs based on choline chloride were synthesized using glycerol (GLY), ethylene glycol (EG), tetraethylene glycol (TEG) and polyethylene glycol (PEG). The characterization of the synthesized DES was carried out via Fourier transform infrared spectroscopy (FTIR) analysis, density, and viscosity determination. According to the screening result, ChCl-PEG (1:4) was found to be the most effective DES for desulfurization using ECODS method, with a removal of up to 47.4% of sulfur containing compounds in model oil in just 10 min per cycle after the optimization of the reaction parameters, and up to 95% desulfurization efficiency could be achieved by six cycles of desulfurization. It is found that the addition of GO as catalyst does not increase the desulfurization performance drastically, hence, future studies for the desulfurization performance of DESs made up from ChCl and PEG and its derivatives can be done simply by using extraction desulfurization (EDS) method instead of ECODS method, for cost reduction purpose and easier regulation of DES waste into environment.

Hydrodesulfurization (HDS) has been commercially employed for the production of ultra-low sulfur fuel oil. However, HDS is unable to remove sterically hindered sulfur-containing compounds such as dibenzothiophene (DBT) and benzothiophene (BT). An alternative way to remove sulfur is via extractive desulfurization system (EDS) using deep eutectic solvents (DES) as sustainable extractant. In this work, liquid polymer DES was synthesized using tetrabutylammonium chloride (TBAC) and poly(ethylene glycol) 400 (PEG) with different molar ratios. Response surface methodology (RSM) was applied to study the effect of independent variables toward extraction efficiency (EE). Three significant operating parameters, temperature (25&ndash, 70 &deg, C), DES molar ratio (1&ndash, 3), and DES volume ratio (0.2&ndash, 2.0), were varied to study the EE of sulfur from model oil. A quadratic model was selected based on the fit summary test, revealing that the extraction efficiency was greatly influenced by the amount of DES used, followed by the extraction temperature and PEG ratio. Although molar ratio of DES was less sensitive towards EDS performance, the EE was much higher at lower PEG ratio. For the realization of an energy-efficient EDS system, optimization of EDS parameters and EE was carried out via a desirability tool. At 25 &deg, C, 1:1 molar ratio of TBAC to PEG, and DES-to-model-oil-volume ratio of 1, removal of DBT reached as high as 79.01%. The present findings could provide valuable insight into the development of practicable EDS technology as a substitute to previous HDS process.

Sulfur containing compounds (SCC) in fuel oil is now becoming a worldwide concern as it released sulfur dioxide, a toxic molecule which give detrimental impact towards human and environment. To encounter this, production of ultra-low sulfur fuel oil that fulfil Euro V standard (

Deep eutectic solvent (DES) is an alternative solvent which has the basic characteristics as conventional ionic liquid. The uniqueness lies on its easy synthesis, less toxic and low-cost production. Three glycol-based DES (ethylene glycol, tetraethylene glycol and poly (ethylene glycol)) with tetrabutylammonium chloride (TBAC) as the hydrogen bond acceptor were successfully prepared. Unusually, all DES was achieved their eutectic mixing as low as 50 °C within 60 min. Thermal analysis study revealed that the most stable DES was the one with higher ethoxy chains. Structure elucidation study via Fourier transformation infrared (FTIR) spectroscopy confirmed the formation of eutectic mixture based on the intermolecular interaction from decreasing hydroxy group stretching frequency. Modifying ethoxy repeating unit in hydrogen bond donor could tailor the design of DES for numerous applications.