Encapsulated deep eutectic solvent for esterification of free fatty acid

A novel encapsulated deep eutectic solvent (DES) was introduced for biodiesel production via a two-step process. The DES was encapsulated in medical capsules and were used to reduce the free fatty acid (FFA) content of acidic crude palm oil (ACPO) to the minimum acceptable level (< 1%). The DES was synthesized from methyltriphenylphosphonium bromide (MTPB) and p-toluenesulfonic acid (PTSA). The effects pertaining to different operating conditions such as capsule dosage, reaction time, molar ratio, and reaction temperature were optimized. The FFA content of ACPO was reduced from existing 9.61% to less than 1% under optimum operating conditions. This indicated that encapsulated MTPB-DES performed high catalytic activity in FFA esterification reaction and showed considerable activity even after four consecutive recycling runs. The produced biodiesel after acid esterification and alkaline transesterification met the EN14214 international biodiesel standard specifications. To our best knowledge, this is the first study to introduce an acidic catalyst in capsule form. This method presents a new route for the safe storage of new materials to be used for biofuel production. Conductor-like screening model for real solvents (COSMO-RS) representation of the DES using σ-profile and σ-potential graphs indicated that MTPB and PTSA is a compatible combination due to the balanced presence and affinity towards hydrogen bond donor and hydrogen bond acceptor in each constituent

Cyclic voltammetry of metallic acetylacetonate salts in quaternary ammonium and phosphonium based deep eutectic solvents

Seven commercially sourced acetylacetonate salts were investigated in deep eutectic solvents (DESs that were prepared from ethylene glycol and trifluoroacetamide hydrogen bond donors) by cyclic voltammetry, to identify electrolytes suitable for future applications in electrochemical energy storage devices. Although the solubilities are low and on the order of 0.02 mol·L−1 for the most soluble salts, some were found to display encouraging quasi-reversible electrochemical kinetics. For instance, the diffusion coefficients of copper(II) acetylacetonate and iron(III) acetylacetonate in the trifluoroacetamide based DES are 1.14 × 10−8 and 5.12 × 10−9 cm2·s−1, which yields rate constants of 3.16 × 10−3 and 8.43 × 10−6 cm·s−1, respectively. These results are better than those obtained with the DESs prepared from ethylene glycol. The poor kinetics of the iron(III) acetylacetonate system was possibly due to the hygroscopic nature of the DESs that resulted in a continuous build-up of moisture in the system in spite of the maintenance of an inert atmosphere by means of a plastic glove bag. Further work is thus envisaged in an inert dry box that could lead to H-type glass cell charge/discharge experiments in the future