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

Evaluation of Molecular Interaction in Binary Mixture of Ionic Liquids + Heterocyclic Nitrogen Compounds: Ab Initio Method and COSMO-RS Model

Ab initio method was applied to investigate the interaction between six heterocyclic nitrogen compounds with 18 ionic liquids. Important quantum chemical descriptors like orbital energy values, orbital energy gap, and global scalar properties including hardness, softness, electronegativity, and electrophilicity index were calculated for each individual species, ionic liquid complexes, and complexes of ionic liquid with heterocyclic nitrogen compounds. The effect of interaction energy and partial charge transfer were also investigated for the ion pair and their complexes. COSMO-RS model is used for qualitative screening of the ionic liquids via σ-profile and σ-potential. Comparison between experimental and COSMO-RS predicted ternary tie-lines were done to validate computational method; good agreement was achieved with average RMSD less than 5%. From the results, ILs based on aromatic ring cations combined with either [EtSO₄] or [Ac] anion are recommended as solvent for extractive denitrification of liquid fuels, with [EPY]­[EtSO₄] being the most favorable IL for removal of heterocyclic nitrogen compounds from liquid fuels at 298.15 K

Performance of p-Toluenesulfonic Acid–Based Deep Eutectic Solvent in Denitrogenation: Computational Screening and Experimental Validation

Deep eutectic solvents (DESs) are green solvents developed as an alternative to conventional organic solvents and ionic liquids to extract nitrogen compounds from fuel oil. DESs based on p-toluenesulfonic acid (PTSA) are a new solvent class still under investigation for extraction/separation. This study investigated a new DES formed from a combination of tetrabutylphosphonium bromide (TBPBr) and PTSA at a 1:1 molar ratio. Two sets of ternary liquid&ndash;liquid equilibrium experiments were performed with different feed concentrations of nitrogen compounds ranging up to 20 mol% in gasoline and diesel model fuel oils. More than 99% of quinoline was extracted from heptane and pentadecane using the DES, leaving the minutest amount of the contaminant. Selectivity was up to 11,000 for the heptane system and up to 24,000 for the pentadecane system at room temperature. The raffinate phase&rsquo;s proton nuclear magnetic resonance (1H-NMR) spectroscopy and GC analysis identified a significantly small amount of quinoline. The selectivity toward quinoline was significantly high at low solute concentrations. The root-mean-square deviation between experimental data and the non-random two-liquid (NRTL) model was 1.12% and 0.31% with heptane and pentadecane, respectively. The results showed that the TBPBr/PTSADES is considerably efficient in eliminating nitrogen compounds from fuel oil

Evaluating the Performance of Deep Eutectic Solvents for Use in Extractive Denitrification of Liquid Fuels by the Conductor-like Screening Model for Real Solvents

A total of 94 deep eutectic solvents (DESs) based on different combinations of salt cation, anion, hydrogen-bond donor (HBD) and salt:HBD molar ratio are screened via the conductor-like screening model for real solvents for potential use in the extractive denitrification of diesel. Five nonbasic and six basic nitrogen compounds were included in this study. The activity coefficient at infinite dilution, γ^∞, of each nitrogen compound in the DESs was predicted; and the values are used to screen the DESs on the basis of selectivity, capacity, and performance index at infinite dilution (<i>S</i>^<i>∞</i>, <i>C</i>^<i>∞</i>, and PI). The extraction of nitrogen compounds using DES is driven by hydrogen-bonding interaction. It was found that nonbasic compounds report higher <i>S</i>^<i>∞</i> and <i>C</i>^<i>∞</i> than basic compounds. Ammonium-based DESs give higher <i>S</i>^<i>∞</i> but phosphonium-based DESs report higher <i>C</i>^<i>∞</i>. DESs combined with Cl^– anion give higher <i>S</i>^<i>∞</i>, but those with Br^– anion report higher <i>C</i>^<i>∞</i>. DESs with alcohol- and amide-based HBDs give higher <i>S</i>^<i>∞</i> but HBDs with carboxylic acid group report high <i>C</i>^<i>∞</i>. Molar ratio has little effect toward <i>S</i>^<i>∞</i> and <i>C</i>^<i>∞</i>. DESs with high values of <i>S</i>^<i>∞</i> generally have high PI

Liquid–Liquid Equilibria for Binary Azeotrope Mixtures of Benzene and Alcohols Using Choline Chloride-Based Deep Eutectic Solvents

In this study, the COSMO-RS approach was used to qualitatively and quantitatively screen five choline chloride-based deep eutectic solvents (DESs) to separate the azeotropic binary formed between benzene and either methanol or ethanol. The activity coefficient at infinite dilution was calculated to evaluate the capacity, selectivity, and performance index of each DES. The interactions between the different species were also analyzed by interpreting the σ-profile and σ-potential of each component. Then, three DESs were selected for experimental validation. They were prepared by combining choline chloride with ethylene glycol, levulinic acid, and 1,2-propanediol. The best performance in terms of distribution ratio and selectivity was achieved with choline chloride/ethylene glycol DES with 1:4 molar ratio. The experimental tie-lines were successfully correlated using the NRTL model. Regardless of the system investigated, no DES was found in the raffinate phase, implying minimal cross-contamination. Finally, 2D NMR analysis was conducted to study the extraction mechanism of alcohol and its effect on the DES structure. This analysis revealed that, when the alcohol concentration exceeds 40 mol %, the DES’ hydrogen bonds are broken such that only one phase occurs and thus the separation becomes impractical

Extraction of Phenolic Compound from Model Pyrolysis Oil Using Deep Eutectic Solvents: Computational Screening and Experimental Validation

Green Deep Eutectic Solvents (DESs) are considered here as an alternative to conventional organic solvents and ionic liquids (IL) for the extraction of phenolic compounds from pyrolysis oil. Although ionic liquids have shown a promising future in extraction processes, DESs possess not only most of their remarkable physico-chemical properties, but are also cheaper, easier to prepare and non-toxic, increasing the infatuation with these new moieties to the detriment of ionic liquids. In this work, phenol was selected as a representative of phenolic compounds, and toluene and heptane were used to model the pyrolysis oil. COSMO-RS was used to investigate the interaction between the considered Dess, phenol, n-heptane, and toluene. Two DESs (one ammonium and one phosphonium based) were subsequently used for experimental liquid&ndash;liquid extraction. A ternary liquid&ndash;liquid equilibrium (LLE) experiment was conducted with different feed concentrations of phenol ranging from 5 to 25 wt% in model oil at 25 &deg;C and at atmospheric pressure. Although both DESs were able to extract phenol from model pyrolysis oil with high distribution ratios, the results showed that ammonium-based DES was more efficient than the phosphonium-based one. The composition of phenol in the raffinate and extract phases was determined using gas chromatography. A similar trend was observed by the COSMO-RS screening for the two DESs

Extraction of Phenolic Compound from Model Pyrolysis Oil Using Deep Eutectic Solvents: Computational Screening and Experimental Validation

Green Deep Eutectic Solvents (DESs) are considered here as an alternative to conventional organic solvents and ionic liquids (IL) for the extraction of phenolic compounds from pyrolysis oil. Although ionic liquids have shown a promising future in extraction processes, DESs possess not only most of their remarkable physico-chemical properties, but are also cheaper, easier to prepare and non-toxic, increasing the infatuation with these new moieties to the detriment of ionic liquids. In this work, phenol was selected as a representative of phenolic compounds, and toluene and heptane were used to model the pyrolysis oil. COSMO-RS was used to investigate the interaction between the considered Dess, phenol, n-heptane, and toluene. Two DESs (one ammonium and one phosphonium based) were subsequently used for experimental liquid–liquid extraction. A ternary liquid–liquid equilibrium (LLE) experiment was conducted with different feed concentrations of phenol ranging from 5 to 25 wt% in model oil at 25 °C and at atmospheric pressure. Although both DESs were able to extract phenol from model pyrolysis oil with high distribution ratios, the results showed that ammonium-based DES was more efficient than the phosphonium-based one. The composition of phenol in the raffinate and extract phases was determined using gas chromatography. A similar trend was observed by the COSMO-RS screening for the two DESs

Natural Eutectic Solvents and Graphene Integrated within Emulsion Liquid Membrane System for Sodium Removal from Crude Biodiesel

This study reports a new technique for sodium ion removal from biodiesel using a green emulsion liquid membrane (GELM) system based on natural deep eutectic solvents (NADESs) and graphene. The DES consists of choline chloride with glycerol and lactic acid, and tetramethylammonium chloride with glycerol and lactic acid. COSMO-RS software was used to compute the intermolecular interaction of sodium with hydrogen bond acceptors and donors of the NADES. The simulation shows that NADES was the most effective stripping phase for sodium ion removal, which follows the experimental results. The investigation on the stability of ELM and sodium (830 ppm of initially) extraction efficiency showed that the GELM-NADES technique can achieves a sodium ion extraction efficiency of 99.6 % (3.17 ppm) with high stability at a homogenization speed of 8000 rpm, homogenization time of 3 min, HBA: HBD molar ratio of 1:4, 3 wt% of span 80, 10 minutes of extraction time, 400 rpm stirring speed and 0.5 treatment ratio. The presence of graphene (0.3 g) in the system further enhanced the efficiency and shortened the required extraction time from 6 to 4 min to meet the ASTM D6752 standards. The transport mechanism of sodium ions into the ELM phases adheres to the first-order kinetics model and film theory mechanisms. The overall mass transfer coefficient K O , mass transfer coefficient of the external phase in agitated reactor K M , and interfacial reaction rate constant KF of 5.188 × 10−9, 1.373 × 10−7, and 5.392 × 10−9 m/s, respectively. ELM system with NADES and graphene can provide a cleaner route for biodiesel downstream processing

Palm raceme as a promising biomass precursor for activated carbon to promote lipase activity with the aid of eutectic solvents

This study concerns the role of activated carbon (AC) from palm raceme as a support material for the enhancement of lipase-catalyzed reactions in an aqueous solution, with deep eutectic solvent (DES) as a co-solvent. The effects of carbonization temperature, impregnation ratio, and carbonization time on lipase activity were studied. The activities of Amano lipase from Burkholderia cepacia (AML) and lipase from the porcine pancreas (PPL) were used to investigate the optimum conditions for AC preparation. The results showed that AC has more interaction with PPL and effectively provides greater enzymatic activity compared with AML. The optimum treatment conditions of AC samples that yield the highest enzymatic activity were 0.5 (NaOH (g)/palm raceme (g)), 150 min, and a carbonization temperature of 400 °C. DES was prepared from alanine/sodium hydroxide and used with AC for the further enhancement of enzymatic activity. Kinetic studies demonstrated that the activity of PPL was enhanced with the immobilization of AC in a DES medium

Removal of Thiophene from Mixtures with <i>n</i>‑Heptane by Selective Extraction Using Deep Eutectic Solvents

This work investigates the use of deep eutectic solvents (DESs) to extract sulfur-based compounds from <i>n</i>-heptane as model diesel compounds. Four DESs were prepared by combining tetrabutylammonium bromide or methyltriphenylphosphonium bromide with ethylene glycol, triethylene glycol, or sulfolane. All DESs showed good ability to extract thiophene with the best extraction efficiency (35%) being observed for the sulfolane-based DES. The extraction efficiency can be further enhanced to reach 98% when five extraction cycles are performed. Moreover, the DESs were easily regenerated using rotary evaporation. In addition,¹H NMR analysis is used to elucidate the extraction mechanism. Finally, the COSMO-RS model was used to predict the ternary tie lines for the studied systems and the NRTL model allowed, correlating the experimental data with an average root-mean-square deviation of <2% for all DESs. These models can be utilized for further simulation analysis of the extraction process