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Saudi Arabia tries to build local desalination water stations to supply water to remote areas. Due to the low cost and energy requirements of reverse osmosis (RO) desalination technology, it has been used to supply fresh water to Arar City in the northeast of Saudi Arabia. In this paper, it is proposed to provide an average of 1000 cubic meters of water per day by using autonomous hybrid renewable energy system (RES). This proposed system contains wind turbines (WTs), photovoltaic (PV), battery, and it is designed to feed the RO system with the energy adequate to produce the required amount of fresh water for the minimum cost and minimum loss of supply probability. The proposed system was designed to generate 2440 kW power to produce this amount of water. Matching study between the site and the best WT among 10 market-available WTs is introduced. Three optimization strategies were used and compared for the design of the proposed system to ensure that no premature convergence can occur. These strategies consisted of two well-known techniques, particle swarm optimization and bat algorithm (BA), and a relatively new technique: social mimic optimization. The simulation results obtained from the proposed system showed the superiority of using a RES for feeding a RO desalination power plant in Arar City, and they also showed that the BA is the fastest and most accurate optimization technique to perform this design problem compared with the other two optimization techniques. This detailed analysis shows that the cost of production of fresh water is $0.745/m3.

Chlorophenols (CPs) are synthetic chemicals that are generated and used widely by different industries such as textile, pharmaceutical, metallurgic, oil, and pulp and paper manufacturing. Except water, most of the solvents used in these industries are volatile and toxic. Therefore, there is an imminent need for replacing these solvents by solvents that have less negative impact on the environment. In addition, CPs are considered as hazardous pollutants due to their resistance to biodegradation and persistence in the environment. Their toxic effects are severe including DNA damage, endocrine disruption, cytotoxicity, mutagenicity, and carcinogenicity. Hence, the water contaminated by CPs must be treated before being released to the environment. Ionic liquids (ILs) are molten salts that are liquid below 100 °C, which have been used as solvents for many processes including liquid-liquid extraction and as electrolytes in electrochemical devices. ILs are characterized by negligible vapor pressure and non-flammability. These compounds are liquid over a wide range of temperatures; possess high thermal and chemical stability. ILs are being used as media for many reactions to reduce the negative impact of traditional solvents on the environment. In addition, using ILs as green solvents in water treatment has become a research hotspot. Solubility data of CPs in ILs is important for assessing the potential use of ILs as reaction media and in water treatment, but relevant data for ILs are scarce. To our best knowledge, no solubility data of chlorophenols in ILs were reported in the literature. Thus, in this study, the solubility of 3-chlorophenol (3-CP), 2,5-dichlorophenol (DCP), 2,4,6-trichlorophenol (TCP), and pentachlorophenol (PCP) in six hydrophobic bis(trifluoromethylsulfonyl)imide based ILs at 25 °C, 35 °C and 45 °C was investigated. It was found that the solubility of 3-CP in all studied ILs at 25 °C was greater than 70 wt%, thus the solubility measurements of 3-chlorophenol in the studied IL were stopped at 70 wt% and further measurement was not conducted. The solubility of other CPs in all studied ILs decreased with increasing the number of chlorine atoms in the CP and increased with the increase in temperature, but the degree of increase depended on the structure of both the IL and chlorinated phenol. In general, it was found that the tested chlorophenols have substantial solubility in pyridinium and imidazolium-based ILs. In addition, the non-random two-liquid model (NRTL) and Conductor-like Screening Model for Real Solvents (COSMO-RS) models were applied to predict the solubility of chlorophenols in all ILs used in this study. There was a good quantitative and qualitative agreement between experimental and calculated solubility data in most of the cases.

Separation of styrene from ethylbenzene is challenging because of their close boiling points and similar chemical characteristics. In this study, we utilized three ammonium-based deep eutectic solvents (DESs) with glycols as hydrogen bond donors to separate styrene from ethylbenzene via liquid-liquid extraction at room temperature and atmospheric pressure, with styrene concentration in the feed mixture ranging from (10 to 80) wt%. Consistency of the experimental data was ascertained by Othmer-Tobias and Hand correlations, and the NRTL binary interaction parameters were also validated for thermodynamic consistency. Distribution ratios of styrene were found to be comparable to that obtained using ionic liquids, although the selectivity values were much lower. The ternary liquid-liquid equilibria for the systems {ethylbenzene (1) + styrene (2) + DES (3)} were correlated with the NRTL model and predicted using the COSMO-RS approach. The average RMSD from the experimental data for NRTL correlation is 1.41% and for COSMO-RS prediction is 4.74%.

The separation of benzene and cyclohexane from their mixture is difficult to perform via conventional distillation because of their close boiling points. In this work, liquid-liquid extraction using ionic liquids (ILs) is suggested for this purpose and 16 cations and 13 anions were selected to form 208 possible ILs screened with the Conductor-like Screening Model for Real Solvents (COSMO-RS) module. The screening result was experimentally validated by liquid–liquid extraction using four of the top ranked ILs, namely 1-ethyl-3-methylimidazolium acetate ([C2mim][Ac]), 1-ethyl-3-methylimidazolium dicyanamide ([C2mim][N(CN)2]), 1-ethyl-3-methylimidazolium thiocyanate ([C2mim][SCN]) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim][Tf2N]). The ternary liquid–liquid equilibria for these ILs with benzene and cyclohexane were investigated at 25 °C and 1 atm with feed concentration of benzene ranging from 10 to 60 wt%. Good agreement was achieved between the tie-lines obtained from the COSMO-RS model and those obtained experimentally. The performance of ILs used in this study was compared with organic solvents, other ILs, and deep eutectic solvents reported in literature. The results of selectivity and distribution ratio confirmed that COSMO-RS was a reliable method for solvent screening and demonstrated the suitability of the selected ILs as extracting solvents. In all ternary systems, no IL was detected in the cyclohexane layer and the concentration of cyclohexane in the IL layer was very low. This observation indicated that there was minimum cross-contamination between the phases and therefore less energy will be required for the solvent recovery.

Separation of azeotropic mixtures is a topic of great industrial interest. In this work, liquid-liquid extraction using deep eutectic solvents (DESs) is explored to separate binary azeotropic mixtures of ethanol and n-hexane, n-heptane or n-octane. Ten DESs were screened using the COSMO-RS approach by predicting the activity coefficient at infinite dilution, γ∞ of ethanol and n-alkanes in each DES. Then, three DESs were selected for experimental validation where Tetrabutylammonium bromide/Levulinic acid (TBAB/LA) with a molar ratio (1:2) gave the best extractive performance for all systems. Ternary liquid-liquid extraction experiments were conducted at room temperature with this DES. It was found that the tie-lines of all systems have positive slopes, indicating that a small amount of solvent is required to extract ethanol. Moreover, the distribution ratio and selectivity values are all greater than unity and the DES was not detected in the raffinate phase which indicate minimal cross-contamination between extract and raffinate phases. Finally, COSMO-RS predictions of the ternary tie-lines were in excellent agreement with experimental data, with an average RMSD value of 1.65%. The experimental data were also successfully correlated with NRTL model with an average RMSD value of 1.50%.

The separation of benzene and cyclohexane is considered one of the most challenging processes in the petrochemical industry. For this study, 40 deep eutectic solvents (DESs) were screened by using the COSMO-RS model. The screening was achieved based on a comparison of selectivity, capacity, and the performance index, all derived from the activity coefficient at infinite dilution. In addition, the sigma σ-profile and σ-potential of each component were used to analyse the interactions between the different species during the extraction process. After screening, five DESs were selected for experimental validation. The liquid–liquid extraction process was conducted, and the ternary diagrams were plotted for the selected DESs at 25 °C under atmospheric pressure. The NRTL model was successfully employed to correlate the experimental tie lines. The results revealed that COSMO-RS was a useful tool for screening potential DESs qualitatively. In addition, observations revealed strong agreement between NRTL and the experiment results, with a root mean square deviation of less than unity for all systems. The findings showed that the selected DESs are feasible for use as extracting solvents for this separation, whereby in all systems no trace of DES was found in the cyclohexane layer.

This work investigates the use of deep eutectic solvents (DESs) to extract sulfur-based compounds from n-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

Selected types of deep eutectic solvents (DESs) were compared for designing CO 2 capturing process. Specifically, the typical absorption–desorption process is examined. A mathematical model based on Peng–Robinson equation of state was developed to estimate the CO 2 solubility and to determine the VLE conditions in the desorption unit. The comparison of the DES performance is based on the solvent requirement in the absorption unit and the temperature condition in the desorption unit. Ethanol amine based DES has shown the best performance when operating the absorber at 10 bar and the stripper at 1 bar. However, the simulation results indicate that in order to reduce the energy requirements in the regeneration process a large amount of solvent is needed. In fact, for 80% CO 2 recovery the solvent intake rate should be at least 5 times the flue gas flow rate. Finally, we have shown that (i) the desorption energy required with MEA based DESs is much lower compared to the classical MEA process and that (ii) the energy required for compression remains the most important drawback for a such process, especially at low CO 2 concentrations.

We investigated the potential use of choline chloride/urea and choline chloride/glycerol deep eutectic solvents (DESs) and their individual constituents (the salt and the hydrogen bond donor) as surfactants for enhanced oil recovery. The interfacial tension (IFT) between Saudi medium crude oil and different concentrations of these DESs (and their individual components) in 10 wt% NaCl aqueous solutions were measured as a function of temperature. Results showed that the IFT values decreased with the increase of both the DES concentration and temperature. The effect of adding the salt and the hydrogen bond donor (HBD) separately, without forming the corresponding DES, on IFT values was also explored. It was found that, in most cases, adding the DES or its corresponding constituents separately has the same effect on the IFT. Furthermore, 1 H NMR and different 2D NMR analysis (NOESY and HOESY) were used to examine the nature of molecular interactions that occur in studied DESs and how water affects these interactions. It was found that while the content of water is below 25 wt% the interactions of DES’ components become weak. However, the addition of 50 wt% water breaks the hydrogen bonding so that no interactions between the HBD and the salt were observed.

Separation of aromatics from aliphatics is a challenging process because of the close range of their boiling points and the formation of several combinations of azeotropes. Until now, no feasible separation process is available for aromatic concentrations below 20 wt%. In this work, we have investigated the possibility of using a selected deep eutectic solvent (DES) for the liquid–liquid extraction of benzene, toluene, ethylbenzene and m-xylene (BTEX) aromatics. The DES used in this work was synthesized by combining tetrabutylammonium salt and sulfolane. Equilibrium data for the ternary system consisting of BTEX aromatics, n-octane and DES were measured at 25 °C and atmospheric pressure. The results showed that the used DESs have comparable distribution ratios and selectivities to those of commercial solvents. In all tested systems, sulfolane was not present in the hydrocarbon layer. It was also found that the selectivity decreases with decreasing polarity of the aromatic compound. The Non-Random Two Liquid (NRTL) model was successfully used to correlate the experimental tie-lines and to calculate the phase compositions of the ternary systems. In addition, the performance of COSMO-RS to predict the ternary tie-lines for the studied systems was evaluated and the σ-profiles were used to explain the interaction between the DES and the aromatic compounds.