The study mainly focuses on the synthesis and characterization of amine-functionalized graphene oxide (GO-NH 2 ) nanoparticles. It also reports the thermal properties and stability analysis of deep eutectic solvent (DES)-and GO-NH 2 -based nanofluids. DES is composed of diphenyl ether as the hydrogen bond acceptor and DL-menthol as the hydrogen bond donor in the molar ratio 1:1. The nanofluid was prepared by a two-step method where two different concentrations of functionalized graphene nanofluids, namely, 0.0033 volume fraction (NF1) and 0.0101 volume fraction (NF2), were reported. XRD and FTIR analyses were used to validate the nanoparticle's identity. Additionally, the morphology and composition of GO-NH 2 nanoparticles were investigated using FESEM, FETEM, EDS, and Raman analyses. After that, the stability of the nanofluids was assessed using ζ potential measurements. The ζ potential measurements revealed increased stability, indicating that no agglomeration occurred in the DES-based nanofluid. Excellent thermal conductivity enhancement was observed at a higher temperature for the GO-NH 2 nanofluid. The density and viscosity of the base fluid and nanofluid decreased with an increase in temperature from 25 to 85 °C. Further, the specific heat capacity of the nanofluids also increased with the increase in temperature and volume fractions of the nanofluid. Thermogravimetric analysis was also performed to evaluate the thermal degradation of the nanofluid under a nitrogen atmosphere. The nanofluid was used in brine recirculation multistage flash desalination where the gained output ratio of less than 10 was obtained through ASPEN simulation.

Deep eutectic solvents (DESs) are an experimentally proven and attractive solvent in the field of green chemistry for aromatic extraction from a mixture of aliphatic–aromatic mixtures. The current work reports a multiscale strategy using quantum chemical calculations, thermodynamic models, process simulation, and multiobjective optimization for the simultaneous production of high-purity hexane and aromatic removal using the DES methyl triphenyl phosphonium bromide/ethylene glycol (1:4). Initially the phase equilibrium data have been benchmarked through the continuum solvation-based COSMO-SAC model, which has a root-mean-square deviation of 5.81%. Thereafter, a conceptual multiloop extraction and solvent recovery process has been developed and simulated that incorporates sensitivity analysis to analyze the impact of different process parameters on the system. These parameters, namely, annualized capital cost, benzene content in the hexane product stream, and hexane recovery, have been further formulated as three separate objective functions to be optimized using a nondominated sorting genetic algorithm. After optimization, a series of solutions have been obtained from the Pareto front. The results provide 92% hexane recovery with a benzene concentration of less than 50 ppm. This shall enable the industrial production of high-purity hexane using efficient and sustainable green solvents.