Mesoporous sorbent composites, evolving from previous work on microporous composites of polyanionic polysaccharides were developed with the purpose of increasing the sorptive features of the materials. Using the widely successful classical surfactant micelle approach, it was observed, in this particular case, that the composites remained essentially microporous. The alternative consisted on the application of deep eutectic solvents (DES). The most common DES (choline chloride + neutral hydrogen bond donor), were tested because of their advantages over other possibilities such as imidazolium-based ionic liquids: lower cost, easy in-house preparation, safe constituents and water stability and solubility. Possible mechanisms underlying the observed mesoporosity were discussed. The surface area ranged between 76 and 267 m 2 /g and the average pore size was in the range 3-5 nm. DES had not a negative effect on synthesis yields and, in the case of fucoidan, composites bearing a higher content of the biopolymer were produced. As a consequence and in line with the initial expectations these new composites revealed highly enhanced Pb (II) sorptive features comparatively to their microporous predecessors: chondroitin sulfate composites-up to a 5 fold capacity enhancement; fucoidan composites-up to a 3.5 fold capacity enhancement. The highest capacity was observed for the fucoidan composite prepared with choline chloride-ethyleneglycol DES, 79 mg Pb (II)/g, which is slightly above the highest value (77 mg Pb (II)/g) found in the literature for Pb (II) sorbents based on polysaccharides, sol-gels or their composites.

For the last few years, molten salt nanomaterials have attracted many scientists for their enhanced specific heat by doping a minute concentration of nanoparticles (up to 1% by weight). Likewise, enhancing the specific heat of liquid media is important in many aspects of engineering such as engine oil, coolant, and lubricant. However, such enhancement in specific heat was only observed for molten salts, yet other engineering fluids such as water, ethylene glycol, and oil have shown a decrease of specific heat with doped nanoparticles. Recent studies have shown that the observed specific heat enhancement resulted from unique nanostructures that were formed by molten salt molecules when interacting with nanoparticles. Thus, such enhancement in specific heat is only possible for molten salts because other fluids may not naturally form such nanostructures. In this study, we hypothesized such nanostructures can be mimicked through in situ formation of fabricated nano-additives, which are putative nanoparticles coated with useful organic materials (e.g., polar-group-ended organic molecules) leading to superstructures, and thus can be directly used for other engineering fluids. We first applied this approach to polyalphaolefin (PAO). A differential scanning calorimeter (DSC), a rheometer, and a customized setup were employed to characterize the heat capacity, viscosity, and thermal conductivity of PAO and PAO with fabricated nano-additives. Results showed 44.5% enhanced heat capacity and 19.8 and 22.98% enhancement for thermal conductivity and viscosity, respectively, by an addition of only 2% of fabricated nanostructures in comparison with pure PAO. Moreover, a partial melting of the polar-group-ended organic molecules was observed in the first thermal cycle and the peak disappeared in the following cycles. This indicates that the in situ formation of fabricated nano-additives spontaneously occurs in the thermal cycle to form nanostructures. Figure of merit analyses have been performed for the PAO superstructure to evaluate its performance for heat storage and transfer media.

Silica nanoparticles and polyethylene-block-poly were doped in sodium acetate trihydrate to in-situ synthesize stelliform nanostructure to enhance the effective specific heat capacity of sodium acetate trihydrate. Sodium dodecyl sulfate and methanol were also used in the synthesis to help the dispersion. A modulated differential scanning calorimeter was employed to characterize the specific heat capacity of pure sodium acetate trihydrate and their nano samples. The measurement was repeated multiple times on different days to confirm the repeatability of the measurement. The result shows the specific heat capacity was enhanced by 11% in comparison with pure sodium acetate trihydrate. The conventional effective specific heat capacity model was compared with the experimental result.

Recent studies have shown that doping nanoparticles (NPs) into a molten salt eutectic can induce salt molecules to form a stelliform nanostructure that can enhance the effective heat capacity of the mixture. This phenomenon can result from a unique characteristic of a eutectic molten salt system, which can self-form a nanostructure on a nanoscale solid surface. Hence, such an enhancement was only observed in a molten salt eutectic. Similarly, a stelliform nanostructure can be artificially synthesized and dispersed in other liquids. Mixing polar-ended molecules with a NP in a medium can induce the polar-ended molecules ionically bonded to a NP to form a stelliform nanostructure. Hence, this may enhance the effective heat capacity of the mixture. In this study, we disperse various NPs and polar-ended materials into a sodium acetate trihydrate (SAT) at different ratios to explore the effect of NP type and concentration as well as polar-ended materials and their concentrations on the resultant heat capacity of SAT. The result shows that the specific heat capacity was the highest with silica NP at 1% concentration of weight and polar-ended material at 4% concentration.