Experimental studies of kerosene gelled fuel using dibenzylidene sorbitol

Abstract

The present study reports the first findings of gelation of kerosene using low molecular mass organic gelator (LMOG), 1,3:2,4-Dibenzylidene-D-sorbitol (DBS), which has been widely used for many applications such as cosmetics, healthcare products, etc. DBS self-assembles to form nanofibrils gel network in various solvents and polymers via a combination of intra- and intermolecular hydrogen bonding at lower concentrations (&lt

5 wt.%). The predictive framework of DBS gelation were determined through Hansen solubility parameters (HSPs). The HSPs of DBS were empirically determined to be ($\delta_D, \delta_P, \delta_H$)=(17.8, 13.6, 6.4) (in $J^{0.5}cm^{-1.5}$). It was found that the DBS solution fails to form gel with kerosene due to their large difference in the HSP values, and to solve this, a small amount of hexanol was added to kerosene as a cosolvent. In the present study, the self-assembly of DBS investigated in detail by varying hexanol in the range of 20 to 50 wt.% and DMSO in the range of 4 to 10 wt.%. Morphological studies were done by obtaining the micro image in scanning electron microscopy (SEM). The compatibility between gellant and solvent was evaluated using Ro which is the distance between HSP parameters of the gellant and solvent in Hansen 3-D space. We classified the sample based on gelation time in the range of $9 \leq R_o \leq 14$ as follows: instant gel (IG) ($R_o &lt

12.25$), slow gel (SG) ($12.25 \leq R_o \leq 13$), and insoluble region (I) ($R_o &gt

13$). Furthermore, the use of HSP has been developed for predicting the phase transition temperature ($T_f$) of samples. Along with the quantitative method, ramp temperature rheological experiments were done to study the thermoreversible properties of gel samples. Experimental Tf value of HDK series was varied from $149 \pm 3.1^circ C$ for HDK1 to $137 \pm 7.4^circ C$ for HDK4, while Hex series ranged from $140 \pm 3.5^circ C$ (Hex20) to $107 \pm 11.4^circ C$ (Hex50). This range was in good agreement with quantitative prediction in a non-polar and slightly polar compounds. The microstructure analysis shows the presence of 3D nano-fibrillar morphology, which further depends on solvent polarity. The structure changes from a &lsquo

web-like&rsquo

structures to &lsquo

rope-like&rsquo

helical fibre aggregate with solvent polarity. In addition, the calorific value of samples was obtained using bomb calorimetry experiments. The result was found that the reduction of calorific value in the gel fuel samples as compared with pure kerosene value was not as high as the reduction of kerosene concentration ($C_K$). This is mainly because the other compounds in the gel fuel samples are flammable. Finally, droplet combustion experiments which widely used in investigating combustion characteristics were done in HDK series. The phenomena happened in the combustion process is the function of $C_{DMSO}$ which results the shell thickness. It changes from abrupt explosion and puffing in a lower $C_{DMSO}$ sample which has a thicker outer layer to ligament bursting and secondary droplet formation in a higher $C_{DMSO}$ sample which has a thinner outer layer. The shell thickness is also correlated to $T_f$ value which results the differences of combustion behavior of samples.