Rice husk ash (RHA) has been recently used as a source of silica (SiO2) production due to its high silica content. Besides, high purity silica nano-powder has been successfully synthesized from RHA and employed in various industries including electronic component manufacturing and fillers in polymers. Meanwhile, silica nanoparticles has been widely used in the application of Enhanced Oil Recovery (EOR). This is due to its ability in enhancing the foam stability besides modifying the wettability of the rocks in the formation. However, the synthesis of silica nanoparticles from RHA for the application in big scale operation such as EOR using conventional method is energy and time consuming. Therefore, the objective of this work is to study the effectiveness of using nano-sized rice husk ash (nano-RHA) as an additive to stabilize normal gas generated surfactant foam used in EOR. In order to decrease the size of the RHA into nano range, planetary ball mill was used in both dry grinding and wet grinding. Different surfactants including anionic and non-ionic were then used to study the polydispersity index of the dispersion and the hydrodynamic diameter using dynamic light scattering in dilute suspension. Besides, the nano-RHA was also characterized using FESEM, EDX, XRD and the change in specific area after grinding process was studied using BET. The foamability of different surfactants were then studied using minor concentration of nano-RHA. Next, the concentration of the nano-RHA was varied from 0.1wt% to 0.9wt% in normal gas bulk foam stability test using the suitable surfactant, the texture of foam was observed as well. Apart from that, the effect of oil on bulk foam was also studied. Finally, the result was compared using pure silica nanoparticles as the foam addictive at the same variation of concentrations. Dispersion stability tests showed that both anionic and non-ionic surfactants can be used to disperse nano-RHA in water. Moreover, in the presence of 0.9wt% of nano-RHA concentration, the bulk foam stability test results revealed that the sodium dodecyl sulfate (SDS) bulk foam half-life increased by 17.9% without the presence of oil, and gave an increment of 20.7% half-life in the presence of oil. Therefore, the study showed a potential of utilizing nano-RHA in stabilizing bulk foam.
Simultaneous effects of rice husk silica and silicon carbide whiskers on the mechanical properties and morphology of sodium geopolymer
