Universiti Teknologi Malaysia

About: Universiti Teknologi Malaysia is a education organization based out in Johor Bahru, Malaysia. It is known for research contribution in the topics: Membrane & Adsorption. The organization has 21644 authors who have published 39500 publications receiving 520635 citations.

Measurement of streaming potential coupling coefficient in sandstones saturated with natural and artificial brines at high salinity

Abstract: We report experimental measurements of the streaming potential coupling coefficient in sandstones saturated with NaCl-dominated artificial and natural brines up to 5.5 M (321.4 g L−1 of NaCl; electrical conductivity of 23 S m−1). We find that the magnitude of the coupling coefficient decreases with increasing brine salinity, as observed in previous experimental studies and predicted by models of the electrical double layer. However, the magnitude of the coupling coefficient remains greater than zero up to the saturated brine salinity. The magnitude of the zeta potential we interpret from our measurements also decreases with increasing brine salinity in the low-salinity domain ( 0.4 M). We hypothesize that the constant value of zeta potential observed at high salinity reflects the maximum packing of counterions in the diffuse part of the electrical double layer. Our hypothesis predicts that the zeta potential becomes independent of brine salinity when the diffuse layer thickness is similar to the diameter of the hydrated counterion. This prediction is confirmed by our experimental data and also by published measurements on alumina in KCl brine. At high salinity (>0.4 M), values of the streaming potential coupling coefficient and the corresponding zeta potential are the same within experimental error regardless of sample mineralogy and texture and the composition of the brine.

Microwave-assisted pyrolysis of oil palm shell biomass

Abstract: A new technique was developed for microwave pyrolysis in which inert nitrogen gas was supplied from the top of the reactor. It is established that by the use of this technique, the problem of bio-oil deposition onto the reactor walls was solved. The pyrolysis of oil palm shell (OPS) was conducted in a microwave oven using an activated carbon as microwave absorber. The temperature profiles, product yield, as well as the properties of the pyrolysis products were found to be effected by the amount of microwave absorber and the stirrer speed, which this fact can be used to control the product quality. It was found that increasing the amount of microwave absorber as well as the stirrer speed reduced the yield of bio-oil. An increase in microwave absorber percentage has the effect of increasing the amount of phenol present in the bio-oil with maximum of 84.76 area % phenol obtained at 75% microwave absorber at 100 rpm stirrer speed. The maximum bio-oil yield of 28 wt. % was obtained at 25% microwave absorber at 50 rpm stirrer speed. The maximum calorific value of the bio-char was found to be 29.5 MJ/kg obtained at 50% microwave absorber at 100 rpm stirrer speed. High calorific value of the biochar could be utilised as solid fuel in many heating applications. Furthermore, the GC-MS characterisation of the bio-oil shows that the constituents are mostly phenol and its derivatives which are valuable chemicals having a wide range of applications and the potential to be an alternative to their petroleum-derived counterparts.