SANS studies of liquid crystalline microemulsion gels

We have investigated by small-angle neutron scattering (SANS) the ternary system containing water, alkane and the surfactant mixture benzyltetradecyldimethylammonium chloride and tetradecyltrimethylammonium bromide, which we have found to form a cubic liquid crystalline phase. A contrast variation experiment with equal volume fractions of water and oil showed three Bragg reflections varying in agreement with theoretically calculated scattering amplitudes for an infinite periodic minimal surface (IPMS) with cubic symmetry. We have, in addition, studied the “ringing” gel phases of the system water/octane/didodecyldimethylammonium bromide by SANS and electron microscopy

Pengaruh Konsentrasi Oksidator pada Proses Hidroksilasi Minyak Jarak (Castor Oil) Dengan atau Tanpa Proteksi Gugus Hidroksi

Oil is derived from the bean of castor plant ricinus communis l., belonging to euphorbiaceae family. Oil rendement per gram of castor bean is 45 "“ 48 % with hight pure product and better than standard resulted by The Association of Official Analytical Chemistry (AOAC). The main components in castor oil are oleic, palmitic and resinoleic acid. Protection process by acetylation occurs well on hydroxyl group of castor oil, indicated by increasing of iodine number and decreasing of hydroxyl number. Oxidation process is more efective on protected oil than non protected oil. The excess of oxidator concentration changed the product to be aldehide and carboxylic acid. Optimum condition was reached when oxidator concentration was 15 %, with hydroxyl value of 1280.438 mg/g and iodine number of 33.093 mg/g

Pertumbuhan dan penambahbaikan nanokomposit Ag-ZnO untuk aktiviti fotomangkin

Kami melaporkan hasil kajian terhadap nanokomposit Ag-ZnO dengan nisbah berat yang berbeza bagi Ag:ZnO (0:10, 7:10 & 25:10) yang telah disediakan melalui kaedah sonokimia. Kajian fotomangkin terhadap nanokomposit Ag-ZnO menunjukkan peningkatan kecekapan fotomangkin terhadap foto-penguraian larutan akues metilena biru berbanding nanobahan ZnO tulen di bawah penyinaran cahaya nampak. Sampel Ag-ZnO pada nisbah 7:10 menunjukkan aktiviti fotomangkin terbaik dan mencapai kadar penguraian sehingga 94% bagi tempoh masa penguraian selama 80 min, diikuti 86% bagi sampel ZnO tulen dengan menggunakan kaedah yang sama. Morfologi, struktur bahan, sifat optik dan kehabluran bagi nanokomposit Ag-ZnO juga dibincangkan menerusi data yang diperoleh melalui mikroskop elektron transmisi, spektroskopi ultralembayung-cahaya nampak dan difraktometer analisis sinar-X. Hasil kajian menunjukkan bahawa dengan penambahan zarah Ag kepada ZnO telah meningkatkan kadar serapan cahaya bagi ZnO di kawasan cahaya nampak dan meningkatkan kadar pemisahan cas foto-aruhan bagi menghasilkan rawatan air tercemar pewarna yang lebih baik

Enhanced Photocatalytic Performance of NiO-Decorated ZnO Nanowhiskers for Methylene Blue Degradation

ZnO nanowhiskers were used for photodecomposition of methylene blue in aqueous solution under UV irradiation. The rate of methylene blue degradation increased linearly with time of UV irradiation. 54% of degradation rate was observed when the ZnO nanowhiskers were used as photocatalysts for methylene blue degradation for 80 min under UV irradiation. The decoration of ptype NiO nanoparticles on n-type ZnO nanowhiskers significantly enhanced photocatalytic activity and reached 72% degradation rate of methylene blue by using the same method. NiO-decorated ZnO was recycled for second test and shows 66% degradation from maximal peak of methylene blue within the same period. The increment of photocatalytic activity of NiO-decorated ZnO nanowhiskers was explained by the extension of the electron depletion layer due to the formation of nanoscale p-n junctions between p-type NiO and n-type ZnO. Hence, these products provide new alternative proficient photocatalysts for wastewater treatment

Optical-fiber thermal-wave-cavity technique to study thermal properties of silver/clay nanofluids

Thermal properties enhancement of nanofluids have varied strongly with synthesis technique, particle size and type, concentration and agglomeration with time. This study explores the possibility of changing the thermal wave signal of Ag/clay nanofluids into a thermal diffusivity measurement at well dispersion or aggregation of nanoparticles in the base fluid. Optical-Fiber Thermal-Wave-Cavity (OF-TWC) technique was achieved by using a small amount of nanofluid (only 0.2 mL) between fiber optic tip and the Pyroelectric detector and the cavity-length scan was performed. We established the accuracy and precision of this technique by comparing the thermal diffusivity of distilled water to values reported in the literature. Assuming a linear Pyroelectric signal response, the results show that adding clay reduced the thermal diffusivity of water, while increasing the Ag concentration from 1 to 5 wt.% increased the thermal diffusivity of the Ag nanofluid from 1.524×10−3 to 1.789×10−3 cm2/s. However, in particular, nanoparticles show the tendency to form aggregates over time that correlated with the performance change of thermal properties of nanofluid. Our results confirm the high sensitivity of OF-TWC technique raises the potential to be applied to measuring the optical and thermal properties of nanofluids. Furthermore, this technique allows the extraction of information not obtained using other traditional techniques