Bismuth tungstate photocatalyst was synthesized by facile microwave hydrothermal method and the morphology evolution was investigated under wide range of microwave irradiation time. Structural, morphological, compositional and optical properties were analyzed by means of X-ray Diffraction (XRD), Raman Spectroscopy, Scanning Electron Microscopy (SEM), and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS) methods. Photocatalytic activity was performed by the decomposition of Rhodamine B (Rh B) under visible light irradiation. Results revealed that the microwave irradiation time is crucial in order to control the morphology of bismuth tungstate nanoparticles. Different morphologies were obtained under different microwave irradiation time and the best conditions of microwave irradiation time for the best photocatalytic activity under visible light were investigated which proves that the microwave could induce various morphology of bismuth tungstate photocatalyst to exhibit the best photocatalytic activity under visible light.

A mixed metal oxide (CuO-ZnO) additives has been successfully synthesized in laboratory by co-precipitation technique. The optimum ratio of CuO and ZnO in mixed metal oxide was found to be 1:1. The sodium lauryl sulfate (SLS) has been used as surfactant. The obtained material was found to be crystalline having crystalline size of 18 nm. The stretching band in FTIR spectra at around 1072 cm-1 to 750 cm-1 and around 600 cm-1 indicates the presence of Zn-O and Cu-O bonds. As prepared nano-particles have been used as nano additive in base oil to improve physio-chemical parameters of lubricants. The results revealed that the additive blended base oil (lubricant) has shown excellent lubrication properties. The higher kinematic viscosity of 33.0504 and 6.0158 at 40°C and 100°C respectively showed that as prepared additive blended lubricant is of ISO-32 category according to ISO grading system for lubricants. Similarly, viscosity index was found to be improved from 101 to 129. The pour point was found to be significantly decreased from -6°C to -24°C. So it can be used as good pour point depressant and could be used even in the extreme cold environment condition. The flash point was found to be increased from 215°C to 220°C indicating that the prepared mixed metal oxide (CuO-ZnO) acts as flash point enhancer. The copper strip corrosion rating was found to be 1b for additive indicating the non corrosive nature. The absence of moisture and pH around the neutral range 6.18 showed the additive blended lubricant is not harmful for machinery devices.

Copper oxide (CuO) nanoadditives were successfully synthesized in laboratory by precipitation technique. X-ray diffraction spectroscopy (XRD) showed the crystalline nature of CuO with the average crystal size of 10 nm. The prepared CuO has been blended with engine oil. Thus prepared modified engine oil showed good kinematic viscosity 158 cSt and 19.06 cSt at 40 ⁰ C and 100 ⁰ C respectively. The viscosity index was also found to be improved to 122. Similarly, the pour point was also found to be considerably decreased to -27 ⁰ C which is due to presence of CuO that acts as good pour point depressant. The flash point of modified engine oil reached to 225 ⁰ C. In addition, modified engine oil was found to be reluctant towards water and it does not contain noticeable amount of water and found to be noncorrosive in nature having copper strip corrosion rating 1b according to ASTM D-130 method. Results revealed that the physio-chemical parameters of engine oil could be improved by the addition of CuO nanoadditive.

Zinc oxide (ZnO) nano additives were successfully synthesized in laboratory by precipitation technique. The XRD showed crystalline nature of ZnO with the average crystallite size of 16 nm. The stretching band of ZnO was found at around 400 cm-1 to 600 cm-1 wave number in FTIR. The prepared nano particle have been used as nano additive and sodium lauryl sulphate (SLS) as surfactant, in base oil to improve physio-chemical parameter of lubricants. The result revealed that the additive blended base oil (lubricant) has shown excellent lubrication properties. The higher kinematic viscosity of 90.72 and 10.40 were obtained at 40oC and 100o C respectively. Similarly, viscosity index were found to be 96 which was improved indicating the use of lubricant in slightly high temperature is possible. The pour point was found to be decreased to -9.2oC which was quite significant and could be used in cold environment. The flash point was also found to be increased from 225o C to 230oC which indicated that the prepared nano additive ZnO acts as flash point enhancer. The corrosion test done by copper strip comparative method and was found to be 1b for additive indicating the non-corrosive nature. The absence of moisture and pH around the neutral range 6.65 showed that the additive blended lubricant is not harmful for machinery devices.