Udaya Bhaskar Reddy Ragula

Nano- and micro-hexagons of bismuth on polycrystalline copper: electrodeposition and heavy metal sensing

Hexagon-shaped bismuth nano- and micro-architectures have been electrodeposited onto polycrystalline copper electrodes from a nitrate bath at both constant current and constant potential conditions. Hexagonal geometries of varying sizes are obtained by tuning the deposition rate vis-a-vis that of a competing reaction, nitrate reduction. Nano-hexagons (100 nm to 1 μm) are obtained at 10 mA cm−2 when the HNO3 concentration is 0.2 M or less, and with 0.4 M HNO3, hexagons of sizes up to 20 μm are deposited. The obtained hexagons are polycrystalline. Further increase in nitric acid concentration results in fused sheet-like morphologies. Increasing bismuth concentration or reducing current density results in large crystallites. The ability of the obtained bismuth morphologies to detect ultratrace levels of lead has been studied. Only the nanohexagons and crystallites are able to detect lead at 1 ppb. The nanohexagons show good sensitivity to the detection of lead (LoD: 0.05 ppb or 0.24 nM; sensitivity: ~0.75 μA ppb−1) using Square-Wave Anodic Stripping Voltammetry (SWASV), and clearly distinct peaks for Pb2+, Zn2+, and Cd2+, indicating the potential for this morphology as an electrocatalytic material.

Kinetics and characterization of transesterification of cottonseed oil to biodiesel using calcined clam shells as catalyst

ABSTRACT The synthesis of biodiesel from cottonseed oil using heterogeneous calcined clam shells by transesterification was studied. The effects of the amount of catalyst and the oil-to-methanol ratio on the yield of the biodiesel produced were determined. A maximum yield of 84% biodiesel was obtained. Various characterization tests such as Fourier transform infrared spectroscopy (FT-IR), Gas Chromatography - Mass Spectrometry and Nuclear Magnetic Resonance Spectroscopy were carried out to ascertain the functional groups and compounds available in the product biodiesel obtained. The properties of the biodiesel using the calcined clamshell catalyst, such as density, viscosity, saponification value, iodine value and ester value, were estimated and compared with the American Society for Testing Materials standard values to determine the quality of the biodiesel produced. The yield of the biodiesel produced was modelled using response surface methodology, and contour regions were obtained. The surface morphology of the catalyst was studied using a scanning electron microscope. From the kinetics results obtained, the forward rate constant of the adsorption of methanol onto the catalyst surface was found to be very low (1.467 × 10−4), confirming that the kinetics of biodiesel production is limited by adsorption of methanol onto the active sites of the catalyst.

Solar based lemon grass essential oil distillation for sustainability and livelihood in tribal community

Lemon grass essential oil is used in manufacture of soaps, beauty products, and mosquito repellents. Nearly, 40% of world lemon grass oil is produced in India and Kerala state plays a major role. Valaramkunnu is a village in Wayanad district of Kerala, situated on the top of a hill with 300 inhabitants. The villagers walk for 8 km down the hill for daily wages as there is no other source of income. 25 acres of land is available, where lemongrass is grown naturally. The village had a history of extracting lemon grass oil, has two problems a) Batch operation — oil extraction is limited by equilibrium and b) Fire wood is used as energy source — this results in deforestation and therefore not a sustainable energy source. To address these challenges, a semi-continuous lab scale distillation was set up to overcome the limitation of equilibrium and was tested. The proposed system was initially tested at lab scale. A prototype lemon grass essential oil is setup in Valaramkunnu. For the prototype, a solar steam generation system is chosen. Effects of process parameters such as drying time, steam temperature, distillation time and packing density on oil yield were studied. It was found that 8 times more essential oil can be extracted, when compared to existing commercial methodologies. It is also estimated that, nearly 55 litres of oil per acre per annum may be produced in Valaramkunnu. Based on the current price of lemon grass oil, the villagers are estimated to earn INR 800,000 per annum. The report will describe the socioeconomic disadvantages faced by the study population, limitations of their attempts to address these disadvantages, and the analysis to rationalize projected benefits from the proposed technological and social interventions.