Comparative study on organic effluent degradation capabilities and electrical transport properties of polygonal ZnCo2O4 spinels fabricated using different green fuels.

The present work highlights biosynthesis of nano-sized heterometalic spinel ZnCo2O4 particles using different green extracts as capping agent. In this work we have fabricated polygonal ZnCo2O4 with Punica granatum peel extract, Camellia sinensis extract, Moringa oleifera leaf extract and green coffee beans extract in an effortless green pathway. Phase pure material synthesis was confirmed using XRD. Microstructural, morphological, compositional and optical characterisations has been carried out using TEM, FESEM, EDX, FTIR, photoluminescence and UV-Vis spectroscopy. Punica granatum peel extract assisted ZnCo2O4 sample shows superior catalytic efficiency of ~84.96% for Rhodamine B pollutant. ZnCo2O4 sample synthesized using pomegranate peel extract shows highest conductivity of ~8.074 × 10-5 Ω-1 cm-1 with activation energy of 2.099 eV at 503 K. Synthesized nanoparticles also show antibacterial activity for B. megaterium, B. subtilis and B. cereus. To the best of our knowledge, synthesis of ZnCo2O4 using these four green extracts and their comparative degradation capability, electrical properties and antibacterial study is explained for the first time in this work.

Plying of speedboats along canals in the city of Kolkata, India, to prevent mosquito breeding.

BACKGROUND: Two long sewerage canals in the city of Kolkata, India were heavily infested with larvae, pupae and egg rafts of the mosquito Culex quinquefasciatus. Although the burden of bancroftian filariasis and other diseases transmitted by C. quinquefasciatus in the city is practically zero, the night-biting mosquitoes are a great nuisance to residents living alongside the canals. It is known that mosquitoes survive poorly in water agitated by wave and wind action. METHOD: The health department of Kolkata Municipal Corporation undertook, from November 2010 to April 2012, a programme of plying speedboats along the canals to prevent C. quinquefasciatus breeding. At the same time, along stretches of canal too shallow to permit the use of speedboats and where the canal banks are inaccessible to spraymen, the edges were treated with larvicidal spray, Temephos 50% EC (emulsifiable concentrate), using small rowing boats as transport. RESULT: The densities of egg rafts and immature and adult insects declined dramatically when the speedboats were deployed and remained low for the duration of the project. For Feburary, the peak month for C. quinquefasciatus breeding, densities for egg rafts, larvae, pupae and adults, respectively, declined from 800, 2942, 1457 and 662 to 3, 75, 15 and 27. The cost was comparable to that of using larvicidal spray where this required the use of rowing boats. CONCLUSION: Speedboat-generated waves are effective in preventing the breeding of mosquitoes in otherwise mosquitogenic canals. Where use of boats is an option and use of insecticides is unfeasible or undesirable, the plying of speedboats is a potentially ecofriendly approach to mosquito control.