Cadmium is an important environmental pollutant and a potent toxicant to bacteria, algae, and fungi. Mechanisms of Cd+2 toxicity and resistance are variable, depending on the organism. The present work reports the use of live and dead Spirulina sp. for sorption of Cd+2. This investigation shows that this biomass takes up substantial amount of Cd+2 ions. IR spectroscopic study, kinetics models, Langmuir & Freundlich adsorption isotherms, scanning electron microscopic analysis of Spirulina sp., and the Spirulina sp. treated with different metal ions have been employed to understand the sorption mechanism. Infrared spectra of live Spirulina treated with Cd+2 ions for different lengths of time have been taken to understand the time dependency of metal interaction.

Metal binding by algae has enormous potential for environmental bioremediation targeting towards detoxification of water bodies. The present work reports the use of live and dead Spirulina sp. for sorption of metals like Cr(3+), Ni(2+), Cu(2+), and Cr(6+) in form of Cr(2)O(7)(2-). Preliminary investigation shows that this biomass takes up substantial amount of metal ions indicated above. IR spectroscopic study, kinetics models, Langmuir and Freundlich adsorption isotherms, SEM analysis, and fluorescence microscopic study of Spirulina sp. and the Spirulina sp. treated with different metal ions have been employed to understand the sorption mechanism. It is hoped that live Spirulina sp. will be a strong candidate for management of industrial wastewater.

The present work delivers the first assessment of BiFeO 3 (BFO) thin films as an absorber for sustainable all-oxide photovoltaic devices. Films are deposited from a metal−organic precursor complex solution followed by annealing in air at 673 K for 2 h. Xray diffraction, complemented by quantitative analysis, indicated formation of pure BFO with rhombohedral structure (R 3 C). Atomic force microscopy suggests deposition of compact and smooth films with spherical particles of sizes ∼150 nm. A direct band gap of 2.2 eV is ascertained from UV−vis−NIR spectroscopy. Mechanistic aspects of the BFO formation are discussed based on thermograveminetric analysis, differential scanning calorimetry, and infrared spectroscopy of the precursor complex. A proof-of-concept BFO/ ZnO heterojunction based solar cell fabricated by solution processing delivered a photoconversion efficiency of 3.98% with open-circuit voltage (V oc ), short-circuit current density, and fill factor of 642 mV, 12.47 mA/cm 2 , and 50.4%, respectively. The device exhibits a maximum external quantum efficiency of nearly 70%. These parameters are among the highest values reported for all oxide PV. Analysis of the V oc , series resistance, and conversion efficiency as a function of temperature revealed valuable information about recombination processes.

A sensor for ammonia gas and ethanol vapour has been fabricated using indium oxide thin film as sensing layer and indium tin oxide thin film encapsulated in poly(methyl methacrylate) (PMMA) as a miniature heater. For the fabrication of miniature heater indium tin oxide thin film was grown on special high temperature corning glass substrate by flash evaporation method. Gold was deposited on the film using thermal evaporation technique under high vacuum. The film was then annealed at 700 K for an hour. The thermocouple attached on sensing surface measures the appropriate operating temperature. The thin film gas sensor for ammonia was operated at different concentrations in the temperature range 323-493 K. At 473 K the sensitivity of the sensor was found to be saturate. The detrimental effect of humidity on ammonia sensing is removed by intermittent periodic heating of the sensor at the two temperatures 323K and 448 K, respectively. The indium oxide ethanol vapour sensor operated at fixed concentration of 400 ppm in the temperature range 293-393 K. Above 373 K, the sensor conductance was found to be saturate. With various thicknesses from 150-300 nm of indium oxide sensor there was no variation in the sensitivity measurements of ethanol vapour. The block diagram of circuits for detecting the ammonia gas and ethanol vapour has been included in this paper.