Bricks as historical record of heavy metals fallout: study on copper accumulation in Agra soils since 1910

Peat, ice deposits and aquatic sediments, which have been used as a geochemical monitor of atmospheric heavy metal pollution until now, are open and dynamic systems and can be easily affected by climatic variations. In contrast, bricks, which are more compact, can act as a better geochemical monitor. Analysis of Cu, Cr, Ni, Pb and Zn in scores of soil and brick (baked/unbaked) samples, collected from a large area in and around a rapidly growing Indian city, Agra, reveals approximately similar concentrations in soils and bricks, thereby showing insignificant fractionation of these metals during brick making. Further, metals concentration in the core of bricks remains unaffected by any significant amount of acidic and alkaline rain. Thus, the feasibility of a novel role of bricks as a geochemical monitor of atmospheric heavy metal pollution has been tested. Utilizing this concept, an attempt has also been made to trace the history of atmospheric copper depositions in the soils of Agra during the last 100 years

Fluoride estimations in water using ion selective electrode: Choice of appropriate TISAB

999-1002Choice of appropriate TISAB (total ionic strength adjusting buffer) plays a crucial role in fluoride (F¯) analysis in water samples by ion selective electrode. Despite this no guideline is, yet, available on the choice of appropri ate TISAB for F¯ analysis in samples, particularly in presence of other ionic and non-ionic species. In this study, the efficacy of ten different TISABs for fluoride estimati on in water samples in presence of F¯ binding cations, viz. A13+ and Fe3+ has been investigated. The study suggests that the TISA B, containing tris- hydroxymethyl aminomethane hydrochloride buffer is probably best suited for F¯ estimation in samples, especially, in presence of high concentrations (1-2 g dm-3) of Al3+

MOFs in photoelectrochemical water splitting: New horizons and challenges

International audienc

Enhanced Photoelectrochemical Response of Zn-Dotted Hematite

Photoelectrochemical response of thin films of α-Fe2O3, Zn doped α-Fe2O3, and Zn dots deposited on doped α-Fe2O3 prepared by spray pyrolysis has been studied. Samples of Zn dots were prepared using thermal evaporation method by evaporating Zn through a mesh having pore diameter of 0.7 mm. The presence of Zn-dotted islands on doped α-Fe2O3 surface exhibited significantly large photocurrent density as compared to other samples. An optimum thickness of Zn dots ∼230 Å is found to give enhanced photoresponse. The observed results are analyzed with the help of estimated values of resistivity, band gap, flatband potential, and donor density

N–TiO2 crystal seeds incorporated in amorphous matrix for enhanced solar hydrogen generation: Experimental & first-principles analysis

International audienceWe present here a combined study on the photoelectrochemical activity of highly active Nitrogen doped titanium dioxide thin-film using experiments and First principle density (DFT) based calculation. Hybridization of N 2p with O 2p and localized valence band upshifting leads to the reduction in band-gap of N–TiO2. To validate theoretical findings, the role of nitrogen in TiO2 is revisited with a focus on partial crystallinity. The best-case photoelectrode, nanostructured partially crystalline nitrogen-doped titanium dioxide (PCNDTO) offered photocurrent density of 24.3 mA/cm2 at 1 V versus saturated calomel electrode (SCE). The absence of well-defined peaks and long-range order in XRD pattern and Raman spectrum respectively suggests partially crystallinity. High-resolution transmission electron microscopy (HR-TEM) images confirm the presence of TiO2 crystals in the amorphous matrix. High photoelectrochemical response can be attributed to the abundance of hydroxyl groups, high electrochemical active surface area, reduced charge transfer resistance, and reduced charge carrier recombination rat