Characterisation of coal and its combustion ash: recognition of environmental impact and remediation.

Energy generation from coal poses an environmental drawback due to the abundance of some potential hazardous elements (PHEs). A few PHEs (As, Sb, Cu, Mn and Zn) are noticed in the coal collected from thermal power plants of India. Among them, As and Sb are depleted while Cu, Mn and Zn are enriched in fly and bottom ash. The short- and long-term exposure of these PHEs into the ecosystem by emission, deposition and leaching causes environmental contamination as well as pollution and health hazards. The water-leaching experiment shows that these elements have feeble mobilisation tendency and low risk. The bioavailability test reflects that bio-uptake of these PHEs into the human system may be the origin of several diseases. Proper storage and recycling of the large amount of fly and bottom ash are a serious concern of thermal power plants. Chemical characterisation of ash, including elemental mapping by scanning electron microscope, calculated enrichment ratio (ER) and relative enrichment index (REI) values, as well as lab-scale water-leaching experiments predict that combustion residues of the studied power generating unit are safe for utilisation in construction, geotechnical and even in agricultural sectors. Chemical characterisation and pre-treatment of ashes before utilisation are urgently required to prevent any possible contamination. Regular scrutiny of emission control device, proper management of ash disposal and frequent utilisation are the keys for clean energy generation. A deep chemical and physical analysis of coal from power plants prior to utilisation is the primary task for sustainable energy generation from environmental aspect.

Is saliva a potential biomarker of arsenic exposure? A case-control study in West Bengal, India.

Saliva is a biological fluid that has not been used extensively as a biomonitoring tool in epidemiological studies. This study presents the arsenic (As) concentrations in saliva and urine samples collected from populations of West Bengal, India who had been previously exposed to high As levels in their drinking water. We found a significant (p < 0.05) association between the Log transformed Daily Ingestion of As (µg day(-1)) and the As concentration in saliva (r = 0.68). Additionally, As concentration of saliva and urine also had a significant positive correlation (r = 0.60, p < 0.05). Male participants, smokers, and cases of skin lesion were independently and significantly associated with an increase in salivary As. Thus our findings show that saliva is a useful biomarker of As exposure in the study population. The study also advocates that measurement of the forms of As in saliva may additionally provide insight into the internal dose and any individual differences in susceptibility to As exposure.

Copper(I) hydroxyapatite catalyzed Sonogashira reaction of alkynes with styrenyl bromides. Reaction of cis-styrenyl bromides forming unsymmetric diynes.

An efficient Sonogashira coupling of terminal alkynes and styrenyl bromides has been achieved under the catalysis of hydroxyapatite-supported copper(I). The trans-styrenyl bromides produce the usual trans-enyne products, whereas the cis-styrenyl bromides lead to unsymmetric 1,3-diynes by the cross coupling of terminal alkyne and the alkyne generated from the cis-styrenyl bromide. A series of trans-enynes and unsymmetric 1,3-diynes have been synthesized by this protocol.

Hydroxyapatite-supported Cu(I)-catalysed cyanation of styrenyl bromides with K4[Fe(CN)6]: an easy access to cinnamonitriles.

An efficient cyanation of styrenyl bromides by K(4)[Fe(CN)(6)] has been achieved under the catalysis of hydroxyapatite-supported copper(I) producing a variety of functionalized cinnamonitriles in high yields. The stereochemistry of the styrenyl double bond is preserved during the process providing the same stereoisomer of product.

Assessment of arsenic exposure from groundwater and rice in Bengal Delta Region, West Bengal, India.

Arsenic (As) induced identifiable health outcomes are now spreading across Indian subcontinent with continuous discovery of high As concentrations in groundwater. This study deals with groundwater hydrochemistry vis-à-vis As exposure assessment among rural population in Chakdaha block, West Bengal, India. The water quality survey reveals that 96% of the tubewells exceed WHO guideline value (10 µg/L of As). The groundwaters are generally anoxic (-283 to -22 mV) with circum-neutral pH (6.3 to 7.8). The hydrochemistry is dominated by HCO(3)(-) (208 to 440 mg/L), Ca(2+) (79 to 178 mg/L) and Mg(2+) (17 to 45 mg/L) ions along with high concentrations of As(T) (As total, below detection limit to 0.29 mg/L), Fe(T) (Fe total, 1.2 to 16 mg/L), and Fe(II) (0.74 to 16 mg/L). The result demonstrates that Fe(II)-Fe(III) cycling is the dominant process for the release of As from aquifer sediments to groundwater (and vice versa), which is mainly controlled by the local biogeochemical conditions. The exposure scenario reveals that the consumption of groundwater and rice are the major pathways of As accumulation in human body, which is explained by the dietary habit of the surveyed population. Finally, regular awareness campaign is essential as part of the management and prevention of health outcomes.

Copper nano-catalyst: sustainable phenyl-selenylation of aryl iodides and vinyl bromides in water under ligand free conditions.

A simple and efficient procedure for the synthesis of aryl- and vinyl-selenides has been developed by a copper nanoparticle catalysed reaction of aryl iodide/vinyl bromide with diphenyl diselenide in the presence of zinc in water. (E)-Vinyl bromides produce (E)-vinyl selenides stereoselectively, whereas (Z)-vinyl bromides provide mixtures of (E) and (Z) isomers. The catalyst was recycled.