Synthesis of Nitrate Doped Polypyrrole Conducting Polymer Membrane and Fabrication of Passive Sampler to Determine Diffusion of Nitrate and Chloride Through Membrane in Aquatic Ecosystem

Nitrate is the most considerable substance in the hydrosphere and high concentration of nitrate can be harmful to the healthy life of creatures and human being. The removal of nitrate from the water is very essential. Therefore this study was focused to synthesis the nitrate doped polypyrrole polymer membrane (PPy-N) and the diffusion of nitrate in the presence of high chloride concentration through the membrane for samples obtained in 5th, 7th, 9th, 11th, 13th days in synthetic freshwater was also studied. Passive samplers have been developed in order to assess water quality over the period of time they have been deployed  and also to simplify sampling and sample preparation processes. Nitrate doped polypyrrole film was synthesized through  chemical polymerization process using Pyrrole and HNO3. The characterization of the membrane was performed by Fourier Transform Infrared Spectroscopy (FTIR). The amount of nitrate and chloride diffused through a nitrate doped polypyrrole films (PPy-N1) were determined using cadmium reduction method and chloride ion selective electrode technique respectively. In order to improve the diffusion of nitrate through the membrane, the laboratory filter paper was used to prepare another nitrate doped  polypyrrole films (PPy-N2). The same techniques that used for PPy-N1 were used to determine diffused nitrate and chloride  through PPy-N2 membrane. The results revealed that, membrane PPy-N2 has exhibited 13.102 ± 0.469 %, 42.969 ± 5.107 %, 55.932 ± 1.579 %, 64.096 ± 2.171 %, and 77.826 ± 1.752 % diffusion of nitrate and 36.989 ± 3.177 %, 43.922 ± 1.823 %, 46.223 ± 0.817 %,  49.042 ± 0.908 %, and 49.679 ± 0.119 % diffusion of chloride through the membrane after 5 days, 7 days, 9 days, 11 days and 13 days respectively. Whereas membrane PPy-N1 exhibited that 11.497 ± 0.715 %, 14.899 ± 1.431 %, 33.932 ± 0.469 %, 35.066 ± 0.592 %, and 42.917 ± 1.875 % diffusion of nitrate and 25.612 ± 1.683 %, 38.959 ± 1.201 %, 36.075 ± 2.151 %, 37.004 ± 2.989 %, and 38.495 ± 1.341 % diffusion of chloride after those days respectively

Natural Plant Extracts as Acid-Base Indicator and Determination of Their pKa Value

Commonly used indicators for acid-base titrations are synthetic, and this work was focused to identify the eco-friendly natural indicators and to determine their pKa values. The analytical potential of the flower extracts is very promising as seen in its application in acid-base titrimetry. These selected flower extracts were found to perform well in titrating strong acid-strong base than in weak acid-strong base. We have obtained a sharp and clear colour change from red to brownish yellow for the Bougainvillea glabra extract, from red to yellow for the Bauhinia purpurea extract, and from red to brownish yellow for the Impatiens balsamina extract. All the three flower extracts gave clear colour change with acids and bases, and the colour change was maintained with different acids and bases. The sharp contrast between their colours in acid and base made the pigment suitable for use as acid-base indicators. As these flower extracts have very simple,cost-effective, environment friendly extraction procedure and excellent performance with sharp colour change in end points of the titrations, it would be possible to replace the standard indicators being used in conventional laboratories with natural flower indicators

From mine to mind and mobiles – Lithium contamination and its risk management

With the ever-increasing demand for lithium (Li) for portable energy storage devices, there is a global concern associated with environmental contamination of Li, via the production, use, and disposal of Li-containing products, including mobile phones and mood-stabilizing drugs. While geogenic Li is sparingly soluble, Li added to soil is one of the most mobile cations in soil, which can leach to groundwater and reach surface water through runoff. Lithium is readily taken up by plants and has relatively high plant accumulation coefficient, albeit the underlying mechanisms have not been well described. Therefore, soil contamination with Li could reach the food chain due to its mobility in surface- and ground-waters and uptake into plants. High environmental Li levels adversely affect the health of humans, animals, and plants. Lithium toxicity can be considerably managed through various remediation approaches such as immobilization using clay-like amendments and/or chelate-enhanced phytoremediation. This review integrates fundamental aspects of Li distribution and behaviour in terrestrial and aquatic environments in an effort to efficiently remediate Li-contaminated ecosystems. As research to date has not provided a clear picture of how the increased production and disposal of Li-based products adversely impact human and ecosystem health, there is an urgent need for further studies on this field

Antimony contamination and its risk management in complex environmental settings:A review

Antimony (Sb) is introduced into soils, sediments, and aquatic environments from various sources such as weathering of sulfide ores, leaching of mining wastes, and anthropogenic activities. High Sb concentrations are toxic to ecosystems and potentially to public health via the accumulation in food chain. Although Sb is poisonous and carcinogenic to humans, the exact mechanisms causing toxicity still remain unclear. Most studies concerning the remediation of soils and aquatic environments contaminated with Sb have evaluated various amendments that reduce Sb bioavailability and toxicity. However, there is no comprehensive review on the biogeochemistry and transformation of Sb related to its remediation. Therefore, the present review summarizes: (1) the sources of Sb and its geochemical distribution and speciation in soils and aquatic environments, (2) the biogeochemical processes that govern Sb mobilization, bioavailability, toxicity in soils and aquatic environments, and possible threats to human and ecosystem health, and (3) the approaches used to remediate Sb-contaminated soils and water and mitigate potential environmental and health risks. Knowledge gaps and future research needs also are discussed. The review presents up-to-date knowledge about the fate of Sb in soils and aquatic environments and contributes to an important insight into the environmental hazards of Sb. The findings from the review should help to develop innovative and appropriate technologies for controlling Sb bioavailability and toxicity and sustainably managing Sb-polluted soils and water, subsequently minimizing its environmental and human health risks