Abstract
Trivalent chromium (Cr(III)) is considered to exhibit hormesis (bi-phasic dose-response) property, where low dose be beneficial and high dose shows toxic effect. The present work describe the development of a bimetallic Ag/Co-polyvinylpyrrolidone nanocomposite (Ag/Co-PVP NPs) probe to detect and quantify Cr(III) ions from aqueous samples. The hydrodynamic size and zeta potential of the particle was determined to be 29 ± 1.3 nm and −37.19 ± 2.4 mV respectively. The interaction of Cr(III) with Ag/Co-PVP probe showed drastic change in colour of NPs from dark brown to pale yellow, with corresponding blue shift, tapering width and increased peak intensity. The probe showed high specificity towards Cr(III) among the tested metal ions. A linearity was observed between various dilutions of Cr(III) ions (10 to 50 nM) and the absorbance of Ag/Co-PVP NPs at 428 nm with R2 value of 0.998. The minimum detectable limit of Cr(III) was calculated to be 0.6 nM. The influence of salinity, temperature and pH on detection was studied. The probe was found to detect Cr(III) at acidic pH effectively. Competitive metal ions did not interfere the detection of Cr(III). The water sample collected from Noyyal river was taken to estimate Cr(III) by using the prepared probe to ensure practical applicability. The sample contains 9.3 nM of Cr(III) that was cross verified with AAS analysis. Hence, it is understood that the reported probe can be used to detect Cr(III) selectively with high accuracy from aqueous samples. In addition, the particles also exhibited excellent photocatalytic activity under visible light. Ag/Co-PVP nanocomposites exhibited excellent antibacterial activity against both gram +ve (B. subtilis) and gram −ve (E. coli) bacteria.
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•Ag/Co-PVP nanocomposite was prepared and used for sensitive colorimetric Cr(III) detection.•The prepared probe able to detect the Cr(III) at nanomolar level•Presence of other metal ions did not interfere with the detection of Cr(III).•Effect of environmental factors including pH, temperature and salinity on Cr(III) detection was investigated.•The probe exhibited good photocatalytic and antibacterial properties.