Detection of heavy metals (Cu+2, Hg+2) by biosynthesized silver nanoparticles

Abstract

Here, we are reporting two methods for detection of Cu ?2 ion and Hg ?2 ions using biosynthesized silver nanoparticles. The detection of Cu ?2 ion was based on changes in absorbance resulting from complex formation of the metal ion. Various concentrations of Cu ?2 ion were used to test the linearity and sensitivity of the method. A new peak at around 770 nm, in addition to the peak of the AgNP at 406 nm, was observed in each case (above 20 lM). With the increase of concentration of Cu ?2 ion solution, the absorbance at 406 nm peak decreased and that of 770 nm increased gradually. The calibration curve obtained from the ratio of the absorption coefficients of these two peaks (Ex 770/406 ) versus concentration of Cu ?2 ions enables one to estimate quantitatively the amount of Cu ?2 ions present in water in lM levels. This AgNP was further functionalized with 3-mercapto-1, 2-propanediol (MPD) for detection of Hg ?2 present in water by colorimetric method. As soon as Hg ?2 solution was added in MPDfunctionalized AgNP (MPD-AgNP), a new peak at around 606 nm appeared along with the peak at 404 nm. The new peak might be due to the aggregations occurred by the recognition of heavy metal ion Hg ?2 by MPD-AgNP through dipropionate ion. A calibration curve between the ratios of the absorption coefficients of these two peaks (Ex 404/606 ) and concentration of Hg ?2 was drawn for quantitative estimation of Hg ?2 present in water at lM level.

‘Green’ synthesis of metals and their oxide nanoparticles: applications for environmental remediation

“…Due to the tunable size and distance-dependent optical properties of metallic nanoparticles, they have been preferably employed for the detection of heavy metal ions in polluted water systems [ 145 , 146 ]. The advantages of using metal NPs as colorimetric sensors for heavy metal ions in environmental systems/samples include simplicity, cost effectiveness, and high sensitivity at sub ppm levels.…”

Heavy-metal detectors based on modified ferrite nanoparticles

“…Recent studies show that nanoparticles can be widely used as heavy-metal detectors. Among others, silver [ 10 – 11 ], gold [ 12 ] and also magnetic nanoparticles [ 13 – 14 ] usually doped with other elements (e.g., Ca, Mn) [ 15 – 16 ] have been tested for this purpose. Therefore, detailed studies on adsorption efficiency on doped magnetite nanoparticles are very interesting and innovative in order to understand the importance of core composition and surface modification.…”

Selective and sensitive colorimetric detection of platinum using Pseudomonas stutzeri mediated optimally synthesized antibacterial silver nanoparticles

“…The possible mechanism of the colorimetric assay for sensing Pt +2 is yet unknown but the methods of determination is reported to rely on their unique size and inter-particle distance-dependent absorption spectra and color change of the solution [24]. As per the previous studies that demonstrated the heavy metal detection by AgNPs, the bacterial proteins responsible for reduction of silver, its stabilization and the peptide linkage (—CONH—) may be responsible for formation of coordination complex with Pt +2 [25].…”