DOI: 10.5061/dryad.wstqjq2t7
title: Lichen biomass for green synthesis of silver nanocolloids

description: Lichen is one of the most abundant non-vascular biomasses, however, a
 systematic study on application of the biomass in nanomaterial synthesis
 is very limited. In this study, aqueous lichen extract was obtained from
 Hypotrachyna cirrhata, one of the most abundant Himalayan Lichen biomass,
 following a simple cold percolation method. The effect of extract to
 silver nitrate mixing ratio, pH, and waiting time in growth and stability
 of nanoparticle was systematically explored. The rate constant for
 bio-reduction was found to be 5.3×10-3 min-1. Transmission electron
 microscopy (TEM) showed a narrow particle size distribution with mean
 particle size of 11.1±3.6 nm (n=200) The X-ray diffraction (XRD) and
 selected area electron diffraction (SAED) techniques confirmed the
 formation of cubic crystals. The synthesized colloidal solution showed
 excellent response for Hg2+ and Cu2+ ions in spiked water samples. The
 limit of detection and calibration sensitivity for Hg2+ and Cu2+ ions were
 found to be 1 mg/L and 5 mg/L, and 2.9×10-3 units/ppm and 1.6×10-3
 units/ppm; respectively. These findings suggested that green synthesis of
 spherical silver nanoparticles having narrow size distribution is possible
 using the aqueous lichen extract and the nanoparticles can be used for
 detection of selected heavy metals.
description: # Lichen biomass for green synthesis of silver nanocolloids Figure 2A:
 UV-Vis spectra recorded at variable extract to silver nitrate volume
 ratio. The first column represents the wavelength (nm). The columns 2-6
 represent absorbance measured with silver nitrate to lichen extract volume
 ratio of 1:1, 1:2, 1:3, 1:5, and 1:9; respectively. Columns 7 and 8
 represent the wavelength (nm) and absorbance data for extract;
 respectively. Figure 2D: FTIR data for the extract. The first column show
 the wavelength data (nm) and the second column transmittance. Figure 3A:
 UV-Vis spectra measured at different waiting time. The first row show the
 wavelength (nm) and the other rows the absorbance at different waiting
 time. Figure 4A: UV-Vis spectra measured at variable pH and waiting time
 of 24 hours. The first column show the wavelength data (nm) the other
 columns the corresponding absorbance measured at different pH. Figure 4C:
 UV-Vis spectra measured at variable pH and waiting time of 4 weeks. The
 first column show the wavelength data (nm) other columns the corresponding
 absorbance values measured at different pH. Figure 5C: XRD data of the
 nanoparticle. The first column show the 2 values and the second columns
 the intensity. Figure 7A: UV-Vis spectra measured in presence of different
 ions. The first row show the wavelength (nm) and the remaining rows the
 absorbance in presence of different ions. Figure 7C: UV-Vis spectra
 measured in presence of Hg++ ions. The first row show the wavelength (nm)
 and the remaining rows the absorbance measured in presence of different
 concentration of Hg++ (in ppm). Figure 7E: UV-Vis spectra measured in
 presence of Cu++ ions. The first row show the wavelength (nm) and the
 remaining rows the absorbance measured in presence of different
 concentration of Cu++ (in ppm).