SYNTHESIS AND CHARACTERIZATION OF AG/FEOOH AND AG/FE2O3 DERIVED FROM IRON ORE TAILINGS

Saswati Samanta , Diptipriya Sethi , Rajib Biswal , Ramasami Sakthivel , Munesh Chandra Adhikary

silver nanoparticle , dehydroxylation, urea hydrolysis, diffraction peaks

This work is an experimental study on nano-crystalline Ag/FeOOH and Ag/Fe2O3 powder derived from the iron ore tailings. Iron ore tailings is a mineral waste contains 15- 20% Fe2O3 remaining mostly SiO2. Iron is extracted out as FeCl3 by hydrochloric acid digestion of iron ore tailings. The obtained aq. FeCl3 solution was precipitated as ferric hydroxide by using different reagents such as aq.NH4OH, aq. NaOH and Urea. Urea hydrolysis was carried out at 95 ?C while in other two cases heating was not employed. Each ferric hydroxide obtained by the above three methods was divided into two portions. One portion of it was directly used as support for silver nanoparticles to obtain Ag/FeOOH. The other portion of FeOOH was calcined at 550 ?C for 4 h to convert it into ferric oxide . These ferric oxides were then used as supports for silver nanoparticles to obtain Ag/Fe2O3. On observation, XRD pattern shows very broad diffraction peaks for the Ag/FeOOH samples and those peaks were identified for goethite phase. But Ag/Fe2O3 samples show very sharp diffraction peaks which were well matched with hematite phase. Raman Spectra of various Ag/FeOOH and Ag/Fe2O3 samples have shown very prominent Raman bands at various region between 200-1400 cm-1. These bands are identified for various modes of vibration for Fe-O. UV-visible (diffuse) spectra of Ag/FeOOH and Ag/Fe2O3 samples show two absorption bands appeared at the same position although the supports for silver were of two different kinds (FeOOH and Fe2O3). TEM picture of Ag/FeOOH and Ag/Fe2O3 samples prepared via urea hydrolysis show that silver nanoparticles are well dispersed/ supported on FeOOH and Fe2O3 matrix. The particle size of FeOOH is found to be 60-70 nm range whereas the particle size of silver nanoparticles supported on FeOOH is observed to be <10 nm. TEM image of Ag/Fe2O3 shows particle size of silver <10 nm and 90-100 nm for Fe2O3. TGA curve of uncalcined Ag/FeOOH prepared using sodium hydroxide shows weight loss at two stages; first stage is below 200 oC and second stage is between 400- 450 oC. They correspond to dehydration of physically adsorbed water molecule and dehydroxylation of FeOOH to form Fe2O3. The present work also showed that the obtained silver loaded ferric oxide hydroxide and ferric oxide possess antibacterial properties which can be exploited to kill bacterial growth in a given region.

Volume 6 Issue 2, March-2018

Pages : 1030-1039