Chitosan stabilized Fe/Ni bimetallic nanoparticles for the removal of cationic and anionic triphenylmethane dyes from water

Abstract

A comparative investigation has been carried out for the effective removal of cationic and anionic triphenylmethane dyes from the water using zero valent iron and iron/nickel bimetallic nanoparticles stabilized by chitosan (CS). The biopolymer chitosan, used as a stabilizer in this study is biodegradable and non-toxic. Chitosan stabilized zero valent iron (CS-Fe) and Chitosan stabilized bimetallic iron/nickel (CS-Fe/Ni) nanoparticles were prepared by chemical reduction method using sodium borohydride as reducing agent under nitrogen atmosphere. The characteristics of CS-Fe/Ni, CS-Fe and CS nanoparticles were examined by HRTEM, XPS, Zeta Potential, zeta potential and FTIR. HRTEM results reveal that iron nanoparticles were successfully coated with chitosan and the prepared particles were in nano dimensions. The average size of these synthesized nanoparticles was below 15 nm. The interaction of hydroxyl and amino groups of chitosan with iron in CS-Fe/Ni and CS-Fe nanoparticles was confirmed by FTIR. The surface compositions of the nanoparticles obtained from the XPS analysis revealed the presence of zerovalent iron and nickel in chitosan. Batch experiments were carried out to evaluate the removal efficiencies of CS-Fe/Ni, CS-Fe and CS in the triphenylmethane dyes. The model pollutants selected for dye removal study were cationic malachite green dye and anionic methyl blue dye. The parameters studied in the dye removal were effects of dosage of the nanoparticle, contact time, initial concentration of the dyes, solution pH and ionic strength. The results indicate that CS-Fe/Ni nanoparticles are more effective in dye removal compared to CS-Fe nanoparticles and CS.