Influence of stabilizing agents on the microstructure of Co-nanoparticles for removal of Congo red☆

Removal of Congo red is a serious environmental problem. Metal nanoparticles are emerging as a efficient catalysts and/or adsorbents to the degradation of dyes due to the large surface area. UV–visible absorption spectroscopy was used to quantify the decolorization of Congo red by Co-nanoparticles with and with out sun light at different time intervals. The experimental results show that the 100% Congo red (2.1×10−4moldm−3) can be mineralized after ca. 1 min with Co-nanoparticles (3.2×10−3moldm−3) in presence of sun light irradiation. The degradation pathway of Congo red under the optimal experimental conditions is also proposed and discussed. In this paper, a simple and nonexpensive method was used to the synthesis of Co-nanoparticles in absence and presence of stabilizers. The morphology, stability and color of cobalt sols strongly depends on the nature and/or presence of stabilizers. Transmission electron microscopic data revealed that the Co-nanoparticles possesses multi-layered aggregated sheet, and dumbly shaped morphology with different stabilizers.