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

• α-cobalt nanomaterials synthesized in presence and absence of stabilizers.•Surfactants (CTAB) and polymer (PVA) has significant impacts on the morphology.•The efficiency of cobalt nanomaterials improved in presence of NaBH4 for the reduction 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.