CTAB-coated magnetic nanoparticles for removal of direct yellow 12 from aqueous solutions

The textile and dye manufacturing industries produce large quantities of dangerous dyes, pigments and metals with a high potential to pollute wastewaters. In this context, some methods for color removal from waters and... [ view full abstract ]

The textile and dye manufacturing industries produce large quantities of dangerous dyes, pigments and metals with a high potential to pollute wastewaters. In this context, some methods for color removal from waters and wastewaters are available such as membrane separation, biologic degradation, chemical oxidation, coagulation and flocculation [1]. More recently, some methods based on magnetically assisted chemical separation have been proposed to be more efficient and produce less waste [2]. In this work, we investigate the removal of direct yellow 12 (DY12) from aqueous solutions using magnetic nanoadsorbents based on ferrite nanoparticles (NP) modified with cetyltrimethylammonium bromide (CTAB). The nanoadsorbents were synthesized using the hydrothermal coprecipitation method in alkaline medium followed by a surface treatment with Fe(NO3)3 leading to CoFe2O4@gamma-Fe2O3 core-shell NP. The surface modification was carried out by mixing the NP and CTAB in aqueous solution at pH = 10 with sonication for 15 min. The influence of time, pH and initial dye concentration were evaluated from batch studies using 0.5 g/L of the nanoadsorbent. After chemical adsorption, the NP were separated using a hand-held magnet and the final concentration of DY12 in decanted solution was determined by UV-VIS spectroscopy at 395 nm. The results of the batch studies were analyzed in the framework of Langmuir and Freundlich models in order to evaluate the maximum adsorption capacity and the extent of affinity. The kinetics data were analyzed with pseudo-first order and pseudo second-order models. It was evidenced that the adsorption reached equilibrium within 30 min and it was independent of initial DY12 concentration. The maximum adsorption occurred at pH 5.0 leading to almost 100% of pollutant removal. The dye adsorption onto the magnetic adsorbents well followed the pseudo-second-order rate indicating that the rate-limiting step involves electrostatic forces between DY12 and nanoadsorbents. Finally, in the view of these results, the developed CTAB coated NP can be used as a low cost and effective adsorbents in removal of DY12 from wastewater.

References:

[1] M. Ghaedi et al, Chem. Eng. J. 187, 133 (2012)
[2] N. M. Mahmoodi et al, J. Environ. Health Sci. Eng. 12, 96 (2014)