Multifunctional smart engineering nano magnetic materials with ultrahigh synergetic adsorption-photocatalytic performance

Abstract

Water contamination by organic dyes is a severe environmental and health issue requiring a sustainable remedial solution. Among different acid dyes, the Acid Violet-19 (AV-19) extensively used for the coloring of fabrics has toxic and carcinogenic effects, which need to be effectively treated with state-of-the-art photocatalysts and techniques. In the present work, a series of nanomagnetic spinel ferrites (MFe2O4: M = Mg, Ca, Mn, Ni, Zn, and Cd) were synthesized for dye remediation through a facile combustion route. The synthesis involved the pioneering use of DL-Glutamic acid as a fuel due to low ignition temperatures (200–250 °C), cost-effectiveness, and environmental compatibility. The nanomagnetic particles with d90 < 200 nm and crystallite sizes lower than 50 nm were synthesized, exhibiting strong superparamagnetic properties and high surface areas. The synthesized nanoparticles exhibited ultrahigh adsorptive elimination and superior photocatalytic degradation of AV-19 under high concentration (250 and 100 mg/L) conditions. High monolayer absorbance capacities of 3905, 1061, and 814 mg/g were achieved for CaFe2O4, MgFe2O4, and CdFe2O4. The AV-19 elimination is well described by the Langmuir isotherm and second-order kinetic model. The dipole-dipole and Yoshida H-bonding interactions are the proposed adsorption mechanisms. The ZnFe2O4 showed exceptionally high photocatalytic dye degradation (∼ 100 % within 1 h), with the first-order kinetic rate constant being 0.063 min−1 at a photocatalyst dose of 0.1 g/L. The synthesized catalyst also showed high removal-degradation efficiency against different cationic and anionic dyes, including Malachite green, crystal violet, and Titan yellow. The solution pH showed an insignificant effect on the synergetic adsorption and photocatalytic degradation efficiency of MFe2O4. The present study shows that synthesized magnetic nanoparticles through the facile combustion route effectively eradicate the dye pollutants from wastewater.