Synthesis of magnetically separable MnFe₂O₄ nanocrystals via salt-assisted solution combustion method and their utilization as dye adsorbent

Abstract

MnFe 2 O 4 nanocrystals with spinel structure were prepared by conventional solution combustion synthesis and salt-assisted solution combustion synthesis, respectively, and their adsorption capacities for Congo red (CR) were also investigated. The results showed that the MnFe 2 O 4 nanocrystals prepared with KCl salt (K-MFO) exhibited much better adsorption capacity for CR than those prepared without KCl (MFO), because the introduction of KCl into the solution combustion synthesis process results in an obvious dispersion and increment of surface area in the obtained MnFe 2 O 4 particles. Meanwhile, the MnFe 2 O 4 nanocrystals exhibited a clearly ferromagnetic behavior under applied magnetic field, which allowed their high-efficient magnetic separation from wastewater. The adsorption ratio of MnFe 2 O 4 nanocrystals prepared with a KCl/M ratio of 2/3 (K-MFO-c) for CR still reached 81% after 5 cycles. By the calculation of Langmuir model, the maximum monolayer adsorption capacity (q m ) of K-MFO-c is 118.76 mg/g and much higher than that of MFO (30.00 mg/g), which must be associated with the higher surface area of K-MFO-c.

Magnetic materials for magnetoelectric coupling: An unexpected journey

“…MnFe2O4 belongs to the inverse spinel ferrites where Mn +2 ions occupy the octahedral sites of lattice structure and half of the Fe +3 cations occupy octahedral sites and the other half stay at the tetrahedral sites of a fcc lattice formed by the oxygen ions and is a wellknown soft ferrite which has been used in various technological applications such as magnetic materials, gas sensors, biomedical tools and absorbent material for hot gas, among others (Stoia et al, 2015). Several methods have been developed to synthesize MnFe2O4 nanoparticles (Mishra et al, 2006), such as solid-phase reactions, mechanical ball-milling (Chen et al, 2013), thermal decomposition (Gabal and Ata-Allah, 2004), hydrothermal method (Hou et al, 2010), coprecipitation (Amighian et al, 2006), combustion (Zhong et al, 2015), microemulsion (Scano et al, 2011) and sol-gel autocombustion (Figure 21) (Shafiu et al, 2013, Shanmugavel et al, 2014. It was reported that at elevated temperatures, MnFe2O4 is unstable in air and Mn 2+…”

Cadmium adsorption using novel MnFe2O4-TiO2-UIO-66 magnetic nanoparticles and condition optimization using a response surface methodology

“…This feature, coupled with the low cost, non-toxicity and applicability of this nanoparticle has led to a special application in adsorption. 12,13 Coupling of this nanoparticle with TiO 2 has been reported in the various sources to facilitate the adsorption and transport of nanoparticles. Besides simplifying the process, it increases the amount of adsorption due to the presence of free electrons in the TiO 2 compound.…”