Amine-Functionalized and Hydroxyl-Functionalized Magnesium Ferrite Nanoparticles for Congo Red Adsorption

Abstract

In this paper, the potential use of either amine-functionalized or hydroxyl-functionalized magnesium ferrite (MgFe2O4) nanoparticles (NPs) as Congo red nanoad­sorbents is explored and compared. The amine-functionalized MgFe2O4 NPs (denoted as MgFe2O4–NH2 NPs) were synthesized by a one-pot coprecipitation method using ethanolamine as a surface modifier, while the hydroxyl-functionalized MgFe2O4 NPs (denoted as MgFe2O4–OH NPs) were prepared by a hydrothermal method. In general, both nanoadsorbents can be successfully produced without calcination and were found to possess superparamagnetic properties with high saturation magnetization (M s). In particular, MgFe2O4–OH NPs exhibit a higher M s value of ∼53 emu g–1, promoting the rapid separation ability of the NPs from the treated solution using an external permanent magnet. The Congo red removal performance of these nanoadsorbents was investigated as a function of the pH of the aqueous solution and contact time. The removal efficiency of Congo red by MgFe2O4–NH2 NPs was found to be ∼96% within 180 min at pH 6, while MgFe2O4–OH NPs provided a removal efficiency at ∼88% within 420 min at pH 8. In addition, the maximum adsorption capacities (q m) calculated using the Langmuir isotherm equation were found to be 71.4 and 67.6 mg g–1 for MgFe2O4–NH2 and MgFe2O4–OH NPs, respectively. The higher q m value of MgFe2O4–NH2 NPs could be attributed to stronger electrostatic interactions with the sulfonate groups of Congo red formed by larger numbers of protonated amine groups than protonated hydroxyl groups of the adsorbents under the performed conditions. Moreover, reusability experiments also revealed that MgFe2O4–NH2 NPs offered a higher removal efficiency than MgFe2O4–OH NPs for the same cycles tested. Therefore, this study demonstrates that MgFe2O4–NH2 NPs synthesized by a simple one-pot synthetic method are applicable as reusable magnetic nanoadsorbents for Congo red removal in current practice.

Surface Modification of Magnesium Ferrite Nanoparticles for Selective and Sustainable Remediation of Congo Red

“…MgFe 2 O 4 − NH 2 NPs can be utilized as efficient adsorbents for the removal of hazardous substances, such as heavy metal ions like Pb(II) and anionic dyes like Congo Red. 15,16 High removal efficiencies (>90%) for these contaminants of MgFe 2 O 4 − NH 2 NPs were obtained. Interestingly, with regard to selectivity, MgFe 2 O 4 −NH 2 NPs provided high selectivity for Pb(II) adsorption in binary solutions containing Pb(II) and various metal ions such as Ca(II), Cd(II), Zn(II), Cu(II), and Ni(II) ions.…”

Adsorptive removal of pollutants from water using magnesium ferrite nanoadsorbent: a promising future material for water purification

“…White precipitates formed were washed thoroughly with ethanol to remove unreacted chemicals. The materials were dried 24 h at 80 °C and finally calcined 2 h at 600 °C to obtain nanoparticles of magnesium ferrite (Chandradass et al 2012;Kaur and Kaur 2014;Zhou et al 2016;Aoopngan et al 2019).…”

“…Different mechanisms have been suggested so far to illustrate the adsorption of pollutants on the magnesium ferrite surface, which are highly depending on the adsorbate and adsorbents used. They are ion-exchange (Verma and Chandrajit 2020), physisorption (Kaur et al 2018;Tatarchuk et al 2020a), chemisorption (Nonkumwong et al 2016), electrostatic attraction (Oladipo and Gazi 2016;Aoopngan et al 2019;Yu et al 2020;Ivanets et al 2021a), surface complexation (Tang et al 2013a;Oladipo and Gazi 2016;Wu et al 2018) and hydrogen bonding (Aoopngan et al 2019;Hoijang et al 2020).…”

“…Two types of surface hydroxyl exist in magnesium ferrite: Fe-OH and Mg-OH. It is well-known that the outermost surface of magnesium ferrite nanoparticles is covered with hydroxyl group when exposed to water (Tang et al 2013a;Aoopngan et al 2019). This hydroxyl group is responsible for surface chemistry which can change with pH.…”

Synthesis of adsorbents from wheat hulls, extracted cellulose and modified with Cetyl trimethyl ammonium chloride to remove Congo Red in aqueous solution

“…Previously, Langmuir's q max parameter values for Congo Red removal have been obtained for different adsorbents, such as: Fe x Co 3 -xO 4 -modified nanoparticles, Fe x Co 3 -xO 4 -modified nanoparticles, Fe x Co 3 -xO 4 (128.6 mg/g) (Liu et al, 2019), Calcium alginate beads impregnated with nanogoethite (181.1 ng/g) (Munagapati & Kim, 2017), sol-gel-derived hydroxyapatite nanoparticle (487.8 mg/g) (Chahkandi, 2017), Hydroxyl-functionalized magnesium ferrite nanoparticles (71.4 mg/g) (Aoopngan et al, 2019), and surfactant functionalized zeolite particles (200 mg/g). Concerning the results reported by other authors, those obtained in the present study for WHC and MWHC are in the range of 71 to 488 mg/g.…”