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

Abstract

Surface modification of silica-coated magnesium ferrite nanoparticles (MgFe 2 O 4 @SiO 2 NPs) by 3-aminopropyltriethoxysilane (APTES) shows enhanced selectivity for the removal of Congo Red (CR) from both single and binary aqueous dye solutions. Before coating the surfaces of amine-functionalized magnesium ferrite nanoparticles (MgFe 2 O 4 −NH 2 NPs) with silica, control studies of the adsorption of cationic, neutral, and anionic dyes were performed using both single and binary dye systems. The studies found that the MgFe 2 O 4 −NH 2 nanoadsorbent favors the adsorption of indigo carmine (IC) and CR in single dye solutions (>90% removal efficiencies). However, MgFe 2 O 4 −NH 2 NPs preferentially adsorb CR in binary dye solutions. Interestingly, the selectivity of CR over IC depends on the initial concentration of IC/CR in the IC/CR binary systems. A further enhancement in the selective removal of CR in both single and binary dye solutions was achieved by coating the MgFe 2 O 4 −NH 2 NPs with silica followed by modification with APTES (i.e., APTES-modified MgFe 2 O 4 @SiO 2 NPs). The highly selective adsorption capacity for CR on the APTES-modified MgFe 2 O 4 @SiO 2 nanoadsorbent was attributed to the mixture of polar functional groups (i.e., −OH and −NH 2 ) on the surface of the nanoadsorbent, which facilitates adsorbent−adsorbate interactions such as electrostatic and hydrogen-bonding interactions, which are amplified for CR with its more numerous polar functional groups (i.e., amine, azo, and sulfonate groups). From the results, the APTES-modified MgFe 2 O 4 @SiO 2 nanoadsorbent offers an effective, inexpensive, and reusable/sustainable system for the selective removal and remediation of Congo Red from wastewaters.

Magnesium Ferrite/Poly(cysteine methacrylate) Nanocomposites for pH-Tunable Selective Removal and Enhanced Adsorption of Indigo Carmine and Methylene Blue

“…These findings indicated that the adsorption of IC and MB by the unmodified MgFe 2 O 4 NPs was independent of pH. In addition, the MgFe 2 O 4 nanoadsorbent preferentially adsorbed the anionic IC dye rather than the cationic MB dye, as observed in a previous study . The efficiency for removal of IC by the MgFe 2 O 4 /PCysMA nanoadsorbent decreased from ∼95 to ∼10% upon increasing the solution pH from ∼2 to ∼10.…”

“…In addition, the MgFe 2 O 4 nanoadsorbent preferentially adsorbed the anionic IC dye rather than the cationic MB dye, as observed in a previous study. 56 The efficiency for removal of IC by the MgFe 2 O 4 /PCysMA nanoadsorbent decreased from The efficiencies for removal of IC and MB by the MgFe 2 O 4 @SiO 2 and MgFe 2 O 4 @SiO 2 /PCysMA nanoadsorbents were also studied to investigate pH-dependent adsorption by the PCysMA-grafted nanoadsorbent, and the results are presented in Figure 6b. At pH ∼2, the MgFe 2 O 4 @SiO 2 nanoadsorbent provided ∼44% IC removal efficiency, whereas no adsorption of IC occurred upon increasing the solution pH from ∼4 to ∼10.…”

Fabrication of bimetallic-doped materials derived from a Cu-based complex for enhanced dye adsorption and iodine capture

“…According to the literature, the mechanism of dye adsorption may be through host–guest interactions, particularly those involving electrostatic interactions, hydrogen bonding, or π–π stacking. 53,54 Furthermore, the zeta potentials of complexes 1 and C-N-1 were measured and found to be 0.0207 and 0.0813 mV, respectively (Fig. S10†), which suggested that electrostatic interactions may have been the main mechanism through which the dye adsorption was achieved.…”

MgFe2O4Nanoparticle/Peracetic Acid Hybrids for Catalytic Oxidative Depolymerization of Lignin

“…The MgFe 2 O 4 nanoparticles were synthesized according to our previous reports. ,, Briefly, CH 3 COONa (15 mmol) was mixed with 10 mL of ethylene glycol followed by heating to 100 °C for 15 min. Mg­(NO 3 ) 2 ·6H 2 O (1 mmol), Fe­(NO 3 ) 3 ·9H 2 O (2 mmol), and 5.0 mL of ethylene glycol were injected into the reaction mixture and subsequently refluxed for 30 min.…”