Fabrication of the magnetic mesoporous silica Fe-MCM-41-A as efficient adsorbent: performance, kinetics and mechanism

Abstract

Antibiotics are emerging pollutants and increasingly present in aquaculture and industrial wastewater. Due to their impact on the environment and health, their removal has recently become a significant concern. In this investigation, we synthesized nano zero-valent iron-loaded magnetic mesoporous silica (Fe-MCM-41-A) via precipitation and applied the adsorption of oxytetracycline (OTC) from an aqueous solution. The effects of competing ions such as Na+, Ca2+ and Cu2+ on the adsorption process under different pH conditions were studied in depth to providing a theoretical basis for the application of nanomaterials. The characterization of the obtained material through transmission electron microscopy demonstrates that the adsorbent possesses hexagonal channels, which facilitate mass transfer during adsorption. The loaded zero-valent iron made the magnetic, and was thus separated under an applied magnetic field. The adsorption of OTC onto Fe-MCM-41-A is rapid and obeys the pseudo-second-order kinetic model, and the maximum adsorption capacity of OTC is 625.90 mg g−1. The reaction between OTC and Fe-MCM-41-A was inner complexation and was less affected by the Na+. The effect of Ca2+ on the adsorption was small under acidic and neutral conditions. However, the promotion effect of Ca2+ increased by the increase of pH. Cu2+ decreased the removal efficiencies continuously and the inhibitory effects decrease varied with the increase of pH. We propose that surface complexing, ion-exchange, cationic π-bonding, hydrogen bonding, and hydrophobicity are responsible for the adsorption of OTC onto Fe-MCM-41-A.

Magnetite-Based Biosensors and Molecular Logic Gates: From Magnetite Synthesis to Application

“…A reaction in a constrained environment could be referred to as both a chemical and biological route of MNP synthesis with uniform dimensions, as various biological and synthetic reactors (templates) are used. They are protein cages of the iron storage proteins, ferritins, which are unique biomineralization systems [ 58 ]; phospholipid bilayers [ 59 ]; nanoporous materials with pore diameters from 2 to 50 nm [ 60 ]; stable dispersions of water/oil/surfactants [ 61 ], etc. Here we want to emphasize that, from our point of view, an ideal template for MNP synthesis is ferritin protein cages, as the protein protects newly formed MNPs from air oxygen oxidation and aggregation [ 62 ].…”

Magnetite Nanoparticles: Synthesis and Applications in Optics and Nanophotonics

“…One of the ways to produce magnetite nanoparticles with uniform dimensions is to perform the reaction in constrained environments. Different synthetic and biological reactors could be used for this synthesis, such as apoferritin protein cages [ 50 ], phospholipid membranes (micelles) [ 51 ], mesoporous materials [ 52 ], microemulsions [ 53 ], etc. Here, we would focus on apoferritin protein cages as constrained environments for magnetite nanoparticles synthesis.…”

A Study on the Ability of Nanomaterials to Adsorb NO and SO2 from Combustion Gases and the Effectiveness of Their Separation

“…Similarly, Cu-Zn-MCM-41 is a material with a linear uniform nanostructure and porous texture, forming an ordered arrangement of hexagonal channels with homogenous pore sizes [21]. Its uniform adsorption of NO and SO 2 shows that Cu and Zn loading does not compromise the mesopore structure [22].…”