Search

Abstract A massive release of harmful substances especially heavy metal ions and dyes to the environment has been a major concern due to many people disregards the proper protocols in the waste management. The freshwater supplies are threatened and huge discharge of pollutants result from various anthropogenic activities may pose a major threat to the living organisms and negatively affect the ecosystem stability. This article reviews the development of magnetic iron oxide nanocomposites for removal of heavy metal ions and dyes from water. The highlight will be focused on current research activities for controlled size and dispersion of magnetic iron oxide nanoparticles within solid matrices including zeolites, silica, clays, carbon, activated carbon, graphene and graphene oxide. The magnetic properties of the nanocomposites will be evaluated to determine whether they possessed sufficient magnetization for easy separation by an external magnet. The unique features of the synthesized materials will be investigated along with their application in the removal of heavy metal ions and dyes. The advantages and limitations of the magnetic nanocomposites will be highlighted to determine their adsorption ability. The effect of various parameters such as pH, contaminants concentration, adsorbent dosage, contact time and temperature will be summarized to identify the best condition for effective pollutants removal. Graphical abstract Image 1 Highlights • Synthesis, properties and application of magnetic iron oxide NCs for the adsorption of heavy metal ions and dyes. • Methods for the preparation of magnetic iron oxide NCs with control over the size, morphology and the magnetic properties. • Factors affecting the adsorption of heavy metal ions and dyes in water by magnetic iron oxide NCs. • Influence of the iron oxide loading and specific surface area of NCs on removal of heavy metal ions and dyes in water. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the effect of OH concentration on the size of Fe3O4 nanoparticles (Fe3O4-NPs). Fe3O4-NPs with different cubic nanocrystal structure and percentage Fe3O4 content were successfully prepared, by use of the chemical co-precipitation method, on the exterior surface of talc, as solid substrate, by an environmentally friendly process. Ferric chloride, ferrous chloride, and sodium hydroxide were used as iron oxide precursors and reducing agent. The results showed that the morphology of the Fe3O4-NPs can be adjusted by changing the reaction conditions, for example volume of reducing agent and concentration of iron salts. Different size, dispersal, and the magnetic properties were obtained by changing the concentration of iron salts and NaOH. The products were characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier-transform infrared spectroscopy. The reaction was conducted in a non-oxidizing, oxygen-free environment. Because the interlamellar spacing of the talc was almost unchanged (ds = 0.94-0.87 nm), the Fe3O4-NPs were formed on the exterior surface of the talc. The average diameter of the Fe3O4-NCs could be varied from 6.62-8.13 nm in adjusting the concentration of NaOH. The size of the nanoparticles decreased as the amount of reducing agent was increased. These talc-Fe3O4nanocomposites (talc-Fe3O4-NCs) may have potential applications in the chemical and biological industries. [ABSTRACT FROM AUTHOR]

The goal of this study was to prepare nanocomposites of rice straw coated with different percentages of Fe3O4 nanoparticles (Fe3O4-NPs) [1.0, 5.0, 10.0, and 20.0 wt. %]. In this process, the size of Fe3O4-NPs changed with varying volumes of NaOH (2M). The Fe3O4-NPs were precipitated with sodium hydroxide from a solution of Fe(II) and (III) chloride in water under ambient conditions and N2 gas by the quick precipitation method using urea as a stabilizer. The rice straw/Fe3O4 nanocomposites (NCs) prepared by this method had magnetic properties in percentages higher than ten (10 wt. %). When the volume of NaOH increased, Fe3O4-NPs with uniform size and better distribution could be prepared, which means that the size of the NPs decreased as the reducing agent was increased. Transmission electron microscopy (TEM) showed that Fe3O4-NPs in rice straw were spherical with diameters from 18.47 to 9.93 nm. The SEM results show that the structure of rice straw underwent no particular change. EDX indicated the presence of Fe3O4- NPs on the surface of rice straw. X-ray powder diffraction (PXRD) indicated that the magnetic Fe3O4-NPs were pure and that the particles were small. The FT-IR results showed that the Fe3O4-NPs were successfully coated on the surface of rice straw. [ABSTRACT FROM AUTHOR]

A green quick precipitation method was successfully used for synthesis of magnetic iron oxide nanoparticles (Fe3O4-NPs) on the surface of sodium/potassium type zeolite. Ferric chloride, ferrous chloride and sodium hydroxide aqueous solutions were used in the synthesis and coating of the Fe3O4-NPs on the surface of the zeolite to produce the zeolite/magnetic iron oxide nanocomposite (zeolite/Fe3O4 -NCs). The reaction was performed in aqueous suspension phase under the ambient condition as green chemistry method. Characterization with Fourier transforms infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), energy dispersive X-ray fluorescence (EDXF) and transmission electron microscopy (TEM) confirmed the formation of Fe3O4-NPs with mean particle sizes of 3.55±1.02 nm on the surface of the zeolite. [ABSTRACT FROM AUTHOR]