Synthesis and surface engineering of magnetic nanoparticles for environmental cleanup and pesticide residue analysis: A review

Abstract

In recent years, water pollution and pesticide accumulation in the food chain have become a serious environmental and health hazard problem. Direct determination of these contaminants is a difficult task due to their low concentration level and the matrix interferences. Therefore, an efficient separation and preconcentration procedure is often required prior to the analysis. With the advancement in nanotechnology, various types of magnetic core-shell nanoparticles have successfully been synthesized and received considerable attention as sorbents for decontamination of diverse matrices. Magnetic core-shell nanoparticles with surface modifications have the advantages of large surface-area-to-volume ratio, high number of surface active sites, no secondary pollutant, and high magnetic properties. Due to their physicochemical properties, surface-modified magnetic core-shell nanoparticles exhibit high adsorption efficiency, high rate of removal of contaminants, and easy as well as rapid separation of adsorbent from solution via external magnetic field. Such facile separation is essential to improve the operation efficiency. In addition, reuse of nanoparticles would substantially reduce the treatment cost. In this review article, we have attempted to summarize recent studies that address the preconcentration methods of pesticide residue analysis and removal of toxic contaminants from aquatic systems using magnetic core-shell nanoparticles as adsorbents.

Synthesis of Polyhedral Magnetite Particles by Hydrothermal Process under High Pressure Condition

“…This iron oxide has a cubic inverse spinel structure as a common ferrite from iron oxides. Magnetite particles have been widely used in separation processes, heat transfer applications, medical applications, biosensors, dynamic sealing, recovery of metal irons, and so on [2][3][4]. Due to the wide potential application of magnetite particles, the synthesis of this material has been studied intensively in recent years, which has makes them suitable for diverse applications [5].…”

“…Several methods have been reported for the formation of magnetite particles in micro-nano scale, such as thermal decomposition, microemulsion, co-precipitation, and hydrothermal methods [2,4]. Each method has its advantages and disadvantages, hence it is difficult to choose one as the simplest or the most feasible for use in industrial methods.…”

“…However, controlling the particle size distribution in this method is restricted, because the crystal growth is controlled by kinetic factors. Therefore, a surfactant or stabilizers are needed in the reaction media to generate stabilized nanoparticles [2,4,6]. In thermal decomposition, magnetite particles are synthesized from organometallic compounds in high-boiling organic solvents.…”

“…Nonetheless, the particles formed frequently congregate with a large size distribution. Hence, surfactants are employed to inhibit the growth of the particles and enhance particle stabilization [2,4,7]. Magnetite particles can also be generated by a micro-emulsion consisting of two different immiscible liquids.…”

“…This method is difficult to control and therefore the particles are produced at a low yield in a relatively wide range of sizes and shapes and require a large amount of solvents. A simple and environmentally friendly method to generate metal oxide particles at micronano scale, including iron oxides, is hydrothermal treatment [2,4,8]. The hydrothermal method has advantages such as facility to control particle size and morphology by changing the pressure and temperature of synthesis; applicability to many materials via direct synthesis in the desired crystalline phase at relatively low temperature; and the ability to produce substances in an elemental oxidation state [8].…”