Development and optimization of magnetic technologies based processes for removal of some toxic heavy metals

Abstract

In the developing countries where the cost is often a decisive factor, extensive studies were undertaken to test the most effective factors on the preparation, optimization and validation of the magnetic particles (or, more accurately, magnetizable particles) for removal of heavy metals from wastewaters. The objective of the proposed work was focused to provide promising solid-phase materials, which, are relatively in expensive and combine high surface capacity with fast efficient treatment. Four various metal oxides including hydrous ferric oxide (HFO), hydrous stannic oxide (HSO) and mixed ferric/stannic oxide (HMO), were prepared by precipitation with ammonia from metal chloride solutions. Two mixed oxides were prepared with different Sn/Fe ratios of 50% and 20%. Optimal conditions for the activation of these particles and the subsequent mixing of various metals oxides are tested together with the utility of the method to get a new composite material with developed chemical characteristics over their individual metal oxides. Factors affecting the sorption behavior of the prepared samples in basic and acid media were elucidated. The magnetic treatment procedure using the mixed oxide (50%) enables the equilibration step to be carried out rapidly mainly due to ferric oxide during the magnetization process and efficiently due to high capacity of the stannic oxide. A key factor in achieving very high uptake percentage is the reduction of non-specific binding of various heavy metals to the solid phase support. This is usually achieved by increasing the ion exchange capability, in addition to their adsorption process.

Silica coated magnetite particles for magnetic removal of Hg2+ from water

“…For example, high selective hollow mesoporous aluminosilicate spheres with nanosized Fe 3 O 4 cores are suitable for adsorption of Hg 2+ [27]. Iron oxide nanoparticles dispersed in chelating resins or coated with adequate chelating agents have been used for the removal of a wide range of metal ions from wastewater [28][29][30][31][32][33][34][35][36], overall displaying higher adsorption capacity than traditional materials such as activated carbon [37][38][39]. More recently, silica coated Fe 3 O 4 functionalized with c-mercaptopropyltrimethoxysilane have been successfully applied for extraction of Cd 2+ , Cu 2+ , Hg 2+ and Pb 2+ in a wide pH range and even in the presence of foreign ions acting as interferents such as Al 3+ , Fe 3+ and Cl À [40].…”

Micromixing Efficiency of Particles in Heavy Metal Removal Processes under Various Inlet Conditions

“…For example, high selective hollow mesoporous aluminosilicate spheres with nanosized Fe 3 O 4 cores are suitable for adsorption of Hg 2+ [20]. Iron oxide nanoparticles dispersed in chelating resins or coated with adequate chelating agents have been used for the removal of a wide range of metal ions from wastewater [21][22][23], overall displaying higher adsorption capacity than traditional materials such as activated carbon [24][25][26]. Silica-coated Fe 3 O 4 functionalized with c-mercaptopropyltrimethoxysilane have been successfully applied for extraction of Cd 2+ , Cu 2+ , Hg 2+ , and Pb 2+ in a wide pH range and even in the presence of foreign ions acting as interferents such as Al 3+ , Fe 3+ , and Cl − [27].…”

Ultra sensitive quantification of Hg2+ sorption by functionalized nanoparticles using radioactive tracker spectroscopy

“…Iron oxide nanoparticles (NP), in particular, form a promising class of magnetic sorbents for environmental applications, due to their separation capability from aqueous solutions by application of an external magnetic field 6,7 . In recent work, we developed magnetic sorbents based on silica-coated magnetite NP functionalized with dithiocarbamate (DTC) groups for the uptake of Hg(II) from water.…”