Research on magnetic separation for complex nickel deep removal and magnetic seed recycling

Abstract

This study investigated the deep removal of complex nickel from simulated wastewater using magnetic separation and magnetic seed recycling. Nano-magnetite (FeO) was used as the magnetic seed. The flocculant applied was N,N-bis-(dithiocarboxy) ethanediamine (EDTC), a highly efficient heavy metal chelating agent included in dithiocarbamate (DTC). Important investigated parameters included hydraulic retention time, magnetic seed dosage, and magnetic field strength. The study also explored the magnetic flocculation mechanism involved in the reaction. The result indicated that the residual Ni concentration was reduced to less than 0.1 mg/L from the initial concentration of 50 mg/L under optimal conditions. Magnetic seed recovery reached 76.42% after a 3-h stirring period; recycled magnetic seeds were analyzed using scanning electron microscope (SEM) and X-ray diffraction (XRD). The zeta potential results illustrated that magnetic seeds firmly combined with flocs when the pH ranged from 6.5 to 7.5 due to the electrostatic attraction. When the pH was less than 7, magnetic seeds and EDTC were also combined due to electrostatic attraction. Particle size did affect microfloc size; it decreased microfloc size and increased floc volume through magnetic seed loading. The effective binding sites between flocs and magnetic seeds increased when adding the magnetic seeds. This led the majority of magnetic flocs to be integrated with the magnetic seeds, which served as a nucleus to enhance the flocculation property and ultimately improve the nickel complex removal rate.

Adsorption of Methylene Blue on Azo Dye Wastewater by Molybdenum Disulfide Nanomaterials

“…At present, the common methods for treating dye wastewater include coagulation [6], ozone oxidation [7], photocatalytic oxidation [8], Fenton oxidation [9], magnetic separation [10], adsorption [11,12], etc. Among them, adsorption method makes the dye molecules in the solution phase transfer to the surface of adsorbent, which is favored because of its high efficiency, low cost, and easy operation.…”

Recovery of Microcrystalline Graphite from Quartz Using Magnetic Seeding

“…By adjusting the physicochemical properties of the target mineral and the magnetite, the magnetite selectively attaches to the target mineral and improves its magnetism. Once the selective attachment takes place, these magnetic agglomerates can be recovered by magnetic separation [15][16][17][18][19][20]. Such techniques have been explored both experimentally and theoretically in mineral processing practices.…”