Determination of phenols in natural and waste waters by capillary electrophoresis after preconcentration on magnetic nanoparticles coated with aminated hypercrosslinked polystyrene

An efficient sorbent for magnetic solid-phase extraction was developed from Fe₃ O₄ nanoparticles covered with aminated hypercrosslinked polystyrene. The sorbent has a saturation magnetization of 47 emu/g and a surface area of 509 mg/g and was tested for the extraction of 11 phenols from aqueous media. The optimum conditions were as follows: pH 3; adsorbent mass, 20.0 mg; adsorption time, 30 min; eluent (acetone) volume, 0.5 mL; and desorption time, 5 min. The enrichment factor after desorption reached 1595-1716 and the maximum adsorption capacity was 501-909 mg/g. Capillary electrophoresis was applied successively to separate 11 phenols after solid-phase extraction. The best separation was achieved using a fused silica capillary and borate buffer (pH 10.7) as a supporting electrolyte. After optimization, the linearity range was from 0.2 to 950 μg/L, and the limits of detection were 0.05-0.2 μg/L. The relative standard deviation varied from 6.1 to 8.7% (C = 1 μg/L) and from 2.9 to 3.5% (C = 500 μg/L). The determination of phenols is complicated in eutrophic water and spring water with a high content of humic and fulvic acids.

Recovery of γ-Fe2O3 from copper ore tailings by magnetization roasting and magnetic separation

To comprehensively reuse copper ore tailings, the recovery of γ-Fe2O3 from magnetic roasted slag after sulfur release from copper ore tailings followed by magnetic separation is performed. In this work, after analysis of chemical composition and mineralogical phase composition, the effects of parameters in both magnetization roasting and magnetic separation process with respect to roasting temperature, residence time, airflow, particle size distribution, magnetic field intensity, and the ratio of sodium dodecyl sulfonate to roasted slag were investigated. Under optimum parameters, a great number of γ-Fe2O3 is recycled with a grade of 66.86% and a yield rate of 67.21%. Meanwhile, the microstructure, phase transformation and magnetic property of copper ore tailings, roasted slag, and magnetic concentrate are carried out.