Search

The effects of cations stress of magnesium ion and sodium ion on the low-grade nickel sulfide ore oxidative leaching in simulated sulfuric acid solutions were investigated. This study was performed in two courses, including the effect of the cations on the valuable metals leaching efficiencies of the nickel ore and its influences on the electrochemical oxidation behavior of the nickel ore. The leaching results present that parts of magnesium-containing gangues and ferrous sulfide are preferentially dissolved into lixivium, and the leaching efficiencies of Ni and Cu decreased much related to the leached concentrations of Mg2+ increased. The results of electrochemical measurements show that the oxidation leaching of the low-grade nickel sulfide ore is controlled by the intermediates oxidative diffusion. Mg2+, as well as Na+, affects the transformations of the Fe3+/Fe2+ couple and sulfur-containing species, and those cations are apt to be attracted by the anions and directionally adhere to the negative active site of the metal sulfide surface, causing an increase in the electrochemical activities, which facilitates the electron transfer between the ore and leaching mediums. By comparative study of the role of Mg2+ and Na+, it is found that Mg2+ negatively affects the oxidative diffusion of the intermediates through promoting the generation of a compact film, which lowers the metals leached efficiencies, and the unfavorable effect of Na+ tends to be the coupled effect of the leached Mg2+ and Fe3+.

In this paper, a new method for the comprehensive recovery and recycle of jarosite residues (JR) is proposed. By direct reduction followed by magnetic separation, lead, zinc and iron are separated and recovered from JR and sulfur is fixed. The non-magnetic tails (NMT) of the magnetic separation is used for removing of Cd, As and Pb heavy metal ions from acidic wastewater of zinc hydrometallurgy. Test work results showed that the volatilization rates of lead and zinc were 96.97% and 99.89%, respectively, the sulfur fixation rate with CaO was 98.91% under optimal conditions of reduced roasting at 1523 K for 60 min. A magnetic iron concentrate was obtained containing 95.68% iron at a recovery of 76.26% by grinding-magnetic separation process. The removal rates of Cd, As and Pb ions were 99.98%, 93.75% and 99.80% respectively. The content of Cd, As and Pb ions in the treated wastewater met the emission standards at 120 g/L NMT dosage and for a contact time of 90 mins. The proposed method is considered as an environmentally-friendly and efficient approach to the comprehensive recovery and recycle of JR and the removal of toxic cadmium, arsenic and lead ions from acidic wastewater of zinc hydrometallurgy.

Recently, the development of methods for the cleanup of large-scale oil spills or organic pollutants from water has been attracting global attention. However, traditional techniques suffer from the limits of low efficiency and high operation cost. Herein, we propose a high efficiency, large-scale and easy operation approach to fabricate a hydrophobic and oleophilic high density polyethylene microfiber bundles with interconnected microchannels for oil/water separation. The microfiber bundles with high porosity, excellent absorption capacity and large water contact angle are continuously fabricated by a melt extrusion and leaching technique. More importantly, they are readily cleaned by centrifugation and exhibit excellent shape-recoverable property, which are very promising for the cleanup of large-scale oil spills. This study provides a great promising way to fabricate multifunctional polymer materials by using common polymer molding method.

Polyaniline-modified TiO2 nanotube arrays (PANI/TNTs) were fabricated by a constant voltage electropolymerization method. The self-organized TiO2 nanotube arrays with an inner diameter of approximately 100 nm and a length of 4 μm were prepared by a two-step anodization at 20 V for 3 h, and then the polyaniline was deposited on the surface of the TiO2 nanotube arrays. The phase composition, morphology and property of PANI/TNTs were characterized by X-ray diffraction, scanning electron microscopy, fourier transform infrared spectroscopy and UV-vis diffuse reflectance spectroscopy. The prepared PANI/TNTs showed enhanced visible light absorption and corresponding visible light photocatalytic activity. Furthermore, the PANI/TNTs also exhibited higher electrochemical behaviour than that of TiO2 nanotube arrays.

The solubilities of 1-fluoro-4-(methylsulfonyl)benzene in five pure organic solvents (ethanol, ethyl acetate, acetone, toluene, and chloroform) at temperatures ranging from (288.40 to 331.50) K under atmospheric pressure were measured experimentally by the dynamic method with a laser monitoring apparatus. It was found that the solubilities in different solvents decreased in the order chloroform > acetone > ethyl acetate > toluene > ethanol. The experimental data were well-correlated using the modified Apelblat equation, with average relative deviations of less than 2.92 % and root-mean-square deviations of no more than 0.30 %.