Characterization of a hybrid polyacrylamide and its flocculation properties in cyanide tailing suspensions.

An inorganic-organic hybrid flocculant Al(OH)3-polyacrylamide (Al-PAM) with narrow molecular weight distribution was synthesized using inverse microemulsion polymerization. The hybrid polymer Al-PAM was characterized by Infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy and scanning electron microscopy, and it was found that it had a 'star-like' structure in which Al(OH)3 colloidal particles acted as cores linking PAM chains. The properties of Al-PAM were investigated in flocculating 10 wt% cyanide tailing suspensions. It was found that as the amount of Al-PAMM1 with high molecular weight and aluminum content increased, the initial settling rate of particles accelerated, achieving the maximum 6.6 m/h, 17.3 times the rate of the control without flocculants. The turbidity of the supernatant decreased to 35 ± 2 NTU accordingly, compared to 353 ± 2 NTU of that in the control, which meant that 90.0% of turbidity was removed from the cyanide tailing suspensions. The flocculation mechanism was further explored by floccule size and ζ potential measurements. The superior performance of cationic Al-PAM in flocculating negatively charged particles compared to commercial non-ionic GG indicated that electrostatic repulsion between tailing particles was a crucial factor in deciding the flocculation performance of the polymer. The study demonstrated that both charge neutralization and bridge adsorption were conductive to the particle flocculation.

Efficient photocatalytic reduction of aqueous Cr(VI) over flower-like SnIn4S8 microspheres under visible light illumination.

Photocatalytic reduction of aqueous Cr(VI) was successfully achieved on nanostructured SnIn(4)S(8). The SnIn(4)S(8) particles with flower-like nanostructure were synthesized via a facile solvothermal method. UV-vis diffuse reflectance spectra (DRS) indicated that the SnIn(4)S(8) particles had strong absorption in visible region and the band gap was estimated to be from 2.27 to 2.35 eV. The photocatalytic reduction of aqueous Cr(VI) by flower-like SnIn(4)S(8) was evaluated under visible light (λ>400 nm) irradiation. The polyvinyl pyrrolidone (PVP) assisted SnIn(4)S(8) sample exhibits excellent removal efficiency of Cr(VI) (~97%) and good photocatalytic stability. The predominant photocatalytic activity is due to its large surface area, strong absorption in visible-light region and excellent charge separation characteristics.

[Study on co-pyrolysis of coking-coal, plastic and dust].

The co-pyrolysis processes of different proportions of coking-coal, plastic, metallurgical dust (MD) were investigated using thermal analyzer (Setaram Labsys) under a neutral atmosphere of N2 at the sweep rate of 30 mL/min, the linear heating rate and the final pyrolysis temperature were 5 degrees C/min and 1000 degrees C respectively in this study. The experimental results indicated that both the pyrolysis process of coking-coal and that of plastic were radical mechanism. In other word, within the relatively lower temperature range, a large amount of radicals were generated during their pyrolysis processes and stabilized through the intra-radical rearrangement reactions or inter-radical combination reactions. This means that sulfur containing in coal and plastic tends to formed gaseous sulfides, such as H2S, COS, CS2, etc. When co-existing with MD, these sulfides will react with metal oxides containing in MD to form metal sulfide with high stability and the cleaner coke oven gas (COG) were obtained. Within higher temperature interval of 500 degrees C-1000 degrees C, some of the gaseous products after pyrolysis (e.g. H2, CO and C) reinforce the reduction atmosphere that the coking reaction system needs and accelerate the reduction of metal oxides in MD and gasification of metal, which were conductive to the effective removal of sulfur in coke. Therefore, it is definitely feasible to adding waste plastic and MD into coking-coal to remove the sulfur in COG and coke simultaneously.