To search a novel class of effective silicate mineral collectors,the Gemini quaternary ammonium salt surfactant(butane-α,ω-bis(dimethyl dodeculammonium bromide),12-4-12) and its corresponding conventional monomeric ...To search a novel class of effective silicate mineral collectors,the Gemini quaternary ammonium salt surfactant(butane-α,ω-bis(dimethyl dodeculammonium bromide),12-4-12) and its corresponding conventional monomeric surfactant(dedecyl trimethyl ammonium bromide,DTAB) were adopted to comparatively study the flotation behaviors of illite,pyrophyllite and kaolinite. Three silicate minerals with the Gemini surfactant as collector reveal floatability far better than with the corresponding traditional one. At pH 6,the best recoveries of illite,pyrophyllite and kaolinite with 3.5×10-4 mol/L 12-4-12 are 99.2%,91.7% and 99.6%,respectively. The fluorescence and contact angle measurement were also conducted for the further investigation of surfactants aggregation behavior and silicate mineral surface hydrophobic properties. FTIR spectra analysis and electrokinetic analysis show that the mechanism of adsorption of collector molecules on mineral surfaces is almost identical for the electronic attraction and hydrogen bonds effect. The superior collecting power of dimeric collector may be attributed primarily to its special structure and its essential properties.展开更多
Microwave irradiation was employed to assist the synthesis of poly(amino-quinone) (PAQ) from p-benzoquinone and diamines in solid state. The effects of power, time, and pattern (continuously or intermittently) of micr...Microwave irradiation was employed to assist the synthesis of poly(amino-quinone) (PAQ) from p-benzoquinone and diamines in solid state. The effects of power, time, and pattern (continuously or intermittently) of microwave irradiation on yield and intrinsic viscosity of PAQs were studied. It is shown that the continuous microwave irradiation at a high power leads to rapid increase of yield and a sudden halt in polymerization afterwards, due to the subsequent loss of volatile reactants at a high reaction temperature. Alternatively, the high-power microwave irradiation is applicable to raising the yield if used intermittently. In contrast, the low-power microwave irradiation favours the way of continuous exposure to ensure sufficient heat for polymerization. In both cases of high and low power, the yield and intrinsic viscosity can be further promoted by prolonging the exposure time. It is found that under a preliminarily optimized condition of intermittent irradiation at 490 W with six sequences of 5 min irradiation followed by 5 min interval, the yield and intrinsic viscosity of PAQ from p-benzoquinone and p-phenylene diamine can reach as high as 83% and 41.9 mL/g, respectively.展开更多
基金Project(2005CB623701) supported by the National Basic Research Program of ChinaProject(50874118) supported by the National Natural Science Foundation of ChinaProjet(2007B52) supported by the Foundation for the Author of National Excellent Doctoral Dissertation of China
文摘To search a novel class of effective silicate mineral collectors,the Gemini quaternary ammonium salt surfactant(butane-α,ω-bis(dimethyl dodeculammonium bromide),12-4-12) and its corresponding conventional monomeric surfactant(dedecyl trimethyl ammonium bromide,DTAB) were adopted to comparatively study the flotation behaviors of illite,pyrophyllite and kaolinite. Three silicate minerals with the Gemini surfactant as collector reveal floatability far better than with the corresponding traditional one. At pH 6,the best recoveries of illite,pyrophyllite and kaolinite with 3.5×10-4 mol/L 12-4-12 are 99.2%,91.7% and 99.6%,respectively. The fluorescence and contact angle measurement were also conducted for the further investigation of surfactants aggregation behavior and silicate mineral surface hydrophobic properties. FTIR spectra analysis and electrokinetic analysis show that the mechanism of adsorption of collector molecules on mineral surfaces is almost identical for the electronic attraction and hydrogen bonds effect. The superior collecting power of dimeric collector may be attributed primarily to its special structure and its essential properties.
基金Project(50804055) supported by the National Natural Science Foundation of China
文摘Microwave irradiation was employed to assist the synthesis of poly(amino-quinone) (PAQ) from p-benzoquinone and diamines in solid state. The effects of power, time, and pattern (continuously or intermittently) of microwave irradiation on yield and intrinsic viscosity of PAQs were studied. It is shown that the continuous microwave irradiation at a high power leads to rapid increase of yield and a sudden halt in polymerization afterwards, due to the subsequent loss of volatile reactants at a high reaction temperature. Alternatively, the high-power microwave irradiation is applicable to raising the yield if used intermittently. In contrast, the low-power microwave irradiation favours the way of continuous exposure to ensure sufficient heat for polymerization. In both cases of high and low power, the yield and intrinsic viscosity can be further promoted by prolonging the exposure time. It is found that under a preliminarily optimized condition of intermittent irradiation at 490 W with six sequences of 5 min irradiation followed by 5 min interval, the yield and intrinsic viscosity of PAQ from p-benzoquinone and p-phenylene diamine can reach as high as 83% and 41.9 mL/g, respectively.
