Solid-liquid separations with a temperature-responsive polymeric flocculant: effect of temperature and molecular weight on polymer adsorption and deposition.
Solid-liquid separations with a temperature-responsive polymeric flocculant: effect of temperature and molecular weight on polymer adsorption and deposition.
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DOI：
10.1016/j.jcis.2010.04.063
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发表时间：
2010-08
影响因子：
9.9
通讯作者：
J. O'Shea;G. Qiao;G. Franks
中科院分区：
文献类型：
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作者：
J. O'Shea;G. Qiao;G. Franks
研究了温度和分子量对温度响应性聚合物聚N-异丙基丙烯酰胺（PNIPAM）在硅铝矿物颗粒固液分离中的影响。在25°C下用PNIPAM给药的悬浮液是稳定的并且不沉降。当温度升高到高于聚合物低临界溶解温度（LCST）（>32°C）时，发现悬浮液具有高沉降速率、大颗粒聚集体尺寸和高悬浮液剪切屈服应力（τy）。这些悬浮液的沉积床固体的体积分数（MSF），被发现增加后，温度降低到低于聚合物LCST，并归因于减少有吸引力的颗粒-颗粒的相互作用所示的剪切屈服应力的相应减少，随着温度的降低。当悬浮液在25°C下投料并在50°C下沉降时，发现沉降速率随分子量增加。增加聚合物分子量导致在25°C下增加的分子聚合物吸附。随着温度从25°C升高至高于发生聚合物相分离的LCST，表面上更大的初始吸附量的聚合物产生更多的成核位点用于沉积额外的聚合物。当聚合物在50°C下投配时，沉降速率非常低。在这些条件下，聚合物分子彼此缔合以形成直径通常为1250 nm的聚合物聚集体。这些胶态聚合物聚集体不容易存款在颗粒表面上，使得矿物颗粒聚集不容易发生。
The effects of temperature and molecular weight of the temperature-responsive polymer, poly(N-isopropylacrylamide) (PNIPAM) were investigated in the solid–liquid separation of silica and alumina mineral particles. Suspensions dosed with PNIPAM at 25°C were stable and did not settle. When the temperature was raised above the polymer lower critical solution temperature (LCST) (>32°C), the suspensions were found to have high settling rates, large particle aggregate sizes and high suspension shear yield stresses (τy). The sediment bed solids volume fraction (ϕf), of these suspensions was found to increase after a temperature decrease below the polymer LCST and was attributed to a decrease in the attractive particle–particle interactions as shown by a corresponding decrease in shear yield stress, with decreasing temperature. Settling rates were found to increase with molecular weight when suspensions were dosed at 25°C and settled at 50°C. Increasing polymer molecular weight resulted in increased molecular polymer adsorption at 25°C. Greater initial adsorbed amounts of polymer on the surface produced more nucleation sites for deposition of additional polymer as the temperature was increased from 25°C to above the LCST where polymer phase separation occurred. When the polymer was dosed at 50°C, the rate of sedimentation was very low. Under these conditions, the polymer molecules associate with each other to form polymer aggregates of typically 1250nm diameter. These colloidal polymer aggregates do not readily deposit on the particles surfaces such that mineral particle aggregation does not readily occur.