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中南学子木虫 (正式写手)
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Generally, the fly ash particles exhibit a pH of 7.0. This indicates that at pH lower than 7.0, the fly ash surface is positively charged and the opposite is true at pH higher than 7.0。Therefore, under the pH conditions at adsorption equilibrium, i.e. pH 4.0–5.0 for both Zn(II) and Ni(II) wastewaters, the surface of the fly ash is negatively charged. At low pH the surfaces of the fly ash were positive and there was a formation of complex [Pb(OH)4]2- and [Cu(OH)4]2-, the complex formed will be adsorbed on the fly ash surfaces. Hydroxyl-metal complex has higher affinity for adsorption than hydrated metal ion, because the formation of an OH group of the metal ion reduces the free energy required for adsorption。Similar results have been reported by other workers working on the adsorption of heavy metal ions on fly ash。At higher pH, the surfaces of the adsorbent were negative and there was an increase on the uptake of Pb2+ and Cu2+ ions by the fly ash. The increase on metal ion uptake, may be explained in terms of electrostatic interaction. This canbe seen by the sharp increase on the amount of metal ions uptake as pH increase from 6 to 10 for Pb2+ ions. The increase in metal ions uptake by fly ash at higher pH values may be attributed to calcium content and (SiO2+Al2O3 + Fe2O3) content that provides alkalinity in the system raising the pH to strongly alkaline values, thereby facilitating the uptake of Pb2+ and Cu2+ ions by the fly ash. At lower pH values between 4 and 6, Cu2+ and Pb2+ ions may be removed from solution by precipitation and can be adsorbed on the surface of fly ash. This is shown by decrease in adsorption by lead ions at lower pH values between 4 and 6. Whereas, at higher pH values higher degree of precipitation of metal ions occur, because hydration of fly ash increases its pH between 10 and 13. Similar results have been reported by some workers working on the adsorption of heavy metal ions on fly ash。 请大侠帮忙翻译一下这2段文字，谢谢~ |
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一般来说,粉煤灰粒子展示的7.0。这表明在pH值低于700、粉煤灰面带正电,事实正好相反,pH值高于7.0.Therefore pH值条件下,4.0-5.0吸附平衡pH值,即为锌(II)和镍(2),粉煤灰的表面 带负电。 在低pH的表面、粉煤灰的形成是一个复杂的[铅(哦)4]和[铜(2 - 2 - 4),复杂的形成将吸附粉煤灰的表面。Hydroxyl-metal复杂的具有较高的亲和力吸附金属离子,因为比水分形成一个哦组中的金属离子减少所需的自由能量adsorption.Similar结果已经 其他的工人在吸附重金属离子对飞ash.At更高的酸碱度,表面的吸附是负面的,有一个 增加的Pb2 +和Cu2 +离子的粉煤灰。增加对金属离子的吸收,可以解释静电相互作用。这个主要的急剧增加的数量上提高金属离子摄取如酸碱度由6至10条为Pb2 +离子。增加了金属离子在高吸粉煤灰的酸碱值可以归结为钙含量和二氧化硅+氧化铝+ Fe2O3)。 内容提供碱度的体系,提高pH值,从而促进强碱性的Pb2 +和Cu2 +离子的粉煤灰。在低pH值4点到6点之间,Cu2 +和Pb2 +离子可以移去解决,可通过降水的表面吸附在飞灰。这是减少铅的吸附离子之间的酸碱值较低4和 6。相反,在较高的酸碱值较高的降水中的金属离子发生,因为水化的粉煤灰增加10%和pH值。类似的结果已经由一些工人的工作条件下的吸附重金属离子对粉煤灰。 |
7楼2009-12-19 16:01:23
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2楼2009-12-09 12:27:40
3楼2009-12-09 12:46:12
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4楼2009-12-09 13:15:12