铁覆膜砂制备温度对其吸附Cr(Ⅵ)性能的影响

The Preparation Temperature of Iron-oxide-coated Sand Effect on the Hexad Chromium Adsorption Characters

本文研究了不同温度下制备的铁覆膜砂吸附性能的差异,对铁覆膜砂吸附Cr(Ⅵ)的性能进行了综合的测试,说明了形成这些差异的内在原因制备温度对IOCS的吸附性能有显著影响,一般低温制备的IOCS要比高温制备的铁覆膜砂吸附性容量较大,去除效率较高;覆盖在石英砂表面的铁氧化物在不同的焙烧温度下形成了不同的物质,110℃的低温一般形成FeOOH(针铁矿),而600℃高温下形成的则为α-Fe2O3(赤铁矿)。IOCS吸附Cr(Ⅵ)为典型的Langmuir模型,为单分子层吸附。IOCS对pH值的影响表现出一个相同的特性:低pH高吸附、高pH低吸附。IOCS的吸附速率初期较快,很快上升到一个平台,其后变化很小或基本没有什么变化。对于浓度为20mg/L的Cr(Ⅵ),IOCS的最佳用量为2.5g左右。

In this paper, the Iron-oxide-coated sand absorption character prepared in different temperatures was studied, mainly tested its absorb hexad chromium, and the inherent reason that formed this differences was explained. Torrefaction temperature is the most important factor affected IOCS's absorption character. The IOCS prepared in the low temperature have more absorption capacity than its prepared in the high temperature. The iron-oxide coated onto quartz sand surface formed different matter: it formed goethite in the temperature of 110, became hematite in the temperature of 600, this is the main reason caused absorption character difference. IOCS absorption to hexad chromium is typical Langmuir model. In the course of absorption, IOCS behave the commonness to absorption anion: the absorption rate is high in the acidic condition, but is very low alkaline condition, the sand prepared in different temperature have dissimilar response to pH' s influence. The kinetic curve of IOCS absorption to hexad chromium change with time: a rapid step followed by a much slower second step, the high sand have a delayed process compared with the low sand. In the experiment of absorption 20mg/L hexad chromium, the optimal dosage of sand are 2.5g, and the absorption capacity of low sand is 3 5 time to high sand sample.