粉煤灰合成沸石去除溶液中硒(Ⅳ)影响因素研究

Study on Removing Selenium(Ⅳ) from Aqueous Solution by Fly-ash Synthesized Zeolite: Influencing Factors

利用粉煤灰为原料合成沸石,研究了合成沸石对溶液中硒(Ⅳ)的去除能力,分析硒(Ⅳ)溶液的初始pH值、沸石投加量、初始浓度、接触时间及温度对吸附过程的影响。结果表明,合成沸石的主要成分为一种无名沸石,沸石吸附硒(Ⅳ)呈现"快速吸附,缓慢平衡"的特点,硒(Ⅳ)的去除率受pH影响较大,当pH<2.0时具有很好的吸附效果,硒(Ⅳ)的去除率随初始浓度的增加而减小,随投加量的增加先增加后减小。吸附过程符合一级反应动力学模型,且基本符合Langmuir和Freundlich吸附等温线模型,而Langmuir吸附等温线模型对吸附数据具有更好的非线性拟合效果,合成沸石对硒(Ⅳ)的最大吸附量为5.36 mg/g。利用粉煤灰合成沸石不仅能较高效地去除水体中的硒(Ⅳ),且实现了粉煤灰的资源化利用。

In this experimental study zeolite is made from fly ash by the synthesis method, with which capacity of selenium（Ⅳ） removal from an aqueous solution is investigated. The influencing factors, such as pH value, adsorbent dosage, initial selenium（Ⅳ） concentration, contact time and temperature were analyzed by batch adsorption experiments. The findings of the study suggest that the main components of the synthesized zeolite is a kind of unnamed zeolite, the adsorption process of selenium（Ⅳ） is characterized by‘fast adsorption and slow balance＇, and the removal efficiency of selenium（Ⅳ） is considerably affected by pH value, with the better adsorption effects as pH drops below 2.0; the removal efficiency decreased with the increase of initial selenium（Ⅳ） concentration, increasing with the increase of dosage at first, then decreased. As to the adsorption mechanism, the process followed the pseudo-first-order model, fitting well with the Langmuir and Freundlich isotherm models, while the Langmuir model is better in respect to non-linear fitting; and the maximum selenium（Ⅳ） adsorption capacity of the synthesized reaches 5.36 mg/g. In conclusion, the utilizing of synthesize zeolite not only effectively remove selenium（Ⅳ）, but also realize the reclamation of fly ash.