摘要
研究了粉煤灰的浓硫酸改性以及改性后的粉煤灰从水中净化磷的过程。通过实验发现粉煤灰改性后对水中磷的净化效果有显著提高。粉煤灰用浓硫酸进行改性后比表面积从8.8m2/g增加到32.5m2/g。而且用浓硫酸改性后,粉煤灰中的金属离子在酸性条件下部分溶解或完全溶解,导致净化过程中水溶液中金属离子浓度增大。改性粉煤灰净化含磷废水的过程中,存在吸附机理和沉淀机理,但沉淀对磷的净化起主要作用。实验结果表明,改性粉煤灰对磷的净化过程速度较快,5min可以达到最大净化率。在pH 5—9范围内磷净化过程影响不显著。通过实验还发现磷的净化率随吸附剂用量的增加而增加。改性粉煤灰对磷的吸附过程比较符合Langmuir吸附等温线,Langmuir常数Q0为9.15mg.g-1。从吸附磷后的改性粉煤灰的XRD图和SEM图可以发现在磷的净化过程中生成了CaHPO4.2H2O,此外磷也与铁和铝反应形成沉淀。
The fly ash was modified by concentrated sulfuric acid,and the process for removal of phosphorus from aqueous solution by modified fly ash was investigated.It was found that modification of fly ash could significantly enhance the purification effect of phosphorus.The specific surface area of the fly ash increased from 8.8m^2/g to 32.5m^2/g after treatment with sulfuric acid.The modification of the fly ash also resulted in increasing of concentrations of acid-soluble metal ions due to partial or complete dissolution of the metals under the acidic conditions.Both adsorption and precipitation mechanism contributed to the removal of phosphorus by the modified fly ash,but precipitation was a major mechanism of phosphorus removal.The experimental results showed that removal of phosphorus by the modified fly ash was quick,and the removal percentage of phosphorus could reach maximum value in 5 minutes.In the pH range of 5 to 9,pH did not significantly affect the removal process of phosphorus.The removal percentage of phosphorus increased with the increasing of adsorbent dosage.The adsorption process of phosphorus by the modified fly ash could be described well by Langmuir isotherm equation,and the Langmuir constant Q0 was 9.15mg·g^-1.It was obtained from XRD patterns and SEM images of modified fly ash after adsorption of phosphorus that CaHPO4·2H2O was formed in the removal of phosphorus.In addition,phosphorus also formed precipitate with aluminum and iron.
出处
《光谱实验室》
CAS
CSCD
2012年第5期2761-2768,共8页
Chinese Journal of Spectroscopy Laboratory
基金
河南省教育厅自然科学项目(2008B610013)
关键词
粉煤灰
改性
磷
净化
Fly Ash
Modification
Phosphate
Removal
