研究报告
焦健,裴元生.给水厂废弃铁铝泥对镉的吸附特征及影响因素[J].环境科学学报,2016,36(3):842-849
给水厂废弃铁铝泥对镉的吸附特征及影响因素
- Characteristics and influence factors for cadmium adsorption by ferric and alum residuals from drinking water treatment
- 基金项目：国家科技支撑计划项目(No.2012BAJ21B08);国家自然科学基金(No.51278055)
- 作者
- 单位
- 焦健
- 北京师范大学环境学院水沙科学教育部重点实验室, 北京 100875
- 裴元生
- 北京师范大学环境学院水沙科学教育部重点实验室, 北京 100875
- 摘要：通过批量实验探讨了给水厂废弃铁铝泥(Ferric and Alum Water Treatment Residuals,FARs)对Cd2+的吸附特征及影响因素.实验结果表明,在最初的6 h内,FARs对Cd2+的吸附量已经达到其平衡吸附量的90%,吸附较符合伪二级动力学模型(R2=0.99),并且Langmuir (R2=0.99)和Freundlich (R2=0.90)方程均能较好地描述FARs对Cd2+的等温吸附过程,其Cd2+的饱和吸附量达35.39 mg·g-1.初始溶液pH由3.0增加到8.0时,FARs对Cd2+的吸附量缓慢增加,当pH升为9.0时,其对Cd2+去除率可达97%.FARs对Cd2+的吸附量随溶液体系离子强度的增加而减小.随着柠檬酸浓度的升高,FARs对Cd2+的吸附量显著降低,而水杨酸和酒石酸则微弱促进了对Cd2+的吸附.解吸实验证明,在pH为3.0时Cd2+的解吸率最高,但仅为11%左右.分级提取结果进一步表明,被吸附的Cd2+主要以酸溶态和残渣态存在.综合实验结果表明,FARs可以作为一种高效的吸附剂用于水体除镉.
- Abstract：Batch experiments were conducted to investigate the characteristics and influence factors for cadmium (Cd2+) adsorption onto ferric and alum water treatment residuals (FARs). The results showed that the majority (90%) of Cd2+ was adsorbed by FARs within six hours and the process was best fitted into the pseudo-second-order kinetics equation (R2=0.99). The steady-state adsorption followed the Langmuir isotherm (R2=0.99) and the Freundlich isotherm (R2=0.90). The maximal adsorption capacity reached 35.39 mg·g-1 based on the Langmuir isotherm. The capacities of Cd2+ adsorption increased slowly in the pH range of 3 to 8, and a high Cd2+ adsorption rate (97%) was observed at a pH of 9. Cadmium adsorption decreased with the increase of ionic strength. As the concentration of citric acid increased, the adsorption of Cd2+ decreased significantly, while adsorption was slightly enhanced in the presence of salicylic acid and tartaric acid. The results from desorption experiments demonstrated that the highest desorption rate was observed at pH 3 and only reached approximately 11%. Fractionation and extraction tests revealed that the absorbed Cd2+ existed mainly in acid-soluble and residual forms. In all, our results demonstrated that FARs can be effective adsorbents for the removal of Cd2+ in surface water.
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