磷酰基乙酸改性粉煤灰基SBA-15及选择性吸附稀土性能

Phosphorylacetic acid modified fly ash-based SBA-15 and its selective adsorption of rare earth

摘要:

以粉煤灰为硅源合成了介孔二氧化硅SBA-15，对其进行磷酰基乙酸（PAA）功能化改性制备了PAA-SBA-15吸附剂，对改性前后的吸附剂进行了XRD，N2-吸脱附、红外光谱表征。结果显示，改性后SBA-15的孔道保持高度有序。将PAA-SBA-15用于模拟溶液中稀土离子吸附，发现PAA-SBA-15对Eu3+、Gd3+、Tb3+、Nd3+和Sm3+的吸附容量分别可达18.6、23.2、21.9、22.6和20.2 mg/g。考察了竞争离子Ca2+、Mg2+、Al3+和Fe3+对稀土离子吸附的影响。结果显示，Fe3+的存在对PAA-SBA-15吸附稀土离子干扰性最强。吸附动力学和热力学结果显示，PAA-SBA-15对稀土离子的吸附符合准二级动力学和Langmuir等温吸附模型，吸附过程中化学吸附占主导作用。

Abstract:

Mesoporous silica SBA-15 was synthesized using fly ash as silicon source, PAA-SBA-15 adsorption material was prepared by surface modification of phosphoryl acetic acid (PAA), and XRD diffraction N2-adsorption desorption and infrared spectrometer characterization were performed on the adsorption material before and after the modification. The results showed that the highly ordered pores in the adsorbent material remained after modification. The PAA-SBA-15 adsorbent was used to adsorb rare earth ions, and it was found that the adsorption capacity for Eu3+, Gd3+, Tb3+, Nd3+, Sm3+ reached 18.6, 23.2, 21.9, 22.6, 20.2 mg/g, respectively. The influence of competing ions Ca2+, Mg2+, Al3+, Fe3+ on the adsorption of rare earths was studied, the results showed that Fe3+ reduced significantly the adsorption efficiency of rare earths. Adsorption kinetics and thermodynamics showed that the adsorption process fitted second level kinetics and Langmuir model, indicating chemical adsorption is dominated in the adsorption process.