FTIR和XPS对沸石合成特性及Cr(Ⅲ)去除机制的谱学表征

以粉煤灰为原料,采用优化的水热晶化法合成沸石,使用XRD,SEM和ζ电位分析沸石产品的组成特性,借助FTIR和XPS等揭示废水中Cr(Ⅲ)的去除机制。合成产品主要为NaP1型沸石,在pH值8～12区间内,ζ电位由-8.72mV降到-24.46mV。准二级方程和Langmuir等温线对试验的拟合效果更好,理论饱和吸附量为33.557 0mg.g-1。FTIR图谱表明—OH和Si—O类官能团在反应过程中有重要贡献。XPS全谱发现:结合能576.45eV为Cr(2p3/2)的特征峰,揭示了吸附过程的有效性。吸附Cr(Ⅲ)后,沸石中Si—Si和Si—O对应的结合能增加了0.25和0.60eV,含Si官能团可能与Cr(Ⅲ)发生了配位反应。O(1s)的结合能在反应后变得更低。这些证据表明:沸石对Cr(Ⅲ)的去除过程是物理吸附和化学吸附共同作用的结果。

FTIR and XPS analysis of characteristics of synthesized zeolite and removal mechanisms for Cr(III)

Zeolite products were synthesized from fly ash using one-stage method, and the characteristics of zeolite were analyzed with approaches of XRD, SEM and zeta potential, the removal mechanism for Cr(III) was further investigated by FTIR and XPS. From the pH value of 8 to 12, the negative zeta potential of NaP1 zeolite products decreased from -8.72 to -24.46 mV. The pseudo-second-order kinetics equation and Langmuir isotherm fit better the reaction, the maximum adsorption capacity was 33.557 0 mg x g(-1). Functional groups of -OH and Si-O were important for Cr(III) removal shown from FTIR spectra. The Cr(2p3/2) peak was found at the binding energy of 576.45 eV, indicating the effectiveness of reaction. The binding energy of Si-Si and Si-O increased by 0.25 eV and 0.60 eV, respectively, coordination effect might work between functional groups and Cr(III), and O(1s) binding energy decreased after the adsorption process. The removal for Cr(III) on zeolite was the comprehensive results of physical and chemical adsorption effects.