Chang Zhibing, Yan Yinuo, Bai Lu, Guo Nan, Xing Zhenguo, Lu Chunwei
School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083, China.
State Key Laboratory of Water Resource Protection and Utilization in Coal Mining, Beijing 102211, China.
ACS Omega. 2024 Dec 16;9(52):51237-51252. doi: 10.1021/acsomega.4c07708. eCollection 2024 Dec 31.
Alkaline fusion is a pivotal process influencing the cost of synthesizing zeolite from coal gangue. This study examined the effects of alkaline fusion temperature ( ), treatment duration ( ) and the NaOH/coal gangue weight ratio ( ) on the composition and properties of the products, as well as their adsorption capacities for Cd ( ) and Pb ( ). Response surface methodology (RSM) was employed to analyze the interactions among these factors, and the adsorption mechanisms for Cd and Pb were investigated using X-ray diffraction, scanning electron microscopy-EDS, Fourier transform infrared, X-ray photoelectron spectroscopy, and N adsorption-desorption techniques. The results reveal that (1) under optimized conditions- of approximately 800 °C, of around 2.8 h and of 1.2-the maximum and for the synthesized NaX zeolite can reach 181.3 and 419.9 mg/g, respectively. (2) The RSM models indicate that increasing the value can lower the required . For and of 150 and 350 mg/g, respectively, with fixed at 2 h, increasing from 0.976 to 1.134 and from 0.900 to 1.289 enables a reduction in from 800 to 600 °C. (3) NaX zeolite primarily adsorbs Cd and Pb through ion exchange, allowing these ions to enter the zeolite's cage structure. Pb can also precipitate as hydrocerussite (Pb(CO)(OH)) within the zeolite channels, while Cd has a more significant impact on the [SiO] and [AlO] tetrahedra. (4) The synthesized NaX zeolite effectively reduces the exchangeable Cd content in contaminated soil from 3.51 to below 1.5 mg/kg. The remediation performance of the NaX zeolite for Cd and Pb in water and soil can be further enhanced by optimizing its Si/Al ratio and pore structure.
碱熔是影响从煤矸石合成沸石成本的关键过程。本研究考察了碱熔温度（）、处理时间（）和NaOH/煤矸石重量比（）对产物组成和性质的影响，以及它们对Cd（）和Pb（）的吸附容量。采用响应面法（RSM）分析这些因素之间的相互作用，并利用X射线衍射、扫描电子显微镜-能谱仪、傅里叶变换红外光谱、X射线光电子能谱和N吸附-脱附技术研究Cd和Pb的吸附机理。结果表明：（1）在优化条件下——约800℃、约2.8h和1.2——合成的NaX沸石对Cd和Pb的最大吸附量分别可达181.3和419.9mg/g。（2）RSM模型表明，增加的值可以降低所需的。对于分别为150和350mg/g的Cd和Pb，在固定为2h的情况下，将从0.976增加到1.134以及从0.900增加到1.289可使从800℃降至600℃。（3）NaX沸石主要通过离子交换吸附Cd和Pb，使这些离子进入沸石的笼状结构。Pb也可在沸石通道内以碳酸铅（Pb(CO)(OH)）的形式沉淀，而Cd对[SiO]和[AlO]四面体有更显著的影响。（4）合成的NaX沸石可有效将污染土壤中可交换Cd含量从3.51mg/kg降低至1.5mg/kg以下。通过优化其硅铝比和孔结构，NaX沸石对水和土壤中Cd和Pb的修复性能可进一步提高。
