紫外辐射影响飞灰-沥青胶浆重金属阻滞机理

Mechanism of Ultraviolet Radiation on Heavy Metal Immobilization in MSWIFA-Asphalt Mastic

摘要:

为了推动垃圾焚烧飞灰（MSWIFA）在沥青道路材料中的资源化应用，对MSWIFA-沥青胶浆进行室内模拟紫外老化处理，再通过扫描电子显微镜、傅里叶变换红外光谱及重金属浸出试验进行多尺度表征，研究了紫外辐射对MSWIFA-沥青胶浆重金属阻滞效能的影响机理。结果表明：紫外辐射可以通过劣化胶浆微观结构和降低体系pH值来影响沥青胶结料对Zn、Cd、Mn的阻滞效能，并且老化过程中形成的特定温度条件和酸性环境可以促进Fe和Cr转化为更稳定的化学状态；MSWIFA中的Ca、Si、Al化合物可能形成了水化硅酸钙凝胶，进而在沥青胶浆中实现对Cu和Pb的特异性固定，有效抑制了二者的浸出。

Abstract:

To promote the application of municipal solid waste incineration fly ash（MSWIFA） in asphalt pavement materials， laboratory-simulated ultraviolet aging was conducted on MSWIFA-asphalt mastic. Multiscale characterization via scanning electron microscopy， Fourier transform infrared spectroscopy and heavy metal leaching tests was employed to investigate the influence mechanism of ultraviolet radiation on the heavy metal immobilization efficacy of MSWIFA-asphalt mastic. The results demonstrate that ultraviolet radiation affects the immobilization efficacy of asphalt binder toward Zn， Cd and Mn by deteriorating the mastic’s microstructure and reducing system pH value. Additionally， specific temperature conditions formed during aging and induced acidic environments promote the transformation of Fe and Cr into more stable chemical states. The Ca， Si and Al compounds in fly ash are potentially capable of forming calcium silicate hydrate gels， enabling the specific immobilization of Cu and Pb in the asphalt mastic and effectively inhibiting their leaching.