Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing, Jiangsu, 210096, China.
State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing, 400044, China; Department of Environmental Science, College of Environment and Ecology, Chongqing University, Chongqing, 400045, China.
Chemosphere. 2023 Dec;344:140292. doi: 10.1016/j.chemosphere.2023.140292. Epub 2023 Sep 26.
Utilizing fly ash to prepare ceramsite is a promising way to immobilize heavy metals and recycle industrial solid waste. However, traditional preparation method of fly ash ceramsite has the disadvantages of large ignition loss. Therefore, the present study applied the pressure molding method to enhance solid content and improve the strength of ceramsite. The optimal preparation conditions of ceramsite were suggested as preheating at 450 °C for 25 min followed by sintering at 1050 °C for 30 min. Under such conditions, ceramsite with high compressive strength of 10.8 Mpa, bulk density of 878 kg m, and 1-h water absorption of 18.5% was fabricated, in compliance with Chinese standard (GB/T 1743.1-2010). The arsenic leaching concentration from the resulting product was considerably lower than Chinese standard (GB 5085.3-2007). Moreover, arsenic volatilization during ceramsite calcination was insignificant, and the vast majority of arsenic remained in resulting ceramsite. A geochemical speciation model developed for the multiple component system in ceramsite suggested that FeAsO, Ca(OH) (AsO), and hydrous ferric oxide adsorption are the primary mechanisms retaining arsenic in ceramsite. Additionally, based on density functional theory calculations and biotoxicity test, the binding site of arsenic atom on mineral components and the environmental safety of ceramsite was determined and evaluated.
利用粉煤灰制备陶粒是一种固定重金属和回收工业固体废物的有前途的方法。然而，传统的粉煤灰陶粒制备方法存在点火损失大的缺点。因此，本研究采用加压成型法来提高固体含量并提高陶粒的强度。建议的最佳陶粒制备条件是在 450°C 下预热 25 分钟，然后在 1050°C 下烧结 30 分钟。在这种条件下，制备出抗压强度为 10.8 Mpa、堆积密度为 878 kg/m³、1 小时吸水率为 18.5%的陶粒，符合中国标准（GB/T 1743.1-2010）。所得产品中砷的浸出浓度明显低于中国标准（GB 5085.3-2007）。此外，在陶粒煅烧过程中砷的挥发并不显著，大部分砷仍留在生成的陶粒中。针对陶粒中多组分体系开发的地球化学形态模型表明，FeAsO、Ca(OH)(AsO)和水合氧化铁吸附是将砷保留在陶粒中的主要机制。此外，基于密度泛函理论计算和生物毒性试验，确定并评价了砷原子在矿物成分上的结合位和陶粒的环境安全性。
