Hebei and China Geological Survey key Laboratory of Groundwater Remediation, Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Shijiazhuang 050061, China.
School of Resources and Environmental Engineering, Hefei University of Technology, Hefei 230009, China.
Int J Environ Res Public Health. 2023 Mar 6;20(5):4635. doi: 10.3390/ijerph20054635.
Biofuel ash (BFA), which is the ash generated by biomass combustion in a biomass power plant, can be prepared as a heavy metal immobilizer and have a good immobilization effect on Cd in the soil environment of southern China, but the long-term effects of BFA on Cd immobilization remained unclear. Therefore, research about BFA aging and its influence on Cd immobilization was conducted in the paper. BFA was naturally aged into BFA-Natural aging (BFA-N) in the soil environment of southern China, and to simulate BFA-N, BFA was also artificially acid aged into BFA-Acid aging (BFA-A). The result indicated that BFA-A could partially simulate BFA-N in physicochemical properties. The Cd adsorption capacity of BFA reduced after natural aging and the decrease was more obvious in BFA-A according to Qm in Langmuir equation and qe from the pseudo-second-order kinetic model. The adsorption processes of BFA before and after aging were mainly controlled by chemical action rather than physical transport. The immobilization of Cd included adsorption and precipitation, and adsorption was the dominant factor; the precipitation proportion was only 12.3%, 18.8%, and 1.7% of BFA, BFA-N, and BFA-A, respectively. Compared with BFA, both BFA-N and BFA-A showed Ca loss, and BFA-A was more obvious than BFA-N. Ca content level was consistent with Cd adsorption level among BFA, BFA-N, and BFA-A. It could be inferred that the main immobilization mechanism of Cd by BFA before and after aging was consistent and closely related to Ca. However, the adsorption mechanism of electrostatic interaction, ion exchange, and hydroxyl complexation changed to varying degrees in BFA-N and BFA-A.
生物燃料灰（BFA）是生物质发电厂燃烧生物质产生的灰分，可以用作重金属固定剂，对中国南方土壤环境中的 Cd 具有良好的固定效果，但 BFA 对 Cd 固定的长期影响尚不清楚。因此，本文研究了 BFA 的老化及其对 Cd 固定的影响。BFA 在南方土壤环境中自然老化为 BFA-自然老化（BFA-N），并模拟 BFA-N，BFA 也被人工酸化老化为 BFA-酸化老化（BFA-A）。结果表明，BFA-A 可以部分模拟 BFA-N 的理化性质。自然老化后，BFA 的 Cd 吸附容量降低，BFA-A 的降低更为明显，根据 Langmuir 方程的 Qm 和准二级动力学模型的 qe 得出。老化前后的吸附过程主要受化学作用控制，而不是物理传输。Cd 的固定包括吸附和沉淀，吸附是主要因素；沉淀比例分别为 BFA、BFA-N 和 BFA-A 的 12.3%、18.8%和 1.7%。与 BFA 相比，BFA-N 和 BFA-A 均表现出 Ca 损失，BFA-A 比 BFA-N 更为明显。BFA、BFA-N 和 BFA-A 中的 Ca 含量水平与 Cd 吸附水平一致。可以推断，BFA 老化前后对 Cd 的主要固定机制是一致的，与 Ca 密切相关。然而，BFA-N 和 BFA-A 中静电相互作用、离子交换和羟基络合的吸附机制发生了不同程度的变化。
