Wan Chunli, Li Huiqi, Zhao Lianfa, Li Zhengwen, Zhang Chen, Tan Xuejun, Liu Xiang
Department of Environmental Science and Engineering, Fudan University, Shanghai, 200438, China.
Department of Environmental Science and Engineering, Fudan University, Shanghai, 200438, China.
J Environ Manage. 2021 Dec 1;299:113602. doi: 10.1016/j.jenvman.2021.113602. Epub 2021 Aug 25.
The pyrolysis of excess sludge derived from wastewater treatment plants to prepare biochar can achieve the mass-reduction and harmlessness of solid waste, but it is also necessary to further explore the application prospect of these biochars as a resource for wastewater treatment. In this study, Fe-modified biochar (BC-Fe) was prepared by pyrolysis of excess sludge modified by FeCl solution. The molecular structure, elemental valence state, and composition of biochars were comprehensively investigated. The results showed that, compared with the biochar prepared from sludge without modification (BC-blank), the O/C ratio of BC-Fe increased from 0.07 to 0.12, and the (N + O)/C ratio increased from 0.21 to 0.27, indicating increased polarity and weakened aromaticity. The ratio of integrated intensity of the D band and G band in the Raman spectrum increased from 1.34 to 2.40, showing the increased defect structure of the biochar obtained by Fe modification. In the reaction between BC-Fe and dicamba, the removal rate of dicamba reached 92.1% within 180 min, which was far higher than the 17.8% of BC-blank. It was confirmed the adsorption removal dominated and accounted for 70.6% of the dicamba removal by BC-Fe, and the adsorption capacity of biochar could be significantly enhanced by Fe-modification by 5.3 times. Moreover, the persistent free radicals (PFRs) on the surface of biochar was detected by an electron paramagnetic resonance analyzer, and the decline of PFRs signals after the reaction revealed that PFRs participated in the degradation process of dicamba. Through Q-TOF analysis, it could be concluded that dicamba was first converted to 3,6-dichlorosalicylic acid (DCSA) by PFRs reduction and then further transformed to 3,6-dichlorogentisic acid (DCGA). This study provided a reference for the understanding of the removal mechanism of dicamba by Fe-modified biochar and offered an application potential of biochar derived from Fe-containing sludge for the pollution control of dicamba pesticide pollutants.
将污水处理厂产生的剩余污泥热解制备生物炭，可实现固体废物的减量化和无害化，但还需进一步探索这些生物炭作为废水处理资源的应用前景。本研究通过对经FeCl溶液改性的剩余污泥进行热解制备了Fe改性生物炭（BC-Fe）。对生物炭的分子结构、元素价态和组成进行了综合研究。结果表明，与未改性污泥制备的生物炭（BC-空白）相比，BC-Fe的O/C比从0.07增加到0.12，(N + O)/C比从0.21增加到0.27，表明极性增强，芳香性减弱。拉曼光谱中D带和G带的积分强度比从1.34增加到2.40，表明Fe改性得到的生物炭缺陷结构增加。在BC-Fe与麦草畏的反应中，180分钟内麦草畏的去除率达到92.1%，远高于BC-空白的17.8%。证实吸附去除占主导，占BC-Fe去除麦草畏的70.6%，Fe改性可使生物炭的吸附容量显著提高5.3倍。此外，通过电子顺磁共振分析仪检测了生物炭表面的持久性自由基（PFRs），反应后PFRs信号的下降表明PFRs参与了麦草畏的降解过程。通过Q-TOF分析可以得出，麦草畏首先通过PFRs还原转化为3,6-二氯水杨酸（DCSA），然后进一步转化为3,6-二氯龙胆酸（DCGA）。本研究为理解Fe改性生物炭去除麦草畏的机制提供了参考，并为含铁污泥衍生生物炭在麦草畏农药污染物污染控制方面提供了应用潜力。
