Zhong Mingtao, Li Weidi, Jiang Menghao, Wang Jingang, Shi Xiaoyan, Song Jianghui, Zhang Wenxu, Wang Haijiang, Cui Jing
Agricultural College, Shihezi University, Shihezi, Xinjiang 832000, People's Republic of China; Key Laboratory of Oasis Ecological Agriculture of Xinjiang Production and Construction Crops, Shihezi University, Shihezi, Xinjiang 832000, People's Republic of China.
Agricultural College, Shihezi University, Shihezi, Xinjiang 832000, People's Republic of China; Key Laboratory of Oasis Ecological Agriculture of Xinjiang Production and Construction Crops, Shihezi University, Shihezi, Xinjiang 832000, People's Republic of China.
Ecotoxicol Environ Saf. 2023 Aug 1;262:115317. doi: 10.1016/j.ecoenv.2023.115317.
In recent years, the improvement of soil cadmium (Cd) contamination remediation effect of biochar by modification has received wide attention. However, the effect of combined modification on biochar performance in soil Cd contamination remediation and the mechanism are still unclear. In this study, cotton straw biochar and maize straw biochar were co-modified by KOH (0, 3, 5 mol L), KPO, and urea. Then, two modified biochars with high Cd adsorption capacity were selected to test the soil Cd contamination remediation effect through a pot experiment. The results showed that the combined modification by using KOH, KPO, and urea significantly increased the specific surface area and nitrogen (N) and phosphorus (P) contents of biochar, providing more adsorption sites for Cd. Among the modified biochar, the cotton straw biochar modified with KOH (3 mol L), KPO, and urea (m3-CSB) had the highest adsorption capacity (111.25 mg g), which was 7.86 times that of cotton straw biochar (CSB). The m3-CSB for adsorption isotherm and kinetics of Cd conformed to the Langmuir model and Pseudo-second-order kinetic equation, respectively. In the pot experiment, under different exogenous Cd levels (0 (Cd0), 4 (Cd4), and 8 (Cd8) mg kg), m3-CSB treatment decreased soil available Cd content the most (51.68%-63.4%) compared with other biochar treatments. Besides, m3-CSB treatment significantly promoted the transformation of acid-soluble Cd to reducible, oxidizable, and residual Cd, reducing the bioavailability of Cd. At the Cd4 level, the application of m3-CSB significantly reduced cotton Cd uptake compared to CK, and the maximum reduction of Cd content in cotton fibers was as high as 81.95%. Therefore, cotton straw biochar modified with KOH (3 mol L), KPO, and urea has great potential in the remediation of soil Cd contamination.
近年来，通过改性提高生物炭对土壤镉（Cd）污染的修复效果受到广泛关注。然而，联合改性对生物炭修复土壤镉污染性能的影响及其机制仍不明确。本研究采用KOH（0、3、5 mol·L）、KPO和尿素对棉秸秆生物炭和玉米秸秆生物炭进行联合改性。然后，选择两种具有高镉吸附能力的改性生物炭，通过盆栽试验测试土壤镉污染修复效果。结果表明，KOH、KPO和尿素联合改性显著增加了生物炭的比表面积以及氮（N）和磷（P）含量，为镉提供了更多吸附位点。在改性生物炭中，用KOH（3 mol·L）、KPO和尿素改性的棉秸秆生物炭（m3-CSB）吸附量最高（111.25 mg·g），是棉秸秆生物炭（CSB）的7.86倍。m3-CSB对镉的吸附等温线和动力学分别符合Langmuir模型和准二级动力学方程。在盆栽试验中，在不同外源镉水平（0（Cd0）、4（Cd4）和8（Cd8）mg·kg）下，与其他生物炭处理相比，m3-CSB处理使土壤有效镉含量降低最多（51.68%-63.4%）。此外，m3-CSB处理显著促进了酸溶性镉向可还原态、可氧化态和残留态镉的转化，降低了镉的生物有效性。在Cd4水平下，与对照相比，施用m3-CSB显著降低了棉花对镉的吸收，棉纤维中镉含量最大降幅高达81.95%。因此，用KOH（3 mol·L）、KPO和尿素改性的棉秸秆生物炭在修复土壤镉污染方面具有巨大潜力。
