| 不同农作物秸秆原料制备生物炭特性及重金属浸出行为 |
| 摘要点击 1657 全文点击 459 投稿时间：2022-01-23 修订日期：2022-04-21 |
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| 中文关键词 生物炭|农作物秸秆|重金属|浸出|环境风险 |
| 英文关键词 biochar|crop straw|heavy metals|leaching|environmental risk |
| 作者 | 单位 | E-mail | | 李家康 | 天津城建大学环境与市政工程学院, 天津 300384 | ljk146053@163.com | | 邱春生 | 天津城建大学环境与市政工程学院, 天津 300384
天津市水质科学与技术重点实验室, 天津 300384 | qcs254@163.com | | 赵佳奇 | 联合赤道环境评价有限公司, 天津 300042 | | | 王晨晨 | 天津城建大学环境与市政工程学院, 天津 300384
天津市水质科学与技术重点实验室, 天津 300384 | | | 刘楠楠 | 天津城建大学环境与市政工程学院, 天津 300384
天津市水质科学与技术重点实验室, 天津 300384 | | | 王栋 | 天津城建大学环境与市政工程学院, 天津 300384
天津市水质科学与技术重点实验室, 天津 300384 | | | 王少坡 | 天津城建大学环境与市政工程学院, 天津 300384
天津市水质科学与技术重点实验室, 天津 300384 | | | 孙力平 | 天津城建大学环境与市政工程学院, 天津 300384
天津市水质科学与技术重点实验室, 天津 300384 | |
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| 中文摘要 |
| 采用水稻秆、大豆秆、小麦秆和玉米秆为原料在550℃缺氧条件下制备生物炭,考察不同原料生物炭理化性质及热解后重金属(Cr﹑Ni、Cu﹑As﹑Cd和Pb)迁移转化特征,及其在不同浸出液中的浸出行为.结果表明,4种原料制备的生物炭的理化特性和元素组成基本一致,其中玉米秆生物炭微孔体积(0.006 cm3·g-1)和比表面积(110.120 m2·g-1)低于其他原料生物炭.秸秆热解后重金属(除Cd外)含量增加了14.04%~410.81%,且大部分重金属(除Cd和Pb外)化学形态由不稳定态(弱酸提取态和可还原态)向稳定态(可氧化态和残渣态)转化.制备的生物炭中的重金属在超纯水和缓冲盐溶液中无浸出或浸出量较少,在乙酸溶液和腐殖酸溶液中浸出量较高.其中Cu在乙酸溶液中浸出量较高,为2.601~4.224 mg·kg-1,As在腐殖酸溶液中浸出量较高,介于0.074~0.166 mg·kg-1.热解后,各种重金属的环境质量指数(PIi)和内梅罗综合污染指数(NPI)值均不同程度增加,但单一重金属污染等级仍为安全,生物炭综合污染水平为清洁.由于水稻秆生物炭Ni、Cd和Pb的生态风险因子(Er)较原料显著升高,水稻秆热解后总潜在生态风险指数RI略有上升,其他3种秸秆热解后由于重金属的稳定化,总潜在生态风险RI显著降低. |
| 英文摘要 |
| In this study, rice straw, soybean straw, wheat straw, and corn straw were chosen as raw materials, and biochars were prepared through the pyrolysis method at 550℃ under oxygen-limited conditions to investigate the physicochemical properties of biochars derived from the straws, the migration and transformation characteristics of heavy metals (HMs) (Cr, Ni, Cu, As, Cd, and Pb) after pyrolysis, and their leaching behaviors in different leaching solutions. The results showed that the physicochemical properties and elemental composition of the biochars were basically consistent. However, compared with that of biochars derived from other straws, biochar derived from wheat straw had a higher ash content (22.48%) and H/C radio (0.06). Meanwhile, biochar derived from corn straw had a smaller micropore volume (0.006 cm3·g-1) and a correspondingly smaller specific surface area (110.120 m2·g-1), which was consistent with the SEM image. After pyrolysis, the content of HMs (except Cd) increased by 14.04% to 410.81%, especially that of Cu and As. However, the content of Cd in soybean straw and corn straw decreased by 20.49% and 8.20% after pyrolysis, respectively, due to the low boiling point of Cd. Furthermore, most of the HMs (except Cd and Pb) tended to transform from unstable (acid-soluble/exchangeable and reducible forms) to stable forms (oxidizable and residual forms), implying that pyrolysis facilitated the stabilization of the HMs. The HMs in biochar were not leached or were leached in small amounts in ultra-pure water and buffered salt solutions, as opposed to leaching in relatively larger amounts in acetic acid solution and humic acid solution. Cr and Ni showed low leaching capacity in all leaching solutions. Cu showed relatively high leaching capacity in acetic acid solution, with the leaching amount ranging from 2.601 mg·kg-1 to 4.224 mg·kg-1, and As showed a relatively high leaching capacity in humic acid solution, with the leaching amount ranging from 0.074 mg·kg-1to 0.166 mg·kg-1. After pyrolysis, the environmental quality index (PIi) and the Nemerow pollution index (NPI) values of various HMs increased by different degrees. However, the pollution of single HMs remained at a safe level, and the integrated pollution of biochars was at the level of "clean". Due to the significant increase in potential ecological risk factors (Er) of Ni, Cd, and Pb after pyrolysis, the potential ecological risk index (RI) of biochar derived from the rice straw increased slightly. However, the potential ecological risk indexes of biochars derived from other straws significantly decreased after pyrolysis, owing to the stabilization of HMs. |
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