生态环境学报 ›› 2022, Vol. 31 ›› Issue (4): 814-823.DOI: 10.16258/j.cnki.1674-5906.2022.04.020

• 研究论文 • 上一篇    下一篇

生物炭中可溶性组分对其吸附镉的影响

赵超凡(), 周丹丹*(), 孙建财, 钱坤鹏, 李芳芳   

  1. 昆明理工大学环境科学与工程学院,云南 昆明 650500
  • 收稿日期:2021-10-08 出版日期:2022-04-18 发布日期:2022-06-22
  • 通讯作者: *周丹丹,E-mail: 01yongheng@163.com
  • 作者简介:赵超凡(1996年生),男,硕士研究生,从事土壤重金属污染修复研究。E-mail: 2361623132@qq.com
  • 基金资助:
    国家自然科学基金青年科学基金项目(41703121);国家自然科学基金青年科学基金项目(41907300);昆明理工大学人才启动项目(KKSY201722006);云南省重点研发计划资助项目(2018BC004)

The Effect of Soluble Components on the Adsorption of Cadmium on Biochar

ZHAO Chaofan(), ZHOU Dandan*(), SUN Jiancai, QIAN Kunpeng, LI Fangfang   

  1. Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, P. R. China
  • Received:2021-10-08 Online:2022-04-18 Published:2022-06-22

摘要:

为研究生物炭中可溶性组分对生物炭吸附重金属的影响,以玉米秸秆和松木屑为原材料,采用限氧升温炭化法,分别于200、400和600 ℃下制备生物炭,并通过批量吸附实验研究生物炭对镉的吸附特性及去除可溶性组分对其吸附Cd2+的影响。研究结果表明,随热解温度升高,生物炭的碳化程度增加,pH值增大,比表面积逐渐增大,含氧官能团数量减少,矿物组分不断富集,溶解性矿物离子K+、Ca2+、Mg2+和PO43-含量降低;去除可溶性组分后生物炭的pH值下降,溶解性矿物离子含量明显降低。LM模型更适合于对松木生物炭和200、400 ℃下制备的玉米秸秆生物炭吸附Cd2+的数据进行拟合,而FM模型更适合于拟合600 ℃下制备的玉米秸秆生物炭对Cd2+的吸附数据。玉米秸秆生物炭对Cd2+的吸附量(29.58—12.21 mg∙g-1)高于松木生物炭(1.72—4.14 mg∙g-1),这与玉米秸秆生物炭中的矿物组分含量明显高于松木生物炭,从而有利于发生共沉淀和离子交换作用有关。去除可溶性组分后,玉米秸秆和松木生物炭对Cd2+的吸附量分别降低25%—42%和15%—40%。共沉淀和离子交换作用是低温生物炭(≤400 ℃)吸附Cd2+的主要机制;而高温生物炭(>400 ℃)吸附Cd2+的主要机制是阳离子-π作用。溶解性矿物离子的含量降低使得Cd2+与生物炭之间的共沉淀和离子交换作用减弱,从而降低生物炭对Cd2+的吸附量。研究结果有助于认识可溶性组分在生物炭对重金属吸附机制中的作用,也将为生物炭在土壤修复中的应用提供科学参考。

关键词: 可溶性组分, 生物炭, 镉, 水洗, 吸附, 矿物组分

Abstract:

In order to study the effects of soluble components in biochar on the adsorption of heavy metals, biochar was prepared from different materials, including different sources of corn straw and pine chips. In this study, we used oxygen-limited pyrolysis in a range of 200?600 ℃. A batch adsorption experiment was conducted to study the effects of the removal of soluble components on the ability of biochar to adsorb Cd2+. The results showed that with an increase of pyrolysis temperature, the C content, pH, and the surface area increased, while the amount of oxygen-containing functional groups decreased. In addition, the content of minerals was enriched, but their solubility (e.g., K/Ca/Mg or phosphater) decreased. After removing soluble components, the pH of biochar decreased, and the content of dissolved mineral ions decreased significantly. The LM model was more suitable for fitting the Cd2+ adsorption data of pine chip biochar and corn straw biochar prepared at 200, 400 ℃, while the FM model was more suitable for fitting the Cd2+ adsorption data of corn straw biochar prepared at 600 ℃. The capacity of corn straw biochar to adsorb Cd2+ (29.58?12.21 mg∙g-1) was significantly higher than that of pine chip biochar (1.72?4.14 mg∙g-1), due to the fact that the content of mineral components that facilitated the occurrence of co-precipitation and ion exchange in corn straw biochar was significantly higher than that in pine chip biochar,. After removing the soluble components, the adsorption capacity of Cd2+ was reduced by 25%?42% and 15%?40% for corn straw and pine chip biochar, respectively. Co-precipitation and ion exchange were the dominant sorption mechanisms of Cd2+ adsorption by low-temperature biochar (≤400 ℃), while the cationic-π interaction was the main mechanism of Cd2+ adsorption by high temperature biochar (>400 ℃). The decrease of soluble mineral ion content weakened the co-precipitation and ion exchange between Cd2+ and biochar, and thus reduced the adsorption capacity of biochar for Cd2+. The results of this study are helpful for understanding the role of soluble components in the mechanism of heavy metal adsorption by biochar, and will provide scientific references for the application of biochar in soil remediation.

Key words: soluble components, biochar, cadmium, washing, adsorption, minerals

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