生态环境学报 ›› 2021, Vol. 30 ›› Issue (7): 1503-1512.DOI: 10.16258/j.cnki.1674-5906.2021.07.019

• 研究论文 • 上一篇    下一篇

铁基改性椰壳生物炭对砷的吸附效果及机制研究

张苏明1,2(), 张建强2,3, 周凯1,*(), 陈志良2,3,*()   

  1. 1.河南科技学院园艺园林学院,河南 新乡 453000
    2.生态环境部华南环境科学研究所,广东 广州 510000
    3.广东省农田重金属污染土壤治理与修复工程技术研究中心,广东 广州 510000
  • 收稿日期:2021-04-19 出版日期:2021-07-18 发布日期:2021-10-09
  • 通讯作者: *周凯(1969年生),男,副教授,博士,研究方向为城市生态环境治理。E-mail: kzhou89@126.com;陈志良(1976年生),男,研究员,博士,研究方向为土壤地下水污染防治。E-mail: chenzhiliang@scies.org
  • 作者简介:张苏明(1995年生),女,硕士研究生,研究方向为景观生态恢复技术研究。E-mail: 861595800 @qq.com
  • 基金资助:
    国家重点研发计划项目(2019YFC1805305);广东省基础与应用基础研究基金项目(2019A1515012131);广东省重点研发计划项目(2019B110207001);广东省重点研发计划项目(2020B1111350002);广东省国际合作项目(2021A0505030045);中央级公益性科研院所基本科研业务专项(PM-zx703-202002-035);河南省科技攻关计划项目(172102310755)

Adsorption Effect and Mechanism of Iron-based Modified Coconut Shell Biochar to Arsenic

ZHANG Suming1,2(), ZHANG Jianqiang2,3, ZHOU Kai1,*(), CHEN Zhiliang2,3,*()   

  1. 1. School of Horticulture and Landscape Architecture, Henan Institute of Science and Technology, Xinxiang 453000, China
    2. South China Institute of Environmental Sciences, Central Department of Ecological and Environmental Engineering, Guangzhou 510000, China
    3. Research Center for Soil Treatment and Restoration of Heavy Metal Pollution in Guangdong Province, Guangzhou 510000, China
  • Received:2021-04-19 Online:2021-07-18 Published:2021-10-09

摘要:

目前针对生物炭修复重金属污染的水体、土壤方面的研究虽然很多,但是对其吸附污染物的机制研究却较少。为了提高生物炭对砷的吸附能力,以农业废弃物椰壳为原料,在300 ℃下利用硫酸及硫酸铁制备铁基改性生物炭,采用SEM-EDS、FTIR、XRD及XPS等手段对椰壳生物炭(CSB)、硫酸改性生物炭(SCSB)以及铁基改性生物炭(SFCSB)表面结构与特征进行表征,通过pH值影响实验、等温吸附实验和动力学吸附实验对CSB、SCSB及SFCSB 3种生物炭吸附砷(As)的效果进行比较。结果表明,硫酸及硫酸铁共同改性使生物炭的比表面积增大了1.56倍,表面官能团新增亚甲基(-CH3)和羧基(-COO),SFCSB表面的Fe吸附As(Ⅴ)后在Fe2p能级生成了Fe2O3和FeOOH,证明铁基改性成功。SFCSB对As(Ⅴ)的吸附符合Elovich动力学模型及Langmiur等温吸附模型,当pH=5时,SFCSB对砷的最大吸附量为14.65 mg∙g-1,与未改性的CSB相比吸附量提高了238倍。SFCSB对As(Ⅴ)的吸附方式为物理化学吸附,吸附机制包括生物炭表面正电荷与阴离子之间的静电吸引、O-H-As氢键结合、砷氧阴离子与铁氧化物的配位体效应和表面羟基官能团络合等。研究表明,铁基改性椰壳生物炭是一种高效的除砷吸附剂。该研究从农业废弃物利用和环境修复的角度出发,为制备更高效、能深度净化污染的生物炭提供参考,也为吸附机制的探讨提供理论依据。

关键词: 椰壳生物炭, 硫酸, 硫酸铁, 改性, 吸附机制

Abstract:

At present, although there are many researches on biochar remediation of heavy metal polluted water and soil, there are few researches on the mechanism of biochar adsorption of pollutants. In order to improve the adsorption capacity of biochar to arsenic, the agricultural waste coconut shell was used as raw material to prepare iron-based modified biochar using sulfuric acid and ferric sulfate at 300 ℃. The surface structure and characteristics of coconut shell biochar (CSB), sulfuric acid modified biochar (SCSB) and iron-based modified biochar (SFCSB) were characterized by SEM-EDS, FTIR, XRD and XPS. The effect of CSB, SCSB and SFCSB biochar on the adsorption of arsenic (As) was studied and compared by pH influence experiment, isothermal adsorption experiment and kinetic adsorption experiment. The results show that the specific surface area of biochar is increased by 1.56 times by the joint modification of sulfuric acid and ferric sulfate, and the surface functional groups of biochar are increased by methylene (-CH3) and carboxyl (-COO). After the adsorption of As(Ⅴ) on the surface of SFCSB, Fe2O3 and FeOOH are generated at the Fe2p level, which proves that the iron-based modification is successful. The adsorption of As(Ⅴ) by SFCSB was consistent with Elovich kinetic model and Langmiur isothermal adsorption model. When pH=5, the maximum adsorption capacity of SFCSB for arsenic is 14.65 mg∙g-1, which is 238 times higher than that of the unmodified CSB. The adsorption mode of SFCSB for As(Ⅴ) is physicochemical adsorption, and the adsorption mechanism includes electrostatic attraction between positive charge and anion on the surface of biochar, O-H-As hydrogen bonding, ligand effect between arsenic oxide anion and iron oxide, and complexation of surface hydroxyl functional groups. Studies have shown that iron-based modified coconut shell biochar is an efficient arsenic removal adsorbent. From the perspective of agricultural waste utilization and environmental remediation, this study provides a reference for the preparation of more efficient biochar that can deeply purify pollution, and also provides a theoretical basis for the discussion of adsorption mechanism.

Key words: coconut shell biochar, sulfuric acid, ferric sulfate, modified, adsorption mechanism

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