A Review of Researches on Biochar Adsorbing Organic Contaminants and its Mechanism

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the National Basic Research Program of China(973 Program)(No.2014CB441105),the National Natural Science Foundation of China (No.41671236)and the “135” Plan and Frontiers Program of Chinese Academy of Sciences (No.ISSASIP1614)

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    Biochar is a kind of porous and carbon-rich material prepared out of waste biomass through pyrolyzation anaerobically or aerobically. Thanks to its high adsorption capacity, handy resources, low preparation cost and environment-friendliness, biochar has aroused more and more attention among the academic circles. Knowledge about mechanism and rules of biochar adsorbing organic contaminants is crucial to proper evaluation of its environmental behaviors and application value. This article reviewed with emphasis reports available on mechanisms of biochar adsorbing organic pollutants, such as partition, surface adsorption, pore interception, etc. Generally speaking, biochar prepared at low temperature adsorbs non-polar organics mainly via partitioning. This non-competitive adsorption mechanism can be used to explain the process of biochar adsorbing pollutant high in concentration.Surface adsorption is a kind of competitive sorption mechanism. Organic contaminants caught on the effective sites on the surface of biochar are adsorbed via electrostatic interaction or hydrogen bonding,ionic bonding,π-electron donor-acceptor (π-π EDA), etc. Pore interception is another microscopic mechanism of biochar adsorbing organic pollutants.Partitioning and adsorption of organic pollutants inside the pores is also an important portion of the biochar adsorption capacity. Both polar and/or non-polar organic contaminants can be sorbed on biochar via pore interception.In fact, the mechanisms of biochar adsorbing organic compounds are various with one dominated and additional other mechanisms also occurred.In addition, this paper analyzed and summarized influencing factors of mechanisms of biochar adsorbing organic contaminants.Physico-chemical properties of biocharincluding high specific area, well-developed porosity, rich polar functional groups and stable aromatic structure are essential to determine the application value of this super-sorbent.Only biochar with properties matchable to organic contaminants in polarity, aromaticity, molecular size can be used to bring their adsorption capacity into full play. Sorption environment such as pH, medium and co-existing ions is also an important factor affecting adsorption effect of biochar. All account for the complex process of biochar adsorbing organic compounds. However,the researches reported in the literature are found to have some problems. For example, some of them remained on the stage of laboratory and little is reported in the literature on using experimental methods to probe mechanisms of biochar adsorbing organic compounds. At the end, the article brought forth solutions to the existing problems and described prospects of the application of biochar in remediation of organic polluted soils in future.

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LI Xiaona, SONG Yang, JIA Mingyun, WANG Fang, BIAN Yongrong, JIANG Xin. A Review of Researches on Biochar Adsorbing Organic Contaminants and its Mechanism[J]. Acta Pedologica Sinica,2017,54(6):1313-1325.

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  • Received:January 04,2017
  • Revised:June 27,2017
  • Adopted:August 18,2017
  • Online: September 04,2017
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