Uchimiya Minori, Wartelle Lynda H, Lima Isabel M, Klasson K Thomas
USDA-ARS Southern Regional Research Center, 1100 Robert E. Lee Boulevard, New Orleans, Louisiana 70124, United States.
J Agric Food Chem. 2010 Dec 8;58(23):12350-6. doi: 10.1021/jf102152q. Epub 2010 Nov 4.
Biochars have received increasing attention in recent years because of a large-scale soil amendment to improve soil fertility, immobilize contaminants, and to serve as a recalcitrant carbon stock. Information is currently lacking in factors controlling the sorption capacity of manure-derived biochars. In this study, sorption isotherms for deisopropylatrazine, a stable metabolite of the widely applied herbicide atrazine, were obtained in acidic aqueous media (pH 5.5) for broiler litter-derived biochars formed by pyrolysis at 350 and 700 °C with and without steam activation at 800 °C. An increase in the Freundlich distribution coefficient (KF) and isotherm nonlinearity (nF) was observed with pyrolysis temperature and steam-activation, suggesting that the surface area and aromaticity (degree of carbonization) are the factors controlling the sorption capacity of chars at low surface coverage. At high surface coverage, the isotherms became increasingly linear, suggesting sorption on noncarbonized fraction of biochars. In binary-solute experiments, the sorption of deisopropylatrazine was significantly diminished by Cu(II), further suggesting the predominance of the surface adsorption mechanism at low surface coverage of biochars.
近年来，生物炭因大规模用于土壤改良以提高土壤肥力、固定污染物并作为顽固性碳库而受到越来越多的关注。目前缺乏控制源自粪便的生物炭吸附能力的因素的相关信息。在本研究中，针对广泛使用的除草剂阿特拉津的稳定代谢物去异丙基阿特拉津，在酸性水介质（pH 5.5）中获得了由肉鸡粪便衍生的生物炭的吸附等温线，这些生物炭是在350和700 °C下通过热解形成的，且在800 °C下有或没有蒸汽活化。随着热解温度和蒸汽活化，弗伦德利希分布系数（KF）和等温线非线性（nF）增加，这表明表面积和芳香性（碳化程度）是在低表面覆盖率下控制生物炭吸附能力的因素。在高表面覆盖率下，等温线变得越来越线性，表明是在生物炭的未碳化部分上发生吸附。在二元溶质实验中，Cu(II)显著降低了去异丙基阿特拉津的吸附，这进一步表明在生物炭低表面覆盖率下表面吸附机制占主导地位。
