College of Geographical Science, Ministry of Education Key Laboratory of Humid Subtropical Eco-geographical Process, Fujian Provincial Key Laboratory for Plant Eco-Physiology, Fujian Normal University, Fuzhou, Fujian, 350007, China.
J Environ Qual. 2020 Mar;49(2):335-345. doi: 10.1002/jeq2.20001. Epub 2020 Jan 19.
Biochar is composed of carbonaceous and inorganic (ash) fractions. The structural properties of carbonaceous fractions and the composition of ash in biochar are both variable with pyrolysis temperature. However, it is unknown whether ash may play different roles in sorption of organic compounds to the carbonaceous fraction of biochars produced at different temperatures. Hence, in this study, the pristine biochars produced at 300-900°C and their corresponding deashed biochars were investigated, and the combined roles of carbonaceous fraction and ash in sorption of triclosan were compared. The results showed that the biochars produced at 300-400°C had high content of uncarbonized organic structure with dominating partition effect. The combination of uncarbonized organic structure and ash had comparable or even higher sorption coefficient (K ) for triclosan at low concentration compared with a single uncarbonized organic structure. However, for the biochars produced at 600-900°C, which were mainly composed of carbonized or graphitized carbon structure, ash had significant effect on triclosan sorption by reducing surface adsorption and pore filling effect. The combination of carbonaceous fraction and ash decreased K values for triclosan at any tested concentrations. In addition, the results of pH effect on sorption indicated that ash possibly decreased the electrostatic repulsion of deprotonated phenolic hydroxyl between biochars and triclosan. Accordingly, it will be more valuable to design biochars for pollutant sorption from the perspective of combined role of carbonaceous fraction and ash rather than a single role of carbonaceous fraction.
生物炭由碳质和无机（灰分）两部分组成。碳质部分的结构特性和生物炭灰分的组成都随热解温度而变化。然而，目前尚不清楚灰分是否可能在不同温度下产生的生物炭的碳质部分对有机化合物的吸附中发挥不同的作用。因此，本研究考察了在 300-900°C 下制备的原始生物炭及其对应的脱灰生物炭，并比较了碳质部分和灰分在三氯生吸附中的综合作用。结果表明，在 300-400°C 下制备的生物炭具有高含量的未碳化有机结构，主导分配作用。与单一未碳化有机结构相比，未碳化有机结构和灰分的组合在低浓度下对三氯生的吸附系数（K）具有相当甚至更高的吸附系数。然而，对于在 600-900°C 下制备的主要由碳化或石墨化碳结构组成的生物炭，灰分通过减少表面吸附和孔填充作用对三氯生的吸附有显著影响。碳质部分和灰分的组合降低了三氯生在任何测试浓度下的 K 值。此外，吸附过程中 pH 值的影响结果表明，灰分可能降低了生物炭和三氯生之间去质子化的酚羟基之间的静电排斥。因此，从碳质部分和灰分的综合作用角度而不是从单一的碳质部分角度来设计生物炭用于污染物吸附将更有价值。
