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Influences of different aging processes on biochar physicochemical properties and the adsorption of phthalic acid esters
Received:September 21, 2020  
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KeyWord:biochar;rice straw;aging;phthalic acid esters;adsorption
Author NameAffiliationE-mail
MIN Lu-juan MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Engineering Center of Environmental Diagnosis and Contamination Remediation, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China  
LIU Jin-ming MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Engineering Center of Environmental Diagnosis and Contamination Remediation, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China  
ZHANG Peng MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Engineering Center of Environmental Diagnosis and Contamination Remediation, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China nkzhangpeng@nankai.edu.cn 
XIAO Hui Tianjin Institute of Agriculture Resource and Environment, Tianjin 300384, China  
SUN Hong-wen MOE Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Engineering Center of Environmental Diagnosis and Contamination Remediation, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China  
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Abstract:
      To determine the effect of common aging processes on biochars in the agricultural soil environment and their influence on the adsorption capacity of the biochars, three original biochars by pyrolyzing rice straw at pyrolysis temperatures(PTs) of 300, 500 and 700℃ under limited oxygen were prepared. The biochars were further aged by water aging, root secretion aging, H2O2 oxidation aging, and acid aging, and their physicochemical properties and the adsorption capacity to two phthalic acid esters(PAEs), diethyl phthalate(DEP) and dibutyl phthalate(DBP), were analyzed. The results showed that the four aging treatments all increased the organic component proportions, specific surface areas, and total pore volumes of the biochars, but decreased the inorganic component proportions. Such effects were increased by aging processes in the following order:acid aging > H2O2 oxidation aging ≈ root secretion aging>water aging. The adsorption well followed the Freundlich model and was higher for DBP than for DEP. The aging treatments all significantly increased the adsorption capacities of moderate- and high-PT biochars(500℃ and 700℃) to PAEs and acid aging was more efficient than the other three aging treatments. This was due to the high proportion of inorganic components in the moderate- and high-PT biochars, which could be easily removed by acid aging, releasing part of the organic adsorption sites and pores, and then increasing the accessibility of adsorption sites for PAEs. Therefore, the biochars prepared at medium-and high-PTs have a strong potential to adsorb DBP and DEP, the most common plasticizers in water and soils. Their application needs to consider the aging process in the soil environment and their physicochemical properties, as well as the targeted pollutants to guide the healthy development of biochar technology.