Effects of rice straw biochar on sorption and desorption of di-n-butyl phthalate in different soil particle-size fractions

Xiang, Lei and Zeng, Li Juan and Du, Pei Pei and Wang, Xiao Dan and Wu, Xiao Lian and Sarkar, Binoy and Lü, Huixiong and Li, Yan Wen and Li, Hui and Mo, Ce Hui and Wang, Hailong and Cai, Quan Ying (2020) Effects of rice straw biochar on sorption and desorption of di-n-butyl phthalate in different soil particle-size fractions. Science of the Total Environment, 702. ISSN 0048-9697

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Abstract

Sorption of organic contaminants by biochar greatly affects their bioavailability and fate in soils. Nevertheless, very little information is available regarding the effects of biochar on sorption and desorption of organic contaminants in different soil particle-size fractions. In this study, di-n-butyl phthalate (DBP), a prevalent organic contaminant in agricultural soils, was taken as a model contaminant. The effects of biochar on DBP sorption and desorption in six particle-size fractions (i.e., coarse sand, fine sand, coarse silt, fine silt, clay, and humic acid fractions) of paddy soil were investigated using batch sorption-desorption experiments. A straw-derived biochar with high specific surface area (116 m2/g) and high content of organic matter (OM) rich in aromatic carbon (67%) was prepared. Addition of this biochar (1% and 5%) significantly promoted the sorption and retention of DBP in all the paddy soil particle-size fractions at environmentally relevant DBP concentrations (2–12 mg/L) with 1.2–132-fold increase of the Kd values. With increasing addition rates of biochar, DBP retention by the biochar enhanced. The biochar's effectiveness was remarkably influenced by the physicochemical properties of the soil particle-size fractions, especially, the OM contents and pore size showed the most striking effects. A parameter (rkd) reflecting the biochar's effectiveness showed negative and positive correlations with OM contents and pore size of the soil particle-size fractions, respectively. Accordingly, strong effect of the biochar was found in the soil fractions with low OM contents and high pore size. The findings of this study gave insight into the effects and influencing factors of biochar on sorption and desorption of organic contaminants in soils at scale of various particle-size factions.

Item Type:
Journal Article
Journal or Publication Title:
Science of the Total Environment
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/2300/2310
Subjects:
ID Code:
140122
Deposited By:
Deposited On:
13 Jan 2020 09:30
Refereed?:
Yes
Published?:
Published
Last Modified:
30 Mar 2020 10:39