|Sun, Ke - Beijing Normal University|
|Kang, Mingjie - Beijing Normal University|
|Libra, Judy - Leibniz Institute|
|Zhao, Ye - Beijing Normal University|
|Xing, Baoshan - University Of Massachusetts|
Submitted to: Chemosphere
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/9/2015
Publication Date: 7/18/2015
Publication URL: http://dx.doi.org/10.1016/j.chemosphere.2015.07.018
Citation: Sun, K., Kang, M., Ro, K.S., Libra, J., Zhao, Y., Xing, B. 2015. Variation in sorption of propiconazole with biochars: The effect of temperature, mineral, molecular structure, and nano-porosity. Chemosphere. 142:56-63. doi: org/10.1016/j.chemosphere.2015.07.018.
Interpretive Summary: Biochar is a carbonaceous solid obtained from the carbonization of biomass. Biochar may be used as a soil amendment to improve soil quality and reduce water pollution potential by sorbing pollutants on its surface. Propiconazole (PROPI) is a fungicide often used in worldwide commerce for controlling harmful microorganisms, inhibiting fungus attack and preventing foliar or root disease. PROPI has been listed as a persistent, potentially toxic compound and possible human carcinogen by the European Union. Its low mobility and relatively high adsorption in soils rich in organic matter result in its accumulation in soils and pose a risk for the soil ecosystem. Organic carbon has been reported to the most important factor in sorption of PROPI by soils. Therefore, addition of carbon-rich biochar should influence the fate of PROPI in soils and water bodies. This study investigated the sorption behaviors of PROPI with biochars made from plant residues (PLABs) and animal manures (ANIBs). These biochars were made at three temperatures (300, 450 and 600 degrees Celsius). Our results showed that PLABs contained more carbon than ANIBs. The sorption of PROPI by biochars was nonlinear and nanopores within aromatic carbon of these biochars were responsible for the nonlinear sorption of PROPI. We found that removal of ashes in the biochar elevated PROPI sorption on both PLABs and ANIBs. Results of this study help us better understand sorption behavior of PROPI and may be useful for assessing ecological risk of PROPI in the soils amended with biochars.
Technical Abstract: Sorption behavior of propiconazole (PROPI) by plant-residue derived biochars (PLABs) and animal manure-derived biochars (ANIBs) obtained at three heating treatment temperatures (HTTs) at 300, 450 and 600 degrees Celsius (denoted as BCs300, BCs450, and BCs600) and their corresponding de-ashed BCs450 was investigated. PLABs belonged to high- or medium-carbon biochars and ANIBs were low-carbon biochars. Surface carbon concentrations of the tested biochars were generally higher than their corresponding bulk cabon. Surface polar groups were mainly composed of oxygen-containing groups of minerals within biochars. The nonlinearity coefficients of PROPI sorption isotherms ranged from 0.23 to 0.64, which was significantly and negatively related to organic carbon-normalized carbon dioxide-surface area of biochars. HTTs or carbon contents do not necessarily regulate PROPI sorption. Removal of minerals from BCs450 elevated PROPI sorption because minerals may exert certain influence on sorption via impacting spatial arrangement of polar groups and/or organic matter-mineral interactions. This study helps to better understand sorption mechanisms of PROPI by organic matter-mineral complexes in biochars, which will be useful for assessing ecological risk of pesticides in soils amended with biochars.