|
| Effect of deashing treatment on sorption kinetics of naphthalene and 1-naphthol on wheat straw-derived biochar |
| Received:June 23, 2020 |
| View Full Text View/Add Comment Download reader |
| KeyWord:biochar;organic pollutants;deashing;sorption kinetics;two-compartment model |
| Author Name | Affiliation | | ZHANG Meng | Co-Innovation Center for Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, Nanjing 210037, China | | LÜ Yao-bin | Co-Innovation Center for Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, Nanjing 210037, China | | ZHU Yi-tao | Co-Innovation Center for Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, Nanjing 210037, China | | LUO Ya-qi | Co-Innovation Center for Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, Nanjing 210037, China | | LI Wei | Co-Innovation Center for Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, Nanjing 210037, China | | LI Ping-ping | Co-Innovation Center for Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, Nanjing 210037, China | | WANG Xi-long | Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China |
|
| Hits: 1604 |
| Download times: 1337 |
| Abstract: |
| To elucidate the mineral effects of biochars on the sorption of organic pollutants(OPs), we investigated the sorption kinetics of naphthalene and 1-naphthol on both pristine and deashed wheat straw-derived biochars obtained at different temperatures. The kinetics data better fitted with the pseudo second-order model, followed by the two-compartment model in comparison with the pseudo first-order model. Deashing treatment increased the aromatic carbon content of biochars, thereby enhancing their p-p and hydrophobic interactions with the two tested compounds. Deashing also reduced the surface polarity of biochars, especially the O-alkyl polar components, thereby enhancing the accessibility of their hydrophobic carbon domains, mainly the aromatic carbon components. Hence, the equilibrium sorption capacity(Qe)of naphthalene and 1-naphthol increased. Reducing the external exposure of polar functional groups by mineral removal enhanced the diffusion of naphthalene molecules toward the hydrophobic sorption sites, thereby increasing its sorption rate constant for the fast-sorbing fraction on biochars(kfast). However, the substituted polar -OH group in 1-naphthol was able to interact with polar groups on biochars or mineral O-containing surfaces via H-bond that greatly contributed to its fast sorption. The H-bonding was weakened after deashing, which could account for a higher kfast value of 1-naphthol by the original biochar than that of its corresponding deashed one. Deashing increased the amount of aromatic components and porous structures in biochars, which were responsible for the slow sorption of naphthalene and 1-naphthol, resulting in increased contributions of the slowly sorbing fraction to the total sorption(kslow). The increased condensation of organic carbon in deashed biochars hindered the diffusion of naphthalene and 1-naphthol molecules into biochars. Additionally, increasing the surface area and porosity of biochars prolonged the sorption equilibrium time, and thus the rate constants for the slow sorption fraction(kslow)of both compounds decreased. The results of this work could help us better understand the effect of minerals, chemical composition, and spatial arrangement of polar functionalities of biochars on the sorption of OPs and predict their fate in soils after biochar application. |
|
|
|
