title: Inhibited transport of graphene oxide nanoparticles in granular quartz sand coated with Bacillus subtilis and Pseudomonas putida biofilms.
abstract: Increasing production and use of graphene oxide nanoparticles (GONPs) boost their wide dissemination in the subsurface environments where biofilms occur ubiquitously, representative of the physical and chemical heterogeneities. This study aimed at investigating the influence of Gram-positive Bacillus subtilis (BS) and Gram-negative Pseudomonas putida (PP) biofilms on the transport of GONPs under different ionic strengths (0.1, 0.5, and 1.0 mM CaCl2) at neutral pH 7.2 in water-saturated porous media. Particularly, the X-ray micro-computed tomography was used to quantitatively characterize the pore structures of sand columns in the presence and absence of biofilms. Our results indicated that the presence of biofilms reduced the porosity and narrowed down the pore sizes of packed columns. Transport experiments in biofilm-coated sand showed that biofilms, irrespective of bacterial species, significantly inhibited the mobility of GONPs compared to that in cleaned sand. This could be due to the Ca2+complexation, increased surface roughness and charge heterogeneities of collectors, and particularly enhanced physical straining caused by biofilms. The two-site kinetic retention model-fitted value of maximum solid-phase concentration (Smax2) for GONPs was higher for biofilm-coated sand than for cleaned sand, demonstrating that biofilms act as favorable sites for GONPs retention. Our findings presented herein are important to deepen our current understanding on the nature of particle-collector interactions.
authors.affiliation: Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Jian-Zhou
authors.initials: JZ
authors.lastname: He
authors.affiliation: Department of Plant and Soil Sciences, University of Delaware, Newark, DE 19716, United States.
authors.forename: Deng-Jun
authors.initials: DJ
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Huan
authors.initials: H
authors.lastname: Fang
authors.affiliation: Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Qing-Long
authors.initials: QL
authors.lastname: Fu
authors.affiliation: Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China. Electronic address: dmzhou@issas.ac.cn.
authors.forename: Dong-Mei
authors.initials: DM
authors.lastname: Zhou
mesh_terms: D001412:Bacillus subtilis / Q000502:physiology*; D018441:Biofilms; D006108:Graphite / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008956:Models, Chemical; D053758:Nanoparticles / Q000737:chemistry*; D009994:Osmolar Concentration; D010087:Oxides; D016062:Porosity; D016958:Pseudomonas putida / Q000502:physiology*; D011791:Quartz / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D055114:X-Ray Microtomography
chemical_list: D010087:Oxides; D014874:Water Pollutants, Chemical; D011791:Quartz; D012822:Silicon Dioxide; D006108:Graphite
keywords: Biofilm; Computed tomography; Graphene oxide nanoparticles; Modeling; Porous media; Transport