title: Adsorption of sulfonamides on reduced graphene oxides as affected by pH and dissolved organic matter.
abstract: With the significant increase in use and application of graphene and the frequent presence of sulfonamides (SAs) in water environments, their interactions have attracted extensive attention. In this study, adsorption of two selected SAs (sulfapyridine and sulfathiazole) by two reduced graphene oxides (rGO1 and rGO2) was examined as affected by pH and dissolved organic matter (DOM). Adsorption of SAs by rGOs was highly pH-dependent, and adsorption affinity of different SAs species followed the order of SA(0) > SA(+) > SA(-). The contribution of SA(0) to the overall adsorption was greater than its species fraction, implying the importance of the neutral species to adsorption. SAs adsorption isotherms at three selected pHs were in the order of pH 5.0 > pH 1.0 > pH 11.0, which was in accordance with the variation of site energy distribution analysis. Hydrophobic interaction, π-π EDA interaction and electrostatic interaction were the main mechanisms responsible for SAs adsorption by rGOs. Three representative natural DOMs including humic acid (HA), bovine serum albumin (BSA), and sodium alginate together with sodium dodecylbenzenesulfonate (SDBS) as a synthetic DOM were used to investigate their effect on SAs adsorption. The inhibition impact of DOM on SAs adsorption was lower for rGOs compared with carbon nanotubes and graphite, which might be attributed to the higher oxygen contents of rGOs. Also, the suppression effect of DOM generally followed an order of SDBS > HA ≥ BSA > alginate, indicating the importance role of DOM compositions. These results should be important for assessing the fate and transport of graphene and antibiotics in the environment.
authors.affiliation: Shandong Provincial Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan, Shandong, 250100, China; Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA, 01003, USA.
authors.forename: Fei-Fei
authors.initials: FF
authors.lastname: Liu
authors.affiliation: College of Environmental Science and Engineering, Ocean University of China, Qingdao, Shandong, 266100, China.
authors.forename: Jian
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Shandong Provincial Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan, Shandong, 250100, China. Electronic address: wsg@sdu.edu.cn.
authors.forename: Shuguang
authors.initials: S
authors.lastname: Wang
authors.affiliation: Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA, 01003, USA. Electronic address: bx@umass.edu.
authors.forename: Baoshan
authors.initials: B
authors.lastname: Xing
mesh_terms: D000327:Adsorption; D000900:Anti-Bacterial Agents / Q000032:analysis; D001557:Benzenesulfonates; D006108:Graphite / Q000737:chemistry*; D006812:Humic Substances / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D037742:Nanotubes, Carbon / Q000737:chemistry; D009930:Organic Chemicals / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D013449:Sulfonamides / Q000737:chemistry*
chemical_list: D000900:Anti-Bacterial Agents; D001557:Benzenesulfonates; D006812:Humic Substances; D037742:Nanotubes, Carbon; D009930:Organic Chemicals; D010087:Oxides; D013449:Sulfonamides; C001114:dodecylbenzenesulfonic acid; D006108:Graphite
keywords: Dissolved organic matter; Reduced graphene oxides; Sulfonamides; pH-dependent adsorption