title: High Adsorption of Sulfamethoxazole by an Amine-Modified Polystyrene-Divinylbenzene Resin and Its Mechanistic Insight.
abstract: Sulfamethoxazole (SMZ) adsorption by a series of amine-modified polystyrene-divinylbenzene resins (PSA/B/C/D) was investigated. All resins showed a similar pH dependent adsorption of SMZ but their capacities were linearly related with the contents of primary amines (-NH2) rather than secondary amines (-NH-). Mechanisms of SMZ adsorption by PSA (highest -NH2 content) were discussed as an example. Due to comparable pKa, H-bonding interactions of -NH2(0) with SMZ(0) (regular H-bond) and SMZ(-) (negative charge-assisted H-bond, (-)CAHB) successively contributed most adsorption (pH 4-9). At weakly acidic pH, -NH2(0) was partially protonated and electrostatic attraction between -NH3(+) and SMZ(-) occurred concurrently, but could be hindered by increased loading of SMZ(0). Hydrophobic/ π-π interactions were not major mechanisms as phenanthrene and nitrobenzenes had little effect on SMZ adsorption. At alkaline pH, where SMZ(-) and -NH2(0) prevailed, adsorption was accompanied by the stoichiometric (∼1.0) proton exchange with water, leading to OH(-) release and the formation of (-)CAHB [SO2N(-)···H···NH2]. The interaction and SMZ spatial distribution in the resin-phase were further confirmed by FTIR and Raman spectra. SMZ was uniformly adsorbed on external and interior surfaces. SMZ adsorption by PSA had low-interference from other coexistent matter, but high stability after multiple regenerations. The findings will guide new adsorbent designs for selectively removing target organics.
authors: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing 210023, P. R. China.|Stockbridge School of Agriculture, University of Massachusetts , Amherst, Massachusetts 01003, United States.
authors: Chen
authors: C
authors: Ling
authors: Stockbridge School of Agriculture, University of Massachusetts , Amherst, Massachusetts 01003, United States.|College of Tourism and Environment, Shaanxi Normal University , Xi'an, Shaanxi 710119, P. R. China.
authors: Xiaoyun
authors: X
authors: Li
authors: Department of Food Science, University of Massachusetts , Amherst, Massachusetts 01003, United States.
authors: Zhiyun
authors: Z
authors: Zhang
authors: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing 210023, P. R. China.
authors: Fuqiang
authors: F
authors: Liu
authors: Stockbridge School of Agriculture, University of Massachusetts , Amherst, Massachusetts 01003, United States.
authors: Yingqing
authors: Y
authors: Deng
authors: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing 210023, P. R. China.
authors: Xiaopeng
authors: X
authors: Zhang
authors: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University , Nanjing 210023, P. R. China.
authors: Aimin
authors: A
authors: Li
authors: Department of Food Science, University of Massachusetts , Amherst, Massachusetts 01003, United States.
authors: Lili
authors: L
authors: He
authors: Stockbridge School of Agriculture, University of Massachusetts , Amherst, Massachusetts 01003, United States.
authors: Baoshan
authors: B
authors: Xing
mesh_terms: D000327:Adsorption; D000588:Amines; D057927:Hydrophobic and Hydrophilic Interactions; D011137:Polystyrenes; D013420:Sulfamethoxazole
chemical_list: D000588:Amines; D011137:Polystyrenes; D013420:Sulfamethoxazole