Agro-Environmental Protection Institute, Ministry of Agriculture of China, Tianjin, 300191, China.
Department of Civil and Environmental Engineering, Shantou University, Shantou, 515063, China.
Environ Sci Pollut Res Int. 2021 Dec;28(45):64503-64515. doi: 10.1007/s11356-021-15376-2. Epub 2021 Jul 26.
The large-scale use of polytetrafluoroethylene has resulted in ever-increasing amounts of polytetrafluoroethylene (PTFE) microplastic particles entering the environment. Given that the environment is polluted with arsenic (As(III)), and that the environment contains significant levels of humic acid (HA) and fulvic acid (FA), how PTFE and As(III) in water interacting in the presence of HA and FA needs to be urgently investigated. The results showed that As(III) was adsorbed by PTFE in the presence of HA and FA more markedly than the absence of them Adsorption equilibrium was reached at approximately 960 min and the adsorption isotherms were found to be best fitted by the Toth model. An increase in temperature was found to destroy hydrogen bonds, resulting in inhibited, non-spontaneous adsorption; a higher pH inhibited adsorption in the range 3-7. Computational and mechanistic studies revealed that PTFE formed π complexes with HA units, which increased the number of oxygen-containing functional groups on its surface. The surface of the PTFE-HA π complex was mostly negatively charged; however, the hydrogen atoms of the hydroxyl and carboxylic acid groups exhibited large positive potentials that enabled the adsorption of As(III). When the oxygen atom on As was close to the oxygen-containing functional group on PTFE-HA, the more electronegative oxygen atom forms a special intermolecular interaction in the form of O-H···O through the medium of hydrogen, which makes As adsorb on the surface of PTFE. Pore filling, hydrogen bonding, and covalent bonding are the main ways in which PTFE adsorbs As(III) in the presence of HA and FA. PTFE also adsorbed more As(III) in the presence of HA than in the presence of FA.
聚四氟乙烯的大规模使用导致越来越多的聚四氟乙烯（PTFE）微塑料颗粒进入环境。鉴于环境中砷（As(III)）污染严重，且环境中含有大量腐殖酸（HA）和富里酸（FA），需要紧急研究水中的 PTFE 和 As(III)在 HA 和 FA 存在下的相互作用。结果表明，HA 和 FA 的存在显著促进了 PTFE 对 As(III)的吸附。吸附平衡约在 960 min 左右达到，吸附等温线最符合托特模型。升高温度会破坏氢键，导致吸附受到抑制，非自发进行；pH 值在 3-7 范围内升高会抑制吸附。计算和机理研究表明，PTFE 与 HA 单元形成了π配合物，增加了其表面含氧官能团的数量。PTFE-HA π 配合物的表面主要带负电荷；然而，羟基和羧酸基团的氢原子表现出较大的正电位，从而能够吸附 As(III)。当 As 上的氧原子靠近 PTFE-HA 上的含氧官能团时，电负性更大的氧原子通过氢键的媒介以 O-H···O 的形式形成特殊的分子间相互作用，使 As 吸附在 PTFE 的表面上。在 HA 和 FA 存在下，PTFE 吸附 As(III)的主要方式是孔填充、氢键和共价键。PTFE 在存在 HA 的情况下也比存在 FA 的情况下吸附更多的 As(III)。
