新制和老化微塑料对多溴联苯醚的吸附

以2,2′,4,4′-四溴联苯醚(BDE-47)为多溴联苯醚(PBDEs)代表化合物,研究了新制和紫外光照射老化的聚乙烯(PE)和聚苯乙烯(PS)微塑料对BDE-47的吸附动力学和等温吸附,分析了盐度和溶解性有机质等环境因素对其吸附的影响,采用扫描电镜、 X射线衍线和全反射红外光谱对新制和老化微塑料进行了表征,探讨了新制和老化微塑料对PBDEs的吸附机制.结果表明,新制与老化PE的主要吸附模式为表面吸附和外液膜扩散,新制与老化PS主要受表面吸附影响.Freudlich模型的拟合度最好,表明微塑料对于BDE-47的吸附均表现为多相多层的不均匀吸附过程.BDE-47在新制PE、老化PE、新制PS和老化PS上的平衡吸附量分别为3.72、 3.76、 6.04和3.46 ng·g~(-1).老化PE与新制PE相比,其平衡吸附量没有变化;但老化PS与新制PS相比,平衡吸附量降低了42.38%.外液膜扩散的分配作用是影响PE吸附的主要机制.与新制PS相比,结晶度和表面含氧官能团的增加,导致老化PS平衡吸附量降低.盐度对BDE-47在新制和老化微塑料上的吸附影响不大,但溶解性有机质的存在会降低新制和老化微塑料对BDE-47的吸附.

Sorption of Polybrominated Diphenyl Ethers by Virgin and Aged Microplastics

The sorption kinetics and isothermal sorption of polybrominated diphenyl ethers (PBDEs) by virgin and aged polyethylene (PE) and polystyrene (PS) microplastics with irradiation by ultraviolet light were studied, with 2,2'',4,4''-tetrabromodiphenyl ether (BDE-47) as a representative compound. The influence of different environmental factors, including salinity and dissolved organic matter, on its sorption were analyzed. The virgin and aged microplastics were characterized by scanning electron microscopy, x-ray diffraction, and total reflection infrared spectroscopy. The different models of kinetics and sorption isotherm were used to fit the data, and the sorption mechanism of PBDEs by microplastics was analyzed. The results showed that the main sorption modes of virgin and aged PE were surface sorption and external liquid film diffusion. The virgin and aged PS presented the surface sorption. The sorption isotherm was consistent with the Freudlich model, indicating that the sorption of BDE-47 by microplastics was characterized by a multi-phase, multi-layer, and non-uniform sorption process. The equilibrium sorption capacities of BDE-47 on virgin PE, aged PE, virgin PS, and aged PS were 3.72, 3.76, 6.04, and 3.46 ng·g^-1, respectively. There was no obvious difference in equilibrium sorption capacity between the aged and virgin PE. However, the equilibrium sorption capacity for the aged PS was decreased by 42.38% compared with that of the virgin PS. The partition of the outer liquid membrane diffusion was the main mechanism affecting sorption of PBDEs by PE. Compared with the virgin PS, the increase in crystallinity and surface oxygen-containing functional groups led to a decrease in the equilibrium sorption capacity of PBDEs on the aged PS. The sorption of BDE-47 was not significantly influenced by salinity. However, dissolved organic matter exerted a negative effect on the sorption of BDE-47.