介质阻挡放电等离子体老化微塑料及对Zn (II)吸附的影响

为了在实验中缩短微塑料的老化时间，更真实地模拟自然老化条件，采用介质阻挡放电（DBD）等离子体老化聚乙烯微塑料（PE-MP）和聚丙烯微塑料（PP-MP），同时研究了老化前后PE-MP和PP-MP对Zn （II）的吸附过程和机理.随着放电时间延长和输入电压升高，微塑料表面出现微小裂纹或孔洞，形成含氧官能团.老化后PE-MP和PP-MP对Zn （II）的吸附容量分别提高了22.7%和14.8%.老化前后微塑料对Zn （II）的吸附均符合准二级动力学模型.颗粒内扩散模型表明，Zn （II）在微塑料上的吸附过程可分为快速吸附，慢速吸附和吸附平衡3个阶段.同时，老化前后微塑料对Zn （II）的吸附均符合Langmuir吸附等温线模型.热力学结果表明，微塑料对Zn （II）的吸附是自发的吸热过程.Ca²⁺、腐殖酸和低pH值不利于微塑料对Zn （II）的吸附.

Dielectric barrier discharge plasma aging of microplastics and its effect on Zn(II) adsorption

In order to shorten the aging time of microplastics and mimic the natural aging conditions in the experiment, dielectric barrier discharge (DBD) plasma was used in the aging experiments of polyethylene microplastics (PE-MP) and polypropylene microplastics (PP-MP). And the adsorption process and mechanism of Zn(II) on PE-MP and PP-MP before and after aging was investigated. With the extension of discharge time and the elevation of input voltage, tiny cracks or holes appeared on the surface of microplastics and oxygen-containing functional groups were formed. The Zn(II) adsorption capacity of aged PE-MP and PP-MP was increased by 22.7% and 14.8%, respectively. The adsorption of Zn(II) on microplastics before and after aging conformed to the pseudo-second-order kinetic model. The intra-particle diffusion model showed that the adsorption process of Zn(II) on microplastics could be involved three processes:rapid adsorption, slow adsorption and adsorption equilibrium. In addition, the adsorption of Zn(II) on microplastics before and after aging conformed by Langmuir model. The thermodynamic results indicated that the adsorption of Zn(II) on microplastics was a spontaneous endothermic process. Ca²⁺, humic acid and low pH were not conducive to the adsorption of Zn(II) by microplastics.