Degradation of Polyethylene Terephthalate Microplastics by Mineral Acids: Experimental, Molecular Modelling and Optimization Studies
Degradation of Polyethylene Terephthalate Microplastics by Mineral Acids: Experimental, Molecular Modelling and Optimization Studies
复制标题
DOI：
10.1007/s10924-022-02578-z
复制
发表时间：
2022-09
影响因子：
5.3
通讯作者：
T. Chowdhury;Qingyue Wang;C. Enyoh
中科院分区：
文献类型：
--
作者：
T. Chowdhury;Qingyue Wang;C. Enyoh
大气中的矿物酸在氧气的作用下分解，向大气中释放酸性气体，产生酸雨，酸雨可以对材料进行化学腐蚀。我们推测，这些矿物酸引起的化学风化也可能影响MPS在环境中的降解或破裂速度。然而，关于环境中无机酸对聚对苯二甲酸乙二醇酯(PET)的化学风化过程的研究尚未见文献报道。在接触时间(30，60,120,720和1440℃)、温度(10，25，40，70,100和130℃)和摇动速度(100,150,200和250转/分)的影响下，用盐酸(HA)、硝酸(NA)和硫酸(SA)等酸对聚酯微塑料(MPS)(1000µm)进行了人工降解。用失重法、变压扫描电子显微镜(VP-SEM)和衰减全反射傅立叶变换红外光谱(ATR-FTIR)对降解过程进行了监测，并用响应面法(RSM)进行了优化。结果表明，随着接触时间、温度和振动速度的增加，失重缓慢，但失重增加。对于这三种酸，由于影响的不同，PET MPS的谱峰损失是相似的。然而，基于ATR-FTIR和失重结果的降解速度遵循温度 >； 摇动速度 >； 接触时间。用蒙特卡罗(MC)模拟和密度泛函理论(DFT)研究了PET MPS与酸之间的表面相互作用。总体而言，ATR-FTIR分析和DFT研究表明，断裂发生在包含氧原子(-OH，C=O)和芳香环的部分PET MPS结构中。然而，RSM的优化结果显示，HA、SA和NA的最佳失重率分别为33%、30%和22%。因此，这些酸可以用于PET MPS的降解，较高的降解速度需要较长的时间、较高的温度和较快的振荡速度。
Mineral acids in the atmosphere breakdown on the action of oxygen and release acid gases into atmosphere causing acid rain, which can chemically weather materials. We hypothesized that the chemical weathering caused by these mineral acids may also influence the rate of degradation or cracking of MPs in the environment. However, studies focusing on the chemical weathering process of mineral acids in the environment on polyethylene terephthalate (PET) is not available in literature. In the present work, PET microplastics (MPs) (1000 µm) were artificially degraded by acids such as hydrochloric acid (HA), nitric acid (NA) and sulphuric acid (SA) under the effect of contact time (30, 60, 120, 720 and 1440 min), temperature (10, 25, 40, 70,100 and 130 °C), and shaking speed (100, 150, 200 and 250 rpm). Degradation was monitored by weight loss, Variable Pressure Scanning Electron Microscope (VP-SEM) and Attenuated total reflectance-Fourier-Transform Infrared (ATR-FTIR) and optimized by Response Surface Methodology (RSM). Results showed that the weight loss were slow but increased with increasing contact time, temperature and shaking speed. For all three acids, the PET MPs spectra peak loss was similar for the different effects. However, the speed of degradation based on the ATR-FTIR and weight loss results followed temperature > shaking speed > contact time. The surface interactions between the PET MPs and acids were investigated usingMonte Carlo(MC) simulations and Density functional theory (DFT) Studies. Overall, ATR-FTIR analysis and DFT studies suggested that the breakdown took place through the parts of the PET MPs structure containing oxygen atoms (–OH, C=O) and the aromatic ring. However, optimization results from RSM showed optimal weight loss of 33%, 30% and 22% for HA, SA and NA respectively. Therefore, these acids can be employed in PET MPs degradation and higher rate of degradation will require longer time, high temperature and shaking speeds.