A potential threat from biodegradable microplastics: mechanism of cadmium adsorption and desorption in the simulated gastrointestinal environment  

作　　者：Timing Jiang Xiang Wu Shushan Yuan Changfei Lai Shijie Bian Wenbo Yu Sha Liang Jingping Hu Liang Huang Huabo Duan Yafei Shi Jiakuan Yang 

机构地区：[1]School of Environmental Science&Engineering,Huazhong University of Science and Technology,Wuhan 430074,China [2]School of Resources and Environmental Science,Hubei University,Wuhan 430062,China [3]Hubei Provincial Engineering Laboratory for Solid Waste Treatment Disposal and Recycling,Wuhan 430074,China [4]School of Civil Engineering,Architecture and Environment,Hubei University of Technology,Wuhan 430068,China [5]State Key Laboratory of Coal Combustion,Huazhong University of Science and Technology,Wuhan 430074,China

出　　处：《Frontiers of Environmental Science & Engineering》2024年第2期63-75,共13页环境科学与工程前沿（英文）

基　　金：supported by the Hubei Provincial Natural Science Foundation of China(Nos.2021CF349 and 2020CFA042).

摘　　要：It has been demonstrated that microplastics (MPs) can accumulate heavy metals from the environment and transfer them into organisms via the food chain. However, adsorption and desorption capacities for biodegradable MPs relative to those for conventional MPs remain poorly understood. In this study, cadmium (Cd(II)) adsorption and desorption characteristics of polylactic acid (PLA), a typical biodegradable MP, were investigated. Two conventional MPs, i.e., polypropylene (PP) and polyamide (PA) were used for comparison. The maximum Cd(II) adsorption capacities of the MPs studied in the adsorption experiments decreased in the order PA (0.96 ± 0.07 mg/g) > PLA (0.64 ± 0.04 mg/g) > PP (0.22 ± 0.03 mg/g). The Pseudo-second-order kinetic model and Freundlich isothermal model described the Cd(II) adsorption behaviors of PLA MPs well. X-ray photoelectron spectroscopy and two-dimensional Fourier transform infrared correlation spectroscopy analysis indicated that oxygen functional groups were the major and preferential binding sites of PLA MPs, which contributed to their high Cd(II) adsorption capacities. Simulated gastric and intestinal fluids both significantly enhanced the desorption capacities of the examined MPs. Notably, degradation of the PLA MPs during in vitro human digestion made the Cd(II) on the PLA MPs more bioaccessible (19% in the gastric phase and 62% in the intestinal phase) than Cd(II) on the PP and PA MPs. These results indicate the remarkable capacities of biodegradable MPs to accumulate Cd(II) and transfer it to the digestive system and show that biodegradable MPs might pose more severe threats to human health than conventional nonbiodegradable MPs.

关 键 词：Biodegradable microplastics CADMIUM Adsorption and desorption Gastrointestinal environment Two-dimensional correlation spectroscopy BIOACCESSIBILITY 

分 类 号：O64[理学—物理化学]