Study On Triclosan Release And Secondary Pollution Caused By Microplastics

Recently,the problem of microplastics(MPs)has become more and more serious,and MPs generated from plastic products can transfer and release pollutants,such as the antimicrobial agent triclosan(TCS),secondary microplastics(SMPs),and the plastic additive di-(2-ethylhexyl)phthalate(DEHP).Thus,this paper focus on biedegradable plastics and aims to study the interaction between typical biodegradable microplastics(Bio-MPs)/non-degradable microplastics(Non-MPs)and pollutants(TCS,SMPs,DEHP)by comparison,to better understand the environmental risks of Bio-MPs.The conclusions of this study are as follows:(1)In the study of the adsorption/desorption behavior of typical Bio-MPs and Non-MPs to TCS,we selected Bio-MPs(polyadipate/butylene terephthalate(PBAT),polybutylene succinate(PBS),and polylactic acid(PLA))and Non-MPs(polyethylene(PE),polystyrene(PS)and polyvinyl chloride(PVC)),to explore their adsorption behavior of TCS and the desorption behavior by adsorbed TCS-saturated MPs(MPs-TCS)in simulated digestive fluid.The results of adsorption kinetics showed that the order of the adsorption equilibrium capacity of MPs to TCS was PBAT > PBS > PLA > PE > PS > PVC,and the order of adsorption rate was PBS >PLA > PBAT > PE > PS > PVC.And the adsorption process was mainly chemical adsorption.The experimental results of desorption showed that the increase of p H significantly enhanced the desorption rate of MPs-TCS in simulated gastric/intestinal fluid.And food reduced the concentration of TCS in the simulated gastric/intestinal fluid during MPs-TCS desorption.(2)In the study of the behavior of SMPs produced from typical biodegradable and nondegradable plastics,biodegradable plastics PBAT,PBS,PLA and PBAT-starch-based-PLA plastic bags(PBAT/PLA bags)were selected as materials in this experiment,and compared with non-degradable plastics PE,PS,PVC and PE plastic bags(PE bags).It was found that different kinds of primary plastics would continuously form SMPs over time after mechanical stress/ultraviolet light aging in artificial seawater/ultrapure water,and the SMPs in the particle size range of 1-50 μm accounted for the highest proportion.Under this experimental condition,neither PBAT/PLA bag’s nor PE bag’s SMPs affected the survival of T.japonicus when the SMPs mixured with TCS.(3)In the study of the release of additives from different Bio-MPs and Non-MPs,we cut PBAT/PLA bags,PLA mulch,PE bags and PE mulch into MPs,and the leaching of the additive DEHP from four kinds of MPs in seawater was studied.The results of leaching experiments showed that the leaching amount of DEHP of the four MPs in seawater was in the order of PE mulch > PE bags > PLA mulch > PBAT/PLA bags.The leaching kinetics fitting model indicated that the leaching of DEHP was mainly physical.By comparing the Raman spectra before and after the experiment,it was found that the leaching of DEHP was not related to the aging of MPs in seawater.