Degradation mechanism and properties of debris of photocatalytically degradable plastics LDPE-TiO2 vary with environments. (January 2022)

• Record Type: Journal Article
• Authors: Wang, Dandan; Zhang, Pengyan; Yan, Mengqin; Jin, Lili; Du, Xiaohan; Zhang, Fan; Wang, Qinqin; Ni, Bingchuan; Chen, Chao
• Is Part Of: Polymer degradation and stability. Volume 195(2022)
• Publication Date: 2022-01
• Subjects: PDP photocatalytically degradable plastics -- water-Cl0 water without NaCl -- water-Cl3.5 water with 3.5% of NaCl -- RAtert-butanol/HO‧ reaction rate for reaction between tert-butanol and HO‧ -- RALDPE/HO‧ reaction rate for reaction between LDPE and HO‧ -- RACl-/HO‧ reaction rate for reaction between chloride and HO‧; Photocatalytically degradable -- LDPE-TiO2 -- Photodegradation -- Debris -- Chloride ion -- Organochlorine -- water-Cl0, water without NaCl -- water-Cl3.5, water with 3.5% of NaCl -- RAtert-butanol/HO‧, reaction rate for reaction between tert-butanol and HO‧, RALDPE/HO‧, reaction rate for reaction between LDPE and HO‧, RACl−/HO‧, reaction rate for reaction between chloride and HO‧; Polymers -- Deterioration -- Periodicals; Stabilizing agents -- Periodicals; Polymères -- Dégradation -- Périodiques; Stabilisants -- Périodiques; 668.9
• DOI: 10.1016/j.polymdegradstab.2021.109806
• Languages: English
• ISSNs: 0141-3910

Abstract

Highights: Environmental conditions affect photocatalytic degradation of LDPE-TiO2. First report the effect of environments on degradation mechanism of LDPE-TiO2. Organochlorine was first observed in the debris of LDPE-TiO2. HO‧ in water containing NaCl attacks LDPE-TiO2 via reaction with Cl − forming Cl. Abstract: Photocatalytically degradable plastics (PDP) are promising in mitigating plastic pollution due to their high degradability. Nevertheless, the unclear impact of environmental conditions on properties of debris for PDP and the knowledge gap in the mechanism from the perspective of photogenerated reactive species' function hinder PDP's application. Here, low-density polyethylene (LDPE) containing TiO2 (LDPE-TiO2 ) was selected as representative PDP. The photocatalytic degradation performance and mechanism of LDPE-TiO2 in water without NaCl, water with NaCl, and air were studied. Compared with water, the air resulted in a higher carbonyl index and higher molecular weight of debris from LDPE-TiO2 whether the irradiation time was the same (120 h) or the mass loss of LDPE-TiO2 was the same (68 ± 2%). Chloride ions in water conditions resulted in CCl bond formation in the debris of LDPE-TiO2 suggesting generation of organochlorine substance. In the air the photogenerated electron ( e − ) contributed to LDPE-TiO2 film degradation, while in the water e − mainly underwent recombination with the photogenerated hole. In water with Cl −, HO‧ attacked LDPE via reaction with Cl − forming organochlorine substance. The effects of environmental conditions on the properties of debris and the functions of photogenerated reactive species for PDP degradation are reported for the first time in this study. The findings provide scientific support for the development of PDP technology. Graphical abstract: Image, graphical abstract