Su Jiana, Ruan Jiahui, Luo Dan, Wang Jinjin, Huang Zhujian, Yang Xingjian, Zhang Yulong, Zeng Qiaoyun, Li Yongtao, Huang Weilin, Cui Lihua, Chen Chengyu
College of Natural Resources and Environment, Guangdong Provincial Key Laboratory of Agricultural & Rural Pollution Abatement and Environmental Safety, South China Agricultural University, 483 Wushan Road, Guangzhou 510642, Guangdong, China.
Department of Environmental Sciences, Rutgers, The State University of New Jersey, 14 College Farm Road, New Brunswick, New Jersey 08901, United States.
Environ Sci Technol. 2023 Oct 17;57(41):15656-15666. doi: 10.1021/acs.est.3c04808. Epub 2023 Sep 25.
Nanoplastics (NPs) have different colors, which could affect their photoaging processes in aquatic environments. This study investigated the effects of irradiation on physicochemical properties and aggregation kinetics of five colored NPs. Photodegradation rates and photooxidation degrees ranked white ≈ yellow > red > blue ≈ black NPs, indicating that NPs with longer color wavelengths photoaged faster. The discoloration process followed color fading (2-14 days, except for white NPs), yellowing (10-16 days), yellow fading (18 days), and turning transparent (20-22 days). White NPs exhibited a different photoaging sequence (C-H → C-OH → C═O → O-C═O) from others. Photodegradation was mainly controlled by singlet oxygen, producing 13 chemicals that were mostly organic acids. The overall colloidal stability of pristine NPs ranked blue > yellow > red > black > white. Irradiation for 16 days retarded aggregation of white and other NPs in NaCl solution, raising the critical coagulation concentration (CCC) by 82.14 and 0.85-7.90%, respectively. Contrarily, irradiation promoted aggregation in CaCl solution by reducing the CCC of white (67.37%) and other (33.33-37.58%) NPs. The findings demonstrate that colored NPs underwent photoaging processes different from white/transparent NPs, which were focused by previous work, highlighting the important role of color in their environmental fate and transport.
纳米塑料（NPs）有不同颜色，这可能会影响它们在水生环境中的光老化过程。本研究调查了辐照对五种有色纳米塑料的物理化学性质和聚集动力学的影响。光降解速率和光氧化程度排序为白色≈黄色>红色>蓝色≈黑色纳米塑料，这表明颜色波长较长的纳米塑料光老化更快。变色过程依次为褪色（2 - 14天，白色纳米塑料除外）、变黄（10 - 16天）、黄褪色（18天）和变透明（20 - 22天）。白色纳米塑料表现出与其他纳米塑料不同的光老化顺序（C - H→C - OH→C═O→O - C═O）。光降解主要由单线态氧控制，产生了13种化学物质，其中大部分是有机酸。原始纳米塑料的整体胶体稳定性排序为蓝色>黄色>红色>黑色>白色。在氯化钠溶液中辐照16天会延缓白色和其他纳米塑料的聚集，使临界聚沉浓度（CCC）分别提高82.14%和0.85 - 7.90%。相反，在氯化钙溶液中辐照会通过降低白色纳米塑料（67.37%）和其他纳米塑料（33.33 - 37.58%）的临界聚沉浓度来促进聚集。研究结果表明，有色纳米塑料经历了与白色/透明纳米塑料不同的光老化过程，而之前的研究主要关注白色/透明纳米塑料，这突出了颜色在它们的环境归宿和迁移中的重要作用。
