Mechanisms, toxicity and optimal conditions - research on the removal of benzotriazoles from water using Wolffia arrhiza

• Published in: The Science of the total environment 2022-11, Vol.847, p.157571-157571, Article 157571
• Main Authors: Polińska, Weronika, Piotrowska-Niczyporuk, Alicja, Karpińska, Joanna, Struk-Sokołowska, Joanna, Kotowska, Urszula
• Format: Article
• Language: English
• Subjects: Benzotriazoles; Phytoremediation; Process optimization; Removal efficiency; Removal mechanisms; Toxicity evaluation
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2022.157571

In the presented work, phytoremediation with the use of floating plant Wolffia arrhiza (L.) Horkel ex Wimm. was proposed as a method of removing the selected benzotriazoles (BTRs): 1H–benzotriazole (1H-BTR), 4-methyl-1H-benzotriazole (4M-BTR), 5-methyl-1H-benzotriazole (5M-BTR) and 5-chlorobenzotriazole (5Cl-BTR) from water. The efficiency of phytoremediation depends on three factors: daily time of exposure to light, pH of the model solution, and the amount of plans. Using a design of experiment (DoE) methods the following optimal values were selected: plant amount 1.8 g, light exposure 13 h and pH 7 per 100 mL of the model solution. It was found that the loss of BTRs in optimal conditions ranged from 92 to 100 % except for 4M-BTR, for which only 23 % of removal was achieved after 14 days of cultivation of W. arrhiza. The half-life values for studied compounds ranged from 0.98 days for 5Cl-BTR to 36.19 for 4M-BTR. The observed rapid vanishing of 5M-BTR is supposed by the simultaneous transformation of 5M-BTR into 4M-BTR. The detailed study of BTRs degradation pointed that the plant uptake is mainly responsible for the benzotriazoles concentration decrease. Toxicity tests showed that the tested organic compounds induce oxidative stress in W. arrhiza, which manifested among others, in reduced levels of chlorophyll in cultures with benzotriazoles compared to control. [Display omitted] •Four benzotriazoles were tested for toxicity to Wolffia arrhiza.•The amount of the plant, the pH, the time of exposure affects the efficiency of removal benzotriazoles.•The roles of hydrolysis, photodegradation, sorption and plant uptake were explored.•Removal efficiency is about 100 % for 5Cl-BTR in a cultivation with Wolffia arrhiza.•Exposure to benzotriazoles causes an oxidative stress on Wolffia arrhiza.