Search

Liquid crystal monomers (LCMs), commonly used in screens of electronic devices, have recently been identified as a group of emerging chemicals of concern associated with e-waste. They are potentially persistent, bioaccumulative, and toxic substances, and may pose a threat to the marine ecosystem. The Pearl River Estuary (PRE) receives organic contaminants discharged from the Pearl River Delta region, where primitive handling of e-waste is widespread. However, information on the pollution status of LCMs in the PRE is absent. Herein, a rapid and robust analytical method was established using ultrasonic extraction, solid phase extraction cleanup, and GC-Orbitrap-MS analysis. The spatial distribution of 39 target LCMs was investigated in 45 surface sediment samples from the PRE. Ten LCMs were detected, with ΣLCMs ranged from 0.9 to 31.1 ng/g dry weight. Our results demonstrated a widespread occurrence of LCMs in the sediments of the PRE, and a gradient of their contamination from inshore to offshore regions, indicating land-based origins. Our reported ΣLCMs concentrations were relatively higher compared to many other legacy and emerging pollutants found in the same investigated area. Preliminary risk assessment showed 3VbcH, Pe3bcH and tFMeO-3bcHP might be the top 3 risk contributors in the PRE. Further investigation on the ecological impact of LCMs on marine benthic ecosystems, as well as identification of their sources and control measures are warranted., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)

Liquid crystal monomers (LCMs) have been proposed as a class of emerging organic pollutants, which were recently detected in indoor dust and sediment samples collected near electronic devices recycling facilities. However, there is a knowledge gap for analytical method, occurrence, and distribution of LCMs in aqueous sample. Herein, a robust method was developed to determine 38 target LCMs in landfill leachate. A combined ultrasonic enhanced liquid-liquid extraction, saponification and silica/florisil packed column purification method achieved recoveries of 76.9~127.1%, 84.5~114.6% and 81.3~104.6% at spiking levels of 2 ng, 10 ng and 50 ng in leachate, respectively. The developed method was validated through determination of target LCMs in leachate samples collected from municipal landfills in Hong Kong (HK) and Shenzhen (SZ), China. There were 23 and 20 LCMs detected in the HK (ΣLCMs=1120 ng/L) and SZ (ΣLCMs=409 ng/L) sample, respectively, with 6 LCMs newly detected in the environment. This study provided the first evidence suggesting that landfill leachate might be a potential sink of LCMs emitted from e-waste. Future study is urged to investigate the potential migration of LCMs from landfill leachate as a point source, and their occurrence, distribution, fate, and ecotoxicological risk in aquatic environments on regional and global scales., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Liquid crystal monomers (LCMs), an emerging group of organic pollutants related to electronic waste, have been frequently detected from various environmental matrices, including landfill leachate. The persistence of LCMs requires robust technology for remediation. The objectives of this study were to evaluate the feasibility, performance and mechanism of the remediation of a typical LCM 4-[difluoro(3,4,5-trifluorophenoxy)methyl]− 3,5-difluoro-4′-propylbiphenyl (DTFPB) via synchronized oxidation-adsorption (SOA) Fenton technology and verify its application in DTFPB-contaminated leachate. The SOA Fenton system could effectively degrade 93.5% of DTFPB and 5.6% of its total organic carbon (TOC DTFPB) by hydroxyl radical oxidation (molar ratio of Fe2+ to H 2 O 2 of 1/4 and pH 2.5–3.0) following a pseudo-first-order model under 0.378 h−1. Additionally, synchronized adsorption of DTFPB and its degradation intermediates by in situ resultant ferric particles via hydrophobic interaction, complexation, and coprecipitation contributed to almost 100% of DTFPB and 33.4% of TOC DTFPB removal. Three possible degradation pathways involving eight products were proposed, and hydrophobic interactions might drive the adsorption process. It was first confirmed that the SOA Fenton system exhibited good performance in eliminating DTFPB and byproducts from landfill leachate. This study provides new insights into the potential of the Fenton process for the treatment of emerging LCMs contamination in wastewater. [Display omitted] • Synchronized oxidation-adsorption (SOA) completely removed e-waste pollutant DTFPB. • Three possible degradation pathways involving eight products were proposed. • Hydrophobic interaction might drive the adsorption of DTFPB and its products. • Particle adsorption compensated for reduced DTFPB removal caused by coexisting ion. • Ferric flocs had a higher adsorption priority to DTFBP than leachate original TOC. [ABSTRACT FROM AUTHOR]