Multiphase Chemistry of Air Pollutants from Urban Cured-In-Place-Pipes Installations: Unrecognized Source of Atmospheric Micro- and Nano-Plastics

Air pollution is a national and global problem with significant adverse impact on human health and wellbeing. Nationwide, there is a growing concern about the emissions of gaseous and particulate air pollutants from urban CIPP (Cured-in-Places-Pipes) installations. The CIPP process is widely utilized to repair leaking sanitary and storm sewer pipes in urban areas.

Recent studies have shown that CIPP emissions consist of complex mixtures of gaseous and liquid organic pollutants containing significant amounts of micro- and nano-plastic particles (MNPs). Because of their low degradation rates and persistence in environmental media (soils, water and air), MNPs pose long-term threats to ecosystems. MNPs are also easily transferred to human bodies through ingestion and inhalation, posing a potential threat to public health.

The goal of this project is to investigate the chemical composition of urban CIPP emissions with a focus on the secondary-formed and directly emitted airborne MNPs. The successful completion of this project will benefit society through the generation of new fundamental knowledge that could inform the design and operations of CIPP installations to control, reduce and minimize the formation and release of MNPs.

Further benefits to society will be achieved through student education and training including the mentoring of two doctoral students.

Despite the growing concern about urban air pollution from CIPP installations, a fundamental understanding of the multiphase chemistry, reactivity, and environmental/health impacts of MNPs from CIPP emissions has remained elusive. The goal of this research is to characterize the composition and multiphase physical chemistry of urban CIPP emissions. To advance this goal, the PI proposes to combine field sampling, laboratory experiments and advanced analytical characterization.

First, the PI proposes to fractionate laboratory and field samples from representative and simulated CIPP emissions into three fractions: 1) water- and solvent-soluble organic fractions, 2) dried (lyophilized) colloids, and 3) individual colloidal particles. For the characterization of the CIPP soluble organic fractions, the PI proposes to combine high performance liquid chromatography (HPLC) and high-resolution mass spectrometry (HRMS) interfaced with soft ionization sources [i.e., electrospray ionization (ESI) and atmospheric pressure photo-chemical ionization (APPI/APCI)] to obtain a broad account of the polar and nonpolar organic compounds that might be present in CIPP emissions.

For the dried (lyophilized) CIPP colloidal fractions, the PI proposes to combine particle flow cytometry with dynamic light scattering to characterize their particle size distributions. Finally, the PI proposes to combine Raman microscopy, SEM (with EDX), and synchrotron-based scanning transmission X-ray microscopy (STXM) complemented by near edge X-ray absorption fine Structure (NEXAFS) to image and analyze the composition of the individual particles (e.g., MNPs) present in the dried (lyophilized) CIPP colloidal fractions.

The successful completion of the proposed research could lead to a comprehensive characterization of MNPs and gaseous/liquid organic pollutants from CIPP emissions ultimately providing new fundamental knowledge to guide the design and operations of CIPP installations to control, reduce and minimize urban air pollution.

This award is jointly funded by the Environmental Engineering program of the NSF/ENG/CBET Division and the Environmental Chemical Sciences program of the NSF/MPS/CHE Division.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.