Peroxymonosulfate activation through LED-induced ZnFe2O4 for levofloxacin degradation

Biodegradation of per- and polyfluoroalkyl substances (PFAS): A review

Biodegradation of per- and polyfluoroalkyl substances (PFAS): A review.

Per- and polyfluoroalkyl substances (PFAS) are a group of over 4700 heterogeneous compounds with amphipathic properties and exceptional stability to chemical and thermal degradation. The unique properties of PFAS compounds has been exploited for almost 60 years and has largely contributed to their wide applicability over a vast range of industrial, professional and non-professional uses. However, increasing evidence indicate that these compounds represent also a serious concern for both wildlife and human health as a result of their ubiquitous distribution, their extreme persistence and their bioaccumulative potential. In light of the adverse effects that have been already documented in biota and human populations or that might occur in absence of prompt interventions, the competent authorities in matter of health and environment protection, the industries as well as scientists are cooperating to identify the most appropriate regulatory measures, substitution plans and remediation technologies to mitigate PFAS impacts. In this review, starting from PFAS chemistry, uses and environmental fate, we summarize the current knowledge on PFAS occurrence in different environmental media and their effects on living organisms, with a particular emphasis on humans. Also, we describe present and provisional legislative measures in the European Union framework strategy to regulate PFAS manufacture, import and use as well as some of the most promising treatment technologies designed to remediate PFAS contamination in different environmental compartments.

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PFAS Molecules: A Major Concern for the Human Health and the Environment

Per- and polyfluoroalkyl substances (PFASs) have highly complex behavior in the environment and are environmentally persistent. Exposure to PFASs causes cancer, liver toxicity, effect on the thyroid hormones, and also brings risks for the animal’s health. PFASs are separated into two categories: non-polymers and polymers, and most parts of the study of PFASs focus on non-polymers because they are more found in the environments. Urban water cycles such as drinking water, surface water, groundwater, and wastewater have been faced with the occurrence of PFASs, and PFOS and PFOA are the most detected PFASs. Various methods have been applied to remove PFASs which are divided into two main categories: separation and destruction. The PFASs destruction is still challenging in practice because of the powerful C–F bond and has only been utilized at the laboratory and small scale. Therefore, sorption is an eco-friendly and cost-effective technique with high efficacy that is commonly applied to eliminate PFASs from wastewater. In this review, most important sorption techniques used to remove long- and short-chain PFASs are collected such as powdered or granular activated carbons, carbon nanotubes, biochar, polysaccharide-based adsorbents, ion exchange resins, and minerals. Additionally, the possible mechanisms of PFASs sorption on various adsorbents are summarized, and different interactions such as electrostatic and hydrophobic interactions are reviewed. However, coexisting of inorganic anions and cations, natural organic matters, and other organic contaminants that generally exist in wastewater can affect the sorption of PFASs. Moreover, environmentally friendly and economical ways for the regeneration of adsorbents were summarized. Although this process needs more research and evaluation.

A review of emerging PFAS contaminants: sources, fate, health risks, and a comprehensive assortment of recent sorbents for PFAS treatment by evaluating their mechanism

Per- and polyfluoroalkyl substances (PFAS) are pollutants that have demonstrated a high level of environmental persistence and are very difficult to remediate. As the body of literature on their environmental effects has increased, so has regulatory and research scrutiny. The widespread usage of PFAS in industrial applications and consumer products, complicated by their environmental release, mobility, fate, and transport, have resulted in multiple exposure routes for humans. Furthermore, low screening levels and stringent regulatory standards that vary by state introduce considerable uncertainty and potential costs in the environmental management of PFAS. The recalcitrant nature of PFAS render their removal difficult, but existing and emerging technologies can be leveraged to destroy or sequester PFAS in a variety of environmental matrices. Additionally, new research on PFAS remediation technologies has emerged to address the efficiency, costs, and other shortcomings of existing remediation methods. Further research on the impact of field parameters such as secondary water quality effects, the presence of co-contaminants and emerging PFAS, reaction mechanisms, defluorination yields, and the decomposition products of treatment technologies is needed to fully evaluate these emerging technologies, and industry attention should focus on treatment train approaches to improve efficiency and reduce the cost of treatment.

https://www.mdpi.com/1660-4601/17/21/8117/pdf

A Review of the Applications, Environmental Release, and Remediation Technologies of Per- and Polyfluoroalkyl Substances.

https://doi.org/10.1016/j.ultsonch.2022.106063

Coupled high and low-frequency ultrasound remediation of PFAS-contaminated soils

In this paper, nonlinearity associated with intense ultrasound is studied by using the one-dimensional motion of nonlinear shock wave in an ideal fluid. In nonlinear acoustics, the wave speed of different segments of a waveform is different, which causes distortion in the waveform and can result in the formation of a shock (discontinuity). Acoustic pressure of high-intensity waves causes particles in the ideal fluid to vibrate forward and backward, and this disturbance is of relatively large magnitude due to high-intensities, which leads to nonlinearity in the waveform. In this research, this vibration of fluid due to the intense ultrasonic wave is modeled as a fluid pushed by one complete cycle of piston. In a piston cycle, as it moves forward, it causes fluid particles to compress, which may lead to the formation of a shock (discontinuity). Then as the piston retracts, a forward-moving rarefaction, a smooth fan zone of continuously changing pressure, density, and velocity is generated. When the piston stops at the end of the cycle, another shock is sent forward into the medium. The variation in wave speed over the entire waveform is calculated by solving a Riemann problem. This study examined the interaction of shocks with a rarefaction. The flow field resulting from these interactions shows that the shock waves are attenuated to a Mach wave, and the pressure distribution within the flow field shows the initial wave is dissipated. The developed theory is applied to waves generated by 20 KHz, 500 KHz, and 2 MHz transducers with 50, 150, 500, and 1500 W power levels to explore the effect of frequency and power on the generation and decay of shock waves. This work enhances the understanding of the interactions of high-intensity ultrasonic waves with fluids.

https://www.mdpi.com/2624-599X/2/1/11/pdf

Nonlinear Behavior of High-Intensity Ultrasound Propagation in an Ideal Fluid

Sonolysis has been suggested as a viable approach for the destruction of per- and polyfluoroalkyl substances (PFAS) in aqueous media. However, the impact of ultrasonic parameters on PFAS degradation must be better understood to transition the technology from the research discovery phase to field application. This study investigated the degradation of perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) and the effect the power density (100–200 W/L) and initial concentration (10–82 μM) on the kinetics of sonolytic degradation. Results show that for a given power density, PFAS degradation was controlled by saturation kinetics, as indicated by an increase in the PFAS degradation rate with an increase in the initial concentration, until a maximum value was reached. Furthermore, the saturation conditions were dependent on the power density. Saturation was reached at a lower concentration of 40 μM at 100 W/L compared to >82 μM at 200 W/L. Results of the study demonstrate that the sonolytic degradation efficiency increases with an increase in the power density and that the optimal rate of degradation is achieved at saturation conditions. Sonolysis is a promising technology to effectively treat PFAS concentrated waste. 

Richard W. Marsh

Papers

A Review of the Applications, Environmental Release, and Remediation Technologies of Per- and Polyfluoroalkyl Substances.

Coupled high and low-frequency ultrasound remediation of PFAS-contaminated soils

Nonlinear Behavior of High-Intensity Ultrasound Propagation in an Ideal Fluid

Kinetics effects of the power density and initial concentration on the sonochemical degradation of PFOS and PFOA in concentrated waste

Contributions of Reactor Geometry and Ultrasound Frequency on the Efficieny of Sonochemical Reactor