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Per- and polyfluoroalkyl substances (PFAS) are persistent, mobile, and toxic chemicals that are hazardous to human health and the environment. Several countries, including the United States, plan to set an enforceable maximum contamination level for certain PFAS compounds in drinking water sources. Among the available treatment options, photocatalytic treatment is promising for PFAS degradation and mineralization in the aqueous solution. In this review, recent advances in the abatement of PFAS from water using photo-oxidation and photo-reduction are systematically reviewed. Degradation mechanisms of PFAS by photo-oxidation involving the holes (h vb + ) and oxidative radicals and photo-reduction using the electrons (e cb - ) and hydrated electrons (e aq - ) are integrated. The recent development of innovative heterogeneous photocatalysts and photolysis systems for enhanced degradation of PFAS is highlighted. Photodegradation mechanisms of alternative compounds, such as hexafluoropropylene oxide dimer acid (GenX) and chlorinated polyfluorinated ether sulfonate (F-53B), are also critically evaluated. This paper concludes by identifying major knowledge gaps and some of the challenges that lie ahead in the scalability and adaptability issues of photocatalysis for natural water treatment. Development made in photocatalysts design and system optimization forges a path toward sustainable treatment of PFAS-contaminated water through photodegradation technologies. [Display omitted] • Degradation mechanisms of PFAS by photo-oxidation and photo-reduction processes are discussed in detail. • Innovative heterogeneous photocatalysts and photolysis systems for enhanced degradation of PFAS are highlighted. • Advancements on the photodegradation of PFAS alternatives are emphasized. • Major knowledge gaps in the PFAS photodegradation are identified. [ABSTRACT FROM AUTHOR]

Abstract: A bibliometric analysis based on Science Citation Index (SCI) published by Institute of Scientific Information (ISI) was carried out to identify the global research related to lead in drinking water field from 1991 to 2007 and to improve the understanding of research trends in the same period. The results from this analysis indicate that there have been an increasing number of annual publications mainly during two periods: from 1992 to 1997 and from 2004 to 2007. United States produced 37% of all pertinent articles followed by India with 8.0% and Canada with 4.8%. Science of the Total Environment published the most articles followed by Journal American Water Works Association and Toxicology. Summary of the most frequently used keywords are also provided. “Cadmium” was the most popular author keyword in the 17years. Furthermore based on bibliometric results four research aspects were summarized in this paper and the historical research review was also presented. [Copyright &y& Elsevier]

Environmental justice is concerned with the fair treatment and meaningful involvement of all people regardless of race, color, national origin, or income with respect to the development, implementation, and enforcement of environmental laws, regulations, and policies. A wide variety of empirical studies have concluded that disparate-impact discrimination does in fact exist since minority and low-income communities are at disproportionate risk for environmental harm. In this paper we examine these issues in the context of enforcing the safe drinking water act (SDWA). Specifically, we focus on the association between race, income, and hazardous levels of arsenic concentration and analyze the broad equity implications of implementing the new arsenic regulation by examining the relationship between community-level exposure to arsenic and socioeconomic and demographic characteristics of the population in Arizona. The results provide no support for the contention that continued selective implementation and enforcement of the revised SDWA arsenic standard is likely to disadvantage minority or low-income groups disproportionately in Arizona. [Copyright &y& Elsevier]