Current research on high‐energy ionizing radiation for wastewater treatment and material synthesis

Abstract

High‐energy ionizing radiation (HEIR) can be a powerful tool for wastewater treatment and material synthesis in industry owing to its strong ionization ability. However, deficiencies in research data have limited the further use of the HEIR method. This review discusses the research data accumulated within the past 10 years for the application of gamma irradiation, X‐rays, and ion and electron beams. Each section contains a discussion on the effective HEIR doses and possible available mechanisms. This article reviews the most recent information and highlights issues for future investigation, for the purpose of promoting the full use of HEIR technology in industry.

Multiple Roles of Dissolved Organic Matter in Advanced Oxidation Processes

“…Advanced oxidation processes (AOPs) include a range of technologies applied in water and wastewater treatment to degrade a wide range of trace organic contaminants (TrOCs), including pharmaceuticals, personal care products, endocrine-disrupting compounds, pesticides and algal toxins, and other pathogens. − AOPs produce radical species (RS) that react to degrade TrOCs. AOPs that produce hydroxyl radicals ( • OH) or sulfate radicals (SO 4 •– ) are widely studied because of those radicals’ high redox potentials (1.90–2.70 V and 2.60–3.10 V, respectively). ,− The superoxide ion (O 2 •– ) and singlet oxygen ( 1 O 2 ) are also often involved but are not as frequently studied. − These reactive oxygen species are generated in situ by activating precursors such as hydrogen peroxide (H 2 O 2 ), peroxymonosulfate (PMS) or peroxydisulfate (PDS) with ultraviolet (UV) or solar light, ozone, metal ions, or carbon- or metal-derived materials, perhaps in nanoscale particles. ,,− Additionally, high-energy ionizing radiation (HEIR) can be used, which uses γ-rays or electron beams to simultaneously generate reactive H atoms, hydrated electrons, and • OH . Other AOPs relying instead on reactive chlorine atoms (Cl • , E 0 ( • Cl/Cl – ) = 2.55 V) have also received attention in recent years. − Specifically, chloramines used to control membrane biofouling pass through the microfiltration and reverse osmosis membranes in wastewater reuse treatment and carry over to the downstream AOP to form a mixed UV/H 2 O 2 and UV/chloramine AOP. ,,− The collective universe of reactive species produced in different AOPs is summarized in Table S1.…”

“…1,3,18−26 Additionally, high-energy ionizing radiation (HEIR) can be used, which uses γ-rays or electron beams to simultaneously generate reactive H atoms, hydrated electrons, and • OH. 27 Other AOPs relying instead on reactive chlorine atoms (Cl • , E 0 ( • Cl/Cl − ) = 2.55 V) have also received attention in recent years. 28−31 Specifically, chloramines used to control membrane biofouling pass through the microfiltration and reverse osmosis membranes in wastewater reuse treatment and carry over to the downstream AOP to form a mixed UV/H 2 O 2 and UV/chloramine AOP.…”