Water decontamination by reactive high-valent iron species

The occurrence of emerging organic contaminants(EOCs)in water bodies has received increasing attention worldwide.EOCs,such as pharmaceuticals and pesticides,when present in trace concentrations,cannot be effectively removed by conventionally designed treatment processes in most wastewater treatment plants.Therefore,advanced oxidation processes(AOPs)have been developed as promising alternatives for trace-level EOC elimination using radicals(e.g.,hydroxyl radicals and sulfate radicals)and non-radical pathways.However,these reactive species are generally nonselective and also exhibit excellent reactivity with background water constituents,leading to excess consumption of oxidants and the possible generation of toxic secondary pollutants[1].Accordingly,selective oxidants have recently become a subject of considerable interest,mainly including singlet oxygen and high-valent metal species[2].They could preferentially attack electron-rich moieties,resulting in selective degradation of EOCs.

Pyrolyzed biomass-derived nanoparticles:a review of surface chemistry,contaminant mobility,and future research avenues to fill the gaps

Nanoparticles are abundant in the subsurface,soil,streams,and water bodies,and are often a critical control on elemental speciation,transport and cycling in the natural environment.This review provides an overview of pyrolyzed biomass-derived nanoparticles(PBNPs),their surface properties and reactivity towards aqueous species.We focus specifically on biochar-derived nanoparticles and activated carbon-derived nanoparticles which fall under our classification of PBNPs.Activated carbon-iron(nano)composites are included in some instances where there are significant gaps in literature because of their environmental relevance.Increased use of activated carbon,along with a resurgence in the manufacture and application of biochar for water treatment and soil amendment,has generated significant concerns about the mobility and toxicity of PBNPs derived from the bulk material in environmental applications.Recent examples are discussed to highlight current progress in understanding the influence of PBNPs on contaminant transport,followed by a critical discussion of gaps and future research directions.