Flash photolysis of per[oxydi]sulfate ions in aqueous solutions. The sulfate and ozonide radical anions
01 Jul 1967-The Journal of Physical Chemistry (American Chemical Society)-Vol. 71, Iss: 8, pp 2511-2516
About: This article is published in The Journal of Physical Chemistry.The article was published on 1967-07-01. It has received 299 citations till now. The article focuses on the topics: Ozonide & Flash photolysis.
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TL;DR: In this article, rate constants have been compiled for reactions of various inorganic radicals produced by radiolysis or photolysis, as well as by other chemical means in aqueous solutions.
Abstract: Rate constants have been compiled for reactions of various inorganic radicals produced by radiolysis or photolysis, as well as by other chemical means in aqueous solutions. Data are included for the reactions of ⋅CO2 −, ⋅CO3⋅−, O3, ⋅N3, ⋅NH2, ⋅NO2, NO3⋅, ⋅PO32−, PO4⋅2−, SO2⋅ −, ⋅SO3 −, SO4⋅−, ⋅SO5⋅−, ⋅SeO3⋅ −, ⋅(SCN)2⋅ −, ⋅CL2⋅−, ⋅Br2⋅ −, ⋅I2⋅ −, ⋅ClO2⋅, ⋅BrO2⋅, and miscellaneous related radicals, with inorganic and organic compounds.
2,958 citations
TL;DR: In this paper, the authors provide a state-of-the-art review on the development in heterogeneous catalysts including single metal, mixed metal, and nonmetal carbon catalysts for organic contaminants removal, with particular focus on peroxymonosulfate (PMS) activation.
Abstract: Sulfate radical-based advanced oxidation processes (SR-AOPs) employing heterogeneous catalysts to generate sulfate radical (SO4 −) from peroxymonosulfate (PMS) and persulfate (PS) have been extensively employed for organic contaminant removal in water. This article aims to provide a state–of–the–art review on the recent development in heterogeneous catalysts including single metal, mixed metal, and nonmetal carbon catalysts for organic contaminants removal, with particular focus on PMS activation. The hybrid heterogeneous catalyst/PMS systems integrated with other advanced oxidation technologies is also discussed. Several strategies for the identification of principal reactive radicals in SO4 −–oxidation systems are evaluated, namely (i) use of chemical probe or spin trapping agent coupled with analytical tools, and (ii) competitive kinetic approach using selective radical scavengers. The main challenges and mitigation strategies pertinent to the SR-AOPs are identified, which include (i) possible formation of oxyanions and disinfection byproducts, and (ii) dealing with sulfate produced and residual PMS. Potential future applications and research direction of SR-AOPs are proposed. These include (i) novel reactor design for heterogeneous catalytic system based on batch or continuous flow (e.g. completely mixed or plug flow) reactor configuration with catalyst recovery, and (ii) catalytic ceramic membrane incorporating SR-AOPs.
1,802 citations
TL;DR: This Critical Review comparatively examines the activation mechanisms of peroxymonosulfate and peroxydisulfates and the formation pathways of oxidizing species and the impacts of water parameters and constituents such as pH, background organic matter, halide, phosphate, and carbonate on persulfate-driven chemistry.
Abstract: Reports that promote persulfate-based advanced oxidation process (AOP) as a viable alternative to hydrogen peroxide-based processes have been rapidly accumulating in recent water treatment literature. Various strategies to activate peroxide bonds in persulfate precursors have been proposed and the capacity to degrade a wide range of organic pollutants has been demonstrated. Compared to traditional AOPs in which hydroxyl radical serves as the main oxidant, persulfate-based AOPs have been claimed to involve different in situ generated oxidants such as sulfate radical and singlet oxygen as well as nonradical oxidation pathways. However, there exist controversial observations and interpretations around some of these claims, challenging robust scientific progress of this technology toward practical use. This Critical Review comparatively examines the activation mechanisms of peroxymonosulfate and peroxydisulfate and the formation pathways of oxidizing species. Properties of the main oxidizing species are scrutinized and the role of singlet oxygen is debated. In addition, the impacts of water parameters and constituents such as pH, background organic matter, halide, phosphate, and carbonate on persulfate-driven chemistry are discussed. The opportunity for niche applications is also presented, emphasizing the need for parallel efforts to remove currently prevalent knowledge roadblocks.
1,412 citations
TL;DR: In this paper, the authors provide an overview of various methods for analysis of persulfate decontamination and their analysis is often prone for interference by other matrix components and hampered by the low stability of peroxydisulfate and peroxymonosulfate in aqueous systems.
1,197 citations
TL;DR: In this article, a chemical probe method was developed to identify the active radical species, and differences between the reactivity of the probe compounds and the potential radical species were observed, and the usage of various probes, including tert-butyl alcohol, phenol, and nitrobenzene, for simultaneously identifying SO4−•/HO• was investigated.
Abstract: Thermal activation can induce persulfate (S2O82−) degradation to form sulfate radicals (SO4−•) that can undergo radical interconversion to form hydroxyl radicals (HO•) under alkaline conditions. The radicals SO4−•/HO• can be present either individually or simultaneously in the persulfate oxidation system. To identify the active radical species, a chemical probe method was developed. An excess of probe compounds was added to the system, and differences between the reactivity of the probes and the potential radical species were observed. The usage of various probes, including tert-butyl alcohol, phenol, and nitrobenzene (NB), for simultaneously identifying SO4−•/HO• was investigated. NB can only react with radicals: it cannot react with persulfate. The reaction rate of NB with HO• is 3000−3900 times greater than that of NB with SO4−•, which is a good candidate for use as a probe for differentiating between SO4−•/HO• reactivity. Furthermore, the effects of pH on the formation of SO4−•/HO• were demonstrated b...
1,018 citations