Nine transition metals were tested for the activation of three oxidants and the generation of inorganic radical species such as sulfate, peroxymonosulfate, and hydroxyl radicals. From the 27 combinations, 14 M/Ox couples demonstrated significant reactivity toward transforming a model organic substrate such as 2,4-dichlorophenol and are further discussed here. It was found that Co(II) and Ru(III) are the best metal catalysts for the activation of peroxymonosulfate. As expected on the basis of the Fenton reagent, Fe(III) and Fe(II) were the most efficient transition metals for the activation of hydrogen peroxide. Finally, Ag(I) showed the best results toward activating persulfate. Quenching studies with specific alcohols (tert-butyl alcohol and ethanol) were also performed to identify the primary radical species formed from the reactive M/Ox interactions. The determination of these transient species allowed us to postulate the rate-determining step of the redox reactions taking place when a metal is coupled with an oxidant in aqueous solution. It was found that when Co(II), Ru(III), and Fe(II) interact with peroxymonosulfate, freely diffusible sulfate radicals are the primary species formed. The same was proven for the interaction of Ag(I) with persulfate, but in this case caged or bound to the metal sulfate radicals might be formed as well. The conjunction of Ce(III), Mn(II), and Ni(II) with peroxymonosulfate showed also to generate caged or bound to the metal sulfate radicals. A combination of sulfate and hydroxyl radicals was formed from the conjunction of V(III) with peroxymonosulfate and from Fe(II) with persulfate. Finally, the conjunction of Fe(III), Fe(II), and Ru(III) with hydrogen peroxide led primarily to the generation of hydroxyl radicals. It is also suggested here that the redox behavior of a particular metal in solution cannot be predicted based exclusively on its size and charge. Additional phenomena such as metal hydrolysis as well as complexation with other counterions present in solution might affect the thermodynamics of the overall process and are further discussed here.

Radical generation by the interaction of transition metals with common oxidants.

The sulfate radical pathway of the room-temperature degradation of two phenolic compounds in water is reported in this study. The sulfate radicals were produced by the cobalt-mediated decomposition of peroxymonosulfate (Oxone) in an aqueous homogeneous system. The major intermediates formed from the transformation of 2,4-dichlorophenol were 2,4,6-trichlorophenol, 2,3,5,6-tetrachloro-1,4-benzenediol, 1,1,3,3-tetrachloroacetone, pentachloroacetone, and carbon tetrachloride. Those resulting from the transformation of phenol in the presence of chloride ion were 2-chlorophenol, 4-chlorophenol, 2,4-dichlorophenol, 2,6-dichlorophenol, 1,1,3,3-tetrachloroacetone, and pentachloroacetone. In the absence of chloride ion, phenol transformed into 2,5-cyclohexadiene-1,4-dione (quinone), 1,2-benzenediol (catechol), and 1,4-benzenediol (hydroquinone). Several parameters were varied, and their impact on the transformation of the organic compounds is also discussed. The parameters varied were the initial concentration of the organic substrate, the dose of Oxone used, the cobalt counteranion, and in particular the impact of chloride ions and the quenching agent utilized for terminating the reaction. This is one of the very few studies dealing with intermediates formed via sulfate radical attack on phenolic compounds. It is also the first studythat explores the sulfate radical mechanism of oxidation, when sulfate radicals are generated via the Co/Oxone reagent. Furthermore, it provides strong evidence on the interaction of chloride ions with sulfate radicals leading to halogenation of organics in water.

Cobalt-mediated activation of peroxymonosulfate and sulfate radical attack on phenolic compounds. implications of chloride ions.

This study explores the potential of heterogeneous activation of Oxone (peroxymonosulfate) in water using cobalt oxides. Two commercially available cobalt oxides, CoO and Co3O4 (CoO·Co2O3) were tested for the activation of peroxymonosulfate and the consequent oxidation of 2,4-dichlorophenol (2,4-DCP) via a sulfate radical mechanism. Both systems, CoO/Oxone and Co3O4/Oxone, were tested at acidic and neutral pH and compared with the homogeneous Co(NO3)2/Oxone. The activity of these systems was evaluated on the basis of the induced transformation of 2,4-DCP as well as the dissolution of cobalt occurred after 2 h of reaction. It was observed that only Co3O4 activates peroxymonosulfate heterogeneously, with its heterogeneity being more pronounced at neutral pH. Both CoO and Co2O3 contained in Co3O4 might be responsible for the observed heterogeneity, and the relative mechanisms are further discussed here. To our knowledge, this is perhaps the first study that documents the heterogeneous activation of peroxymon...

Heterogeneous Activation of Oxone Using Co3O4

Three distinctive phases of BHA reactivity toward UV/ S2O8(2-) at acidic, neutral, and basic pH range were examined, where 80-100% mineralization has been observed within an hour of irradiation under 254 nm. A reduction in solution pH during the reaction was observed mainly due to the complete conversion of S2O8(2-) to sulfate ion together with proton generation. Seven measurable intermediates were found via an oxidation and dimerization process at all tested pH levels. The BHA decay mechanisms are quite different in acidic condition and at other pH levels. There are three unique intermediates that are only detectable at pH 3 via two additional pathways. This is due to the generation of weaker oxidants or radicals which results in a slower degradation of the BHA, and therefore, the accumulation of these intermediates to detectable levels. The rate of BHA decay generally increases from low to high pH levels; however, the corresponding mineralization at higher pH is retarded due to the futile process of recombining radicals and involvement of intermediates. Therefore, neutral pH was suggested to be the optimum condition in terms of mineralization and moderate efficiency in removing BHA.

The Aqueous Degradation of Butylated Hydroxyanisole by UV/S2O82-: Study of Reaction Mechanisms via Dimerization and Mineralization

Hypoxic-reperfusion injury in the inflamed human joint

Free radicals : chemistry, pathology and medicine

This is a history of tuberculosis, including its social, artistic and human impact. Thomas Dormandy's account of the search for the cure is complemented by a description of its complex natural history; portraits of individual sufferers, including writers, artists and musicians, whose lives were shaped (and often curtailed) by the disease. Tuberculosis is not a disease of the past, in many parts of the world it is still a bigger killer than AIDS; while in America and Europe drug-resistant strains threaten its resurgence.

The White Death: A History of Tuberculosis

Is opium a vile curse on society, a blessed medicine from God, or possibly both? This fresh history offers surprising new insights. Opium and its derivatives morphine and heroin have destroyed, corrupted, and killed individuals, families, communities, and even whole nations. And yet, for most of its long history, opium has also been humanity's most effective means of alleviating physical and mental pain. This extraordinary book encompasses the entire history of the world's most fascinating drug, from the first evidence of poppy cultivation by stone-age man to the present-day opium trade in Afghanistan. Dr. Thomas Dormandy tells the story with verve and insight, uncovering the strange power of opiates to motivate major conflicts yet also inspire great art and medical breakthroughs, to trigger the rise of global criminal networks yet also revolutionize attitudes toward well-being. Opium: Reality's Dark Dream traverses the globe and the centuries, exploring opium's role in colonialism, the Chinese Opium Wars, laudanum-inspired sublime Romantic poetry, American "Yellow Peril" fears, the rise of the Mafia and the black market, 1960s counterculture, and more. Dr. Dormandy also recounts exotic or sad stories of individual addiction. Throughout the book the author emphasizes opium's complex, valuable relationship with developments in medicine, health, and disease, highlighting the perplexing dual nature of the drug as both the cause and relief of great suffering in widely diverse civilizations.

Opium: Reality's Dark Dream

Donatello, Titian, Hals, Turner, Renoir and a large number of other major artists lived to be over 75 years of age and executed some of their finest and most distinctive work during their later years. This work examines the frequency of and reasons for this later success.

Old Masters: Great Artists in Old Age

Dr Dormandy's choice for his creators of modern medicine—Laennec, Semmelweis, Lister, Reed—is `not entirely arbitrary'. They were all medically qualified, all active in the 19th century, and their discoveries all changed clinical practice within their own lifetime—a telling point given that three died young between the ages of 45 and 51. Three were concerned with microbial infections (puerperal fever, `hospital sepsis' and yellow fever) and the fourth, Laennec, used his stethoscope pre-eminently to describe the evolution of pulmonary tuberculosis. Only Lister would ever have seen the relevant microorganisms under the microscope. Dormandy's choices neatly draw on four nationalities and four branches of medicine, and they provide the basis for an enjoyable book.

Moments of Truth: Four Creators of Modern Medicine

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Thomas Dormandy

Author Tools

Chat about Author