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.

Generation of sulfate radical through heterogeneous catalysis for organic contaminants removal: Current development, challenges and prospects

Hydrogen peroxide (H2O2) is widely used in almost all industrial areas, particularly in the chemical industry and environmental protection. The only degradation product of its use is water, and thus it has played a large role in environmentally friendly methods in the chemical industry. Hydrogen peroxide is produced on an industrial scale by the anthraquinone oxidation (AO) process. However, this process can hardly be considered a green method. It involves the sequential hydrogenation and oxidation of an alkylanthraquinone precursor dissolved in a mixture of organic solvents followed by liquid–liquid extraction to recover H2O2. The AO process is a multistep method that requires significant energy input and generates waste, which has a negative effect on its sustainability and production costs. The transport, storage, and handling of bulk H2O2 involve hazards and escalating expenses. Thus, novel, cleaner methods for the production of H2O2 are being explored. The direct synthesis of H2O2 from O2 and H2 using a variety of catalysts, and the factors influencing the formation and decomposition of H2O2 are examined in detail in this Review.

http://www.sciencemadness.org/talk/files.php?pid=171164&aid=9838

Hydrogen Peroxide Synthesis: An Outlook beyond the Anthraquinone Process

3. Soluble Metal Oxides 2459 3.1. Polyoxometalates 2459 3.2. Peroxotungstates 2459 3.3. Peroxomolybdates 2460 3.4. Methyltrioxorhenium 2461 3.5. Other Metal Oxides 2461 4. Metal Oxides Generated in Situ 2461 4.1. Selenium and Arsenic Compounds 2461 4.2. Simple Metal Salts 2462 5. Coordination Complexes 2463 5.1. Manganese Porphyrins 2463 5.2. Iron Porphyrins 2464 5.3. Manganese Salen Complexes 2466 5.4. 1,4,7-Triazacyclononane (TACN) Complexes 2466 5.5. Iron and Manganese Pyridyl-Amine Complexes 2468

/pdf/metal-catalyzed-epoxidations-of-alkenes-with-hydrogen-3kxbglgruw.pdf

Metal-Catalyzed Epoxidations of Alkenes with Hydrogen Peroxide

Cellulose nanocrystals, a class of fascinating bio-based nanoscale materials, have received a tremendous amount of interest both in industry and academia owing to its unique structural features and impressive physicochemical properties such as biocompatibility, biodegradability, renewability, low density, adaptable surface chemistry, optical transparency, and improved mechanical properties. This nanomaterial is a promising candidate for applications in fields such as biomedical, pharmaceuticals, electronics, barrier films, nanocomposites, membranes, supercapacitors, etc. New resources, new extraction procedures, and new treatments are currently under development to satisfy the increasing demand of manufacturing new types of cellulose nanocrystals-based materials on an industrial scale. Therefore, this review addresses the recent progress in the production methodologies of cellulose nanocrystals, covering principal cellulose resources and the main processes used for its isolation. A critical and analytical examination of the shortcomings of various approaches employed so far is made. Additionally, structural organization of cellulose and nomenclature of cellulose nanomaterials have also been discussed for beginners in this field.

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Recent progress in cellulose nanocrystals: sources and production

Hydrogen peroxide (H2O2) is an important commodity chemical and its demand is growing significantly in the chemical synthesis due to its “green” character. Currently, H2O2 is produced almost exclusively by the anthraquinone auto-oxidation (AO) process. The AO process involves indirect oxidation of hydrogen and thus avoids potentially explosive H2/O2 mixture. However, this large-scale process presents significant safety issues associated with the transport of bulk H2O2. Moreover, the AO process can hardly be considered an environmentally friendly method. In view of this, more economical and environmentally cleaner routes have been explored for the production of H2O2. The liquid-phase catalytic direct synthesis of H2O2 from H2 and O2 offers an attractive green technology for small-scale/on-site production of H2O2. However, the direct synthesis process suffers from two major drawbacks: (i) potential hazards associated with H2/O2 mixtures and (ii) poor selectivity for H2O2 because the catalysts used for H2O2 synthesis are also active for its decomposition and hydrogenation to water as well as for H2 combustion. These serious issues and the recent developments in the direct H2O2 synthesis are discussed in this review. The roles of protons (H+) and halide ions in promoting the H2O2 selectivity are also examined in detail.

Direct synthesis of hydrogen peroxide from hydrogen and oxygen: An overview of recent developments in the process

Sodium perborate and sodium percarbonate: Cheap, safe and versatile oxidising agents for organic synthesis

Recent research progress in catalytic systems for potential use with hydrogen peroxide in industrial chemical synthesis is reviewed, with special focus on work published in the last five years. The main types of chemistry employed are critically appraised regarding their suitability for industrial exploitation. The most significant catalyst types are discussed in terms of the positive features identified to date, and the obstacles yet to be surmounted in order to become more widely adopted. It is believed that fully inorganic systems have more scope for commercialization than those containing organic ligands or supports, however robust. Critical targets are larger-pore analogs of titanium silicalite TS-1, more exploration of smectite- based materials, effective immobilization of activated metal peroxo systems, and improvements in design and manipulation of polyoxometallate compounds. Cooperation between branches of chemistry that have not traditionally worked closely together is advocated.

/pdf/cleaner-industrial-processes-using-hydrogen-peroxide-3szo0vs2hu.pdf

Cleaner industrial processes using hydrogen peroxide

Sodium perborate and sodium percarbonate: further applications in organic synthesis

A dilute solution of a lower aliphatic peracid such as peracetic acid, having an equilibrium composition, is produced by contacting hydrogen peroxide with a lower aliphatic acid each at initial high concentrations in an aqueous reaction mixture to rapidly form a reaction mixture containing, for example, up to 30% wt of peracid and diluting the reaction mixture with water and with any required quantities of lower aliphatic acid and/or hydrogen peroxide to reproduce the equilibrium composition of the dilute solution, the process being characterised in that the reaction mixture rich in lower aliphatic peracid is diluted before it has itself reached equilibrium, for example when it contains from 20 to 80% of its potential equilibrated content of peracid The process provides a quick plant-efficient process for the production of stable dilute lower aliphatic peracid solutions for industrial disinfection purposes or for personal or domestic hygiene use

Solutions of peracids

A process for the washing and/or disinfection of eggs is provided. The process comprises contacting the eggs with a nonionic surfactant, an amphoteric surfactant and an aqueous solution of a peracid. The surfactants and peracid solution may be combined, or may be employed in separate stages. Preferably, the solutions are sprayed onto the eggs, optionally in the presence of an antifoam. The preferred peracid is peracetic acid.

William Ronald Sanderson

Papers

Sodium perborate and sodium percarbonate: Cheap, safe and versatile oxidising agents for organic synthesis

Cleaner industrial processes using hydrogen peroxide

Sodium perborate and sodium percarbonate: further applications in organic synthesis

Solutions of peracids

Egg washing and disinfection process