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

Application of peroxymonosulfate and its activation methods for degradation of environmental organic pollutants: Review

New perspectives for Advanced Oxidation Processes.

In-situ chemical oxidation: Principle and applications of peroxide and persulfate treatments in wastewater systems

Effect of inorganic anions on the performance of advanced oxidation processes for degradation of organic contaminants

In this study, the activation of peroxymonosulfate (PMS) was investigated by activated carbon (AC) along with UV for 2,4,6-trichlorophenol (TCP) degradation. The effects of operating parameters including pH, PMS concentration, AC dosage, initial TCP concentration and reaction time on TCP degradation were studied and optimized at pH 5.0, 8.0 mM PMS, 0.75 g/L AC and 75 min. Single step or two step additions of PMS made no marked difference in terms of TCP removal. The results of PMS decomposition showed that, AC/UV configuration was able to significantly activate PMS to degrade TCP compared to sole application of AC or UV. The contribution of UV in activation of PMS was more than that of AC. The rate constants of TCP degradation were in range of 0.0103–0.0512 min −1 for initial TCP concentrations of 5–50 mg/L. Scavenging experiments revealed that sulfate radical was the dominant radical of its kind for degradation of TCP, although hydroxyl radical was also partly effective. The results indicated that contribution of free radicals in solution was higher than that of surface-bound radicals. Moreover, mineralization of TCP was evaluated by COD, TOC and chlorine release and related results were 50.2%, 31.2% and 55%, respectively.

Degradation of 2,4,6-trichlorophenol in aqueous solutions using peroxymonosulfate/activated carbon/UV process via sulfate and hydroxyl radicals

Exposure to high concentration of nitrate through drinking water poses a threat to human health and environment. Electrocoagulation (EC) is an alternative water treatment process that involves electrogeneration of coagulant agents. In the present study, EC was exerted for the nitrate removal in a batch reactor using aluminum and iron anodes simultaneously. The effects of the main parameters including electrical current, initial pH, NaCl dosage, initial nitrate concentration and presence of turbidity on NO3
 − removal were investigated. NO2
 − as a by-product was monitored during electrolysis, and nitrate–nitrite index was calculated. The results indicated that optimum condition was pH of 5, 300 mA electrical current, 100 mg/L NaCl and electrolysis time of 40 min, under which removal efficiency was 81.5 %. Nitrite anion was generated during electrolysis of nitrate solution which increases nitrate–nitrite index at the first reaction time, and it was eliminated after 20-min electrolysis time. Reaction kinetic of nitrate removal in the absence and presence of turbidity was first-order and zero-order, respectively.

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Simultaneous application of iron and aluminum anodes for nitrate removal: a comprehensive parametric study

Olive oil mill wastewater (OOMW) is a complex effluent that must be treated before discharge into the environment. In this study, a combination of various mechanisms was conducted in an electrochemical cell. Copper and PbO2 anodes were used, while hydrogen peroxide was electro-generated at an activated carbon fiber cathode. Fenton-like reaction and electrooxidation occurred during electrolysis for organic compounds degradation in OOMW. The effects of pH, dilution of OOMW, and electrical current on COD and phenol removals were investigated. The results showed that 78.5% phenol and 60% COD removals were obtained at optimum conditions of 300 mA electrical current, 150 min electrolysis, and pH 3–3.5 (regulated). The regulation of pH during electrolysis significantly developed the treatment efficiency of electrochemical process. Phenol and COD removal kinetics were likely to follow second-order model and first-order model, respectively. Simultaneous application of two anodes had synergic effect on remo...

Simultaneous application of copper and PbO2 anodes for electrochemical treatment of olive oil mill wastewater

The Capacitive Deionization Technology (CDI) with carbon aerogel is a new process to remove salt from saline and brackish waters. Carbon aerogel is type of organic carbon, which your unique porous structure is suitable for desalinating. Low potential for clogging, production low wastewater, electrostatic regeneration aerogels and consequently no need to be acid, including the benefits of this technology. In this regard, the first polymerization resorcinol compounds and formaldehyde in the air pressure and the pyrolysis compounds obtained, Will attempt to create carbon aerogel pages. By manufacturing device in the pilotscale, the effect of different parameters includes the input of NaCl concentration, electric current, flow, distance between electrodes and pH, on NaCl absorption by aerogel carbon electrodes was investigated. Absorption rate by increasing flow and NaCl concentration in the input flow were increases more and increasing the distance between the electrodes, Flow and pH decrease the amount of absorption rate. Results in optimal conditions, Shows the absorption rate 1.43×10 -4 moles of NaCl Per

http://www.textroad.com/pdf/JAEBS/J.%20Appl.%20Environ.%20Biol.%20Sci.,%204(3)145-149,%202014.pdf

Fariba Gohari

Papers

Degradation of 2,4,6-trichlorophenol in aqueous solutions using peroxymonosulfate/activated carbon/UV process via sulfate and hydroxyl radicals

Simultaneous application of iron and aluminum anodes for nitrate removal: a comprehensive parametric study

Simultaneous application of copper and PbO2 anodes for electrochemical treatment of olive oil mill wastewater

Investigation of Saline and Brackish Waters Desalination by Carbon Aerogel Technology