Photocatalysis assisted by peroxymonosulfate and persulfate for benzotriazole degradation: effect of pH on sulfate and hydroxyl radicals

2015 ◽  
Vol 72 (11) ◽  
pp. 2095-2102 ◽  
Author(s):  
Mehdi Ahmadi ◽  
Farshid Ghanbari ◽  
Mahsa Moradi
Keyword(s):  
Water Resources ◽  
Hydroxyl Radicals ◽  
Catalyst Surface ◽  
Oxygen Demand ◽  
Emerging Pollutants ◽  
Acidic Ph ◽  
Total Organic Carbon Removal ◽  
Emerging Pollutant ◽  
Neutral Conditions ◽  
Degradation Effect

Recently, notable attempts have been devoted to removing emerging pollutants from water resources. Benzotriazole (BTA) as an emerging pollutant has widely been detected in the aquatic environment and water resources. In the current work, peroxymonosulfate (PMS) and persulfate (PS) were added to a TiO2/UV system for BTA degradation, as electron acceptors to overcome recombination of hole and electron. Additions of PMS and PS to the photocatalysis process considerably increased removal efficiency. The rate constants of UV/TiO2/PMS, UV/TiO2/PS and UV/TiO2 were 0.0217 min−1, 0.0152 min−1 and 0.0052 min−1 respectively. The results showed that pH significantly affected the UV/TiO2/PMS system while it marginally affected UV/TiO2/PS. Scavenging experiments using alcohols indicated that in acidic pH, the dominant oxidant was sulfate radical in both systems. The contribution of hydroxyl radical in BTA degradation was boosted at alkaline and neutral conditions especially in the UV/TiO2/PMS system. Moreover, other scavenging experiments implied that reaction of radicals occurred at both the catalyst surface and in solution. The mineralization results showed that PMS and PS significantly increased chemical oxygen demand and total organic carbon removal efficiencies. In general, presence of PMS in the photocatalysis process had a better performance compared to PS in terms of BTA removal and mineralization.

scholarly journals Iron release from haemosiderin and production of iron-catalysed hydroxyl radicals in vitro

1988 ◽  
Vol 250 (2) ◽  
pp. 589-595 ◽  
Author(s):  
M Ozaki ◽  
T Kawabata ◽  
M Awai
Keyword(s):  
Hydroxyl Radicals ◽  
Ph Dependence ◽  
Weight Ratio ◽  
Acidic Ph ◽  
Iron Release ◽  
Physiological Conditions ◽  
Radical Production ◽  
Acidic Conditions ◽  
Neutral Conditions

Isolated haemosiderin contained iron and nitrogen in a weight ratio of 6.75, with phosphorus and no detectable haem. Considerably more iron was released from haemosiderin under acidic conditions than under neutral conditions in the presence of ascorbate, nitrilotriacetate or dithionite. Unlike the situation with ascorbate, chelators such as citrate, ADP or succinate induced the release of only some iron, with almost no pH-dependence. Dehydroascorbate (the oxidized form of ascorbate with no reducing capacity) behaved like citrate, ADP, succinate or desferal, rather than like ascorbate itself, in releasing iron. GSH had less effect on the release of iron than these chelators, but in the presence of a small amount of chelator the release of iron increased, especially under acidic conditions. Thus reduction, chelation and pH were all found to be important factors involved in the release of iron from haemosiderin. Investigation by e.p.r. of hydroxyl-radical production by the released iron showed high radical productivity at an acidic pH. However, at a physiological pH, almost no radical formation was detected, except in the presence of nitrilotriacetate. These findings suggested that, under physiological conditions, haemosiderin was not an effective iron donor and was almost not involved in radical production. Under acidic conditions, however, such as in inflammation, hypoxia and in a lysosomal milieu, it could possibly be an iron donor and is thought to be implicated in radical production and tissue damage in iron-overloaded conditions.

scholarly journals Removal of Emerging Pollutants from Water Using Environmentally Friendly Processes: Photocatalysts Preparation, Characterization, Intermediates Identification and Toxicity Assessment

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 215
Author(s):  
Nina Finčur ◽  
Paula Sfîrloagă ◽  
Predrag Putnik ◽  
Vesna Despotović ◽  
Marina Lazarević ◽  
...  
Keyword(s):  
Emerging Contaminants ◽  
Sol Gel ◽  
Toxicity Assessment ◽  
Emerging Pollutants ◽  
Simulated Sunlight ◽  
Aquatic Life ◽  
Mgo Nanoparticles ◽  
Emerging Pollutant ◽  
Wheat Germination ◽  
Modern Technologies

Pharmaceuticals and pesticides are emerging contaminants problematic in the aquatic environment because of their adverse effects on aquatic life and humans. In order to remove them from water, photocatalysis is one of the most modern technologies to be used. First, newly synthesized photocatalysts were successfully prepared using a sol–gel method and characterized by different techniques (XRD, FTIR, UV/Vis, BET and SEM/EDX). The photocatalytic properties of TiO2, ZnO and MgO nanoparticles were examined according to their removal from water for two antibiotics (ciprofloxacin and ceftriaxone) and two herbicides (tembotrione and fluroxypyr) exposed to UV/simulated sunlight (SS). TiO2 proved to be the most efficient nanopowder under UV and SS. Addition of (NH4)2S2O8 led to the faster removal of both antibiotics and herbicide fluroxypyr. The main intermediates were separated and identified for the herbicides and antibiotic ciprofloxacin. Finally, the toxicity of each emerging pollutant mixture and formed intermediates was assessed on wheat germination and biomass production.

scholarly journals Effect of Salinity on UVA-Vis Light Driven Photo-Fenton Process at Acidic and Circumneutral pH

Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1315
Author(s):  
Iván Vallés ◽  
Lucas Santos-Juanes ◽  
Ana M. Amat ◽  
Javier Moreno-Andrés ◽  
Antonio Arques
Keyword(s):  
Hydroxyl Radicals ◽  
Acidic Medium ◽  
Emerging Pollutants ◽  
Clofibric Acid ◽  
Fenton Process ◽  
Simulated Sunlight ◽  
Scavenging Effect ◽  
Aqueous Matrices ◽  
Ph Dependent ◽  
Pollutants Removal

In the present work, the treatment of a mixture of six emerging pollutants (acetamiprid, acetaminophen, caffeine, amoxicillin, clofibric acid and carbamazepine) by means of photo-Fenton process has been studied, using simulated sunlight as an irradiation source. Removal of these pollutants has been investigated in three different aqueous matrices distinguished by the amount of chlorides (distilled water, 1 g L−1 of NaCl and 30 g L−1 of NaCl) at a pH of 2.8 and 5.0. Interestingly, the presence of 1 g L−1 was able to slightly accelerate the pollutants removal at pH = 5, although the reverse was true at pH = 2.8. This is attributed to the pH-dependent interference of chlorides on photo-Fenton process, that is more acute in an acidic medium. As a matter of fact, the fastest reaction was obtained at pH = 3.5, in agreement with literature results. Monitoring of hydrogen peroxide consumption and iron in solution indicates that interference with chlorides is due to changes in the interaction between iron and the peroxide, rather than a scavenging effect of chloride for hydroxyl radicals. Experiments were also carried out with real seawater and showed higher inhibition than in the NaCl experiments, probably due to the effect of different dissolved salts present in natural water.

scholarly journals Photocatalytic activity of micron-scale brass on emerging pollutant degradation in water: mechanism elucidation and removal efficacy assessment

RSC Advances ◽  
2020 ◽  
Vol 10 (65) ◽  
pp. 39931-39942
Author(s):  
Irwing M. Ramirez-Sanchez ◽  
Onur G. Apul ◽  
Navid B. Saleh
Keyword(s):  
Photocatalytic Activity ◽  
Ultraviolet Radiation ◽  
Hydroxyl Radicals ◽  
Emerging Contaminants ◽  
Pollutant Degradation ◽  
Emerging Pollutant ◽  
Efficacy Assessment

Micron-scale brass is a catalyst that can be activated with ultraviolet radiation to remove emerging contaminants from water via oxidation by hydroxyl radicals.

scholarly journals New Eco-Materials Derived from Waste for Emerging Pollutants Adsorption: The Case of Diclofenac

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 3964
Author(s):  
Ario Fahimi ◽  
Alessandra Zanoletti ◽  
Stefania Federici ◽  
Ahmad Assi ◽  
Fabjola Bilo ◽  
...  
Keyword(s):  
Fly Ash ◽  
Wastewater Treatment Plants ◽  
Coal Fly Ash ◽  
Bottom Ash ◽  
Emerging Pollutants ◽  
Emerging Pollutant ◽  
Pharmaceutical Removal ◽  
Heating Treatment ◽  
Sustainable Materials ◽  
Potential Use

This work proposes new eco-materials for the adsorption of diclofenac (DCF). The large consumption of this nonsteroidal anti-inflammatory drug combined with the inefficiency of wastewater treatment plants (WWTPs) leads to its presence in aquatic environments as an emerging pollutant. The adsorption technique is widely used for pharmaceutical removal. Moreover, due to the large effect of commercial adsorbents, in the frame of the Azure Chemistry approach, new sustainable materials are mandatory for removal as emerging pollutants. The work proposes three adsorbents that were obtained from different stabilization methods of fly ash derived from an incinerator plant; the stabilization techniques involved the use of various industrial by-products such as bottom ash, flue gas desulphurization residues, coal fly ash, and silica fume. The best performance, although less than activated carbon, was obtained by COSMOS (COlloidal Silica Medium to Obtain Safe inert: the case of incinerator fly ash), with a removal efficacy of approximately 76% with 15 g/L of material. Several advantages are expected not only from the DCF removal but also from an economic perspective (the newly obtained adsorbents are eco-materials, so they are cheaper in comparison to conventional adsorbents) and in terms of sustainability (no toxic reagents and no heating treatment are involved). This work highlights the adsorption performance of the new eco-materials and their potential use in WWTPs.

scholarly journals Evaluation Methods of Water Environment Safety and Their Application to the Three Northeast Provinces of China

2019 ◽  
Vol 11 (18) ◽  
pp. 5135 ◽  
Author(s):  
Li ◽  
Sun ◽  
Yuan ◽  
Liu
Keyword(s):  
Principal Component Analysis ◽  
Water Resources ◽  
Chemical Oxygen Demand ◽  
Water Environment ◽  
Oxygen Demand ◽  
Principal Component ◽  
Component Analysis ◽  
Analysis Method ◽  
Industry Output ◽  
Per Capita

Focusing on the topic of water environment safety of China, this paper has selected the three northeast provinces of China as the research object due to their representativeness in economic development and resource security. By using the Entropy Weight Method, the Grey Correlation Analysis Method, and the Principal Component Analysis Method, this paper has first constructed a water environment safety evaluation system with 17 indicators from the economic, environmental, and ecological aspects. Furthermore, this paper has screened the initially selected indicators by the Principal Component Analysis Method and finally determined 11 indicators as the evaluation indicators. After indicator screening, this paper has adopted the improved Fuzzy Comprehensive Evaluation Method to evaluate the water environment safety of the three northeast provinces of China and obtained the change in water environment safety of different provinces from 2009 to 2017. The results show that the overall water environment safety of the region had improved first but worsened afterward, and that in terms of water safety level, Jilin Province ranked first, followed by Heilongjiang Province and Liaoning Province. The three factors that have the greatest impact on the water environment safety of the three provinces are: Liaoning—Chemical Oxygen Demand (score: 17.10), Per Capita Disposable Income (score: 13.50), and Secondary Industry Output (score: 11.50); Heilongjiang—Chemical Oxygen Demand (score: 18.64), Per Capita Water Resources (score: 12.75), and Concentration of Inhalable Particles (score: 10.89); Jilin—Per Capita Water Resources (score: 15.75), Chemical Oxygen Demand (score: 14.87), and Service Industry Output (score: 11.55). Based on analysis of the evaluation results, this paper has proposed corresponding policy recommendations to improve the water environment safety and promote sustainable development in the northeast provinces of China.

An ecological compensation standard based on emergy theory for the Xiao Honghe River Basin

2015 ◽  
Vol 71 (10) ◽  
pp. 1463-1470 ◽  
Author(s):  
Xinjian Guan ◽  
Moyu Chen ◽  
Caihong Hu
Keyword(s):  
Water Resources ◽  
River Basin ◽  
Research Output ◽  
Economic Value ◽  
Oxygen Demand ◽  
Calculation Model ◽  
Ecological Compensation ◽  
Ecological Economic ◽  
Compensation Standard ◽  
Value Of Water

The calculation of an ecological compensation standard is an important, but also difficult aspect of current ecological compensation research. In this paper, the factors affecting the ecological–economic system in the Xiao Honghe River Basin, China, including the flow of energy, materials, and money, were calculated using the emergy analysis method. A consideration of the relationships between the ecological–economic value of water resources and ecological compensation allowed the ecological–economic value to be calculated. On this basis, the amount of water needed for dilution was used to develop a calculation model for the ecological compensation standard of the basin. Using the Xiao Honghe River Basin as an example, the value of water resources and the ecological compensation standard were calculated using this model according to the emission levels of the main pollutant in the basin, chemical oxygen demand. The compensation standards calculated for the research areas in Xipin, Shangcai, Pingyu, and Xincai were 34.91 yuan/m3, 32.97 yuan/m3, 35.99 yuan/m3, and 34.70 yuan/m3, respectively, and such research output would help to generate and support new approaches to the long-term ecological protection of the basin and improvement of the ecological compensation system.

Performance of denitrifying microbial fuel cell subjected to variation in pH, COD concentration and external resistance

2013 ◽  
Vol 68 (1) ◽  
pp. 250-256 ◽  
Author(s):  
Jin-Tao Li ◽  
Shao-Hui Zhang ◽  
Yu-Mei Hua
Keyword(s):  
Fuel Cell ◽  
Chemical Oxygen Demand ◽  
Microbial Fuel Cell ◽  
Electricity Generation ◽  
Oxygen Demand ◽  
Pollutant Removal ◽  
Acidic Ph ◽  
External Resistance ◽  
Weakly Alkaline ◽  
Effects Of Ph

The effects of pH, chemical oxygen demand (COD) concentration and external resistance on denitrifying microbial fuel cell were evaluated in terms of electricity generation characteristics and pollutant removal performance. The results showed that anodic influent with weakly alkaline or neutral pH and cathodic influent with weakly acidic pH favored pollutant removal and electricity generation. The suitable influent pH of the anode and cathode were found to be 7.5–8.0 and 6.0–6.5, respectively. In the presence of sufficient nitrate in the cathode, higher influent COD concentration led to more electricity generation and greater pollutant removal rates. With an anodic influent pH of 8.0 and a cathodic influent pH of 6.0, an influent COD concentration of 400 mg/L was deemed to be appropriate. Low external resistance favored nitrate and COD removal. The results suggest that operation of denitrifying microbial fuel cell at a lower external resistance would be desirable for pollutant removal but not electricity generation.

An electrochemical mechanisms study on steel/IrO2–Sb2O3 electrodes for oxidation of phenol in water

2015 ◽  
Vol 93 (5) ◽  
pp. 536-541
Author(s):  
Pavithra Bhakthi Jayathilaka ◽  
Gayani Chathurika Pathiraja ◽  
Athula Bandara ◽  
Nalaka Deepal Subasinghe ◽  
Nadeeshani Nanayakkara
Keyword(s):  
Chemical Oxygen Demand ◽  
Removal Efficiency ◽  
Hydroxyl Radicals ◽  
Oxygen Demand ◽  
Oxidation Mechanism ◽  
Constant Current ◽  
Anode Surface ◽  
Radical Scavenger ◽  
Chemical Oxygen Demand Removal ◽  
Constant Current Density

Phenol, a known water pollutant, was electrochemically oxidized on a steel/IrO2–Sb2O3 novel anode. Since the oxidation mechanisms vary based on the anode material, a mechanisms study of electrooxidation of phenol on it was conducted. The phenol oxidation was carried out at 20 mA/cm2 constant current density with a pH 11.00 Na2SO4 medium at room temperature. During 6 h of electrolysis, samples were tested for chemical oxygen demand removal efficiency of the anode. The steel/IrO2–Sb2O3anode showed 76.3% chemical oxygen demand removal efficiency. Both 4-nitroso-N,N-dimethylaniline and the HCO3–/CO32– radical scavenger tests confirmed the formation and presence of the hydroxyl radicals in the system. Therefore, it was concluded that the hydroxyl radicals that are generated on the anode surface are the main cause for the oxidation mechanism. Moreover, ICE, HPLC, and UV-vis absorbance and cyclic voltammetry results confirmed the presence of catechol and benzoquinone as intermediates and the reaction mechanism.

scholarly journals Insight into the comparison of thermally and Fe(II) activated persulfate on sludge dewaterability and disintegration

2021 ◽  
Author(s):  
Shaodong Guo ◽  
Long Zhou ◽  
Yuxin Huang ◽  
Xinghu Huang
Keyword(s):  
Extracellular Polymeric Substances ◽  
Three Dimensional ◽  
Oxygen Demand ◽  
Ammonia Nitrogen ◽  
Fluorescence Excitation ◽  
Capillary Suction ◽  
Extracellular Polymer Substance ◽  
Sludge Dewaterability ◽  
Oxidation Efficiency ◽  
Degradation Effect

Abstract The effects of thermally and Fe(II) activated potassium persulfate (PPS) on sludge dewatering performance were compared systematacially. Sludge dewaterability was monitored by measuring capillary suction time (CST) and sludge specific resistance to filtration (SRF), and the degradation effect was characterized by Chemical oxygen demand (COD), total organic carbon (TOC), ammonia nitrogen (NH4+-N) and extracellular polymeric substances (EPS). The Change of extracellular polymer substance (EPS) including soluble, loosely bound and tightly bound EPS (S-EPS, LB-EPS and TB-EPS) with time and PPS dosage was monitored to discuss the oxidation efficiency of thermally and Fe(II) activated PPS. Sludge supernate were analyzed by three dimensional fluorescence excitation-emission spectrum (3D-EEM) to confirm the proteins transformation. The result showed that sludge dewaterability in terms of CST and SRF were enhanced with increasing PPS dosage and condition time of both two activated methods. While Fe(II) activated PPS could reduce sludge CST and SRF to preferred values at low PPS dosage and short condition time. Maenwhile, sludge degradation effect was also more obvious. Mechanically, sludge TB-EPS in proteins and polysaccharides converted to SB-EPS was more quickly with Fe(II) activated PPS. Besides, thermally activated PPS tended to oxidize the protein in the supernatant first.

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