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

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.

Download Full-text

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

Nanomaterials ◽

10.3390/nano11010215 ◽

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.

Download Full-text

Separation and Properties of Polysaccharides from Asparagus (Officinalis L) Old Stalks

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.361-363.789 ◽

2011 ◽

Vol 361-363 ◽

pp. 789-793 ◽

Cited By ~ 1

Author(s):

Jia Song ◽

Yue Ma ◽

Chao Zhang ◽

Xiao Yan Zhao ◽

Hai Feng Qian

Keyword(s):

Molecular Weight ◽

Antioxidant Capacity ◽

Hydroxyl Radicals ◽

Average Molecular Weight ◽

Antioxidative Capacity ◽

Scavenging Effect ◽

Ethanol Precipitation

The polysaccharides of the asparagus old stalks was seperated by ethanol precipitation and ultrafiltration. The molecular weigh distribution and antioxidative capacity of the extracts of the alcohol precipitation(C-1), ultrafiltration retention(C-2), and ultrafiltration penetrates (C-3) were further evaluated. The polysaccharides yields of the C-1, C-2, and C-3 were 1.53, 1.21, and 0.71%, respectively. The weigh average molecular weight of C-1, C-2, and C-3 were 163900, 135880, and 61063 Da, respectively. C-2 showed the strongest antioxidant capacity in all extracts by the scavenging effect on DPPH, superoxide and hydroxyl radicals. Therefore, the ultrafiltration was an alternative to separate the polysaccharides from the asparagus old stalks and kept their antioxidatant capacity.

Download Full-text

First Direct and Unequivocal Electron Spin Resonance Spin-Trapping Evidence for pH-Dependent Production of Hydroxyl Radicals from Sulfate Radicals

Environmental Science & Technology ◽

10.1021/acs.est.0c04410 ◽

2020 ◽

Vol 54 (21) ◽

pp. 14046-14056

Author(s):

Hui-Ying Gao ◽

Chun-Hua Huang ◽

Li Mao ◽

Bo Shao ◽

Jie Shao ◽

...

Keyword(s):

Electron Spin Resonance ◽

Hydroxyl Radicals ◽

Electron Spin ◽

Spin Trapping ◽

Sulfate Radicals ◽

Spin Resonance ◽

Ph Dependent ◽

Resonance Spin

Download Full-text

Photocatalytic degradation of clofibric acid by g-C3N4/P25 composites under simulated sunlight irradiation: The significant effects of reactive species

Chemosphere ◽

10.1016/j.chemosphere.2017.01.015 ◽

2017 ◽

Vol 172 ◽

pp. 193-200 ◽

Cited By ~ 52

Author(s):

Ping Chen ◽

Fengliang Wang ◽

Qianxin Zhang ◽

Yuehan Su ◽

Lingzhi Shen ◽

...

Keyword(s):

Photocatalytic Degradation ◽

Reactive Species ◽

Clofibric Acid ◽

Simulated Sunlight ◽

Sunlight Irradiation

Download Full-text

Integrated Bioprocessing for the pH-Dependent Production of 4-Valerolactone from Levulinate in Pseudomonas putida KT2440

Applied and Environmental Microbiology ◽

10.1128/aem.01769-09 ◽

2009 ◽

Vol 76 (2) ◽

pp. 417-424 ◽

Cited By ~ 22

Author(s):

Collin H. Martin ◽

Danyi Wu ◽

Kristala L. Jones Prather

Keyword(s):

Pseudomonas Putida ◽

Metabolic Pathways ◽

Acidic Medium ◽

High Titer ◽

Chemical Transformations ◽

Terminal Sequence ◽

Pseudomonas Putida Kt2440 ◽

Specific Chemical ◽

Mild Conditions ◽

Ph Dependent

ABSTRACT Enzymes are powerful biocatalysts capable of performing specific chemical transformations under mild conditions, yet as catalysts they remain subject to the laws of thermodynamics, namely, that they cannot catalyze chemical reactions beyond equilibrium. Here we report the phenomenon and application of using extracytosolic enzymes and medium conditions, such as pH, to catalyze metabolic pathways beyond their intracellular catalytic limitations. This methodology, termed “integrated bioprocessing” because it integrates intracellular and extracytosolic catalysis, was applied to a lactonization reaction in Pseudomonas putida for the economical and high-titer biosynthesis of 4-valerolactone from the inexpensive and renewable source levulinic acid. Mutant paraoxonase I (PON1) was expressed in P. putida, shown to export from the cytosol in Escherichia coli and P. putida using an N-terminal sequence, and demonstrated to catalyze the extracytosolic and pH-dependent lactonization of 4-hydroxyvalerate to 4-valerolactone. With this production system, the titer of 4-valerolactone was enhanced substantially in acidic medium using extracytosolically expressed lactonase versus an intracellular lactonase: from <0.2 g liter−1 to 2.1 ± 0.4 g liter−1 at the shake flask scale. Based on these results, the production of 4-hydroxyvalerate and 4-valerolactone was examined in a 2-liter bioreactor, and titers of 27.1 g liter−1 and 8.2 g liter−1 for the two respective compounds were achieved. These results illustrate the utility of integrated bioprocessing as a strategy for enabling production from novel metabolic pathways and enhancing product titers.

Download Full-text

Pharmaceutical emerging pollutants removal from water using powdered activated carbon: Study of kinetics and adsorption equilibrium

Journal of Environmental Management ◽

10.1016/j.jenvman.2019.01.116 ◽

2019 ◽

Vol 236 ◽

pp. 301-308 ◽

Cited By ~ 32

Author(s):

Nasly Delgado ◽

Alberto Capparelli ◽

Agustín Navarro ◽

Damián Marino

Keyword(s):

Activated Carbon ◽

Adsorption Equilibrium ◽

Emerging Pollutants ◽

Powdered Activated Carbon ◽

Pollutants Removal

Download Full-text

Photo-Fenton and photo-Fenton-like processes for the degradation of methyl orange in aqueous medium: Influence of oxidation states of iron

Chemical Papers ◽

10.2478/s11696-010-0011-0 ◽

2010 ◽

Vol 64 (3) ◽

Cited By ~ 17

Author(s):

L. Devi ◽

S. Kumar ◽

K. Anantha Raju ◽

K. Eraiah Rajashekhar

Keyword(s):

Methyl Orange ◽

Hydroxyl Radicals ◽

Ammonium Persulfate ◽

Oxidation States ◽

Fenton Process ◽

Lower Efficiency ◽

Sulfate Ions ◽

Solution Efficiency ◽

Degradation Of Methyl Orange ◽

Medium Influence

AbstractDegradation of methyl orange (MO) was carried out by the photo-Fenton process (Fe2+/H2O2/UV) and photo-Fenton-like processes (Fe3+/H2O2/UV, Fe2+/S2O82−/UV, and Fe3+/S2O82−/UV) at the acidic pH of 3 using hydrogen peroxide and ammonium persulfate (APS) as oxidants. Oxidation state of iron had a significant influence on the efficiency of photo-Fenton/photo-Fenton-like processes. It was found that a process with a source of Fe3+ ions as the catalyst showed higher efficiency compared to a process with the Fe2+ ion as the catalyst. H2O2 served as a better oxidant for both oxidation states of iron compared to APS. The lower efficiency of APS is attributed to the generation of excess protons which scavenges the hydroxyl radicals necessary for degradation. Further, the sulfate ions produced from S2O82− form a complex with Fe2+/Fe3+ ions thereby reducing the concentration of free iron ions in the solution. This process can also reduce the concentration of hydroxyl radicals in the solution. Efficiency of the various MO degradation processes follows the order: Fe3+/H2O2/UV, Fe3+/APS/UV, Fe2+/H2O2/UV, Fe2+/APS/UV.

Download Full-text

Mesoporous Co-O-C Nanosheets for Electrochemical Production of Hydrogen Peroxide in Acidic Medium

Journal of Materials Chemistry A ◽

10.1039/d1ta10416k ◽

2022 ◽

Author(s):

Lingyan Jing ◽

Qiang Tian ◽

Panan Su ◽

Haitao Li ◽

Yao Zheng ◽

...

Keyword(s):

Hydrogen Peroxide ◽

Oxygen Reduction Reaction ◽

Environmental Remediation ◽

Acidic Medium ◽

Low Cost ◽

Reduction Reaction ◽

Fenton Process ◽

On Demand ◽

Production Of Hydrogen ◽

Electrochemical Production

Electrochemical two-electron oxygen reduction reaction (2e− ORR) to produce hydrogen peroxide (H2O2) enables promising electro-Fenton process for on-site and on-demand environmental remediation. However, there is still lack of low-cost electrocatalysts...

Download Full-text