scholarly journals Removal of cephalexin from aqueous solutions using the fenton photocatalytic process

Akademos ◽  
2021 ◽  
pp. 53-60
Author(s):  
Larisa Mocanu ◽  
◽  
Maria Gonta ◽  
Vera Matveevici ◽  
Gheorghe Duca ◽  
...  
Keyword(s):  
Hydroxyl Radical ◽  
Photocatalytic Oxidation ◽  
Model Systems ◽  
Process Efficiency ◽  
Optimum Conditions ◽  
Mineralization Process ◽  
Treatment Unit ◽  
Oxidation Treatment ◽  
Oxidizing Power ◽  
Free Hydroxyl

This paper aims to study the degradation and oxidation/mineralization process of cephalexin in model systems using Fenton’s reagent for UV irradiation (λ = 254 nm). The effect of pH (2-11), concentration of H2O2 (0,3434 mg/L) and concentration of Fe(II) (0-28 mg/L) on the degradation of 50 mg/L CPX were investigated. It has been determined optimum conditions for photocatalytic oxidation of CPX. Increasing the amount of H2O2 plays an inhibitory role in the production of hydroxyl radicals and reduces the process efficiency. This can be attributed to the reaction of excess peroxide with •OH and the formation of HO2 •, which has less oxidizing power compared to free hydroxyl radical. And as the concentration of the catalyst increases to the optimum, the excess of Fe(II) ions reacts with the hydroxyl radical and, therefore, the efficiency of the process also is reduced. Accordingly, the optimum degradation efficiency of 88 % and 83% for COD was obtained under the following conditions: pH 2,5, H2O2 concentration – 3,4 mg/L, Fe(II) ions concentration – 5,6 mg/L, cephalexin concentration – 50 mg/L, and reaction time – 60 min. Thus, the current study demonstrated that the photo-Fenton reactor can be used effectively as an advanced oxidation treatment unit for degradation of cephalexin under optimized environmental conditions.

Inorganic greywater matrix impact on photocatalytic oxidation: does flocculation of TiO2 nanoparticles impair process efficiency?

2011 ◽  
Vol 63 (12) ◽  
pp. 2808-2813 ◽  
Author(s):  
A. Armanious ◽  
A. Özkan ◽  
U. Sohmen ◽  
H. Gulyas
Keyword(s):  
Rate Constants ◽  
Electric Double Layer ◽  
Photocatalytic Oxidation ◽  
Process Efficiency ◽  
Point Of Zero Charge ◽  
Inorganic Salts ◽  
Co2 Absorption ◽  
Oh Radical ◽  
Radical Scavengers ◽  
Subsequent Formation

This study was conducted in order to clarify whether photocatalyst flocculation – as observed in biologically pretreated greywater – contributes to photocatalytic oxidation (PCO) efficiency impairment. Aqueous solutions of tetraethyleneglycol dimethylether spiked with different inorganic salts in concentrations as found in biologically treated greywater were investigated with respect to TiO2 flocculation and PCO mineralisation kinetics. Flocculation of the photocatalyst primarily depended on pH (which was affected by the salts) and how close pH was to the point of zero charge (PZC). Photocatalyst agglomeration was maximum at pH 5.5. With salt concentrations >7 mmol L−1, flocculation was strong even at pH far above PZC due to electric double layer compression. PCO rate constants were not unequivocally related to flocculation. Increasing pH was observed as the clearest factor deteriorating PCO efficiency. This was interpreted to result from impaired adsorbability of negatively charged oxidation intermediates as well as from enhanced CO2 absorption with increasing pH and subsequent formation of HCO3− anions which are OH radical scavengers.

scholarly journals Serum Hydroxyl Radical Scavenging Capacity as Quantified with Iron-Free Hydroxyl Radical Source

2009 ◽  
Vol 45 (2) ◽  
pp. 193-201 ◽  
Author(s):  
Nobuyuki Endo ◽  
Shigeru Oowada ◽  
Yoshimi Sueishi ◽  
Masashi Shimmei ◽  
Keisuke Makino ◽  
...  
Keyword(s):  
Hydroxyl Radical ◽  
Radical Scavenging ◽  
Radical Scavenging Capacity ◽  
Scavenging Capacity ◽  
Free Hydroxyl

scholarly journals Efficient optimization and mineralization of UV absorbers: A comparative investigation with Fenton and UV/H2O2

2018 ◽  
Vol 16 (1) ◽  
pp. 702-708
Author(s):  
Anum Sahar ◽  
Shaukat Ali ◽  
Tanveer Hussain ◽  
Nazish Jahan ◽  
Muhammad Anjum Zia
Keyword(s):  
Irradiation Time ◽  
Oxygen Demand ◽  
Comparative Investigation ◽  
Fenton Oxidation ◽  
Optimum Conditions ◽  
Chemical Oxygen Demand Removal ◽  
Mineralization Process ◽  
Textile Materials ◽  
Uv Absorbers ◽  
Living Species

AbstractUV absorbers developed for finishing of textile materials play a significant role in protection against UV radiations but their discharge in wastewater during processing and laundry action also retain serious concern to living species due to their recalcitrant nature. The current study examined the mineralization and degradation of two vinylsulfone and nitrogen (N-) containing UV absorber compounds (1a, 2a) via two effective Fenton and UV/H2O2 oxidation. The results showed that both the Fenton and UV/H2O2 processes mineralized the synthesized UV absorbers effectively; however the mineralization process with Fenton oxidation was more effective than the UV/H2O2. The mineralization of synthesized UV absorbers was affected by process parameters (dosage of Fe2+ and H2O2 pH and reaction time). Under attained optimum conditions of Fenton oxidation, dose of Fe2+ (15 mg/L), H2O2 (500 mg/L), pH (3.0) and contact time (120 minutes), 75.43 and 77.54% of Chemical Oxygen Demand removal was achieved for 1a and 2a, respectively. Whereas, the optimum conditions of UV/H2O2 process were H2O2 (700 mg/L), pH(3.0) and irradiation time (200 minutes) that brought 54.33 and 57.65% COD removal in case of 1a and 2a, respectively. The results indicated that the Fenton oxidation can be successfully employed for the mineralization of triazine based UV absorbers.

Studies of oxidations by fenton's reagent using redox titration. V. Effect of complex formation on reaction mechanism

1973 ◽  
Vol 26 (5) ◽  
pp. 1021 ◽  
Author(s):  
DL Ingles
Keyword(s):  
Reaction Mechanism ◽  
Complex Formation ◽  
Hydroxyl Radical ◽  
Butyl Alcohol ◽  
Fenton’S Reagent ◽  
Redox Titration ◽  
Fenton's Reagent ◽  
Free Hydroxyl ◽  
Electron Transfers ◽  
H2o2 System

The effect of complex formation on the oxidation of substrate in the Fe2+-H2O2 system has been studied. t-Butyl alcohol which is normally oxidized to the dimer, 2,5-dimethylhexane-2,5-diol, by Fenton's reagent has been used as a probe for the presence of free hydroxyl radical. ��� It is shown that when suitable complexes are formed substrates are not oxidized by free hydroxyl radical. Instead, new mechanisms involving one- and two-electron transfers within a substrate-ferrous ion-peroxide complex are proposed.

Improvements in Functionalities of Porcine Serum Protein Hydrolysates Induced by Free Hydroxyl Radical

2012 ◽  
Vol 554-556 ◽  
pp. 1487-1492
Author(s):  
He Hong Yang ◽  
Pei Jun Li ◽  
Bao Hua Kong ◽  
Yan Qing Li ◽  
Ju Yang Zhao ◽  
...  
Keyword(s):  
Hydroxyl Radical ◽  
Functional Properties ◽  
Plasma Protein ◽  
Food Systems ◽  
Activity Index ◽  
Early Stage ◽  
Protein Hydrolysates ◽  
Free Hydroxyl ◽  
Foaming Capacity ◽  
Mediated Oxidation

Hydrolysated peptides from kinds of proteins have been applied as natural ingredients in food industry, mainly due to their good functional properties. However, the fate of them under different processing conditions is rarely understood. In our study, changes of functional properties in porcine plasma protein hydrolysates (PPH) were evaluated in a free hydroxyl radical-mediated oxidation system. PPH was obtained by hydrolyzing porcine plasma protein with Alcalase for 5 h at pH 8.0, 55°C. When exposed to free radical-mediated oxidation, functional properties of PPH improved dramatically with growing oxidant concentrations and reaction time, especially at 20°C. Solubility, foaming capacity and emulsification of PPH increased significantly (P < 0.05) during early stage of oxidation, with solubility increasing from 83.1% (non-oxidized PPH) to 97.4%(20°C, 10mM H2OSubscript text2, 5 h), emulsifying activity index and foaming capacity rising form 1.24m2/g to 2.73 m2/g, and 144% to183%, respectively. Stability for emulsifying and foaming were also found to be reinforced. The improvements in functional properties of PPH helped to play theoretical basis for applying the peptides in food systems.

scholarly journals Free hydroxyl radical is not involved in an important reaction of lignin degradation by Phanerochaete chrysosporium Burds

1985 ◽  
Vol 226 (2) ◽  
pp. 455-460 ◽  
Author(s):  
T K Kirk ◽  
M D Mozuch ◽  
M Tien
Keyword(s):  
Hydroxyl Radical ◽  
Phanerochaete Chrysosporium ◽  
Fenton Reaction ◽  
Lignin Degradation ◽  
Mechanism Of Formation ◽  
Mass Spectral ◽  
Free Hydroxyl ◽  
Lignin Model ◽  
Trapping Agent ◽  
Fenton System

Hydroxyl radical (HO.) has been implicated in the degradation of lignin by Phanerochaete chrysosporium. This study assessed the possible involvement of HO. in degradation of lignin substructural models by intact cultures and by an extracellular ligninase isolated from the cultures. Two non-phenolic lignin model compounds [aryl-C(alpha)HOH-C(beta)HR-C(gamma)H2OH, in which R = aryl (beta-1) or R = O-aryl (beta-O-4)] were degraded by cultures, by the purified ligninase, and by Fenton's reagent (H2O2 + Fe2+), which generates HO. The ligninase and the cultures formed similar products, derived via an initial cleavage between C(alpha) and C(beta) (known to be an important biodegradative reaction), indicating that the ligninase is responsible for model degradation in cultures. Products from the Fenton degradation were mainly polar phenolics that exhibited little similarity to those from the biological systems. Mass-spectral analysis, however, revealed traces of the same products in the Fenton reaction as seen in the biological reactions; even so, an 18O2-incorporation study showed that the mechanism of formation differed. E.s.r. spectroscopy with a spin-trapping agent readily detected HO. in the Fenton system, but indicated that no HO. is formed during ligninase catalysis. We conclude, therefore that HO. is not involved in fungal C(alpha)-C(beta) cleavage in the beta-1 and beta-O-4 models and, by extension, in the same reaction in lignin.

Photochemical Oxidation of Water by 2-Methyl-1,4-benzoquinone:  Evidence against the Formation of Free Hydroxyl Radical

2002 ◽  
Vol 106 (12) ◽  
pp. 2889-2894 ◽  
Author(s):  
Aude Pochon ◽  
Pamela P. Vaughan ◽  
Daqing Gan ◽  
Peter Vath ◽  
Neil V. Blough ◽  
...  
Keyword(s):  
Hydroxyl Radical ◽  
Photochemical Oxidation ◽  
Free Hydroxyl

Preparation of Zinc Phthalocyanine-Calcium Alginate Gel Beads and its Use for Photocatalytic Oxidation Decolorization of Methyl Orange

2014 ◽  
Vol 809-810 ◽  
pp. 252-257
Author(s):  
Min Hong Xu ◽  
Hai Feng Chen ◽  
Guo Xiang Pan ◽  
Pei Song Tang
Keyword(s):  
Methyl Orange ◽  
Hydroxyl Radicals ◽  
Calcium Alginate ◽  
Photocatalytic Oxidation ◽  
Water Soluble ◽  
Zinc Phthalocyanine ◽  
Alginate Gel ◽  
Gel Beads ◽  
Calcium Alginate Gel ◽  
Free Hydroxyl

A supported photocatalyst zinc phthalocyanine-calcium alginate gel beads (Zn-MPc-SA) was prepared through the mixture of water-soluble zinc phthalocyanine (Zn-MPc) and sodium alginate was drip into 5% (w/v) CaCl2 solution. The Zn-MPc-SA was characterized by IR. Methyl orange was selected as a substrate to investigate the photocatalytic activity of Zn-MPc-SA. The results shown that: the surplus of methyl orange was 22.05% at the condition of pH 3, methyl orange 10mg/L 25mL, H2O2 50μL, Zn-MPc-SA 0.1460g and visible light irradiation for 3h. Zn-MPc-SA remains efficient in repetitive test cycles with no obvious degradation of catalytic activity. The reaction mechanism was likely to involve free hydroxyl radicals.

Decolorization of Basic Turquise Blue X-GB and Basic Blue X-GRRL by the Fenton’s Process and its Kinetics

2019 ◽  
Vol 233 (3) ◽  
pp. 361-373 ◽  
Author(s):  
Naeem-Ul-Haq Khan ◽  
Haq Nawaz Bhatti ◽  
Munawar Iqbal ◽  
Arif Nazir
Keyword(s):  
Waste Water ◽  
Water Pollution ◽  
Oxidation Process ◽  
Human Life ◽  
Correlation Coefficients ◽  
Fenton Process ◽  
Optimum Conditions ◽  
Oxidation Treatment ◽  
Textile Industries ◽  
Life On Earth

Abstract Textile industries use dyes to color their products and release waste water containing dyes, causing water pollution which is a serious problem for survival of human life on earth. The decolorization of basic turquise blue X-GB (BTB X-GB) 250% and basic blue X-GRRL (BB X GRRL) 250% dyes was examined by advanced (Fenton process) oxidation process. The effects of different parameters (initial dye concentration, pH, concentrations of hydrogen peroxide (H2O2) and reaction time) have been examined and optimum conditions were determined. It has been noted that percentage decolorization of both dyes (50 mg/L) increases with increase in concentration of H2O2. At optimum conditions (pH=3.0, H2O2=4.8 mM, temperature=50°C, time=80 min of BTB X-GB, and pH=5.0, H2O2=5.6 mM, temperature=40°C, time=60 min of BB X-GRRL) the decolorization obtained by Fenton process was 85.83% of BTB X-GB and 74.98% for BB X-GRRL. 1st order, 2nd order and BMG kinetic models were used to analyze the data. BMG model gives us the higher values of correlation coefficients for all data. Results showed that Fe2+/H2O2 are most effective for oxidation treatment of waste water effluents containing dyes as main pollutants.

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