scholarly journals Electrolysis-Assisted Mn(II)/Sulfite Process for Organic Contaminant Degradation at Near-Neutral pH

Water ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1608
Author(s):  
Lixin Jia ◽  
Xingwang Pei ◽  
Fei Yang
Keyword(s):  
Advanced Oxidation Process ◽  
Removal Rate ◽  
Dominant Role ◽  
Radical Scavenging ◽  
Water Electrolysis ◽  
Contaminant Removal ◽  
Contaminant Degradation ◽  
Sulfite Oxidation ◽  
Reaction Solution ◽  
Neutral Conditions

Manganese-catalyzed sulfite activation (i.e., Mn(II)/sulfite) has emerged as an advanced oxidation process to produce sulfate radical (SO4•−) for water treatment. However, to maintain the catalytic activity of Mn(II) ion, solution acidity has to be kept below pH 4, which is difficult to maintain in practice. Moreover, Mn(II)/sulfite reaction is a strongly oxygen-dependent process, and purging air into reaction solution is another extra cost. To solve the above issues, we devised to implement electrolysis into Mn(II)/sulfite (i.e., electro/Mn(II)/sulfite process) for organic compound (bisphenol A, BPA) oxidation. It was revealed that, under near-neutral conditions (pH 6), the removal rate of 10 μM BPA was increased from 46.3%, by Mn(II)/sulfite process, to 94.2% by electro/Mn(II)/sulfite process. The enhancement of BPA removal after implementation of electrolysis to Mn(II)/sulfite process was investigated, and concluded to be a result of several pathways. In detail, the produced oxygen from water electrolysis, direct sulfite oxidation on anode, and local acidic pH at anode vicinity together play a role in promoting SO4•− production and, therefore, contaminant removal. Radical-scavenging assays confirmed the dominant role of SO4•− in electro/Mn(II)/sulfite process.

Numerical Prediction of Contaminant Removal from Cavity in Horizontal Channel by Constrained Interpolated Profile Method

2014 ◽  
Vol 695 ◽  
pp. 384-388
Author(s):  
Nor Azwadi Che Sidik ◽  
A.S. Ahmad Sofianuddin ◽  
K.Y. Ahmat Rajab
Keyword(s):  
Reynolds Number ◽  
Aspect Ratio ◽  
Removal Rate ◽  
Contaminant Removal ◽  
Square Cavity ◽  
Profile Method ◽  
Aspect Ratios ◽  
Contaminants Removal ◽  
Parabolic Flow ◽  
High Removal Rate

In this paper, Constrained Interpolated Profile Method (CIP) was used to simulate contaminants removal from square cavity in channel flow. Predictions were conducted for the range of aspect ratios from 0.25 to 4.0. The inlet parabolic flow with various Reynolds number from 50 to 1000 was used for the whole presentation with the same properties of contaminants and fluid. The obtained results indicated that the percentage of removal increased at high aspect ratio of cavity and higher Reynolds number of flow but it shows more significant changes as increasing aspect ratio rather than increasing Reynolds number. High removal rate was found at the beginning of the removal process.

scholarly journals USE OF HYDROGEN PEROXIDE AND PERCARBONATE TO TREAT CHLORINATED AROMATIC HYDROCARBON-CONTAMINATED SOIL

2014 ◽  
Vol 22 (1) ◽  
pp. 30-39 ◽  
Author(s):  
Marika Viisimaa ◽  
Anna Goi
Keyword(s):  
Hydrogen Peroxide ◽  
Soil Ph ◽  
Liquid Hydrogen ◽  
Natural Soil ◽  
Contaminant Removal ◽  
Contaminant Degradation ◽  
Solid Carrier ◽  
Liquid Carrier ◽  
Initial Ph ◽  
Ph Conditions

This study compared treatment methods that utilised a liquid carrier of hydrogen peroxide and a solid carrier, percarbonate, for p-dichlorobenzene, p-chloro-m-cresol and p-chlorothymol degradation in the soil. The targeted chlorinated aromatic contaminants in the soil degraded to a certain level when treated with the liquid hydrogen peroxide, but the removal efficacy was not dependent on the dosage. In contrast, an increase in the percarbonate dosage enhanced the contaminant removal. Supplementary ferrous iron was more effective for the treatment that employed the liquid carrier of hydrogen peroxide than the treatment employing the solid carrier. Although acidic pH conditions (initial pH of 2.5) favoured contaminant degradation using liquid hydrogen peroxide, the treatment involving percarbonate resulted in more effective contaminant removal without any soil pH preadjustment. Therefore, the solid carrier of hydrogen peroxide, percarbonate, was concluded to be an effective alternative to the liquid carrier, resulting in greater contaminant removal at natural soil pH values.

scholarly journals Advanced Oxidation Process for Degradation of Carbamazepine from Aqueous Solution: Influence of Metal Modified Microporous, Mesoporous Catalysts on the Ozonation Process

Catalysts ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 90 ◽  
Author(s):  
Soudabeh Saeid ◽  
Matilda Kråkström ◽  
Pasi Tolvanen ◽  
Narendra Kumar ◽  
Kari Eränen ◽  
...  
Keyword(s):  
Heterogeneous Catalysts ◽  
Advanced Oxidation Process ◽  
Degradation Products ◽  
Degradation Kinetics ◽  
Removal Rate ◽  
Influence Of Temperature On ◽  
Two Temperatures ◽  
Kinetics Of ◽  
Ozonation Process ◽  
Mcm 41

Carbamazepine (CBZ), a widely used pharmaceutical compound, is one of the most detected drugs in surface waters. The purpose of this work was to identify an active and durable catalyst, which, in combination with an ozonation process, could be used to remove CBZ and its degradation products. It was found that the CBZ was completely transformed after ozonation within the first minutes of the treatment. However, the resulting degradation products, 1-(2-benzaldehyde)-4-hydro-(1H,3H)-quinazoline-2-one (BQM) and 1-(2-benzaldehyde)-(1H,3H)-quinazoline-2,4-dione (BQD), were more resistant during the ozonation process. The formation and degradation of these products were studied in more detail and a thorough catalytic screening was conducted to reveal the reaction kinetics of both the CBZ and its degradation products. The work was performed by non-catalytic ozonation and with six different heterogeneous catalysts (Pt-MCM-41-IS, Ru-MCM-41-IS, Pd-H-Y-12-EIM, Pt-H-Y-12-EIM, Pd-H-Beta-300-EIM and Cu-MCM-41-A-EIM) operating at two temperatures 20 °C and 50 °C. The influence of temperature on degradation kinetics of CBZ, BQM and BQD was studied. The results exhibited a notable difference in the catalytic behavior by varying temperature. The higher reactor temperature (50 °C) showed a higher activity of the catalysts but a lower concentration of dissolved ozone. Most of the catalysts exhibited higher removal rate for BQM and BQD compared to non-catalytic experiments in both temperatures. The Pd-H-Y-12-EIM catalyst illustrated a higher degradation rate of by-products at 50 °C compared to other catalysts.

The Experimental Study of Contaminant Removal in Water Quenched Slag Biological Aerated Filter (BAF)

2012 ◽  
Vol 602-604 ◽  
pp. 1171-1174
Author(s):  
Long Long Gao ◽  
Yan Zhen Yu ◽  
Miao Wan Li ◽  
Yu Xing Zhou ◽  
Hua Dong Zhang
Keyword(s):  
Experimental Study ◽  
Wastewater Treatment ◽  
Removal Rate ◽  
Filter Material ◽  
Experimental Results ◽  
Filter Medium ◽  
Contaminant Removal ◽  
Biological Aerated Filter ◽  
Aerated Filter ◽  
Second Use

In order to effectively resolve pollution issue of water quenched slag and its comprehensive use or second use of materials, the water quenched slag filter material is developed using water quenched slag with the addition of adhesion-increasing agent and porogen by commingle, pelletizing and curing. Experimental results indicate that water quenched slag filter material is used as filter medium in biological aerated filter for wastewater treatment,and the removal rate of COD, NH3-N comes up to 84.62%,90.20% respectively. The filter material is much more predominant and possesses a much wider application prospect in the treatment of wastewate.

Advanced Oxidation Process with Peracetic Acid and Fe(II) for Contaminant Degradation

2019 ◽  
Vol 53 (22) ◽  
pp. 13312-13322 ◽  
Author(s):  
Juhee Kim ◽  
Tianqi Zhang ◽  
Wen Liu ◽  
Penghui Du ◽  
Jordan T. Dobson ◽  
...  
Keyword(s):  
Peracetic Acid ◽  
Advanced Oxidation Process ◽  
Oxidation Process ◽  
Advanced Oxidation ◽  
Contaminant Degradation

scholarly journals Assessing the Self-Purification Capacity of Surface Waters in Lake Baikal Watershed

Water ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1505 ◽  
Author(s):  
Mikhail Yu. Semenov ◽  
Yuri M. Semenov ◽  
Anton V. Silaev ◽  
Larisa A. Begunova
Keyword(s):  
Lake Baikal ◽  
Water Body ◽  
Removal Rate ◽  
Water Discharge ◽  
Contaminant Removal ◽  
Removal Rates ◽  
Selenga River ◽  
Removal Capacity ◽  
Polycyclic Aromatic ◽  
The Difference

The removal of trace metals (TM), dissolved organic carbon (DOC), mineral nitrogen (Nmin.), and polycyclic aromatic hydrocarbons (PAHs) from the water of Lake Baikal and its tributaries was evaluated. The contaminant removal rate (CRR) and the contaminant removal capacity (CRC) were used as water self-purification parameters. The CRR was calculated as the difference between contaminant mass flow rates at downstream and upstream gauging stations. The CRC was calculated as the quotient of the CRR and the change in water discharge between downstream and upstream gauging stations. Whether the CRR and CRC have positive or negative values depends on whether contaminant release or removal occurs in the water body. The CRR depends on the size of the water body. The lowest and the highest CRRs observed for Baikal were equal to −15 mg/s (PAHs) to −7327 g/s (DOC), whereas the highest PAH and DOC removal rates observed for Selenga River (the major Baikal tributary) in summer were equal to −9 mg/s and −3190 g/s correspondingly. The highest PAH and DOC removal rates observed for small tributaries were equal to 0.0004 mg/s and −0.7 g/s respectively. The amplitude of annual CRR oscillations depends on contaminant abundance. The highest amplitude was typical for most abundant contaminants such as Nmin. and DOC. In unpolluted sections of the Selenga River the highest rates of N and C removal (−85 g/s and −3190 g/s, respectively) were observed in summer and the lowest rates (4 g/s and 3869 g/s, respectively) were observed in the spring. The lowest amplitude was typical for PAHs and some low-abundance TM such as V and Ni. The highest summer rates of V and Ni removal were equal to −378 mg/s and −155 mg/s respectively, whereas lowest spring rates are equal to 296 mg/s and 220 mg/s. The intermediate CRR amplitudes were typical for most abundant TM such as Sr, Al, and Fe. The spatial CRR variability depends on water chemistry and the presence of pollution sources. The lowest (up to 38 g/s) rates of Nmin. removal was observed for polluted lower Selenga sections characterized by low water mineralization and high DOC concentrations. The highest rates (−85 g/s) were observed for unpolluted upper sections. Seepage loss from the river to groundwater was also recognized as an important means of contaminant removal. The CRC values depend mostly on water residence time. The DOC removing capacity value of Baikal (−26 g/m3) were lower than those of Selenga in summer (−35 g/m3) but higher than the CRCs of all tributaries during the other seasons (from 30 mg/m3 to −10 g/m3).

A DFT STUDY ON THE ROLE OF DIFFERENT OH GROUPS IN THE RADICAL SCAVENGING PROCESS

2012 ◽  
Vol 11 (04) ◽  
pp. 871-893 ◽  
Author(s):  
K. SADASIVAM ◽  
R. JAYAPRAKASAM ◽  
R. KUMARESAN
Keyword(s):  
Antioxidant Activity ◽  
Density Functional ◽  
Dominant Role ◽  
Food Additives ◽  
Radical Scavenging ◽  
Theory Approach ◽  
Oh Groups ◽  
Flavonoid Compounds ◽  
Dissociation Enthalpy

The molecular properties of robinetin and melanoxetin which are the two naturally occurring flavonoid compounds have been studied theoretically by means of density functional theory approach (DFT) at the level of B3LYP/6-311G(d,p). The analysis of computed bond dissociation enthalpy (BDE), proton dissociation enthalpy (PDE), proton affinity (PA), electron transfer enthalpy (ETE) values for both the flavonoid compounds indicate the role of B-ring for the significant antioxidant characteristics and the instability of the A-ring. It also concerns the dominant role of BDE mechanism for antioxidant activity than PDE, PA and ETE mechanisms. Ionization potential (IP) is also found to be trustworthy in the study of antioxidant activity and the computed IP magnitudes are in agreement with the values of synthetic food additives. Further, the various molecular descriptors along with the plot of frontier molecular orbitals and Mulliken spin population analysis have been obtained and the validity of Koopmans' theorem is also verified with reference to antioxidant behavior.

scholarly journals Comparison of the degradation of molecular and ionic ibuprofen in a UV/H2O2 system

2018 ◽  
Vol 77 (9) ◽  
pp. 2174-2183 ◽  
Author(s):  
Rongkui Su ◽  
Liyuan Chai ◽  
Chongjian Tang ◽  
Bo Li ◽  
Zhihui Yang
Keyword(s):  
Quantum Yield ◽  
Rate Constant ◽  
Degradation Rate ◽  
Molecular Form ◽  
Degradation Kinetics ◽  
Dominant Role ◽  
Radical Scavenging ◽  
Operating Conditions ◽  
Direct Photolysis ◽  
H2o2 System

Abstract The advanced oxidation technologies based on •OH can effectively degrade the pharmaceutical and personal care products under operating conditions of normal temperature and pressure. In this study, direct photolysis of ibuprofen (IBU) is slow due to the relatively low molar extinction coefficient and quantum yield. Compared to direct photolysis, the degradation kinetics of IBU was significantly enhanced in the UV/H2O2 system, mainly by •OH radical mediated oxidation. In the UV/H2O2 system, the degradation rate of ionic IBU was slightly faster than that of the molecular form. Kinetic analysis showed that the second-order reaction rate constant of ionic IBU (5.51 × 109 M−1 s−1) was higher than that of the molecular form (3.43 × 109 M−1 s−1). The pseudo first-order rate constant for IBU degradation (kobs) increased with increasing H2O2 dosage. kobs can be significantly decreased in the presence of natural organic matter (NOM), which is due to (i) NOM radical scavenging effects (dominant role) and (ii) UV absorption. The degradation of IBU was inhibited by HCO3–, which was attributed to its scavenging effect. Interestingly, when NO3– was present in aqueous solution, a slight increase in the degradation rate was observed, which was due to NO3– absorbing photons to generate •OH at a low quantum yield. No obvious effects were observed when SO42 and Cl− were present.

scholarly journals Preventing Silica Scale Formation Using Hydroxide Ions Generated by Water Electrolysis

Membranes ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 154
Author(s):  
Sano ◽  
Yamaguchi
Keyword(s):  
Power Generation ◽  
Inductively Coupled Plasma ◽  
Water Electrolysis ◽  
Polymerization Reaction ◽  
Practical Applications ◽  
Inductively Coupled ◽  
Reaction Solution ◽  
Silica Scale ◽  
Calcium Compound ◽  
Proton Generation

The reaction of silica with various cations in a solution and with hydroxide ions generated by water electrolysis was investigated as a means of preventing the formation of silica scales in geothermal binary power generation. Through batch and continuous experiments, it was found that all silica in the cathode phase of a reaction device could be removed if the necessary amounts of magnesium and calcium were present. This occurs because a silica-magnesium-calcium compound is produced via a polymerization reaction with cations in a solution and with hydroxide ions generated by electrolysis. Analysis by inductively coupled plasma and energy dispersive X-ray spectroscopy shows that this material has the formula 2CaO-5MgO-8SiO2-H2O, and thus is likely generated by the reaction proposed by Sheikholeslami et al. (2019). Increasing the current sent through the reaction solution subsequently produces calcium carbonate. This technique for the separation of silica and calcium from aqueous solutions can be operated continuously without channel clogging, which indicates the possibility of practical applications. However, overly high currents promote the migration of protons from the anode to cathode phases, which inhibits the formation of precipitates due to a neutralization reaction. The proposed method is an effective approach for removing silica from a solution in geothermal binary power generation; although, a means of suppressing the effects of proton generation will be necessary if the process is also to be used to remove calcium ions.

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