scholarly journals Degradation of high-concentration p-nitrophenol by Fenton oxidation

2020 ◽  
Vol 81 (10) ◽  
pp. 2260-2269
Author(s):  
Xiao Qing Lin ◽  
Wei Min Kong ◽  
Xiao Lin
Keyword(s):  
Degradation Rate ◽  
Removal Rate ◽  
Oxidative Degradation ◽  
Oxygen Demand ◽  
Fenton Oxidation ◽  
Utilization Efficiency ◽  
Molar Ratio ◽  
High Concentration ◽  
Initial Concentration ◽  
Toc Removal

Abstract This work aimed to degrade high-concentration p-nitrophenol (PNP) by Fenton oxidation. We studied various reaction parameters during Fenton oxidation, such as the iron dosage (as Fe2+), the initial concentration and temperature of PNP, and the dosage of hydrogen peroxide (H2O2), especially the influence of temperature on the PNP degradation rate and degree. Under the addition of the same molar ratio of H2O2/Fe2+ and H2O2 dosage according to the theoretical stoichiometry, the PNP degradation rate and the removal rate of total organic carbon (TOC) increased significantly with the increase in the initial PNP concentration. Moreover, the oxidative degradation effect was significantly affected by temperature. The increased reaction temperature not only significantly reduced the Fe2+ dosage, but also greatly promoted the removal rate of chemical oxygen demand (COD) and TOC, and improved the utilization efficiency of H2O2. For example, when the initial concentration of PNP was 4,000 mg·L−1, and the dosage of Fe2+ was 109 mg·L−1 (H2O2/Fe2+ = 200), the removal rates of COD and TOC at 85 °C reached 95% and 71% respectively. Both were higher than the 93% COD removal rate and 44% TOC removal rate when the dosage of Fe2+ was 1,092 mg·L−1 (H2O2/Fe2+ = 20) at room temperature.

scholarly journals Treatment of ultrahigh chemical oxygen demand chemical wastewater by Fenton oxidation

2021 ◽  
Vol 2109 (1) ◽  
pp. 012011
Author(s):  
Xingfu Xue
Keyword(s):  
Oxidation Process ◽  
Removal Rate ◽  
Oxygen Demand ◽  
Fenton Oxidation ◽  
Molar Ratio ◽  
Chemical Plants ◽  
Clear Liquid ◽  
Second Stage ◽  
Optimum Ph ◽  
Fenton Oxidation Process

Abstract The article focuses on the Fenton oxidation process for the treatment of ultrahigh COD chemical wastewater from chemical plants. Optimum pH was determined as 2.0 and 10.0 for the first (oxidation) and second stage (coagulation) of the Fenton process, respectively. 0.465gFeSO4·7H2O, H2O2(30%)2ml, the mole tatio of H2O2 : Fe2+=10:1, adjust the pH of the solution to 10, after 1.5 hours of agitation, then add 5% PAM2ml to the solution, filtrate, extract, filtrate the clear liquid and dilute it three times, take 200ml of the diluted liquid, and add 0.465gFeSO4·7H2O, H2O2(30%)2ml, the mole tatio of H2O2 : Fe2+=10:1, adjust the pH of the solution to 10, after 1.5 hours of agitation, then add 5% PAM2ml to the solution, static stratification. For chemical wastewater, when the molar ratio H2O2/Fe2+ is 10:1, the removal rate of COD is the highest, provided 86.21–86.45% COD removal.

scholarly journals Arsenic (III) Removal from a High-Concentration Arsenic (III) Solution by Forming Ferric Arsenite on Red Mud Surface

Minerals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 583
Author(s):  
Dongdong He ◽  
Yuming Xiong ◽  
Li Wang ◽  
Wei Sun ◽  
Runqing Liu ◽  
...  
Keyword(s):  
Red Mud ◽  
Arsenic Removal ◽  
Ferric Hydroxide ◽  
Morphological Properties ◽  
Molar Ratio ◽  
Inorganic Pollutants ◽  
High Concentration ◽  
Initial Concentration ◽  
X Ray ◽  
Alkaline Agent

Arsenic (As) is considered one of the most serious inorganic pollutants, and the wastewater produced in some smelters contains a high concentration of arsenic. In this paper, we purified the high-concentration arsenic solution with red mud and Fe3+ synergistically. In this system, arsenite anions reacted with Fe(III) ions to form ferric arsenite, which attached on the surface of red mud particles. The generated red mud/Fe1−x(As)x(OH)3 showed a better sedimentation performance than the pure ferric arsenite, which is beneficial to the separation of arsenic from the solution. The red mud not only served as the carrier, but also as the alkaline agent and adsorbent for arsenic treatment. The effects of red mud dosage, dosing order, pH, and molar ratio of Fe/As on arsenic removal were investigated. The efficiency of arsenic removal increased from a pH of 2 to 6 and reached equilibrium at a pH of 7. At the Fe/As molar ratio of 3, the removal efficiency of arsenic ions with an initial concentration of 500 mg/L reached 98%. In addition, the crystal structure, chemical composition, and morphological properties of red mud and arsenic removal residues (red mud/Fe1−x(As)x(OH)3) were characterized by XRD, XPS, X-ray fluorescence (XRF), SEM-EDS, and Raman spectroscopy to study the mechanism of arsenic removal. The results indicated that most of the arsenic was removed from the solution by forming Fe1−x(As)x(OH)3 precipitates on the red mud surface, while the remaining arsenic was adsorbed by the red mud and ferric hydroxide.

Electrochemical oxidative degradation of indigo wastewater based on chlorine-containing system

2020 ◽  
Vol 49 (1) ◽  
pp. 46-54 ◽  
Author(s):  
Wei Zhang ◽  
Weiwei Lv ◽  
Xiaoyan Li ◽  
Jiming Yao
Keyword(s):  
Chemical Oxygen Demand ◽  
Response Surface ◽  
Electrochemical Oxidation ◽  
Surface Analysis ◽  
Removal Rate ◽  
Oxidative Degradation ◽  
Oxygen Demand ◽  
Single Factor ◽  
Dyeing Wastewater ◽  
Content Type

Purpose In this study, the oxidative degradation performance of indigo wastewater based on electrochemical systems was explored. The decolourization degrees, removal rate of chemical oxygen demand and biochemical oxygen demand of the indigo wastewater after degradation were evaluated and optimized treatment conditions being obtained. Design/methodology/approach The single factor method was first used to select the electrolyte system and electrode materials. Then the response surface analysis based on Box–Behnken Design was chosen to determine the influence of four independent variables such as FeCl3 concentration, NaCl concentration, decolourization time and voltage on the degradation efficiency. Findings On the basis of single factor experiment, the electrode material of stainless steel was selected in the double cell, and the indigo wastewater was electrolyzed with FeCl3 and NaCl electrolytes. The process conditions of electrochemical degradation of indigo wastewater were optimized by response surface analysis: the concentration of FeCl3 and NaCl was of 16 and 9 g/L, respectively, with a decolourization time of 50 min, voltage of 10 V and decolourization percentage of 98.94. The maximum removal rate of chemical oxygen demand reached 75.46 per cent. The highest ratio of B/C was 3.77, which was considered to be more biodegradable. Research limitations/implications Dyeing wastewater is bringing out more and more pollution problems to the environment. However, there are some shortcomings in traditional technologies such as adsorption and filtration. As a kind of efficient and clean water treatment technology, electrochemical oxidation has been applied to the treatments of various types of wastewater. The decolourization and degradation of indigo wastewater is taken as an example to provide reference for the treatment of wastewater in actual plants. Practical implications The developed method provided a simple and practical solution for efficiently degrading indigo wastewater. Originality/value The method for the electrochemical oxidation technology was novel and could find numerous applications in the degradation of printing and dyeing wastewater.

scholarly journals Treatment of Landfill Leachates with Combined Acidification/Coagulation and The Fe0/H2O2 Process

Water ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 194 ◽  
Author(s):  
Jan Bogacki ◽  
Piotr Marcinowski ◽  
Balkess El-Khozondar
Keyword(s):  
Statistical Analysis ◽  
Processing Time ◽  
Oxygen Demand ◽  
Treatment Method ◽  
Environmental Concerns ◽  
Landfill Leachates ◽  
Complex Composition ◽  
Combined Process ◽  
Initial Concentration ◽  
Toc Removal

One of the major environmental concerns associated with waste disposal is the large amount of generated landfill leachates (LL), which are considered a type of wastewater with a complex composition. There is an urgent need to find an effective LL treatment method. LL were subjected to pretreatment followed by the Fe0/H2O2 process. Pretreatment efficiency was coagulation at pH 6.0 >> coagulation at pH 9.0 > acidification at pH 3.0. Coagulation at pH 6.0 in an optimal Fe3+ dose of 1000 mg/L decreased total organic carbon (TOC) from the initial concentration of 1061 mg/L to 491 mg/L while acidification to pH 3.0 decreased TOC to 824 mg/L. After acidification, the Fe0/H2O2 process with 8000/9200 mg/L Fe0/H2O2 reagent doses decreased TOC to 499 mg/L after a processing time of 60 min. Performance of the Fe0/H2O2 process after coagulation at pH 6.0 for optimal Fe0/H2O2 8000/5540 mg/L reagent doses decreased TOC to 268 mg/L (75% TOC removal). Treatment of landfill leachates with combined process coagulation and Fe0/H2O2 also increased their susceptibility to biodegradation, expressed as the biochemical oxygen demand/chemical oxygen demand (BOD5/COD) ratio from 0.13 to 0.43, allowing LL to be considered as susceptible to biodegradation. Fe0/H2O2 process kinetics was described. A statistical analysis confirmed the obtained results. The proposed method can be successfully applied for LL treatment.

scholarly journals Improved Ozonation Efficiency for Polymerization Mother Liquid from Polyvinyl Chloride Production Using Tandem Reactors

Molecules ◽  
2019 ◽  
Vol 24 (24) ◽  
pp. 4436 ◽  
Author(s):  
Zhiyong Yang ◽  
Penglei Wang ◽  
Yagang Zhang ◽  
Xingjie Zan ◽  
Wenjuan Zhu ◽  
...  
Keyword(s):  
Reaction Time ◽  
Chemical Oxygen Demand ◽  
Polyvinyl Chloride ◽  
Ozone Concentration ◽  
Degradation Rate ◽  
Oxygen Demand ◽  
Cod Removal ◽  
Utilization Efficiency ◽  
High Ozone Concentration ◽  
In Series

Polymerization mother liquid (PML) is one of the main sources of wastewater in the chlor-alkali industry. The effective degradation of the PML produced in PVC polymerization using three or five ozone reactors in tandem was designed with a focus on improving the ozonation efficiency. The ozonation efficiency of the tandem reactors for the degradation of PML, along with the effect of ozone concentration, the number of reactors utilized in series, and the reaction time on the chemical oxygen demand (COD) removal were investigated in detail. The results showed that the COD removal increased as the ozone concentration was increased from 10.6 to 60 mg·L−1, achieving 66.4% COD removal at ozone concentration of 80.6 mg·L−1. However, when the ozone concentration was increased from 60 mg·L−1 to 80 mg·L−1, the COD removal only increased very little. The COD decreased with increasing ozone concentration. During the initial degradation period, the degradation rate was the highest at both low and high ozone concentrations. The degradation rate decreased with reaction time. The rate at a low ozone concentration decreased more significantly than at high ozone concentration. Although high ozone concentration is desirable for COD removal and degradation rate, the utilization efficiency of ozone decreased with increasing ozone concentration. The ozone utilization efficiency of the five-reactor device was three times higher than that of three tandem reactors, demonstrating that ozonation utilization efficiency can be improved by increasing the number of tandem reactors. Ozonation in tandem reactors is a promising approach for PML treatment.

Ozone-enhanced photocatalytic degradation of natural organic matter in water

2006 ◽  
Vol 6 (3) ◽  
pp. 53-61 ◽  
Author(s):  
P. Zhang ◽  
L. Jian
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Photocatalytic Degradation ◽  
Natural Organic Matter ◽  
Retention Time ◽  
Degradation Rate ◽  
Removal Rate ◽  
Water Source ◽  
Drinking Water Source ◽  
Toc Removal

Ozone-enhanced photocatalytic degradation of macromolecular natural organic matter (NOM) in drinking water source was investigated. The influences of ozone dosage, retention time and bicarbonate concentration on the NOM degradation rate were studied. The change of molecular weight distribution of NOM caused by ozone-enhanced photocatalysis was analysed, as well as the degradation rate of NOM with different molecular weight (MW). It was shown that ozone-enhanced photocatalysis was much better for NOM degradation than sole ozonation or photocatalysis. Increase of both ozone dosage and retention time could effectively increase the TOC removal rate, while biodegradability could be improved solely by an increase in ozone dosage. The existence of bicarbonate significantly reduced the photocatalytic degradation rate of NOM; however, its impact was effectively offset by the addition of ozone into the photocatalytic process. Macromolecular NOM was transformed into smaller molecules, and the larger NOM was mineralized by ozone-enhanced photocatalysis much faster than the smaller NOM.

A comparative treatment of bleaching wastewater by physicochemical processes

2017 ◽  
Vol 76 (9) ◽  
pp. 2367-2379 ◽  
Author(s):  
Ninad Oke ◽  
Swati Singh ◽  
Anurag Garg
Keyword(s):  
Mixing Time ◽  
Oxygen Demand ◽  
Chloride Ion ◽  
Paper Mill ◽  
Ion Concentration ◽  
Treated Wastewater ◽  
Molar Ratio ◽  
Chlorinated Organic Compounds ◽  
H2o2 Treatment ◽  
Toc Removal

Abstract The bleaching effluent discharged from a pulp and paper mill contains chlorinated organic compounds which are toxic to living matter. Physicochemical treatments such as coagulation and different advanced oxidation processes (AOPs) were employed for combined bleaching effluent generated from the first two stages (i.e. chlorination and alkali extraction) (pH = 3.5, chemical oxygen demand (COD) = 1,920 mg/L, and total organic carbon (TOC) = 663 mg/L). At optimum conditions (pH = 7.5, polyaluminium chloride (PAC) dose = 3.84 g/L and slow mixing time = 25 min), ∼68% removal in UV254 and ∼23% TOC removal was obtained during coagulation. Among various AOPs, UV/Fe2+/TiO2/H2O2 system showed the highest TOC and COD removals (∼78%) after 2 h duration (Fe2+:H2O2 molar ratio = 1:100). After the AOP process, chloride ion concentration and biodegradability of the treated wastewater was increased to 2,762 mg/L and 0.46 from an initial value of 2,131 mg/L and 0.29, respectively. The wastewater and sludge analysis showed oxidation and adsorption as the major mechanisms for organics removal. Upon reuse of the regenerated catalysts, TOC removal was reduced significantly. It was found that three times more sludge per unit TOC removal was generated after coagulation in comparison to that produced after UV/Fe2+/TiO2/H2O2 treatment.

A Study of Removing 4-Toluene Sulfonic Acid in Wastewater Treatment by Aerobic Bio-Fluidized Bed

2014 ◽  
Vol 522-524 ◽  
pp. 665-671
Author(s):  
Zhen Huang ◽  
Yu Dong Song ◽  
Yue Xi Zhou ◽  
Xu Wen He ◽  
Jie Xu
Keyword(s):  
Fluidized Bed ◽  
Sulfonic Acid ◽  
Degradation Rate ◽  
Ph Value ◽  
Oxygen Demand ◽  
Technological Parameters ◽  
High Concentration ◽  
Water Load ◽  
Toluene Sulfonic Acid ◽  
The Impact

Based on the problem of industrial wastewater of 4-Toluene Sulfonic Acid (4-TSA) with characteristics of high concentration and high toxicity, also low treatment efficiency by common biological treatment , this study was used aerobic biological fluidized bed (ABFB) to analyze the impact of 4-TSA treatment by changing water load chemical oxygen demand (COD), aeration amount, and pH value of input water, and so on technological parameters. The result showed that the average degradation rate of 4-TSA in wastewater can researched to 96.9% under condition of reactor steadily running, HRT=9 h, temperature 25°C, pH=8.0, ORP-141~-93 mV,DO 3.5~8.72 mg/L, the inflow water 4-TSA concentration 600 mg/L, aerobic amount 210 L/h. Therefore, the best aerobic amount to treat wastewater contained 4-TSA is 210 L/h in aerobic biological fluidized bed. The degradation rate of 4-TSA is decreased as the increasing of water load. The scanning electronic microscope (SEM) indicated that the bacillus is the mainly part on the biological carrier, suspended sludge is composed by aurous and bacillus.

The highest inhibition coefficient of phenol biodegradation using an acclimated mixed culture

2015 ◽  
Vol 73 (5) ◽  
pp. 1033-1040 ◽  
Author(s):  
Mojtaba Mohseni ◽  
Payman Sharifi Abdar ◽  
S. Mehdi Borghei
Keyword(s):  
Mixed Culture ◽  
Degradation Rate ◽  
Growth Parameters ◽  
Removal Rate ◽  
Substrate Inhibition ◽  
Phenol Degradation ◽  
Oxygen Demand ◽  
Synthetic Wastewater ◽  
Phenol Biodegradation ◽  
Culture Substrate

In this study a membrane biological reactor (MBR) was operated at 25 ± 1 °C and pH = 7.5 ± 0.5 to treat synthetic wastewater containing high phenol concentrations. Removal efficiencies of phenol and chemical oxygen demand (COD) were evaluated at four various hydraulic retention times (HRTs) of 24, 12, 8, and 4 hours. The removal rate of phenol (5.51 kg-Phenol kg-VSS−1 d−1), observed at HRT of 4 h, was the highest phenol degradation rate in the literature. According to COD tests, there were no significant organic matter in the effluent, and phenol was degraded completely by mixed culture. Substrate inhibition was calculated from experimental growth parameters using the Haldane, Yano, and Edward equations. The results show that the Haldane equation is fitted to the experimental data in an excellent manner. Kinetic parameters were derived by nonlinear regression with a correlation coefficient (R2) of 0.974. The values for Haldane constants μmax, Ks, and Ki were 0.3085 h−1, 416 mg L−1 and 1,886 mg L−1, respectively. The Ki value is the highest value obtained for mixed cultures degrading phenol under batch conditions.

Kinetic degradation of guar gum in oilfield wastewater by photo-Fenton process

2016 ◽  
Vol 75 (1) ◽  
pp. 11-19 ◽  
Author(s):  
Shunwu Wang ◽  
Ziwang Li ◽  
Qinglong Yu
Keyword(s):  
Guar Gum ◽  
Oxidative Degradation ◽  
Oxygen Demand ◽  
Cod Removal ◽  
Fenton Process ◽  
Experimental Conditions ◽  
Initial Concentration ◽  
Initial Ph ◽  
Main Component ◽  
The Cost

Guar gum is considered as a main component of oilfield wastewater. This work is intended to optimize the experimental conditions (H2O2 dosage, Fe2+ dosage, initial concentration of organics, initial pH and temperature) for the maximum oxidative degradation of guar gum by Fenton's reagent. The kinetics of guar gum removal were evaluated by means of the chemical oxygen demand (COD) and the absorbance measurements. The batch experiment results showed that the optimum conditions were: H2O2 dosage, 10,000 mg/L; Fe2+dosage, 2,000 mg/L; initial concentration of organics, 413 mg/L; pH, 3 and temperature, 35 °C, under which the COD removal could reach 61.07% and fairly good stability could be obtained. Under the optimum experimental conditions, using UV irradiation to treat the wastewater, the photo-Fenton systems can successfully eliminate COD from guar gum solution. The COD removal always obeyed a pseudo-first-order kinetics and the degradation rate (kapp) was increased by 25.7% in the photo-Fenton process compared to the Fenton process. The photo-Fenton system needed less time and consequently less quantity of H2O2 to obtain the same results as the Fenton process. The photo-Fenton process needs a dose of H2O2 20.46% lower than that used in the Fenton process to remove 79.54% of COD. The cost of the photo/Fenton process amounted to RMB9.43/m3, which was lower than that of the classic Fenton process alone (RMB10.58/m3) and the overall water quality of the final effluent could meet the class Ι national wastewater discharge standard for the petrochemical industry of China.

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