scholarly journals Evaluation of wet air oxidation variables for removal of organophosphorus pesticide malathion using Box-Behnken design

2016 ◽  
Vol 75 (3) ◽  
pp. 619-628 ◽  
Author(s):  
Melike Isgoren ◽  
Erhan Gengec ◽  
Sevil Veli
Keyword(s):  
Removal Efficiency ◽  
Applied Pressure ◽  
Organophosphorus Pesticide ◽  
Operating Conditions ◽  
Quadratic Model ◽  
Air Oxidation ◽  
Wet Air Oxidation ◽  
Reaction Conditions ◽  
Efficient Treatment ◽  
Optimum Reaction

This paper deals with finding optimum reaction conditions for wet air oxidation (WAO) of malathion aqueous solution, by Response Surface Methodology. Reaction conditions, which affect the removal efficiencies most during the non-catalytic WAO system, are: temperature (60–120 °C), applied pressure (20–40 bar), the pH value (3–7), and reaction time (0–120 min). Those were chosen as independent parameters of the model. The interactions between parameters were evaluated by Box-Behnken and the quadratic model fitted very well with the experimental data (29 runs). A higher value of R2 and adjusted R2 (>0.91) demonstrated that the model could explain the results successfully. As a result, optimum removal efficiency (97.8%) was obtained at pH 5, 20 bars of pressure, 116 °C, and 96 min. These results showed that Box–Behnken is a suitable design to optimize operating conditions and removal efficiency for non-catalytic WAO process. The EC20 value of raw wastewater was measured as 35.40% for malathion (20 mg/L). After the treatment, no toxicity was observed at the optimum reaction conditions. The results show that the WAO is an efficient treatment system for malathion degradation and has the ability of converting malathion to the non-toxic forms.

scholarly journals Impact of Precipitants on the Structure and Properties of Fe-Co-Ce Composite Catalysts

2016 ◽  
Vol 2016 ◽  
pp. 1-8
Author(s):  
Yongli Zhang ◽  
Shujuan Dai ◽  
Yanbo Zhou ◽  
Kai Lin
Keyword(s):  
Particle Size ◽  
Methyl Orange ◽  
Removal Efficiency ◽  
Cod Removal ◽  
Catalytic Wet Air Oxidation ◽  
Structure And Properties ◽  
Air Oxidation ◽  
Wet Air Oxidation ◽  
Composite Catalysts ◽  
Cod Removal Efficiency

Fe-Co-Ce composite catalysts were prepared by coprecipitation method using CO(NH2)2, NaOH, NH4HCO3, and NH3·H2O as precipitant agents. The effects of the precipitant agents on the physicochemical properties of the Fe-Co-Ce based catalysts were investigated by SEM, TEM, BET, TG-DTA, and XRD. It was found that the precipitant agents remarkably influenced the morphology and particle size of the catalysts and affected the COD removal efficiency, decolorization rate, and pH of methyl orange for catalytic wet air oxidation (CWAO). The specific surface area of the Fe-Co-Ce composite catalysts successively decreased in the order of NH3·H2O, NH4HCO3, NaOH, and CO(NH2)2, which correlated to an increasing particle size that increased for each catalyst. For the CWAO of a methyl orange aqueous solutions, the effects of precipitant agents NH3·H2O and NaOH were superior to those of CO(NH2)2and NH4HCO3. The catalyst prepared using NH3·H2O as the precipitant agent was mostly composed of Fe2O3, CoO, and CeO2. The COD removal efficiency of methyl orange aqueous solution for NH3·H2O reached 92.9% in the catalytic wet air oxidation. Such a catalytic property was maintained for six runs.

scholarly journals Fabrication of Core-Shell Structural SiO2@H3[PM12O40] Material and Its Catalytic Activity

2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
Xin Yang ◽  
Junhai Wang ◽  
Qi Zhang ◽  
Xu Wang ◽  
Linlin Xu ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Heterogeneous Catalysts ◽  
Sol Gel ◽  
Operating Conditions ◽  
Core Shell ◽  
Catalytic Wet Air Oxidation ◽  
Air Oxidation ◽  
Wet Air Oxidation ◽  
Heterogeneous Catalytic ◽  
Room Condition

Through a natural tree grain template and sol-gel technology, the heterogeneous catalytic materials based on polyoxometalate compounds H3[PM12O40] encapsulating SiO2: SiO2@H3[PM12O40] (SiO2@PM12, M = W, Mo) with core-shell structure had been prepared. The structure and morphology of the core-shell microspheres were characterized by the XRD, IR spectroscopy, UV-Vis absorbance, and SEM. These microsphere materials can be used as heterogeneous catalysts with high activity and stability for catalytic wet air oxidation of pollutant dyes safranine T (ST) at room condition. The results show that the catalysts have excellent catalytic activity in treatment of wastewater containing 10 mg/L ST, and 94% of color can be removed within 60 min. Under different cycling runs, it is shown that the catalysts are stable under such operating conditions and the leaching tests show negligible leaching effect owing to the lesser dissolution.

Evaluation of Substances Released from Hydrothermal Pretreated Municipal Sludge and Performance of Hydrogen Production by the Corresponding Supernatant

2013 ◽  
Vol 726-731 ◽  
pp. 2468-2475 ◽  
Author(s):  
Li Yu ◽  
Cheng Lin Sun ◽  
Yong Hui Yu ◽  
Wen Tian Jiang
Keyword(s):  
Hydrogen Production ◽  
Hydrogen Yield ◽  
Air Oxidation ◽  
Wet Air Oxidation ◽  
Production Potential ◽  
Reaction Conditions ◽  
Stirring Rate ◽  
And Performance ◽  
Temperature Time ◽  
Central Composite

Response surface methodology (RSM) with central composite design was adopted to investigate the optimum condition for carbohydrate released from hydrothermal pretreated sludge in an autoclave used for WAO (wet air oxidation). Temperature, time and stirring rate were chosen as variables. The maximum carbohydrate release (1356.8 mg/L) was estimated at the temperature of 161.2 °C, the time of 48 min and the stirring rate of 661 r/min. This statistical method could precisely optimize reaction conditions and predict the experimental data. Only 11.2 mL methane was generated with little hydrogen production of raw sludge. In contrast, hydrogen production potential of 25 mL was reached by using supernatant as substrate with a COD removal of 78.14%. Hydrogen yield was increased from 0.13 mL/g-VS (raw sludge) to 13.16 mL/g-VS (supernatant of pretreated sludge).

Study on Catalyst of Catalytic Wet Oxidation of High-concentration Industrial Organic Wastewater

2011 ◽  
Vol 233-235 ◽  
pp. 2994-2999 ◽  
Author(s):  
Qing Lin Peng ◽  
Jing Zeng
Keyword(s):  
Removal Rate ◽  
Space Velocity ◽  
Preparation Condition ◽  
Bubble Columns ◽  
Catalytic Wet Oxidation ◽  
Air Oxidation ◽  
Wet Air Oxidation ◽  
High Concentration ◽  
Reaction Conditions ◽  
Oxidation Technology

A kind of compound catalyst containing the main activate component CuO, the second activate component ZrO2 and electronic promoter La2O3 was prepared. It was applicable to treat with high-concentration dimethyl acetylsuccinate (DMAS) production wastewater with catalytic wet air oxidation technology which was used in continuous bubble columns reactor. In this article the influences of concentration of soaked liquid of every component and the second activate component were studied, and the best preparation condition has been determined. The experimental results indicated that the catalyst of CuO-ZrO2-La2O3/ZSM-5 had a higher activity when handling high-concentration DMAS production wastewater. With this catalyst the CODcr removal rate could get 98.7% while non-catalyst only 35.8％ at the reaction conditions as follows: reaction temperature 240°C, reaction pressure 3.5MPa, liquor space velocity＝2.0 h-1, V (oxygen): V（wastewater）＝250:1 and influent wastewater pH=7.

scholarly journals Efficiency of the electrochemical treatment of textile effluent using two configurations of sacrificial electrodes

2018 ◽  
Vol 18 (1) ◽  
pp. 13
Author(s):  
Leandro Fleck ◽  
Jeysa Piza Santana Passos ◽  
Andrieli Cristina Helmann ◽  
Eduardo Eyng ◽  
Laércio Mantovani Frare ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Electrode Array ◽  
Electrochemical Reactor ◽  
Electrochemical Treatment ◽  
Operating Conditions ◽  
Color Removal ◽  
Textile Effluent ◽  
Parallel Plates ◽  
Cylindrical Electrode ◽  
Efficient Treatment

Textile industries have as main characteristic the generation of effluents with high color, and efficient treatment techniques are necessary. In this context, this study compared the efficiency of the electrochemical treatment for color removal from synthetic textile effluent using two configurations of sacrificial electrodes, parallel plates and array of cylindrical electrodes. For application of the electroflocculation technique, an electrochemical reactor was used, in a laboratory scale, operated in a continuous flow. The synthetic textile effluent was prepared with preset concentrations of reactive dye Blue 5G and sodium chloride. Sacrificial iron (Fe) electrodes with different configurations were used: parallel plates and cylindrical electrodes. The Hydraulic Retention Time (HRT) and electric current density (j) were controlled, and their effects on color removal were evaluated using a Central Composite Rotational Design (CCRD) composed of 12 trials. For the electrochemical treatment using parallel plates, the color removal efficiency ranged from 56.13% to 98.95% and for the electrochemical treatment using an array of cylindrical electrode, the color removal efficiency varied from 2.11% to 97.84%. The mathematical models representative of the process explained a high proportion of the total data variability, with a coefficient of variation of 99.49% and 97.21% for parallel plates and arrangement of cylindrical electrodes, respectively. The electrochemical treatment using parallel plates presents advantages over the configuration using a cylindrical electrode array, since the color removal efficiency is superior under the same operating conditions, representing economic and environmental gains.

Reaction mechanisms and kinetics of chemical pretreatment of bioresistant organic molecules by wet air oxidation

1997 ◽  
Vol 35 (4) ◽  
pp. 119-127 ◽  
Author(s):  
D. Mantzavinos ◽  
R. Hellenbrand ◽  
A. G. Livingston ◽  
I. S. Metcalfe
Keyword(s):  
Organic Pollutants ◽  
Reaction Mechanisms ◽  
Noble Metals ◽  
Heterogeneous Catalysts ◽  
Operating Conditions ◽  
Air Oxidation ◽  
Wet Air Oxidation ◽  
Total Oxidation ◽  
Analytical Technique ◽  
The Impact

The partial wet air oxidation of aqueous solutions of p-coumaric acid and polyethylene glycol, two model organic pollutants typically found in wastewaters of agricultural origin and polymer-manufacturing respectively, has been investigated at temperatures from 373 K to 513 K and oxygen partial pressures from 0.2 MPa to 3 MPa. Reaction intermediates have been identified and their concentration profiles have been determined using liquid chromatography as the main analytical technique, and reaction mechanisms and pathways have been postulated. The impact of various heterogeneous catalysts, such as metal oxides and noble metals, on the kinetics and mechanisms of the reaction has also been studied. Conversion of these model compounds through various oxidation intermediates to end-products, such as carboxylic acids, could be easily achieved even under mild operating conditions, while further total oxidation proved to be difficult even under more severe conditions. Catalysts were found to be, in general, capable of increasing the rates of both partial and total uncatalysed oxidation. The stability of some of the catalysts used has also been studied with respect to metal leaching and deactivation. The implications for complete removal of bioresistant organic pollutants by partial wet oxidation followed by a biological treatment step are also discussed.

Influence Factors of Landfill Leachate Treatment with CWAO Method

2013 ◽  
Vol 849 ◽  
pp. 127-131
Author(s):  
Qing Yu Wang ◽  
Wei Li Chen ◽  
Jin Bing Lin
Keyword(s):  
Reaction Time ◽  
Landfill Leachate ◽  
Removal Rate ◽  
Operating Conditions ◽  
Catalytic Wet Air Oxidation ◽  
Air Oxidation ◽  
Wet Air Oxidation ◽  
High Concentration ◽  
Leachate Treatment ◽  
Decolorization Rate

Landfill Leachate is a kind of organic wastewater with high concentration and non-biochemical character, and Catalytic Wet Air Oxidation (CWAO) is suitable for this kind of wastewater treatment. In this study, Landfill leachate was treated with Catalytic Wet Air Oxidation (CWAO) method. The monitoring indicators consist of CODCr, absorbance, pH and chroma. The results show that: CODCr removal rate and decolorization rate of landfill leachate reduce with the reduction of the influent pH, the increment of water concentration and the extension of the reaction time; Under the optimized operating conditions: the influent pH of 8.10, the influent CODCr of 16611 mg/L, the reaction time of 90 min, the CODCr removal rate and decolorization rate of landfill leachate reach 56.8% and 83.7%, respectively. The effluent pH is 8.33 and chroma is 1600 times.

scholarly journals Synthesis of Benzil by Air Oxidation of Benzoin and M(Salen) Catalyst

2019 ◽  
pp. 1-8 ◽  
Author(s):  
Qiuxin Shen ◽  
Liting Xu ◽  
Yiyan Jiang ◽  
Ran Zheng ◽  
Yiping Zhang
Keyword(s):  
Catalytic Activity ◽  
High Performance ◽  
Low Cost ◽  
Catalytic Performance ◽  
Air Oxidation ◽  
Catalyst Recycling ◽  
Reaction Conditions ◽  
Salen Complex ◽  
1H Nuclear Magnetic Resonance ◽  
Optimum Reaction

Bis salicylaldehyde ethylenediamine Schiff base (Salen) and its complexes with three metal ions (Co2+, Ni2+, Zn2+) were prepared, and characterized by infrared spectroscopy(IR). Using air as oxygen source, the optimum reaction conditions for the catalytic oxidation of 0.05 mol benzoin by Co (Salen) were obtained by orthogonal test as follows: base KOH 2 g, catalyst 1.5 g, N, N-dimethylformamide(DMF) as solvent, reaction temperature 40 °C, reaction time 1 h. Under these conditions, the catalytic performances of different metal complexes were investigated. The catalytic activity of Co(Salen) was the best one, the yield of benzil was up to 93.6%, the number of Ni(Salen) and Zn(Salen) was 86.3% and 82.1%, respectively. The reused catalytic performance of M(Salen) complex was also studied. The catalytic activity of Co(Salen), Ni(Salen) and Zn(Salen) was stable after 4 times recycle, the yield of benzil was 71.4%, 63.3% and 57.4%, respectively, and it was easy for catalyst recycling. The oxidation product was certainly benzil with high purity according to the characterization results of melting point(MP), IR, high performance liquid chromatography(HPLC) and 1H nuclear magnetic resonance(1H NMR). Compared with the common synthetic method of benzil, this one has the advantages of friendly environment, low cost and easy operation. It is a simple and green way to synthesize benzoyl efficiently.

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