Effects of physicochemical factors on Cr(VI) removal from leachate by zero-valent iron and α-Fe2O3 nanoparticles

2010 ◽  
Vol 61 (11) ◽  
pp. 2759-2767 ◽  
Author(s):  
T. Y. Liu ◽  
L. Zhao ◽  
X. Tan ◽  
S. J. Liu ◽  
J. J. Li ◽  
...  
Keyword(s):  
Reaction Temperature ◽  
Ph Value ◽  
Removal Rate ◽  
Substantial Reduction ◽  
Chromium Concentration ◽  
Zero Valent Iron ◽  
Fe2o3 Nanoparticles ◽  
Pseudo First Order Reaction ◽  
Physicochemical Factors ◽  
Raw Wastewater

The effects of nanoparticle dosage, initial hexavalent chromium concentration, pH value, reaction temperature, and initial concentration of humic acid (HA) on chromate (CrO42−) removal from landfill leachate by nanoscale zero-valent iron (NZVI) and hematite (α-Fe2O3) nanoparticles were examined in the present investigations. The Cr(VI) removal rate decreased as the initial Cr(VI) concentration and the reaction temperature increased, whereas corresponding removal rate by NZVI was higher than that of α-Fe2O3. The optimum pH for the removal of Cr(VI) by NZVI was found to be 5.0 and more than 99.0% of Cr(VI) was removed within 5 h. However, the removal rate by α-Fe2O3 decreased as pH increased. Presence of HA resulted in substantial reduction in the rate and extent of Cr(VI) removal by NZVI, whereas Cr(VI) removal rate by α-Fe2O3 did not significantly decrease as HA concentration increased from 0.5 g/L to 3.0 g/L. Increasing the dosage of nanoparticles enhanced the rate constant and the removal of Cr(VI) by NZVI and α-Fe2O3 followed pseudo-first-order reaction kinetics. The information should be very useful for the successful application of NZVI and α-Fe2O3 for the treatment of groundwater or raw wastewater.

Removal of U(VI) from Leaching Process Wastewater by Zero-Valent Iron

2014 ◽  
Vol 539 ◽  
pp. 815-818
Author(s):  
Hua Zeng ◽  
Wei Ming Zhang ◽  
Yi Ran Li ◽  
Yuan Yuan Liu
Keyword(s):  
Iron Powder ◽  
Ph Value ◽  
Removal Rate ◽  
Zero Valent Iron ◽  
Removal Mechanism ◽  
Leaching Process ◽  
Process Wastewater ◽  
Better Than

The removing effectiveness of U(VI) in leaching process wastewater by Zero-valent iron (ZVI)(iron powder and waste scrap) has been studied. The effects of the dosage of ZVI, pH, shaking time and temperature on treatment effiency are investigated. The results showed that: ZVI has very good removal effect on U (VI), and when pH value of solution is 6, the dosage of ZVI is 1.5 g, the shaking time is 80 min, the removal rate reached 98.6%.The removing efficiency of iron powder is sightly better than waster scrap.Acorrding to the experiment, the optimum experiment conditions and the influence of these parameters are obtained. The removal mechanism of U(VI) in leaching process wastewater by ZVI is discussed.

Study on Catalytic Wet Oxidation of H-Acid Containing Water over Fe/SiO2 Catalyst

2013 ◽  
Vol 641-642 ◽  
pp. 281-284
Author(s):  
Hong Ya Li ◽  
Bin Xia Zhao ◽  
Wei Li Bai ◽  
Xiao Li Zhang
Keyword(s):  
Hydrogen Peroxide ◽  
Reaction Temperature ◽  
Ph Value ◽  
Removal Rate ◽  
Disulfonic Acid ◽  
Peroxide Oxidation ◽  
Catalytic Wet Oxidation ◽  
Hydrogen Peroxide Oxidation ◽  
Initial Ph ◽  
Catalyst Dosage

This study has investigated the degradation of H-acid (1-amino-8-naphthol-3, 6-disulfonic acid) containing water by catalytic wet hydrogen peroxide oxidation method, in which the catalyst of Fe/SiO2 was prepared by impregnation technology. The effect of catalyst dosage, initial pH value, amount of hydrogen peroxide and reaction temperature on the degradation process have been discussed, and the results indicated that wet hydrogen peroxide oxidation is an effective method for treating the wastewater containing H-acid, under the conditions that: catalyst dosage was 2 g, initial pH value was 7, amount of hydrogen peroxide was 10 mL (0.83 time of theoretical required amount) and reaction temperature was 80 °C, the COD and color removal rate can reach 87.3% and 96.5%, respectively.

scholarly journals Characterization and Dimethyl Phthalate Flocculation Performance of the Cationic Polyacrylamide Flocculant P(AM-DMDAAC) Produced by Microwave-Assisted Synthesis

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 624 ◽  
Author(s):  
Peng Zhang ◽  
Dong Qin Zhao
Keyword(s):  
Reaction Temperature ◽  
Sodium Benzoate ◽  
Ph Value ◽  
Removal Rate ◽  
Ammonium Persulfate ◽  
Microwave Assisted Synthesis ◽  
Dimethyl Phthalate ◽  
Synthesis Conditions ◽  
Good Solubility ◽  
Optimum Synthesis

A composite flocculant P(AM–DMDAAC) was synthesized by the copolymerization of acrylamide (AM) and dimethyl diallyl ammonium chloride (DMDAAC). By using microwave (MV) assistance with ammonium persulfate as initiator, the synthesis had a short reaction time and yielded a product with good solubility. Fourier-transform infrared spectroscopy, scanning electron microscopy, and differential thermal analysis–thermogravimetric analysis were employed to determine the structure and morphology of P(AM–DMDAAC). The parameters affecting the intrinsic viscosity of P(AM–DMDAAC), such as MV time, mass ratio of DMDAAC to AM, bath time, reaction temperature, pH value, and the dosages of ammonium persulfate initiator, EDTA, sodium benzoate, and urea were examined. Results showed that the optimum synthesis conditions were MV time of 1.5 min, m(DMDAAC):m(AM) of 4:16, 0.5 wt‰ initiator, 0.4 wt‰ EDTA, 0.3 wt‰ sodium benzoate, 2 wt‰ urea, 4 h bath time, reaction temperature of 40 °C, and pH of 2. The optimal dimethyl phthalate (DMP) removal rate can reach 96.9% by using P(AM–DMDAAC), and the P(AM–DMDAAC) had better flocculation than PAM, PAC, and PFS.

Advanced Treatment of Biochemical Treated Coking Wastewater by Ozonation Process

2013 ◽  
Vol 726-731 ◽  
pp. 2515-2520 ◽  
Author(s):  
De Min Yang ◽  
Jian Mei Yuan
Keyword(s):  
Reaction Time ◽  
Reaction Temperature ◽  
Ozone Concentration ◽  
Ph Value ◽  
Removal Rate ◽  
Color Removal ◽  
Advanced Treatment ◽  
Coking Wastewater ◽  
Initial Ph ◽  
Ozonation Process

Advanced treatment of biochemical treated coking wastewater was studied experimentally with ozonation process. The effects of initial pH value, ozone concentration, reaction temperature, and reaction time on the COD and color removal rate were investigated. The results showed that ozonation was an effective method for advanced treatment of biochemical treated coking wastewater. The increasing of initial pH value, ozone concentration, reaction temperature, and reaction time has enhanced the removal rate of COD and color. Meanwhile, the results also revealed that the maximal COD and color removal rate of 69.65% and 92.27% could be reached under the optimal conditions of the initial pH value is 10.5, ozone concentration is 150 mg/L, reaction temperature is 298 K, and reaction time is 30 min.

Study on Adsorption of Chromium in Wastewater by Diatomite

2014 ◽  
Vol 1004-1005 ◽  
pp. 983-989
Author(s):  
Kai Yong Zhang ◽  
Ling Huang
Keyword(s):  
Theoretical Basis ◽  
Adsorption Mechanism ◽  
Ph Value ◽  
Removal Rate ◽  
Physical Adsorption ◽  
Chromium Concentration ◽  
Adsorption Ability ◽  
Adsorption Time ◽  
Adsorption Removal ◽  
The Cost

Adsorption ability of chromium in wastewater by purified diatomite as the adsorbent material was studied. The influence of the diatomite dosage, adsorption time, chromium concentration, pH value and reaction temperature to chromium removal rate was got. The results show that under the condition of the diatomite dosage of 9.0g, adsorption time of 90 min, chromium concentration in wastewater of 5mg/L, wastewater pH of 6, and temperature of 30°C, diatomite adsorption removal rate to hexavalent chromium can reach 91.6%. The main adsorption mechanism is the combination of physical adsorption and chemical adsorption, and the latter is dominant. The cost of diatomite as adsorbent is low, and a good removal rate of chromium can be reached, which provides a solid theoretical basis for the removal of chromium in wastewater.

Treatment of wastewater from oil manufacturing plant by yeasts

1996 ◽  
Vol 34 (11) ◽  
pp. 51-58 ◽  
Author(s):  
K. Chigusa ◽  
T. Hasegawa ◽  
N. Yamamoto ◽  
Y. Watanabe
Keyword(s):  
Pilot Plant ◽  
Removal Rate ◽  
Oil Removal ◽  
Oxidation Activity ◽  
Single Strain ◽  
Manufacturing Plants ◽  
Yeast Strains ◽  
Hexane Extracts ◽  
One Year ◽  
Raw Wastewater

Nine strains of yeasts capable of decomposing oil were isolated in order to directly treat wastewater from oil manufacturing plants with no pretreatment. The oil decomposing ability of these yeast strains was evaluated in terms of lipase activity and β-oxidation activity. Since the mixture of the isolated yeasts was superior to any single strain in the oil removal rate, a pilot plant utilizing the mixed strains was operated at the soybean oil factory. Following a one year pilot plant operation, it was found that 10,000 mgℓ−1 of hexane extracts in the raw wastewater could be reduced by yeast treatment to a concentration of about 100 mgℓ−1. This concentration was further treated by the activated sludge process to 2 mgℓ−1. The dominant yeasts in the pilot plant were found to form mycelial or pseudomycelial pellets and have low fermenting ability.

scholarly journals Lignocellulose@ Activated Clay Nanocomposite with Hierarchical Nanostructure Enhancing the Removal of Aqueous Zn(II)

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1710 ◽  
Author(s):  
Xiaotao Zhang ◽  
Yinan Hao ◽  
Zhangjing Chen ◽  
Yuhong An ◽  
Wanqi Zhang ◽  
...  
Keyword(s):  
Ph Value ◽  
Removal Rate ◽  
Weight Ratio ◽  
Order Kinetic ◽  
Adsorption Parameters ◽  
Hierarchical Nanostructure ◽  
Desorption Temperature ◽  
Desorption Time ◽  
Adsorption Temperature ◽  
Hcl Concentration

A lignocellulose@ activated clay (Ln@AC) nanocomposite with a hierarchical nanostructure was successfully synthesized by the chemical intercalation reaction and applied in the removal of Zn(II) from an aqueous solution. Ln@AC was characterized by N2 adsorption/desorption isotherms and X-Ray Diffraction (XRD), scanning Electron Microscope (SEM), transmission Electron Microscopy (TEM) and Fourier Transform Infrared Spectroscopy (FTIR) analysis, and the results indicate that an intercalated–exfoliated hierarchical nanostructure was formed. The effects of different adsorption parameters on the Zn(II) removal rate (weight ratio of Ln to AC, Ln@AC dosage, initial Zn(II) concentration, pH value, adsorption temperature, and time) were investigated in detail. The equilibrium adsorption capacity reached 315.9 mg/g under optimal conditions (i.e., the weight ratio of Ln to AC of 3:1, Ln@AC dosage of 1 g/L, initial Zn(II) concentration of 600 mg/L, pH value of 6.8, adsorption temperature of 65 °C, and adsorption time of 50 min). The adsorption process was described by the pseudo-second-order kinetic model, Langmuir isotherm model, and the Elovich model. Moreover, Zn(II) could be easily eluted by HCl, and the effects of HCl concentration, desorption temperature, and ultrasonic desorption time on desorbed amount were tested. Desorption studies revealed that with an HCl concentration of 0.25 mol/L, desorption temperature of 70 °C, and ultrasonic desorption time of 20 min, the maximum desorption capacity and efficiency were achieved at 202.5 mg/g and 64.10%, respectively. Regeneration experimental results indicated that the Ln@AC exhibited a certain recyclable regeneration performance. Due to such outstanding features, the novel Ln@AC nanocomposite proved to have great adsorption potential for Zn(II) removal from wastewater, and exhibited an extremely significant amount of adsorbed Zn(II) when compared to conventional adsorbents.

Study on Treatment of Chromium(VI) Wastewater by Cuprous Oxide

2015 ◽  
Vol 713-715 ◽  
pp. 2909-2912
Author(s):  
Bin Zhao ◽  
Li Ke Zou ◽  
Guo Yong Li
Keyword(s):  
Photocatalytic Activity ◽  
Reaction Temperature ◽  
Cuprous Oxide ◽  
Oxide Catalyst ◽  
Removal Rate ◽  
Optimal Conditions ◽  
Chromium Vi

Cuprous oxide catalyst was prepared and applied as photocatalist to treat chromium (VI) in wastewater, and the photocatalytic activity of the cuprous oxide was studied. The optimal conditions for the treatment was as follows: the pH of wastewater was 3, the amount of catalysts was 0.3 g/L, the reaction temperature was 60°C. Under the optimal conditions, the removal rate of chromium (IV) in wastewater reached 50% in the presence of cuprous oxide catalyst.

scholarly journals Numerical Simulation of Decontamination of Airborne Fission Products during In-Vessel Release Phase by Containment Spray

2018 ◽  
Vol 2018 ◽  
pp. 1-19
Author(s):  
Khurram Mehboob
Keyword(s):  
Droplet Size ◽  
Failure Time ◽  
Ph Value ◽  
Removal Rate ◽  
Droplet Diameter ◽  
Fission Products ◽  
Product Release ◽  
Spray System ◽  
Spray Solution ◽  
Proposed Model

The containment spray system (CSS) has a significant role in limiting the risk of radioactive exposure to the environment. In this work, the optimal droplet size and pH value of spray water to prevent the fission product release have been evaluated to improve the performance of the spray system during in-vessel release phase. A semikinetic model has been developed and implemented in MATLAB. The sensitivity and removal rate of airborne isotopes with the spray system have been simulated versus the spray activation and failure time, droplet size, and pH value. The alkaline (Na2S2O3) spray solution and spray water with pH 9.5 have similar scrubbing properties for iodine. However, the removal rate from the CSS has been found to be an approximately inverse square of droplet diameter (1/d2) for Na2S2O3 and higher pH of spray water. The numerical results showed that 450 μm–850 μm droplet with 9.5 pH and higher or the alkaline (Na2S2O3) solution with 0.2 m3/s–0.35 m3/s flow rate is optimal for effective scrubbing of in-containment fission products. The proposed model has been validated with TOSQAN experimental data.

Influence Factors of Denitration Study on Catalyst Mn-Ce/TiO2

2013 ◽  
Vol 634-638 ◽  
pp. 526-530
Author(s):  
Chun Xiang Geng ◽  
Qian Qian Chai ◽  
Wei Yao ◽  
Chen Long Wang
Keyword(s):  
Reaction Temperature ◽  
Catalytic Reduction ◽  
Removal Rate ◽  
Load Capacity ◽  
Fixed Bed ◽  
Influence Factors ◽  
Space Velocity ◽  
Molar Ratio ◽  
Impregnation Method ◽  
Ammonia Gas

Selective Catalytic Reduction (SCR) processes have been one of the most widely used denitration methods at present and the property of low tempreture catalyst becomes a hot research. The Mn-Ce/TiO2 catalyst was prepared by incipient impregnation method. The influence of load capacity, reaction temperature, O2 content, etc. on denitration were studied by a fixed bed catalyst reactor with ammonia gas. Results showed that catalyst with load capacity 18% performed high NO removal rate of 90% at conditions of reaction temperature 160°C, low space velocity, NH3/NO molar ratio 1: 1, O2 concentration 6%.

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