Pretreatment of arsenic-bearing gold ore with microwave-assisted alkaline leaching

2016 ◽  
Vol 5 (3) ◽  
Author(s):  
Hongzhou Ma ◽  
Chao Yan ◽  
Yaoning Wang
Keyword(s):  
Reaction Time ◽  
Sodium Hydroxide ◽  
Influencing Factors ◽  
Microwave Power ◽  
Removal Rate ◽  
Sulfur Removal ◽  
Air Oxidation ◽  
Sodium Hydroxide Concentration ◽  
Gold Ore ◽  
Removal Of Arsenic

AbstractIn this paper, the removal of arsenic from arsenic-bearing gold ore through air oxidation and sodium hydroxide leaching with microwave irradiation was studied. Firstly, single-factor experiments were carried out. The results indicated that the removal rate of arsenic was influenced by the sodium hydroxide concentration, ratio of liquid to solid, microwave power, and reaction time. Then, orthogonal experiments were done to determine the main influencing factors. The results obtained from the experiments of orthogonal arrays showed that reaction time and microwave power were the important influencing factors, and the optimum conditions of sodium hydroxide concentration, reaction time, microwave power, and ratio of liquid to solid were 18 wt.%, 60 min, 700 W, and 5, respectively. Under the optimal conditions, the removal of arsenic could reach approximately 81.46 wt.% and, at the same conditions, the sulfur removal rate was about 55.56 wt.%. The results of X-ray diffraction analysis revealed that AsS and FeAsS were decomposed during the leaching process, while FeS

scholarly journals Central Composite Design and Desirability of RSM for Optimization of Biodiesel Production from Mixture of Animal Waste Fat Oil and used Cooking Oil

2020 ◽  
Vol 9 (4) ◽  
pp. 1565-1571
Keyword(s):  
Reaction Time ◽  
Sodium Hydroxide ◽  
Maximum Yield ◽  
Animal Waste ◽  
Sodium Hydroxide Concentration ◽  
Used Cooking Oil ◽  
Input Parameters ◽  
Desirability Approach ◽  
Central Composite ◽  
Waste Fat

In this work, central composite design(CCD) and desirability approach of Response surface methodology (RSM) has been used for optimization of biodiesel yield produced from mixture of animal waste fat oil and used cooking oil (AWO) in the ratio of 1:1through alkaline transesterification process. In this work, methanol quantity, reaction time and sodium hydroxide concentration are selected as input parameters and yield selected as response. The combined effect of methanol quantity, reaction time and sodium hydroxide concentration were investigated and optimized by using RSM. The second order model is generated to predict yield as a function of methanol quantity, reaction time and sodium hydroxide concentration. A statistical model predicted the maximum yield of 96.9779% at 35ml methanol quantity (% v/v of oil), 75 min. reaction time and 0.6g (% wt./v of oil) of sodium hydroxide. Experimentally, the maximum yield of 97% was obtained at the above optimized input parameters. The variation of 0.02% was observed between experimental and predicted values. In this work, an attempt has also made to use desirability approach of RSM to optimize the input parameters to predict maximum yield. Desirability approach predicts maximum yield (97.075%) at CH3OH (35.832% vol. /vol. of oil), NaOH (0.604 % wt./vol. of oil) and reaction time (79.054min.) was found for the AWO.

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.

A Combined Electrocoagulation-Electrooxidation Treatment on CTMP Wastewater

2011 ◽  
Vol 233-235 ◽  
pp. 619-622 ◽  
Author(s):  
Zhi Jun Hu ◽  
You Ming Li
Keyword(s):  
Reaction Time ◽  
Sodium Chloride ◽  
Influencing Factors ◽  
Removal Rate ◽  
Color Removal ◽  
Current Intensity ◽  
Optimum Conditions ◽  
Charged Species ◽  
Synergistic Combination

A synergistic combination of electrocoagulation and electrooxidation was introduced for the treatment of CTMP wastewater in which most of the colloids and charged species had been removed by electrocoagulatio, then small organics could be mineralized by electrooxidation effectively.The mainly influencing factors for electrocoagulation such as electrolyte, sodium chloride dosage, voltage intensity, current intensity and reaction time were assessed. The optimum conditions were obtained, and the results showed that sodium chloride dosage of 1g/L, voltage intensity of 7.5V, current intensity of 0.6A, 60 min reaction time, its color removal rate was above 90% and CODCr removal rate was about 40%. After electrocoagulation the electrooxidation could further reduce CODCr above 80%.

scholarly journals Optimization of Deep Oxidative Desulfurization Process Using Ionic Liquid and Potassium Monopersulfate

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Yinke Zhang ◽  
Hang Xu ◽  
Mengfan Jia ◽  
Zhuang Liu ◽  
Deqiang Qu
Keyword(s):  
Response Surface Methodology ◽  
Ionic Liquid ◽  
Ionic Liquids ◽  
Reaction Time ◽  
Removal Rate ◽  
Sulfur Removal ◽  
Oxidative Desulfurization ◽  
Optimal Conditions ◽  
Experimental Conditions ◽  
Desulfurization Process

Response surface methodology (RSM) was selected to optimize a desulfurization process with metal based ionic liquids ([Bmim]Cl/CoCl2) and potassium monopersulfate (PMS) together to remove benzothiophene (BT) from octane (simulating oil). The four experimental conditions of PMS dosage, [Bmim]Cl/CoCl2 dosage, temperature, and reaction time were investigated. The results showed that the quadratic relationship was built up between BT removal and four experimental variables with 0.9898 fitting coefficient. The optimal conditions were 1.6 g (20 wt%) PMS solution, 3.2 g [Bmim]Cl/CoCl2, 46°C, and 23 min, which were obtained based on RSM and experimental results. Under the optimal condition, predicted sulfur removal rate and experimental sulfur removal rate were 96.7% and 95.4%, respectively. The sequence of four experimental conditions on desulfurization followed the order temperature > time > [Bmim]Cl/CoCl2 dosage > PMS solution dosage.

Study on the Chemical Modification Process of Jute Fiber

TAPPI Journal ◽  
2010 ◽  
Vol 9 (2) ◽  
pp. 23-29 ◽  
Author(s):  
Wei-ming Wang ◽  
Zai-sheng Cai ◽  
Jian-yong Yu
Keyword(s):  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Treatment Time ◽  
Jute Fiber ◽  
Process Conditions ◽  
Silicate Concentration ◽  
Sodium Hydroxide Concentration ◽  
Liquor Ratio ◽  
Degumming Process ◽  
Selection Of

Degumming of pre-chlorite treated jute fiber was studied in this paper. The effects of sodium hydroxide concentration, treatment time, temperature, sodium silicate concentration, fiber-to-liquor ratio, penetrating agent TF-107B concentration, and degumming agent TF-125A concentration were the process conditions examined. With respect to gum decomposition, fineness and mechanical properties, sodium hydroxide concentration, sodium silicate concentration, and treatment time were found to be the most important parameters. An orthogonal L9(34) experiment designed to optimize the conditions for degumming resulted in the selection of the following procedure: sodium hydroxide of 12g/L, sodium silicate of 3g/L, TF-107B of 2g/L, TF-125A of 2g/L, treatment time of 105 min, temperature of 100°C and fiber to liquor ratio of 1:20. The effect of the above degumming process on the removal of impurities was also examined and the results showed that degumming was an effective method for removing impurities, especially hemicellulose.

Catalytic wet air oxidation of dyeing and printing wastewater

1997 ◽  
Vol 35 (4) ◽  
pp. 311-319 ◽  
Author(s):  
L. Lei ◽  
X. Hu ◽  
H. P. Chu ◽  
G. Chen ◽  
P. L. Yue
Keyword(s):  
High Pressure ◽  
Reaction Time ◽  
Textile Industry ◽  
Porous Alumina ◽  
Supported Catalyst ◽  
Metal Salts ◽  
Treated Wastewater ◽  
Catalytic Wet Air Oxidation ◽  
Air Oxidation ◽  
Wet Air Oxidation

The treatment of dyeing and printing wastewater from the textile industry by oxidation was studied. The reaction was carried out in a two-litre high pressure reactor. In order to promote the oxidation of organic pollutants present in the wastewater, experiments were conducted using various catalysts including metal salts, metal oxides, and porous alumina supported metals. All catalysts tested were able to enhance the conversion of organic compounds in wastewater, shorten the reaction time, and lower the reaction temperature. The alumina supported catalyst has an advantage over other catalysts in that it can be easily separated from the treated wastewater by filtration and recycled. The conditions in preparing the catalyst supported by porous alumina were experimentally optimised.

scholarly journals Preparation and Characterization of High-Efficiency Magnetic Heavy Metal Capture Flocculants

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1732
Author(s):  
Yuanyuan Yu ◽  
Yongjun Sun ◽  
Jun Zhou ◽  
Aowen Chen ◽  
Kinjal J. Shah
Keyword(s):  
Heavy Metal ◽  
Reaction Time ◽  
High Efficiency ◽  
Removal Rate ◽  
Low Cost ◽  
Monomer Concentration ◽  
Synthesis Process ◽  
Response Surface Optimization ◽  
Metal Capture ◽  
Total Monomer Concentration

In this study, a high-efficiency magnetic heavy metal flocculant MF@AA was prepared based on carboxymethyl chitosan and magnetic Fe3O4. It was characterized by SEM, FTIR, XPS, XRD and VSM, and the Cu(II) removal rate was used as the evaluation basis for the preparation process. The effects of AMPS content, total monomer concentration, photoinitiator concentration and reaction time on the performance of MF@AA flocculation to remove Cu(II) were studied. The characterization results show that MF@AA has been successfully prepared and exhibits good magnetic induction characteristics. The synthesis results show that under the conditions of 10% AMPS content, 35% total monomer concentration, 0.04% photoinitiator concentration, and 1.5 h reaction time, the best yield of MF@AA is 77.69%. The best removal rate is 87.65%. In addition, the response surface optimization of the synthesis process of MF@AA was performed. The optimal synthesis ratio was finally determined as iron content 6.5%, CMFS: 29.5%, AM: 53.9%, AMPS: 10.1%. High-efficiency magnetic heavy metal flocculant MF@AA shows excellent flocculation performance in removing Cu(II). This research provides guidance and ideas for the development of efficient and low-cost flocculation technology to remove Cu(II) in wastewater.

Study on Pretreatment of Dye Wastewater by Fenton Oxidation Process

2012 ◽  
Vol 627 ◽  
pp. 378-381
Author(s):  
Bi Rong Wang
Keyword(s):  
Reaction Time ◽  
Oxidation Process ◽  
Removal Rate ◽  
Fenton Oxidation ◽  
Dye Wastewater ◽  
Dyeing Wastewater ◽  
Reaction Conditions ◽  
Fenton Oxidation Process

Fenton pretreatment has been used for treating dye wastewater. The effects of the dos of H2O2 and FeSO4, reaction time and pH on the removal COD were investigated. It was found that, when the reaction conditions are as follows: COD 2850 mg/L dyeing wastewater, the dosage of H2O2 is 140mmol/L, FeSO4 17.02 mmol/L, pH 7.6, and reaction time 1.0 h, the CODcr of dye wastewater removal rate of up to 70%. Fenton pretreatment process of dye wastewater has a broad prospect.

Lab Scale Study on Synergistic Disinfection of WWTPS Secondary Effluent by Ultrasonic and Ozone

2012 ◽  
Vol 433-440 ◽  
pp. 4751-4756 ◽  
Author(s):  
Hao Wu ◽  
Zi Fu Li ◽  
Xin Jin ◽  
Xin Zhao ◽  
Fu Rong Deng
Keyword(s):  
Reaction Time ◽  
Removal Rate ◽  
Research Direction ◽  
Synergistic Action ◽  
Color Removal ◽  
Secondary Effluent ◽  
Disinfection Methods ◽  
Number Of Microorganisms ◽  
New Research ◽  
Ozone Disinfection

Secondary effluent from WWTPS still contains a large number of microorganisms, therefore, disinfection is essential. There are many disadvantages in using traditional disinfection methods, so the combination of disinfection techniques is a new research direction. Ozone combined with ultrasound is one of them. In this experiment, the inactivation of the total coli forms, color removal and UV254 removal of secondary effluent by a combination of ultrasonic (frequency20 kHz; power100W) and ozone disinfection was investigated. The results show that the effect of the synergistic action of 30s US and ozone disinfection is superior to the effect of individual ozone disinfection. After 15min synergistic disinfection, the total coli forms inactivation rate is up to 99.9%, simultaneously color removal rate to 80% and UV254 removal rate to 52%. Compared with individual ozone disinfection, reaction time was reduced by 5 min.

Arsenic Removal from Wastewater Using Adsorptive Mediums

2011 ◽  
Vol 189-193 ◽  
pp. 404-409
Author(s):  
Fu Quan Peng ◽  
Zhen Cheng Xu ◽  
Jian Hong Huang ◽  
Qing Wei Guo ◽  
Feng Nie
Keyword(s):  
Arsenic Removal ◽  
Removal Rate ◽  
National Standards ◽  
Ferrous Oxide ◽  
Anion Resin ◽  
Quartz Sands ◽  
Long Time ◽  
Removal Of Arsenic ◽  
Adsorptive Properties

Different adsorptive mediums and adsorbents’ compounds were chosen to remove arsenic from Yangzonghai Lake wastewater. Results showed that Ca(OH)2, attapulgite, bentonite, LDHs these adsorptive mediums had adsorptive capacities of less than 2.5 mg/g of As removal and it took long time for sediment before monitoring; adsorbents compounds’ results showed Fe2O3 and quartz sands had best removal rate and quartz sands had little removal of arsenic. Both strong anion resin and hydrated ferrous oxide-loaded on polystyrene diethanolamine resin(designated as PDR-HFO) can decrease As concentration to less than 0.01 mg/L reaching national standards for arsenic; anions such as SO42- can not be removed when strong anion resin was regenerated causing its loss of exchange ions; PDR-HFO exhibited excellent adsorptive properties and recyclability.

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