scholarly journals Pretreatment of evaporated condensate generated during metal cutting process by Fe-C micro-electrolysis

2018 ◽  
Vol 79 (3) ◽  
pp. 580-588 ◽  
Author(s):  
Weiteng Lin ◽  
Ji Li ◽  
Xiaolei Zhang ◽  
Wenyi Dong
Keyword(s):  
Reaction Time ◽  
Organic Contaminants ◽  
Metal Cutting ◽  
Degradation Mechanism ◽  
Oxygen Demand ◽  
Cutting Process ◽  
Gas Chromatography Mass Spectrometry ◽  
Contaminant Removal ◽  
Liquid Ratio ◽  
Solid Liquid

Abstract Fe-C micro-electrolysis was employed to the pretreatment of evaporated condensate generated during metal cutting process. The effect of the reaction conditions on the contaminant removal and degradation mechanism were studied. Through single-factor experiments, the effects of solid–liquid ratio, gas–liquid ratio and reaction time on the treatment of wastewater were preliminarily determined. The optimal reaction condition obtained was: 500 g/L solid–liquid ratio, 30:1 gas–liquid ratio with 4 h reaction time. Under the optimal condition, the chemical oxygen demand (COD) removal efficiency of micro-electrolysis could reach around 25%, and the biodegradability of wastewater increased from 0.12 to 0.32. According to the analysis results of gas chromatography-mass spectrometry (GC-MS) qualitative analysis, it was observed that the most organic contaminants in the influent were degraded or converted into simple structures under Fe-C micro-electrolysis, indicates that Fe-C micro-electrolysis pretreatment could improve the biodegradability of the evaporated condensate generated during metal cutting process and achieve certain degree removal of COD.

scholarly journals Modeling and optimizing electro-persulfate processes using Fe and Al electrodes for paper industry wastewater treatment

2020 ◽  
Vol 81 (2) ◽  
pp. 345-357 ◽  
Author(s):  
Gamze Varank ◽  
Senem Yazici Guvenc ◽  
Ahmet Demir ◽  
Nihal Kavan ◽  
Nurten Donmez ◽  
...  
Keyword(s):  
Reaction Time ◽  
Design Method ◽  
Paper Industry ◽  
Oxygen Demand ◽  
Correlation Coefficients ◽  
Cod Removal ◽  
Contaminant Removal ◽  
Optimization Of Process Parameters ◽  
Appropriate Treatment ◽  
Central Composite

Abstract In this study, the treatment of paper industry wastewaters by the electrocoagulation (EC) process with a strong oxidant, persulfate addition, was investigated. Persulfate was activated by dissolution of Fe and Al from electrodes during the process. Central composite design method, being one of the response surface methods, was applied for the optimization of process parameters and the development of a mathematical model for chemical oxygen demand (COD) removal from paper industry wastewaters. The effects of S2O8−2/COD ratio, current, pH, and reaction time, being the variables of process, were assessed on the efficiency of contaminant removal. For COD removal in EC processes in which Fe and Al electrodes were used, the model's correlation coefficients (R2) were determined as 90.14% and 87.46%, respectively. As the result of experimental study actualized under optimum conditions determined by the model in order to obtain maximum contaminant removal, COD removal efficiencies were determined as 63.5% and 72.8% respectively for the Fe electrode (S2O8−2/COD ratio: 1.25, current: 4.14 A, pH: 6, and reaction time: 5 minutes), and the Al electrode (S2O8−2/COD ratio: 0.5, current: 4.25 A, pH: 7.25, and reaction time: 25 minutes). Electro-activated persulfate process is an appropriate treatment alternative for COD removal from paper industry wastewaters.

Study on the Separation of Waste Polyester-Cotton Fiber with Dilute Acid

2011 ◽  
Vol 295-297 ◽  
pp. 2088-2091
Author(s):  
Wei Kong ◽  
Yong Ling Yu ◽  
Li Hua Lv
Keyword(s):  
Reaction Time ◽  
Reaction Temperature ◽  
Cotton Fiber ◽  
Mass Fraction ◽  
Orthogonal Experiment ◽  
Cotton Fibers ◽  
Dilute Acid ◽  
Liquid Ratio ◽  
Priority Order ◽  
Solid Liquid

Process of the separation of waste polyester-cotton fiber with dilute hydrochloric acid was studied. Acid mass fraction, reaction time, reaction temperature and solid-liquid ratio were studied on the effect of separation with the method of Orthogonal experiment. The results showed that the priority order of the factors was reaction time > acid mass fraction > reaction temperature > solid-liquid ratio. The optimal conditions through serious research on such factors were: acid mass fraction 10%, solid-liquid ratio 4g/100ml, reaction temperature 95°Cand reaction time 90 minutes. Through the microscope, polyester and cotton fibers were separated completely in which polyester into fibrous and cotton fibers were hydrolyzed into tiny powder.

Optimization of Nickel Chemical Extraction from Hazardous Residue

2016 ◽  
Vol 14 (1) ◽  
pp. 175-183 ◽  
Author(s):  
Mahdi Gharabaghi ◽  
Amirreza Azadmehr
Keyword(s):  
Reaction Time ◽  
Acid Concentration ◽  
Acid Leaching ◽  
Quadratic Model ◽  
Chemical Extraction ◽  
Liquid Ratio ◽  
Nickel Extraction ◽  
Process Factors ◽  
Solid Liquid ◽  
Significant Factors

AbstractStatistical design of experiments was used for design and analysis of nickel extraction from hazardous waste. Sulphuric acid leaching of zinc plant residue has been performed for monitoring and evaluating the effects of process factors on the nickel leaching yield. Factorial design was planned first in order to study the effect of six process factors and screen main variables. These factors were reaction time, acid concentration, solid-liquid ratio % (w/v), particle size, stirring speed and reaction temperature. The main factors and their interaction were studied by analysis of variance (ANOVA), and the results showed that the reaction time, acid concentration and solid-liquid ratio were the most significant factors. In the second set of experiments, response surface methodology (RSM) was used for modelling and optimisation of significant factors. Quadratic model was derived for the prediction of nickel extraction. The optimum values for maximum nickel was identified to be a leaching time of 30 min, acid concentration 10% (V/V) and solid liquid ratio of 10%. Using these optimum conditions, more than 94% nickel was extracted. In addition the results of model equation showed a good agreement with the experimental data.

Auto-Catalytic Ethanol Pulping of Corncob Acid Hydrolyzed Residua

2012 ◽  
Vol 560-561 ◽  
pp. 428-433
Author(s):  
Jie Li ◽  
Lian Xiong ◽  
Hai Rong Zhang ◽  
Fei Ding ◽  
Xin De Chen
Keyword(s):  
Reaction Time ◽  
Ethanol Concentration ◽  
Liquid Ratio ◽  
Solid Liquid ◽  
Electronic Microscope

The effects of ethanol concentration, reaction time, solid-liquid ratio and temperature on auto-catalytic ethanol pulping reaction of corncob acid hydrolyzed residua were investigated. The relationships of those four factors and pulping selectivity(Y/K ratio) were also discussed. The optimal pulping conditions were determined, which were ethanol concentration 55%, reaction time 2.0h, solid-liquid ratio 1:10, temperature 175°C. The temperature has the most influential effect. Structures of corncob acid hydrolyzed residua and dry pulp were observed by electronic microscope. The process of pulping reaction and the delignification were also verified.

Degradation mechanism of Methyl Orange by electrochemical process on RuOx–PdO/Ti electrode

2011 ◽  
Vol 63 (7) ◽  
pp. 1539-1545 ◽  
Author(s):  
Lin Du ◽  
Jin Wu ◽  
Song Qin ◽  
Changwei Hu
Keyword(s):  
Methyl Orange ◽  
Degradation Mechanism ◽  
Reaction System ◽  
Oxygen Demand ◽  
Electrochemical Process ◽  
Gas Chromatography Mass Spectrometry ◽  
Low Molecular Weight ◽  
Electrochemical Degradation ◽  
Derivatives Of ◽  
Present Reaction System

The electrochemical degradation of Methyl Orange in 0.1 M NaCl solution over RuOx–PdO/Ti anode was investigated. Chemical oxygen demand (COD), ion chromatography (IC), Fourier Transform Infrared Spectroscopy (FTIR) and Gas chromatography-mass spectrometry (GC-MS) were employed to detect the intermediates formed during the electrochemical degradation. In the present reaction system, Methyl Orange could be effectively degraded. After 1 h treatment, the discoloration could reach 97.9% with COD removal of 57.6%. The results indicated that in the presence of chloride, the electrolysis was able to oxidise the dye with partial mineralisation of carbon, nitrogen and sulfur into CO2, NO3− and SO42−, respectively. After 8 h electrolysis, 62% of sulfur contained in Methyl Orange was transformed to SO42−, and 17.6% of nitrogen changed to NO3−. The intermediates during electroprocess were detected to be low molecular weight compounds, chlorinated compounds, derivatives of benzene and long chain alkanes. Based on these data, a possible degradation mechanism of Methyl Orange was proposed.

The Preparation of Micro-Molecular Dextran in Sub-Critical Water/CO2

2013 ◽  
Vol 712-715 ◽  
pp. 502-505
Author(s):  
Shu Qiong Liao ◽  
Xiao Yu Peng ◽  
Xue Wang Zhang ◽  
Ke Lin Huang ◽  
Ben Wang ◽  
...  
Keyword(s):  
Reaction Time ◽  
Reaction Temperature ◽  
Temperature Reaction ◽  
Liquid Ratio ◽  
Reaction Conditions ◽  
Reaction Pressure ◽  
Optimum Reaction ◽  
Ft Ir ◽  
Solid Liquid ◽  
Hydrolysis Of

Micro-molecular dextran was prepared in sub-critical water/CO2 by hydrolysis of dextran20. The obtained products were mainly characterized by FT-IR and GPC. Furthermore, the reaction temperature, reaction time, reaction pressure, solid-liquid radio and stirring speed were systematically investigated during the work. The optimum reaction conditions are as follows: the reaction temperature was 160°C; the reaction time was 60 min; the reaction pressure was 2.5MPa; the solid-liquid ratio was 0.6 and the stirring speed was 300r/min.

Effect of Hydrothermal Conditions on the Cation Exchange Capacity of MSWI Fly Ash

2006 ◽  
Vol 510-511 ◽  
pp. 110-113
Author(s):  
Young Sook Shim ◽  
Woo Keun Lee
Keyword(s):  
Fly Ash ◽  
Reaction Time ◽  
Cation Exchange ◽  
Reaction Temperature ◽  
Cation Exchange Capacity ◽  
Exchange Capacity ◽  
Waste Incinerator ◽  
Liquid Ratio ◽  
Hydrothermal Conditions ◽  
Solid Liquid

In this study, we studied to find the most suitable condition for the preparation of adsorbent by hydrothermal treatment of fly ash from the municipal solid waste incinerator (MSWI). There are many variables that affect the adsorptive characteristics in our study. With the variation of which discussed the effect such as the concentration of NaOH, reaction temperature, reaction time, solid/liquid ratio, and so on. The phase of adsorbent, its morphology and cation exchange capacity (CEC) were analyzed to evaluate their effects. The phase of adsorbent after treatment was identified by X-ray diffraction (XRD), the morphology was examined by scanning electron microscopy (SEM), and the CEC was analyzed by the ammonium acetate method. The maximum CEC value was obtained under the condition of 3N NaOH, 100°C of reaction temperature, 12 hr of reaction time, and 1:10 of solid/liquid ratio. The CEC was 68 meq/100g in this condition, which was 8 times the amount of raw fly ash.

scholarly journals Research on treatment and mechanism of salicylhydroxamic acid flotation wastewater by O3-BAF process

2020 ◽  
Vol 82 (5) ◽  
pp. 861-876
Author(s):  
Liping Zhang ◽  
Shengnian Wu ◽  
Jun Xiang ◽  
Xiaofei Jiao ◽  
Jing Wang
Keyword(s):  
Reaction Time ◽  
Ph Value ◽  
Degradation Mechanism ◽  
Oxygen Demand ◽  
Organic Load ◽  
Combined Process ◽  
Salicylhydroxamic Acid ◽  
Removal Ratio ◽  
Optimal Experiment ◽  
Water Ratio

Abstract Salicylhydroxamic acid is an effective and selective collector for tungsten and molybdenum ores. However, the salicylhydroxamic acid flotation wastewater discharge may cause damage to the water environment for the residual processing reagents with poor biodegradability. Combined O3 and biological aerated filter (BAF) has a well-known potential for removing refractory or toxic organic pollutants. Combined process of O3 and BAF (O3-BAF) was applied to treat the simulated wastewater from W-Mo mineral processing in this study. Compared single ozonation to O3-BAF, various influencing factors were discussed like O3 dosage, reaction time, initial pH value, gas–water ratio and organic loading. Meanwhile, degradation mechanism of salicylhydroxamic acid was reduced. Under the optimal experiment conditions as pH value 8, O3 dosage 1.3 mg·L−1, reaction time 15 min, the five-day biochemical oxygen demand (BOD5)/chemical oxygen demand of potassium dichromate (CODCr) value increased to from 0.19 to 0.35. The effluent was pumped to the following BAF process, when the optimal experiment conditions was organic load = 0.82 kgCODCr (m−3·d−1), gas-water ratio = 6:1, CODCr concentration of effluent was 28.92 mg·L−1 and the removal ratio was 86.26%, while the removal ratio could higher to 91.12% for the O3-BAF combined process. The effluent could meet the discharge and reuse emission standards requirements in China. UV-vis absorption spectra and high performance liquid chromatography showed the degradation pathway of salicylhydroxamic acid by ozone oxidation was salicylhydroxamic acid → salicylic acid + hydroxylamine → catechol → maleic → small molecular organic acid → carbon dioxide + water.

scholarly journals Preparation and Characterization of the Sulfur-Impregnated Natural Zeolite Clinoptilolite for Hg(II) Removal from Aqueous Solutions

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 217
Author(s):  
Marin Ugrina ◽  
Martin Gaberšek ◽  
Aleksandra Daković ◽  
Ivona Nuić
Keyword(s):  
Chemical Modification ◽  
Aqueous Solutions ◽  
Specific Surface ◽  
Surface Area ◽  
Natural Zeolite ◽  
Contact Time ◽  
Liquid Ratio ◽  
X Ray ◽  
Solid Liquid

Sulfur-impregnated zeolite has been obtained from the natural zeolite clinoptilolite by chemical modification with Na2S at 150 °C. The purpose of zeolite impregnation was to enhance the sorption of Hg(II) from aqueous solutions. Chemical analysis, acid and basic properties determined by Bohem’s method, chemical behavior at different pHo values, zeta potential, cation-exchange capacity (CEC), specific surface area, X-ray powder diffraction (XRPD), scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), as well as thermogravimetry with derivative thermogravimetry (TG-DTG) were used for detailed comparative mineralogical and physico-chemical characterization of natural and sulfur-impregnated zeolites. Results revealed that the surface of the natural zeolite was successfully impregnated with sulfur species in the form of FeS and CaS. Chemical modification caused an increase in basicity and the net negative surface charge due to an increase in oxygen-containing functional groups as well as a decrease in specific surface area and crystallinity due to the formation of sulfur-containing clusters at the zeolite surface. The sorption of Hg(II) species onto the sulfur-impregnated zeolite was affected by the pH, solid/liquid ratio, initial Hg(II) concentration, and contact time. The optimal sorption conditions were determined as pH 2, a solid/liquid ratio of 10 g/L, and a contact time of 800 min. The maximum obtained sorption capacity of the sulfur-impregnated zeolite toward Hg(II) was 1.02 mmol/g. The sorption mechanism of Hg(II) onto the sulfur-impregnated zeolite involves electrostatic attraction, ion exchange, and surface complexation, accompanied by co-precipitation of Hg(II) in the form of HgS. It was found that sulfur-impregnation enhanced the sorption of Hg(II) by 3.6 times compared to the natural zeolite. The leaching test indicated the retention of Hg(II) in the zeolite structure over a wide pH range, making this sulfur-impregnated sorbent a promising material for the remediation of a mercury-polluted environment.

scholarly journals Study on Chromaticity Removal from Mineral Processing Wastewater with Salicylic Hydroxamic Acid by Granular Activated Carbon Catalyzed Ozonation

Minerals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 359
Author(s):  
Liping Zhang ◽  
Shengnian Wu ◽  
Nan Zhang ◽  
Ruihan Yao ◽  
Eryong Wu
Keyword(s):  
Activated Carbon ◽  
Reaction Time ◽  
Hydroxamic Acid ◽  
Ph Value ◽  
Oxygen Demand ◽  
Granular Activated Carbon ◽  
Mineral Processing ◽  
Ultraviolet Absorption Spectrum ◽  
Experimental Conditions ◽  
Removal Ratio

Salicylic hydroxamic acid is a novel flotation reagent used in mineral processing. However, it impacts the flotation wastewater leaving behind high chromaticity which limits its reuse and affects discharge for mining enterprises. This study researched ozonation catalyzed by the granular activated carbon (GAC) method to treat the chromaticity of the simulated mineral processing wastewater with salicylic hydroxamic acid. The effects of pH value, ozone (O3) concentration, GAC dosage, and reaction time on chromaticity and chemical oxygen demand (CODCr) removal were discussed. The results of individual ozonation experiments showed that the chromaticity removal ratio reached 79% and the effluent chromaticity exceeded the requirement of reuse and discharge when the optimal experimental conditions were pH value 3, ozone concentration 6 mg/L, and reaction time 40 min. The orthogonal experimental results of catalytic ozonation with GAC on chromaticity removal explained that the chromaticity removal ratio could reach 96.36% and the chromaticity of effluent was only 20 when the optimal level of experimental parameters was pH value 2.87, O3 concentration 6 mg/L, GAC dosage 0.06 g/L, reaction time 60 min respectively. The degradation pathway of salicylic hydroxamic acid by ozonation was also considered based on an analysis with ultraviolet absorption spectrum and high-performance liquid chromatography (HPLC).

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