scholarly journals Removal of COD in Wastewater By Magnetic Coagulant Prepared From Modified Fly Ash

2021 ◽  
Author(s):  
Wen Wang ◽  
Liqiang Qi ◽  
Pan Zhang ◽  
Jichen Luo ◽  
Jingxin Li
Keyword(s):  
Fly Ash ◽  
Power Plants ◽  
Removal Rate ◽  
Langmuir Equation ◽  
Cod Removal ◽  
Impregnation Method ◽  
Order Kinetic ◽  
Experimental Conditions ◽  
Magnetic Components ◽  
Modified Fly Ash

Abstract In order to investigate the effective method of COD removal from desulfurization wastewater, acid-modified fly ash (AFA) and base-modified fly ash (BFA) were prepared by impregnation method. Then, magnetic coagulants (Fe-AFA, Fe-BFA) were prepared by mixing the modified fly ash with magnetic components. The structural characterization results showed that the specific surface area and the porosity of fly ash were obviously increased after modification. Fe-AFA magnetic coagulant has the best performance and superparamagnetism. Under the same experimental conditions, the maximum COD removal amounts of FA, BFA, AFA, Fe-BFA and Fe-AFA were 2.180, 3.209, 4.631, 3.710 and 5.687 mg/g, respectively. The COD removal amount of Fe-AFA was increased by 112.43% compared with the raw FA. The quasi-second-order kinetic and Langmuir equation could well fit the COD coagulation process of five coagulants. After five cycles, the COD removal amount of Fe-AFA was 2.735 mg/g, and the removal rate still reached 67.53%. These findings provide a feasible method for the treatment of fly ash from coal-fired power plants and the preparation of highly efficient COD trapping magnetic coagulants.

scholarly journals Preparation of grafting copolymer of acrylic acid onto loess surface and its adsorption behavior

2020 ◽  
Vol 82 (4) ◽  
pp. 673-682
Author(s):  
Fengqin Tang ◽  
Di Gao ◽  
Li Wang ◽  
Yufeng He ◽  
Pengfei Song ◽  
...  
Keyword(s):  
Acrylic Acid ◽  
Adsorption Capacity ◽  
Removal Rate ◽  
Vinyl Pyrrolidone ◽  
Mineral Particle ◽  
Gravimetric Analysis ◽  
Order Kinetic ◽  
Experimental Conditions ◽  
Order Kinetic Model ◽  
Grafting Copolymer

Abstract Loess is a typical natural mineral particle distributed widely around the world, and it is inexpensive, readily accessible, and harmless to the environment. In this study, loess was modified by surface grafting copolymerization of functional monomers, such as acrylic acid, N-vinyl pyrrolidone, and N,N-methylenebisacrylamide as a cross-linking agent, which afforded a novel loess-based grafting copolymer (LC-PAVP). After being characterized by scanning electron microscopy, thermal gravimetric analysis and Fourier-transform infrared spectroscopy, its adsorption capacity and mechanism of removing lead ions (Pb2+) were investigated. With the study of the optimal experimental conditions, it was demonstrated that the removal rate of Pb2+ by LC-PAVP can reach up to 99.49% in 60 min at room temperature. It was also found that the kinetic characteristics of the adsorption capacity due to the pseudo-second-order kinetic model and the thermodynamics conformed well with the Freundlich model. In summary, as a lost-cost and eco-friendly loess-based adsorbent, LC-PAVP is a good potential material for wastewater treatment.

scholarly journals Composition and Morphology Characteristics of Magnetic Fractions of Coal Fly Ash Wastes Processed in High-Temperature Exposure in Thermal Power Plants

2019 ◽  
Vol 9 (9) ◽  
pp. 1964 ◽  
Author(s):  
Dinh-Hieu Vu ◽  
Hoang-Bac Bui ◽  
Bahareh Kalantar ◽  
Xuan-Nam Bui ◽  
Dinh-An Nguyen ◽  
...  
Keyword(s):  
Fly Ash ◽  
Power Plants ◽  
Coal Fly Ash ◽  
Thermal Power ◽  
Combustion Process ◽  
Mineralogical Composition ◽  
Striking Difference ◽  
Thermal Power Plants ◽  
Power Stations ◽  
Magnetic Components

Coal-fired power stations are one of the primary sources of power generation in the world. This will produce considerable amounts of fly ash from these power stations each year. To highlight the potential environmental hazards of these materials, this study is carried out to evaluate the characterization of fly ashes produced in thermal power plants in northern Vietnam. Fly ash was firstly fractionated according to size, and the fractions were characterized. Then, each of these fractions was analyzed with regard to their mineralogical features, morphological and physicochemical properties. The analytical results indicate a striking difference in terms of the characteristics of particles. It was found that magnetic fractions are composed of magnetite hematite and, to a lower rate, mullite, and quartz. Chemical analyses indicate that the non-magnetic components mainly consist of quartz and mullite as their primary mineral phases. As the main conclusion of this research, it is found that the magnetic and non-magnetic components differ in terms of shape, carbon content and mineralogical composition. In addition, it was found that magnetic components can be characterized as more spheroidal components compared to non-magnetic ones. This comprehensive characterization not only offers a certain guideline regarding the uses of different ash fractions but it will also provide valuable information on this common combustion process.

Experimental Research on Fly Ash Modified Adsorption of Mercury Removal Efficiency of Flue Gas

2013 ◽  
Vol 800 ◽  
pp. 132-138 ◽  
Author(s):  
Li Li ◽  
Si Wei Pan ◽  
Jiang Jun Hu ◽  
Ji Fu Kuang ◽  
Min Qi ◽  
...  
Keyword(s):  
Fly Ash ◽  
Removal Efficiency ◽  
Flue Gas ◽  
Power Plants ◽  
Physical Adsorption ◽  
Adsorption Properties ◽  
Mercury Removal ◽  
Immersion Method ◽  
Adsorption Temperature ◽  
Modified Fly Ash

Mercury in the flue gas in coal-fired power plant as the research object using halogen compound as the modified material, the fly ash was modified by chemical immersion method，Study on adsorption agent, the adsorption temperature, modified material and loading on mercury adsorption of flue gas in coal-fired power plants. Experiments showed that, iodine adsorption properties of modified fly ash was the most significant, with the increase of the sorbent dosage, Hg removal efficiency increased, fly ash adsorption amount of change was not obvious, between 80-140°C temperature range, fly ash on mercury existed mainly physical adsorption, the mercury removal efficiency decreased with the increase of temperature, chemical adsorption occurred at 160°C, mercury removal efficiency increased.

Experimental Research on Mercury-Containing Wastewater in PVC Production by Fly Ash Processing Calcium Carbide Method

2014 ◽  
Vol 878 ◽  
pp. 578-584 ◽  
Author(s):  
Yan Li ◽  
Ping Sun
Keyword(s):  
Fly Ash ◽  
Ph Value ◽  
Removal Rate ◽  
Operating Cost ◽  
Calcium Carbide ◽  
Emission Standard ◽  
Removal Capacity ◽  
Positive Treatment ◽  
The Government ◽  
Modified Fly Ash

To study the removal capacity of modified fly ash in wastewater containing mercury ions under different conditions, the dust from a calcium carbide furnace was added to fly ash, and the pyrogenic process was employed to modify the fly ash. The result indicated that the wastewater had a pH value of 9, the modified fly ash dosage was 0.2 g, the adsorption equilibrium time was 40 minutes, the reaction temperature was 30 °C, and the removal rate could reach 91.9%. Using modified fly ash in polyvinyl chloride production via the calcium carbide method to remove mercury-containing wastewater can help meet the government-prescribed emission standard. This method has advantages such as positive treatment effect, simple operation, and low operating cost.

scholarly journals Influence of Activators on Mechanical Properties of Modified Fly Ash Based Geopolymer Mortars

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1033 ◽  
Author(s):  
Piotr Prochon ◽  
Zengfeng Zhao ◽  
Luc Courard ◽  
Tomasz Piotrowski ◽  
Frédéric Michel ◽  
...  
Keyword(s):  
Fly Ash ◽  
Power Plants ◽  
Thermal Power ◽  
Biomass Combustion ◽  
Fly Ashes ◽  
Binding Properties ◽  
Alkali Activated ◽  
Modified Fly Ash ◽  
Scanning Electron ◽  
And Calorimetry

The aim of this work was to study the influence of the type of activator on the formulation of modified fly ash based geopolymer mortars. Geopolymer and alkali-activated materials (AAM) were made from fly ashes derived from coal and biomass combustion in thermal power plants. Basic activators (NaOH, CaO, and Na2SiO3) were mixed with fly ashes in order to develop binding properties other than those resulting from the use of Portland cement. The results showed that the mortars with 5 mol/dm3 of NaOH and 100 g of Na2SiO3 (N5-S22) gave a greater compressive strength than other mixes. The compressive strengths of analyzed fly ash mortars with activators N5-S22 and N5-C10 (5 mol/dm3 NaOH and 10% CaO) varied from 14.3 MPa to 5.9 MPa. The better properties of alkali-activated mortars with regular fly ash were influenced by a larger amount of amorphous silica and alumina phases. Scanning electron microscopy and calorimetry analysis provided a better understanding of the observed mechanisms.

Treatment of Cr(VI) WasteWater with Modified Coal Fly Ash

2015 ◽  
Vol 768 ◽  
pp. 561-566 ◽  
Author(s):  
Jing Wang ◽  
Hui Yang Yu ◽  
Jun Fa Lin
Keyword(s):  
Fly Ash ◽  
Removal Rate ◽  
Orthogonal Experiment ◽  
Coal Fly Ash ◽  
Optimum Combination ◽  
Processing Conditions ◽  
Initial Concentration ◽  
Ph Values ◽  
Single Factor Experiment ◽  
Modified Fly Ash

In this work, modified fly ash by Na2CO3 was prepared and used to remove the Cr (VI) in simulate wastewater, which was rarely reported in domestic and foreign. In the meantime, every single-factor experiment, which maybe influenced the removal ratio of Cr (VI), was done. The major-minor order of test factors and the optimum combination processing conditions influencing the treatment effects of Cr (VI) were determined according to the orthogonal experiment. The results showed that the major-minor order was initial concentration of Cr (VI), dosage of modified fly ash, adsorption duration, temperature and pH values. And the optimum combination of above discussed factors was 15 mg/L, 5 g, 90 min, 30 oC and 2.5, respectively. Under this optimum condition, the removal rate of Cr (VI) can reach more than 74.86%, approximately 1.35 times compared to that of original fly ash.

scholarly journals Catalytic wet peroxide oxidation degradation of magenta wastewater and preparation of FeOCl/montmorillonite

2021 ◽  
Author(s):  
Tiancheng Hun ◽  
Binxia Zhao ◽  
Tingting Zhu ◽  
Linxue Liu ◽  
Zhiliang Li ◽  
...  
Keyword(s):  
Removal Rate ◽  
Oxygen Demand ◽  
Cod Removal ◽  
Impregnation Method ◽  
Dye Wastewater ◽  
Peroxide Oxidation ◽  
Melting Method ◽  
Wet Peroxide Oxidation ◽  
Catalytic Wet Peroxide Oxidation ◽  
Cod Removal Rate

Abstract The iron oxychloride/pillared montmorillonite (FeOCl/MMT) catalyst was prepared by wet impregnation method and solid melting method. Various characterization techniques were used to analyze the microscopic morphology and structure of a series of catalysts. Moreover, the catalysts were used to treat magenta simulated dye wastewater through catalytic wet peroxide oxidation (CWPO) degradation. The magenta removal rate and chemical oxygen demand (COD) removal rate of the magenta simulated dye wastewater were used to evaluate the catalytic performance of the catalyst, and the optimal catalyst preparation conditions were selected. The results showed that the solid melting method was more favorable to the preparation of the catalyst, and the COD removal rate of wastewater can reach 70.8% when the FeOCl load was 3%. Moreover, 96.2% of the magenta in the solution has been removed. The COD removal rate of the magenta wastewater decreased by only 12.4% after the catalyst was repeatedly used six times, indicating that the catalyst has good activity and stability. The Fermi equation can simulate the reaction process of the catalyst treating magenta wastewater at high temperature.

scholarly journals Evaluation of Zeolitic Materials Synthetized from Coal Fly Ash as Potential Cd(II) Adsorbents from Aqueous Solutions

2020 ◽  
Vol 71 (9) ◽  
pp. 125-142
Author(s):  
Claudia Maria Simonescu ◽  
Alina Melinescu ◽  
Culita Daniela Cristina ◽  
Dhuha Hasan ◽  
Bianca Zarnescu ◽  
...  
Keyword(s):  
Fly Ash ◽  
Power Plant ◽  
Specific Surface ◽  
Thermal Power Plant ◽  
Power Plants ◽  
Coal Fly Ash ◽  
Thermal Power ◽  
Order Kinetic ◽  
Simple Method ◽  
Cadmium Ions

The aim of this research paper is to present a simple and efficient method to prepare zeolite materials from thermal power plant fly ash which is one of the most important waste resulted from power plants. The method of preparation of zeolite materials consists of alkaline activation followed by calcination at different temperatures. The zeolite materials prepared were studied by FT-IR spectroscopy, specific surface determination, X-ray fluorescence spectroscopy (XRF), scanning electron microscopy (SEM) and particle size composition. XRF data indicated that the zeolites synthesized are characterized by Si/Al ratio between 1.21 and 1.26, being mainly composed of Na-P1 zeolite. The optimum conditions of cadmium ions removal process by adsorption onto zeolite materials have been determined. It was concluded that increase of calcination temperature has as result increase of specific surface area and cosequently the increase of sorption capacity. An equilibrium, kinetic and thermodynamic study has been performed. The high value of correlation coefficient for the Langmuir isotherm reveals that the Cd(II) sorption onto zeolite materials occurs as a monolayer coverage of Cd(II) ions on homogenous zeolite surface. The pseudo-second-order kinetic model fits the experimental results of the Cd(II) sorption onto zeolite materials processes. As a results, the mechanism involved in Cd(II) sorption onto zeolite materials is based on chemical reactions. The thermodynamic results indicate that the Cd(II) adsorption process is more encouraging at higher temperatures.The results established that valuable NaP1 zeolite materials with high adsorption capacity can be prepared from thermal power plant fly ash through a simple method. The materials prepared can be utilized to remediate cadmium ions-bearing wastewater.

The removal of As(V) ions by lime-modified fly ash and reuse of the exhausted adsorbent as an additive for construction material

2020 ◽  
Author(s):  
Milica Karanac ◽  
Maja Đolić ◽  
Vladimir Pavićević ◽  
Aleksandar Marinković
Keyword(s):  
Fly Ash ◽  
Power Plants ◽  
Low Cost ◽  
Construction Material ◽  
Thermal Power ◽  
Construction Materials ◽  
Practical Applications ◽  
The Impact ◽  
By Products ◽  
Modified Fly Ash

<p>Coal thermal power plants (TPP) actively generate numerous solid combustion by-products, including fly ash and bottom ash. These TPP by-products have already found use in a variety of civil engineering applications, such as a substitute for sand and gravel in structures, as well as a binding component in certain types of cement (generally, concrete and masonry). Furthermore, such by-products have become a subject of increasing interest in environmental engineering as a low-cost and effective adsorbent for the removal of organic pollutants and heavy metals from wastewaters.</p><p>In order to minimize the impact of material cost, novel solutions for the development of a high capacity and long-term adsorbent have provided a high performance adsorbent for practical applications. This study is focused on the use of modified fly ash (MFA) activated by lime (Ca(OH)<sub>2</sub>) as an effective and low-cost adsorbent for the removal of As(V) ions. The adsorption capacity of the MFA adsorbent was found to be 35.40 mg g<sup>-1</sup>, while the kinetic and thermodynamic parameters indicated a spontaneous and endothermic process. Due to the low desorption potential of the exhausted adsorbent (MFA/As(V), their effective further material reuse was established to be feasible. The reuse of the exhausted adsorbent was obtained through pozzolanic MFA particles and Ca(OH)<sub>2, </sub>thereby formulating a construction material of a cementitious calcium-silicate hydrate. The toxicity leaching test (TCLP) and mechanical properties of the new construction material containing exhausted MFA (CM-MFA/As(V)) confirm its safe use in the laboratory as well as its semi-industrial application.</p><p>The specific objectives of this study have been: (i) to improve the adsorption performance of the MFA; (ii) to evaluate the material’s equilibrium, as well as the process’ kinetic and thermodynamic aspects, including  estimating its limiting step; and (iii) to investigate the possible reuse of the exhausted adsorbent in the production of construction materials. The kinetic data were successfully fitted by a pseudo-second-order equation and the Weber-Morris model. The metal-desorption experiments performed on the exhausted FA and MFA indicate a low recovery of the selected pollutants.</p><p>The major outcome of this study, indicates that double-valorization of fly ash opens new directions for waste management toward reuse in effective practical applications; i.e., for actual water –purification systems, as well as in the production of construction material.</p>

Experimental Research on Mercury-Containing Wastewater by Fly Ash

2013 ◽  
Vol 456 ◽  
pp. 559-563 ◽  
Author(s):  
Yan Li ◽  
Ping Sun
Keyword(s):  
Fly Ash ◽  
Adsorption Process ◽  
Adsorption Equilibrium ◽  
Ph Value ◽  
Removal Rate ◽  
Practical Application ◽  
Mercury Ions ◽  
Removal Capacity ◽  
Carbide Slag ◽  
Modified Fly Ash

To study the removal capacity of modified fly ash in wastewater containing mercury ions under different conditions, the carbide slag was added to fly ash, and the pyrogenic process was employed to modify the fly ash. The result indicated that the wastewater had a pH value of 11, the modified fly ash dosage was 2.0 g, the adsorption equilibrium time was 40 minutes, the reaction temperature was 30 °C, the removal rate could reach 97.1%, and the Freundlich-type adsorption isotherm can be used to simulate the adsorption process effectively. The modified fly ash can be used in the removal of mercury-containing wastewater, the overall result of the experiment is satisfactory, which indicates that the modified fly ash has potential value for practical application.

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