scholarly journals Hexavalent Chromium Adsorption on Magnetic Nanoparticles Synthesized from Tay Nguyen Red Mud from Vietnam

2020 ◽  
Vol 32 (3) ◽  
pp. 602-606
Author(s):  
Pham Thi Mai Huong ◽  
Truong Anh Thu ◽  
Chu Qui Thuong ◽  
Tran Hong Con ◽  
Nguyen Thi Huong
Keyword(s):  
Hexavalent Chromium ◽  
Fe3o4 Nanoparticles ◽  
Red Mud ◽  
Kinetic Data ◽  
Waste Product ◽  
Precipitation Method ◽  
Diffraction Field ◽  
Silicon Iron ◽  
Alumina Production ◽  
Free Environment

Tay Nguyen red mud abundantly found in Vietnam, is a waste product of alumina production formed during processing of bauxite. It is rich in aluminate, residual alkaline, and oxides, such as silicon, iron, and titanium oxides. Iron oxide, which constitutes 45-55 % of Tay Nguyen, is useful for Fe3O4 nanoparticles synthesis. In this study, a Fe3O4 nanoparticles were synthesized using Tay Nguyen by the chemical co-precipitation method, which required a non-oxidizing oxygen-free environment. Fe3O4 nanoparticles were characterized using X-ray diffraction, field emission scanning electron microscopy, Brunauer-Emmett-Teller analysis, and vibrating-sample magnetometry. Adsorption of hexavalent chromium by the nanocomposite was conducted under batch conditions. Pseudo-second-order equations were used to describe kinetic data of adsorption reactions; the equations were fitted to kinetic data as shown by the results. The isotherms of adsorption were also studied using the linear forms of the Langmuir and Freundlich equations. The Langmuir equation exhibited higher linear correlation with the experimental data than the Freundlich equation did. The maximum monolayer coverage, qmax at 297 K was 31.44 mg/g.

scholarly journals A Study of the Potential Use of Red Mud to Obtain Compositions Based on Portland Cement

2020 ◽  
Author(s):  
Ekaterina Gerasimova ◽  
Elizaveta Gumirova
Keyword(s):  
Portland Cement ◽  
Red Mud ◽  
Waste Product ◽  
Cement Stone ◽  
Mathematical Planning ◽  
Alumina Production ◽  
Mineral Additive ◽  
Composition Properties ◽  
Planning Of Experiments ◽  
Potential Use

The paper deals with the problem of utilization of red mud which is a waste product from alumina production using the Bayer method. The principal possible use for the red mud of JSC “Bogoslovsky aluminum plant” (Sverdlovsk region) for the compositions based on Portland cement is shown. It was found that the mud introduction accelerates beginning of the cement paste setting and thickens the paste reducing its mobility. It is concluded that the introduction of red mud up to 30 % is justified in terms of strength indicators. The work is carried out using mathematical planning of experiments. Keywords: red mud, Portland cement, active mineral additive, composition, properties, bauxite, chemical composition, cement stone strength, mathematical planning of experiments

scholarly journals Physico - Chemical and Morphologic Structural Characterization of the Red Mud Obtained in the Romanian Alumina Plant

2019 ◽  
Vol 70 (2) ◽  
pp. 565-570
Author(s):  
Vasile Georgescu ◽  
Mihaela Bombos ◽  
Catalina Calin ◽  
Dorin Bombos
Keyword(s):  
Red Mud ◽  
Waste Product ◽  
Morphological Structure ◽  
Dispersion Analysis ◽  
Average Chemical Composition ◽  
Alumina Production ◽  
Distribution Method ◽  
Research Activities ◽  
Physico Chemical

The red mud is the main insoluble waste product from the manufacture of alumina by the Bayer hydrometallurgical process. Due to the accumulation in large quantities (0.8-1.2 metric tons waste / 1 metric ton of alumina) with a relatively high content of residual alkali and small granulation, it has been subject to many research activities, especially related to the techniques of neutralizing and enhancing its reuse under the form of various subproducts. This paper presents the results of the work undertaken by the collective of authors to evaluate the physico-chemical and morphological structure of red mud resulting from alumina production. The physico-chemical and morphological structure were analyzed using complex analytical methods (ICP-AES/OES, DCP, AAS, EDS-EDAX, SEM, DTAC, XRF, XRD, optical microscopy). The aim was to identify potentially active compounds for various environmental applications. To estimate the average chemical composition, by element, we used dispersion analysis, through the Gauss normal distribution method.

scholarly journals Influence of Sodium Sulfate Addition on Iron Grain Growth during Carbothermic Roasting of Red Mud Samples with Different Basicity

Metals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1571
Author(s):  
Pavel Grudinsky ◽  
Dmitry Zinoveev ◽  
Denis Pankratov ◽  
Artem Semenov ◽  
Maria Panova ◽  
...  
Keyword(s):  
Magnetic Separation ◽  
Grain Growth ◽  
Red Mud ◽  
Sodium Sulfate ◽  
Phase Distribution ◽  
Solid Phase ◽  
Alumina Production ◽  
Metallic Particles ◽  
Iron Phase ◽  
High Alkalinity

Red mud is an iron-containing waste of alumina production with high alkalinity. A promising approach for its recycling is solid-phase carbothermic roasting in the presence of special additives followed by magnetic separation. The crucial factor of the separation of the obtained iron metallic particles from gangue is sufficiently large iron grains. This study focuses on the influence of Na2SO4 addition on iron grain growth during carbothermic roasting of two red mud samples with different (CaO + MgO)/(SiO2 + Al2O3) ratio of 0.46 and 1.21, respectively. Iron phase distribution in the red mud and roasted samples were investigated in detail by Mössbauer spectroscopy method. Based on thermodynamic calculations and results of multifactorial experiments, the optimal conditions for the roasting of the red mud samples with (CaO + MgO)/(SiO2 + Al2O3) ratio of 0.46 and 1.21 were duration of 180 min with the addition of 13.65% Na2SO4 at 1150 °C and 1350 °C followed by magnetic separation that led to 97% and 83.91% of iron recovery, as well as 51.6% and 83.7% of iron grade, respectively. The mechanism of sodium sulfate effect on iron grain growth was proposed. The results pointed out that Na2SO4 addition is unfavorable for the red mud carbothermic roasting compared with other alkaline sulfur-free additives.

Deactivation of Red Mud by Primary Aluminum Production Wastes

2021 ◽  
Vol 1040 ◽  
pp. 109-116
Author(s):  
V.Yu. Piirainen ◽  
A.A. Barinkova ◽  
V.N. Starovoytov ◽  
V.M. Barinkov
Keyword(s):  
Carbon Dioxide ◽  
Red Mud ◽  
Negative Impact ◽  
Waste Product ◽  
Primary Aluminum ◽  
Raw Material ◽  
Aluminum Production ◽  
Environmentally Safe ◽  
Primary Aluminum Production ◽  
Knowledge Intensive

Current global environmental challenges and, above all, global warming associated with a change in the carbon balance in the atmosphere has led to the need for urgent and rapid search for ways to reduce greenhouse gas emissions into the atmosphere, which primarily include carbon dioxide as a by-product of human activity and technological progress. One of these ways is the creation of industries with a complete cycle of turnover of carbon dioxide. Aluminum is the most sought-after nonferrous metal in the world, but its production is not environmentally safe, so it constantly requires the development of knowledge-intensive technologies to improve the technological process of cleaning and disposal of production waste, primarily harmful emissions into the atmosphere. Another environmental problem related to aluminum production is the formation and accumulation in mud lagoon of huge amounts of so-called highly alkaline "red mud," which is a waste product of natural bauxite raw material processing into alumina - the feedstock for aluminum production. Commonly known resources and technological methods of neutralizing red mud and working with it as ore materials for further extraction of useful components are still not used because of their low productivity and cost-effectiveness. This article describes the negative impact of waste in the form of "red" mud and carbon dioxide of primary aluminum production on the environment. The results showed that thanks to carbonization of red mud using carbon dioxide, it is possible to achieve rapid curing and its compact formation for safer transportation and storage until further use. Strength tests of concrete samples filled with deactivated red mud were also carried out, which showed the prospects of using concrete with magnesia binder.

Performance of Chitosan Micro/Nanoparticles to Remove Hexavalent Chromium From Residual Water

2017 ◽  
pp. 262-288
Author(s):  
Jimena Bernadette Dima ◽  
Noemí Zaritzky
Keyword(s):  
Chemical Analysis ◽  
Hexavalent Chromium ◽  
Kinetic Data ◽  
Chitosan Nanoparticles ◽  
Living Systems ◽  
Cross Linking ◽  
Residual Water ◽  
Acid Media ◽  
Best Fitting ◽  
Pseudo Second Order

Hexavalent chromium Cr(VI) is toxic to living systems and must be removed from wastewater. Chitosan is a cationic, biocompatible, biodegradable, biopolymer obtained from marine wastes. The performance of chitosan particles (CH) and chitosan nanoparticles (CHN) to remove Cr(VI) from aqueous solutions is discussed in the present chapter. CHN were obtained by reticulation with tripolyphosphate (TPP), and physico-chemically characterized. The performance of CHN decreased at higher pH due to the cross-linking process with TPP. Langmuir isotherm described the equilibrium adsorption values and pseudo-second order rate provided the best fitting to the kinetic data. Chemical analysis to determine the oxidation state of the adsorbed Cr, showed that Cr(VI) was adsorbed on CH particles without further reduction; in contrast Cr(VI) removed from the solution was reduced and bound to the CHN as Cr(III). Chitosan crosslinking was essential to adsorb Cr(VI) at pH<3 due to the dissolution of CH in acid media.

Synthesis of Fe3O4 Nanoparticles Prepared by Various Surfactants and Studying their Characterizations

2008 ◽  
Vol 273-276 ◽  
pp. 22-27 ◽  
Author(s):  
Ali Shokuhfar ◽  
S. Alibeigi ◽  
Mohammad Reza Vaezi ◽  
Sayed Khatiboleslam Sadrnezhaad
Keyword(s):  
Fe3o4 Nanoparticles ◽  
Cetyl Trimethyl Ammonium Bromide ◽  
Precipitation Method ◽  
Ammonium Bromide ◽  
X Ray Diffraction ◽  
Mixed Salt ◽  
Magnetite Fe3o4 ◽  
Cetyl Trimethyl Ammonium ◽  
Size And Morphology ◽  
Co Precipitation

Magnetite (Fe3O4) nanoparticles were prepared simply by the reverse co-precipitation method from the solution of ferrous/ferric mixed salt in the presence of cationic surfactant (cetyl trimethyl ammonium bromide, CTAB) and nonionic surfactant (Polyethylene glycol, PEG) in two concentrations. Meanwhile, Fe3O4 nanoparticles without surfactant are also synthesized under the same condition for comparison. In addition via the reverse co-precipitation method, the pH which is an important factor in synthesis of magnetite was controlled at high values easily. The experimental results reveal that addition of surfactants affected on the size and morphology of the nanoparticles based on the X-ray diffraction (XRD) and scanning electron microscope (SEM) characterizations.

Bayern`s Method of Al2O3 Production – Possibilities of Red Mud Disposal and Utilization

2011 ◽  
Vol 176 ◽  
pp. 11-20 ◽  
Author(s):  
Mariola Saternus
Keyword(s):  
Chemical Composition ◽  
Red Mud ◽  
Building Materials ◽  
Short Description ◽  
Iron Recovery ◽  
Alumina Production ◽  
Advantages And Disadvantages ◽  
Primary Aluminium

Bayern`s method is the first stage of obtaining primary aluminium. The product of this process is alumina. The paper presents how much alumina was produced in the last couple of years and who were its leading producers. As the main ore for alumina production is bauxite; it was necessary to describe its characteristics: chemical composition and types of bauxites. Short description of the method (digestion, precipitation and calcination) was presented. During this process a lot of pollution is usually emitted to the atmosphere, but mostly a lot of red mud is generated. This is the main waste of the process, which at the same time is very harmful to the environment. The ways red mud is disposed or utilized were reviewed. Two kinds of red mud disposal are known: wet and dry disposal. Both were characterized and their advantages and disadvantages were outlined. The possibilities of red mud utilization were shown. The focus was put on iron recovery or recovery of compounds such as Al2O3 or TiO2. The use of red mud in building materials was discussed. Radioactivity of such materials was also analyzed. Possibility of red mud utilization as a pigment and radiopaque material was also mentioned.

scholarly journals Assessing Options for Remediation of Contaminated Mine Site Drainage Entering the River Teign, Southwest England

Minerals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 721 ◽  
Author(s):  
Abigail Jordan ◽  
Rachel Hill ◽  
Adrienne Turner ◽  
Tyrone Roberts ◽  
Sean Comber
Keyword(s):  
Red Mud ◽  
Metal Removal ◽  
Environmental Concern ◽  
Low Cost ◽  
Waste Product ◽  
Treatment Method ◽  
Mining Operations ◽  
Metal Concentrations ◽  
Cost Treatment ◽  
Mine Sites

The river Teign in Devon has come under scrutiny for failing to meet environmental quality standards for ecotoxic metals due to past mining operations. A disused mine known as Bridford Barytes mine, has been found to contribute a significant source of Zn, Cd and Pb to the river. Recently, studies have been focused on the remediation of such mine sites using low-cost treatment methods to help reduce metal loads to the river downstream. This paper explores the metal removal efficiency of red mud, a waste product from the aluminium industry, which has proven to be an attractive low-cost treatment method for adsorbing toxic metals. Adsorption kinetics and capacity experiments reveal metal removal efficiencies of up to 70% within the first 2 h when red mud is applied in pelletized form. Further, it highlights the potential of biochar, another effective adsorbent observed to remove >90% Zn using agricultural feedstock. Compliance of the Teign has been investigated by analysing dissolved metal concentrations and bioavailable fractions of Zn to assess if levels are of environmental concern. By applying a real-world application model, this study reveals that compressed pellets and agricultural biochar offer an effective, low-cost option to reducing metal concentrations and thus improving the quality of the river Teign.

scholarly journals Improving the flame retardancy of ethylene vinyl acetate composites by incorporating layered double hydroxides based on Bayer red mud

e-Polymers ◽  
2019 ◽  
Vol 19 (1) ◽  
pp. 129-140 ◽  
Author(s):  
Yi Qian ◽  
Kangjia Jiang ◽  
Long Li
Keyword(s):  
Vinyl Acetate ◽  
Flame Retardancy ◽  
Layered Double Hydroxides ◽  
Red Mud ◽  
Ethylene Vinyl Acetate ◽  
Precipitation Method ◽  
Infrared Spectrometry ◽  
Cone Calorimeter Test ◽  
Bayer Red Mud ◽  
Double Hydroxides

AbstractNowadays, reducing the hazards of bayer red mud (BRM) is an important research direction in the fields of environmental and safety. In this article, Mg/Al/Fe ternary layered double hydroxides (Mg/Al/Fe-LDHs) were synthesized successfully by a co-precipitation method based on introducing Mg2+ into the BRM suspension. The thermogravimetric analysis (TGA) results showed that the decomposition rate of LDHs is higher than that of BRM, which indicates that LDHs can absorb more heat than BRM during the decomposition process. Subsequently, BRM and LDHs were added into the ethylene vinyl acetate (EVA) to investigate its effects on reducing flammability of the composites. The cone calorimeter test (CCT) results demonstrated that 50 wt% LDH-B can make the peak value of HRR (PHRR) decrease from 1694.8 kW/m2 (EVA) to 199.2 kW/m2 (ELDH2). The smoke density test (SDT) results showed that the luminous flux of ELDH2 is nearly 95% at the end of test with a pilot flame, which is much higher than that of EVA and EBRM. The thermogravimetry-Fourier transform infrared spectrometry (TG-FTIR) results confirmed that LDHs can improve the thermal stability of composites and reduce the production of some toxic gases. Compared with BRM, the improved flame retardancy of Mg/Al/Fe-LDHs is ascribed to the introduction of Mg2+, which offering an enhanced catalytic carbonization capability, as well as the physical barrier effect of char residue layer catalyzed by the lamellar LDHs

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