Red mud, a waste product generated during alumina extraction from bauxite, could be used as a low-cost adsorbent. Here, the effect of thermal treatment on the adsorption of Reactive Blue 19 (RB19) dye by red mud was compared with the adsorption capacity of untreated red mud. Thermal treatment of red mud at 500°C results in an increase in adsorption capacity from 357 mg g-1 (untreated red mud) to 416 mg g-1, under acidic conditions. Red mud samples thermally treated at 600°C and 800°C show a reduction in adsorption capacity, however, falling to 337 mg g-1 , in acid medium. The change in the maximum adsorption capacity of red mud to RB19 following thermal treatment is associated with specific surface area. Red mud subjected to 500°C can be used for the treatment of water and wastewaters with a higher efficiency than untreated red mud, thus finding possible application in the textile industry
M.L.P. Antunes, F.T. Conceição , G.R.B. Navarro, A.M. Fernandes, S.F. Durrant
Low-cost adsorbent; isotherms models; environmental management; cleaner production.
Bauxite residue (BR), a by-product of alumina and aluminum production, consists of high aluminum, silica, and iron content, and sodium from the bauxite ore digestion during the Bayer process. This waste is still being disposal into the lakes of mud, causing some environmental problems. So, the search for its application has gained interest. Studies reported in literature point out that one of the most promising applications is in association with Portland cement, which can also help to reduce the environmental impact caused by the CO2-emissions in its production. In this work, a combined evaluation of oscillatory rheometry and isothermal calorimetry was performed for the monitoring of the hardening stage of Portland cement (PC) compositions blended with BR generated in different sites in Brazil. The time-sweep test was applied to obtain the consistency gain of suspensions over-time, allowing us to understand the physical parameters of consolidation, while the changes in the hydration reaction showed considerable differences in the chemical contribution. As a conclusion, it was clear the impact of each BR, mainly due to the aspects related to soluble aluminates, silicates, and sodium, which in association with the soluble ions from PC, affected the chemical reaction and agglomeration/flocculation forces of particles.
R.C.O. Romano; J.A.F.S. de Mesquita; H.M. Bernardo; D.A. Niza; M.H. Maciel; M.A. Cincotto; R.G. Pileggi;
Management; cleaner production.
The introduction of potentially toxic elements (PTEs) from industrial activities in water bodies, highlights the vulnerability of the environment and the need for actions focused on the implementation of mechanisms that help in the control and remediation of these impacts. The objective of the study was based on the integration of instrumental analytical methods, multivariate statistics, and computer simulation models, with the proposal of implementing realistic scenarios of the red mud plume behavior in the Pará River. The selected location was the municipality of Barcarena-PA, where is located an important alumina/aluminum industrial center. With the aid of the inductively coupled plasma optical emission spectrometer (ICP OES), the chemical elements Al, B, Cr, Fe, Mn, P, Ti, and Zn were quantified and the principal component analysis (PCA) allowed to select Al, B, Fe, P, and Zn as the most relevant with 98.68% of the accumulated variance. Some scenarios were proposed by the simulated hydrodynamic model, which evidenced that the Trambioca community would be the most affected in the first 13 h after the effluent overflowed, and the other locations in domino effect. The main scientific gain of the proposal is the possibility of the predictive scenarios to help the actions of containment and mitigation of environmental damages by public control agencies, institutions involved, and other competent bodies.
P.M.S. Júnior ; S.F.P. Pereira; R.M. Rocha; M.H.D. Alves; L.S. Pinheiro; D.P. Nogueira; O.M.M. Teixeira; A.C.S. Gonçalves
Multivariate; hydrodynamic models; chemical elements
The continuous change in the strength and other properties, environmental problems, hike in cement price, advancement of construction industry makes the usage of alternative materials as Functionally graded materials (FGM) which leads to a new materials on concrete as Functionally graded concrete (FGC), In this present paper, investigation has carried out on the functionally graded concrete by using red mud and also fly ash. In this M20 grade of concrete is used as the conventional concrete in compression zone and M25 with the replacement of cement by red mud and flyash with varying percentage (5%, 10% 15%) respectively in the tension zone. The results indicated that the 10% of the red mud and 10% of the fly ash as the optimum value for the concrete beam and by load deflection curve, it is evident that functionally graded concrete beam has more advantages than ordinary concrete since it has more durability and strength characteristics. Scanning electron microscope analysis was also carried out on the red mud functionally graded concrete and fly ash functionally graded concrete. It clearly indicated the pores present in the materials which tends to increase in strength of the concrete
S.M. Palaniappan, V. Govindasamy , A.B. Jabar
Functionally graded concrete, M20 and M25 grade, Scanning electron microscope, Red mud, Flyash
Neste trabalho foi proposta uma rota tecnológica visando analisar o comportamento das transformações de fases dos minerais presentes na lama vermelha durante o processo de redução da hematita à magnetita. As análises de fluorescência e difração de raios X mostraram que a lama vermelha apresentou em sua composição aproximadamente 5% de óxido de titânio como anatásio e 28% de óxido de ferro, nas formas de hematita e goethita. Foram realizados experimentos envolvendo a redução da hematita à magnetita utilizando tratamento térmico. O material foi calcinado nas temperaturas de 500, 600 e 1000 ºC durante 2 h. Em seguida, foram realizadas análises de difração de raios X e espectroscopia Raman, as quais mostraram que a hematita foi reduzida à magnetita em todas as condições experimentais. Para as temperaturas de calcinação de 500 e 600 ºC, o óxido de titânio permaneceu na forma livre de anatásio, porém para a calcinação realizada a 1000 ºC, o óxido passou para a forma combinada com ferro (ilmenita). A rota proposta neste trabalho possibilitou a obtenção de um material com características magnéticas, o qual poderá ser utilizado como fonte de titânio após a extração dos compostos de ferro por separação magnética ou lixiviação ácida.
B.M. Viegas; E.M. Magalhães; J.A.S. Souza; E.N. Macêdo;
Lama vermelha; ferro; titânio
