Materials Science Forum Vol. 820

Abstract: In this work, the removal of zinc and lead (Zn²⁺ and Pb²⁺) from aqueous solutions was investigated using a Brazilian bofe clay. The mineral clays were characterized through XRD analysis and CEC. A finite bath system was used to evaluate the main effects of pH values in the range from 3.0 to 5.0 and Zn²⁺ and Pb²⁺ initial concentrations (from 10 to 50 mg/L) on the removal process capacity. The combinations of the XRD and CEC showed characteristics of the group smectite clays. Up to 3.38 mg/g of Lead removal capacity (99.97% efficiency) was reached and values as high as 98.47 % of removal Zinc efficiency and 3.93 mg/g of removal capacity were reached in the assays. Thus indicating that the use of Bofe clay has great potential in the removal of Lead and Zinc.

Abstract: In this work the smectite clays Chocobofe from the state of Paraíba was investigated to evaluate their affinity and capacity for removal of zinc using a finite bath system. The clay was characterized by means of X-Ray Diffraction (XRD), Infrared Spectroscopy in the Region (IV) and Cation Exchange Capacity (CEC) and Physical Adsorption of Nitrogen (BET method). A 2² factorial design was conducted with three center points in a finite bath system to determine the percentage removal (% Rem) and removability (qeq) of the clay. Values of 83.35 to 98.83% and the percentage removal from 3.83 to 4.24 mg / g removal were achieved in experiments, indicating that the use of clay Chocobofe appears as a promising alternative to remove of Zn²⁺

Abstract: The negative impact of soil salinity on agricultural yields is disturbing and significant, especially when related to agricultural plants, whose sensitivity to salinity is frequently, but not exclusively, associated with the abundance of Na⁺ in the soil, which in excess becomes toxic for plants. This work aims to propose an alternative for the control of Na⁺ present in waters from saline soils, by the possibility of applying bovine hydroxyapatite as a way to remedy this problematic. Hydroxyapatite powders were processed from bovine bone. The powders were characterized by X-ray diffraction analyses. Preliminary experiments were performed in batches at room temperature, adding together 5g hydroxyapatite and a dilute solution of sodium chloride. Liquid samples were analyzed by atomic absorption spectrophotometry. The results showed that the hydroxyapatite could be a promising alternative for the reduction of Na⁺ concentration in waters from saline soils.

Abstract: Tailings from the concentration of iron ore can be substituted in part for the production of concrete blocks due to the ability of encapsulation or enveloping the concrete. Many tests were conducted to recycle Concentration Tailings of Iron Ore for the Production of Concrete Block, replacing the silica sand. The Concentration Tailings of Iron Ore showed to be viable materials for the replacement of coarse and fine aggregate concrete blocks (pavers), with regard to mechanical strength after 28 days cure. Specifically, the simple substitution of hail for coarse tailings concentration of iron ore has the potential to increase the compression resistance of the concrete blocks. It was also verified that the addition of fine tailings with magnetic concentration may complicate demolding.The water absorption of the concrete block was obtained in accordance with the standards, and some blocks were within the required standards. And through the leaching test was observed that the addition of the tailings concrete blocks poses no risk to the environment when exposed to weather.

Abstract: Residue materials accumulated in the working yards of building construction in Brazil are commonly discarded into landfill areas, which represents a non-sustainable procedure. To revert this situation, a possible remediation could be the selection of these residues to be recycled as useful materials in the same building construction. In the present work, clay ceramic wastes, such as broken bricks and tiles, obtained as civil construction residues, were used in substitution of washed sand currently applied in concrete fabrication. It was found that a 30% substitution presented, within the standard deviation, a smaller strength to the concrete with comparable trace of sand, but still complying with the norm.

Abstract: This paper has the objective to evaluate the technical feasibility of incorporation of leather powder in mortars. First a physical characterization of aggregate was carried and then preceded to the dissolution of the leather powder in alkaline solution, in the proportion of 1:1:1 of waste, alkaline solution and water respectively, obtaining the processed waste. In the next step, it has been molded specimen using two reference recipes in terms of mass, 1:3 of cement and sand, and 1:1:6 of cement, hydrated lime and sand respectively, keeping constant the flow table consistency of 130 ±10 mm and 220±10 mm, for each respectively recipe. Two groups of mortars were produced: one without processed waste, one with 5% and one with 10% in ratio to the cement mass. Tests had been carried such as compressive strength to axial compression, tensile strength to diametrical compression, and adherence strength on surfaces. The resistance tests performed; also the analyses of the leachate and solubilized extracts confirmed the feasibility of incorporation of leather powder in mortars.

Abstract: Ceramic bodies composed of steatite residues from workshops from the region of Ouro Preto (MG-Brazil) and 15, 20 and 25% of kaolinite clay were fired at 1000 and 1200 °C for 2hrs in air to evaluate their technological properties. Essays of flexural strength and water absorption showed that ceramic bodies have a performance for their use as commercial bricks with values in accordance to those defined by the Brazilian standards. The mixture material, raw and fired, was analyzed using X-ray diffraction, ICP/OES and SEM. After fired, the samples showed a more compact surface and an advanced sintering process. Talc and kaolinite are the dominant minerals in raw ceramics. After being fired, talc changes to enstatite and at 1200°C, mullite, periclase and cordierite appear. These minerals affect the physical properties of the ceramic bodies such as reduction of the porosity, increase of the sintering process and consequently, increased flexural strength. The results show that mixtures kaolinite clay and steatite have potential for application in ceramic industry which can also contribute to reducing the environmental impact of industrial waste from steatite.

Abstract: The WTPs generate a residue in decanters called sludge, which, despite having a similar chemical composition of clay minerals, does not behave as such when embedded in such clays. Several surveys conducted indicate a decrease in Flexural Strength for the ceramic body when incorporated. The objective of this study is to evaluate the incorporation of the sludge generated at a WTP, which uses aluminum sulfate coagulant, to clay. By the method of pressure casting, samples were prepared with different percentages of sludge containing the said coagulant. Test runs with previously calcined sludge at 700°C were also performed in order to obtain sludge without the coagulant. In both cases, the final bodies were fired at 900°C and were tested for water absorption and flexural strength. The results reveal that the incorporation of non-calcined sludge positively change the quality of the ceramics prepared.

Abstract: This work is an analysis of incorporation of leather powder residue to soil in order to apply it in soil-cement bricks. The leather powder is a byproduct of the finishing step of leather manufacturing that contains chromium in its composition. This element, when in its hexavalent form, is carcinogenic. Experiments were performed regarding brick pressing, water absorption, simple pressing, leaching and solubilization so that the mixtures have the minimum requisites for using the brick. The doses were 0%, 10%, 15%, 20%, and 30% in volume of leather powder in soil. Only the 10% dose met the requisites of ABNT: NBR 8491:1984 that prescribes a minimum resistance of 2 MPa and absorption content lower than 20%. For this dosage, according to the limits stated in ABNT regulation NBR 10004:2004 , the leaching extract was classified as a Class II non-inert, which makes it possible to use it for civil construction purposes.

Abstract: The grits is an inorganic solid residue generated during the Kraft process by the pulp and paper industry, which presents in its composition the main ingredients of Portland cement. According to some authors, the grits can be classified as a non inert, non hazardous, granular solid industrial waste. With this in mind, a study was proposed with the objective of evaluating, initially, the applicability of grits in mortar, by means of physical and chemical testing. The physical evaluations were realized through the following tests: determination of bulk gravity saturated - surface - dry (SSD) and water absorption; determination of the pulverulent material content; and the determination of particle size distribution. To chemically test the grits, a reading of the metal concentrations present in the grits was realized as well as an analysis of the leaching and solubilization extracts. It was concluded that the addition of grits to mortar is a potential alternative.