Abstract: The surface characterisation of new activated carbons produced from tire residues by activation with carbon dioxide was studied. The activated carbons produced were mainly basic with point of zero charge values above 8.8. The main surface functional groups identified by FTIR were ether, quinones, lactones, ketones, hydroxyls (free and phenol) and pyrones. The XRD analysis shows that the materials produced have a microstructural organisation with microcrystallite height around 1.5nm and width from 3 to 5.3nm. This analysis indicates also the possible presence of oxides (single or mixture) of the following heteroatoms: Fe, Al, Ca, Mg, Ti, Si, K, Pb, Cd, Ba, Zn and Sn. The results have shown the significant potential of this type of residues for activated carbon production. Furthermore, the environment friendly use of an industrial residue is also noteworthy.
Abstract: Na-LTA, Na-X and HS zeolites have been prepared from Tunisian sand and aluminum scraps. The alkaline attack of the sand leads to the metasilicate sol used as a source of silica. The aluminum source was prepared by dissolving aluminum in NaOH solution. The influence of several physicochemical parameters such as temperature, crystallization time and the alkalinity of the reaction mixture on the nature and the purity of the obtained products have been investigated.
Abstract: Coating plaster residues (CPR) used in the civil construction industry account for a considerable percentage of building debris. The debris generated at construction sites represents 40% of domestic waste in Brazilian municipalities, causing serious environmental problems, given that a large portion of the residue is discarded in inappropriate places. The incorporation of CPR into the mass formulations of red ceramic may be economically and environmentally beneficial. In the present study 5%, 10% and 15% of CPR was added to formulation D, with a 1:1 composition by weight of different medium plastic clays, a composite that showed the best physical and mechanical properties in a study conducted with three formulations of a ceramic industry containing compositions of 1:1, 1:2 and 2:1. The test specimens were compressed uniaxially, oven-dried (110 °C) and sintered at 850 °C, 950 °C and 1050 °C, with constant temperature for two hours. Lineal shrinkage, water absorption, apparent density, bending stress failure and section of fracture micrographs of the sample, with EDS microanalysis, were analyzed.
Abstract: Over the last decades the literature has shown the possibility of producing activated carbons (AC) from a wide variety of raw materials, and to use them as one of the most environment-friendly solutions for waste disposal . Simultaneously, it has been shown that the adsorption of pollutants from different sources by activated carbons is one of the most efficient techniques for remediating or solving this kind of problem . In this context, phenolic compounds represent one of the most important classes of pollutant present in the environment . In this perspective, we present a study involving the production of AC from cork (Quercus suber L.), PEEK (polyetheretherketone) wastes or granulated recycled PET (polyethyleneterephthalate) and their applicability for the adsorption of phenolic compounds from the liquid phase. All samples were characterised in relation to their structural properties and chemical composition, by different techniques, including nitrogen adsorption at 77 K, elemental analysis (C, H, N, O and S) and point of zero charge (PZC). The activated carbons produced demonstrated high adsorption capacities both in the gas and liquid phase as exemplified by N2 and phenolic compounds adsorption experiments. Based on the structural and chemical properties, and on the kinetic and equilibrium studies of liquid phase adsorption, it is possible to conclude that it is the porous volume of the ACs that predominantly controls the process of phenolic compounds adsorption.
Abstract: The present project explains how crude biodiesel (crude BD) has been obtained by using coconut oil and ethyl alcohol as well as sodium hydroxide as a catalyst. The coconut oil was extracted with water which was submitted to evaporation afterwards. This experiment was carried out by adding the coconut oil in a 500 mL glass flask. The catalyst was dissolved in ethyl alcohol and mixed together with the coconut oil. Once obtained the mixture, this was stirred for 25 minutes at temperatures from 20, 30, 40, 50 to 60 °C. During the reaction, two phases were formed: crude biodiesel (top layer) and crude glycerol (bottom layer). The characterization was done by determination of pH (using an electrode located in the top layer connected to a computer by RS-232 interface system). When the separation concluded, the crude BD was rinsed in order to remove the catalyst. The characterization of washed biodiesel was determined by density and Saybolt viscosity. Fourier Transform Infrared (FTIR) analysis was also made. The results by FTIR indicated the two functional groups of fatty acid ethyl esters (C=O, 1733 cm-1 and C-O, 1154 cm-1) and the OH wide band group of glycerol at 3400 cm-1. When the reaction time ended, the maximum pH value registered was 12.7. The values for pH, density and Saybolt viscosity were acceptable for crude BD and crude glycerol.
Abstract: With a significant production of waste fibrous material, textile companies are now looking for applications where waste materials could be an added-value material. One viable application of these waste materials is in the combination with polymeric matrices, producing composite materials with interesting properties for specific applications, from furniture to thermal and acoustic insulations. The aim of this work was to study the physical and mechanical properties of waste fibre reinforced composites and the influence of different parameters on their mechanical behaviour. Results show that a wide range of different properties and performances may be designed by altering various production parameters, such as thickness of the nonwovens used, time and temperature of the compression moulding, relationship between fibre/matrix ratio, polymeric film used and number of layers.
Abstract: The importance of recovering and valorising the residues generated by industrialized societies is mainly due to the environmental impact that such residues may cause. In this connection, scrap tires constitute a major source of pollution. In the recent years large amounts of scrap tires have been recycled in order to recover the metals contained in this residue. Tires have also been grinded and the small particles produced have found different applications. In addition to metals and rubber particles, reinforcing fibers are also produced in the recycling process of scrap tires. As a previous step for the valorisation of this third constituent of waste tires, a characterization of such fibers is strongly recommended. Thermal analysis techniques make it possible to identify the fibers through the thermal transitions that may take place. Usually, such transitions result mainly in cotton and rayon. Furthermore, the combination of pyrolysis, gas chromatography and mass spectrometry techniques corroborates the identification of several compounds derived from the decomposition of the fibers as well as some materials used in the preparation of tires.
Abstract: Laboratorial studies were carried out to characterise the influence of different cutting systems (grab shredder and cutting mill) on the physical processing efficiency of spent Zn-MnO2 batteries. The grab shredder operate based on an indented cutting rotor which applies shear and abrasion stresses with a moderate rotation speed, while the cutting mill operation is based on shear and impact stresses at higher rotation speed. After shredding with the grab shredder, two fractions of material were obtained (above and below the 6 mm discharge grid), which allows a previous separation of the scrap. With the cutting mill, all the grinded material passed the bottom grid (with the same 6mm opening). Results obtained showed that alkaline batteries were more efficiently shredded than saline batteries, mainly with the grab shredder. Average diameters (d50) for saline and alkaline batteries fragmented with the grab shredder were 2.29 and 1.47 mm respectively, while with the cutting mill were 3.09 and 1.54 mm respectively. Chemical analyses were carried out for different size fractions allowing identifying metals distribution through size categories. In general chemical composition was not substantially different using both shredding systems. Zinc distribution was almost constant with the grain size while manganese distribution decreased with particle size. More than 94% of the iron scrap from the battery cases presents a particle size higher than 1.4 mm using both cutting systems. Due to this result, it is possible to separate the scrap retained in the coarse fraction by sieving with the identified mesh. Maximum selectivity points, corresponding to the maximum separation of zinc plus manganese from iron, were also determined. Higher zinc and manganese recoveries were obtained with the grab shredder, despite iron contamination (20-25%) can be considered significant.
Abstract: In electronic appliances, printed circuit boards (PCB) represent an important component, containing high grade of valuable metals, besides organic resins and some ceramic materials. Copper is the major metal in PBC’s composition (normally higher than 20% w/w) but many other secondary and minor metal elements, including precious metals, are found in PCB’s. Recycling of PCB´s involves firstly the shredding operation, which is crucial in order to liberate particles from different materials, allowing its further processing by other mechanical, physical and chemical technologies. An efficient shredding operation is difficult to achieve due to the high heterogeneity of these wastes involving materials with different mechanical properties and complex assemblies. This paper presents results from laboratorial studies of shredding of PCB’s and the evaluation of size reduction efficiency as well as the chemical characterization of the obtained shredded fractions. Results showed that an efficient size reduction (characteristic average diameter d50=1.0mm) is obtained using two shredding stages of PCB’s, the first one with a grab shredder and the second one with a cutting mill. Chemical analysis of shredded PCB’s indicated that copper is the principal metal present (28%) followed by Sn, Zn, Pb and Al (3-5%) and many other minor elements. The fine fractions were rich in plastic materials while the metals were essentially present in the intermediate fractions (0.3-1.5 mm). These results can lead to guidelines regarding further design of the physical separation steps in the recycling processes.
Abstract: In statistical analysis of failure data of brittle materials, the use of maximum likelihood estimators shows many advantages compared to other methods. The applicability and the robustness of the maximum likelihood method to analyze and to distinguish the data in several mixtures of two Weibull populations is demonstrated in this work. Estimations of percentage of data belonging to each of the populations, as well as Weibull parameters of the populations, are relatively simple to be conducted using adequate software.