Produção e caracterização de espumas cerâmicas obtidas a partir de lodo de anodização de alumínio

Ceramic foams were produced from a sludge generated in the aluminum anodizing process by using an industrial polyurethane foam (replication method) with open cell sizes of 10 ± 5 ppi (porosity = 97%) which were impregnated with suspensions containing 50-61 wt.% alumina, 1 wt.% citric acid, 6 wt.% bentonite and fired at 1600 ºC for 2 h. The aluminum anodizing sludge shows a high alumina content (87.5 wt.%) and a low particle size (~1.7 mm) after calcination and milling. The obtained filters show porosity of approximately 70%, filtration capability (mass water flow) of 1.7 kg/s and mechanical strength under compression of 2.40 MPa.

Acúmulo de cargas elétricas em propelente sólido compósito com matriz de polibutadieno líquido hidroxilado

Composite solid propellants prepared with HTPB prepolymer - Hydroxyl Terminated Polybutadiene, AP - Ammonium Perchlorate as oxidizer and aluminum particles as an additive metal, have characteristics of high electrical resistivity. The loading process of the polymer matrix did not obtain homogeneity, resulting in clusters, mainly of metal particles. The effect of clustering in the composite was studied and observed experimentally, and this effect was one of the factors explaining the phenomenon of electrical charging of the composite. This electrical potential, when discharged abruptly, can generate an electric spark with sufficient energy for sustained ignition of a solid rocket motor.

Avaliação da remoção de fármacos e de desreguladores endócrinos em águas de abastecimento por clarificação em escala de bancada

In this work, the efficiency of clarification treatment (coagulation, flocculation and sedimentation) with polyaluminum chloride (PAC) and aluminum sulfate (SA) as coagulants was evaluated in the removal of 7 microcontaminants (diclofenac - DCF, sulfamethoxazole - SMX, ethinylestradiol - EE2, bisphenol-A - BPA, estradiol - E2, estrone - E1 and estriol - E3) in water of low and high turbidity. The clarification treatment led to poor removal rates (40% at most) for all microcontaminants except SMX which exhibited intermediate removal efficiency (67 to 70%). Overall, PAC application yielded better performance compared to SA.

Avaliação da labilidade de alumínio em infusões de erva-mate empregando voltametria adsortiva de redissolução catódica

Infusions of yerba mate obtained at different stages of industrialization were evaluated to determine the bioavailable fraction of Al. Adsorptive Cathodic Stripping Voltammetry using DASA (complexing agent) was applied to determine the labile fraction of Al at pH 5.0 and pH 8.0 for the total fraction of dissolved Al. The results indicate that on average 60% of Al is complexed with organic compounds, minimizing their bioavailability; however, the labile fraction exceeds by up to 4 times the maximum weekly intake recommended by the World Health Organization.

ACIDITY OF MODIFIED MORDENITES SYNTHESIZED FROM RICE HUSK SILICA AND CATALYTIC TRANSFORMATION OF METHYLBUTYNOL

Mordenite (MOR) was synthesized using rice husk silica and modified by base (B), acid (A) or acid-base (AB) and converted to H-form. The modification did not destroy the MOR structure but increased surface area and generated mesopores. Lewis acidity of the parent and modified MOR samples investigated by aluminum NMR and NH3-TPD showed a decrease in the following order: HMOR > BMOR > ABMOR > AMOR. For the catalytic transformation of methylbutynol, ABMOR provided the highest conversion and selectivity of products from acid sites.

USE OF A LOW-COST TEMPLATE-FREE ZSM-5 FOR ATMOSPHERIC PETROLEUM RESIDUE PYROLYSIS

To understand the physicochemical properties and catalytic activity during the pyrolysis of atmospheric petroleum residue, a template-free ZSM-5 zeolite was synthesized using a direct method without additional seeds or an organic structure director and compared with conventionally synthesized ZSM-5. The crystallinities of the two zeolites were evaluated by XRD and FTIR and were quite similar; however, structural analyses using SEM and argon physisorption revealed that the zeolites diverged in particle diameter and in the external surface area of the micropores. The synthesis procedure without a template incorporated additional aluminum into the crystalline network, according to ICP-AES and TPD NH3 experiments. The catalytic pyrolysis performed over the template-free ZSM-5 generated results comparable to those for pyrolysis performed over the conventional ZSM-5 according to its hydrocarbon distribution. The selectivity to aromatics compounds was exactly the same for both ZSM-5 zeolites, and these values stand out compared to thermal pyrolysis. The template-free ZSM-5 produced 20% of light hydrocarbons (C4-C6), where such compounds are olefins and paraffins of great interest to the petrochemical industry. Therefore, template-free ZSM-5 is promising for industrial use due to its lowered synthesis time, low-cost and significant distribution to light hydrocarbons.

Ultrakevyen rahtialuksen kansiluukkujen sekä luukkujen siirto- ja varastointijärjestelmän suunnittelu hyödyntäen kevytrakennekonsepteja

Tämän työn tarkoituksena oli tutkia miten rahtialuksen kansiluukut voitaisiin valmistaa mahdollisimman kevyiksi. Katettavan ruuman pinta-ala on n. 10 m x 40 m. Luukkujen suuresta jännevälistä johtuen, rakenteelta vaaditaan suurta jäykkyyttä. Erilaisina vaihtoehtoina tutkittiin vaahtomaista alumiinia, alumiinisia kennorakenteita ja polyuretaanisia sandwich-rakenteita. Työssä vertailtiin myös erilaisia geometrisia ratkaisuja, joilla kansiluukkujen jäykkyyttä pyrittiin lisäämään ja sitä kautta pääsemään pienempään materiaalin tarpeeseen. Geometriaa suunniteltaessa huomioitiin myös vaikutukset ruuman tilavuuteen ja lainsäädännön asettamat reunaehdot. Lainsäädännöstä saatiin esimerkiksi turvakaiteiden minimikorkeus, joka vaikuttaa suoraan ruuman tilavuuteen, kun aluksen korkeimmaksi kohdaksi on valittu laivan keskilinja ja tämä korkeus on annettu suunnittelun lähtötietona. Tietokoneavusteisen lujuuslaskennan avulla eri vaihtoehdoista muodostettiin elementtimallit. Malleja varioimalla ja tuloksia vertailemalla saatiin selville kevyin mahdollinen rakenne ja geometria. Malleista saatiin selville myös luukkujen tukireaktiovoimat, eli voimat, jotka luukut kohdistavat aluksen muihin rakenteisiin. Lisäksi työssä mietittiin erilaisia tapoja ruuman avaamiseen ja avaamistavan vaikutusta kansiluukkujen painoon, geometriaan ja ruuman tilavuuteen.