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The potential of Bioclastic Granules - BG (calcium-carbonate-based material) using the algae Lithothamnium calcareum as sorbent for the removal of Cd(II) from aqueous solutions by sorption was evaluated through batch and continuous systems tests using a fixed-bed column. Sorption process variables, in particular pH (2-7), particle size (<38-300 μm), initial BG concentration (0.1-1.0 g L), initial Cd(II) concentrations (5-400 mg L) and contact time (5-240 min), were evaluated. Adsorption isotherm profiles of Cd(II) per BG were similar to an L-type, or Langmuir type, with the adsorption forming a monolayer of approximately 0.61 μm, with a q of 188.74 mg g and k of 0.710 L mg. Thomas's model considers that sorption is not limited to a chemical reaction but is controlled by mass transfer at the interface. In the present study, the obtained value of k was 0.895 mL h mg, reaching a sorption capacity q of 124.4 mg g. For the Yoon-Nelson model, it was possible to obtain two important parameters to describe the behavior of the column, the rate constant (k), obtaining a value of 0.09 h and an τ of 82.12 h corresponding to the time required for sorption to occur of 50% of the solute in the rupture curve. X-ray diffraction and scanning electron microscopy analyses coupled to the X-ray dispersive energy system (SEM/EDS) of the BG after the Cd(II) ion sorption tests evidenced the formation of crystals with the prevalence of a new mineral phase (otavite).

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Experimental methods were assessed for accurately characterizing through-the-thickness fiber volume fraction gradients in fiber-reinforced composite laminates. Two optical microscopy-based image analysis methods were considered for this purpose: the areal method and the fiber counting method. Although the areal method currently appears to be the more commonly used method, the fiber counting method was determined to be the preferred optical microscopy-based method when an accurate measure of fiber cross-sectional area is available. Based on this determination, the fiber counting method was used to perform ply-by-ply fiber volume fraction determinations on four sets of autoclave-cured carbon/ epoxy unidirectional and symmetric cross-ply laminates. Although all four laminates displayed out-of-plane curvature following curing, no statistically significant through-the-thickness fiber volume fraction gradient was found in any of the laminates.

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There are two principal types of nickel (Ni) deposits: sulfide and laterite ores. Interest in low‐grade Ni‐laterite ores has increased in recent years as high‐grade Ni‐sulfide deposits are being quickly depleted. However, processing of Ni laterites has proven technically difficult and costly, and the development of alternative low‐cost biotechnologies for Ni solubilization has been encouraged. In this context, by the first time, a sample of Brazilian Ni‐laterite ore was analyzed mineralogically and subjected to bioleaching tests using a heterotrophic Bacillus subtilis strain. SEM‐analysis indicated that the primary Ni carrier mineral is goethite. Chemical analysis of different grain size fractions indicated a homogeneous distribution of Ni. XRF‐analysis showed that the ore consists mainly in lizardite (32.6% MgO) and contains1.0% NiO (0.85% Ni). Bioleaching batch experiments demonstrated that about 8.1% Ni (0.7 mg Ni/g ore) were solubilized by the B. subtilis after 7 days. Application of microwave heating as a Ni‐laterite pretreatment was also tested. This pretreatment increased the bioextraction of Ni from 8% to 26% (2.3 mg Ni g−1 ore).