Polymeric membranes of poly(ethylene oxide) (PEO) and sodium trifluoroacetate (PEO:CF3COONa) combined with different concentrations of aluminum oxide (Al2O3) particles were analyzed by impedance spectroscopy, differential scanning calorimetry (DSC) and thermogravimetry (TGA). DSC results show changes in the crystalline fraction of PEO when the concentration of Al2O3 is increased. TGA analysis showed thermal stability up to 430 K showing small changes with the addition of alumina particles. The decrease in crystalline fraction for membranes with low Al2O3 concentration is associated with the increase in conductivity of (PEO)10CF3COONa + x wt.% Al2O3 composites.

In this work, we present a novel strategy for the numerical solution of a coupled system of partial differential equations that describe reaction–diffusion processes of a mixture of metals and ligands that can be absorbed by a sensor or a microorganism, in an aqueous medium. The novelty introduced in this work consisted of an adequate database management in conjunction with a direct iterative schema, which allowed the construction of simple, fast and efficient algorithms. Except in really adverse conditions, the calculation is converging and satisfactory solutions were reached. Computing times showed to be better than those obtained with some commercial programs. Although we concentrate on the solution for a particular system (Diffusive Gradients in Thin Films [DGT] sensors), the proposed algorithm does not require major modifications to consider new theoretical or experimental configurations. Since the quality of numerical simulations of reaction–diffusion problems often faces some drawbacks as the values of reaction rate constants increase, some additional effort has been invested in obtaining proper solutions in those cases.

The present study evaluated the removal efficiency of two dyes, Congo red (CR) and malachite green (MG), using either fresh or dry fungal biomass of two species of Trichoderma (T. virens and T. viride) and activated carbon. After 24 h, the CR removal efficiency obtained with fresh biomass was higher than that obtained with activated carbon. For the MG dye, the average removal with activated carbon (99%) was higher than those obtained with dry and fresh biomass of T. viride and T. virens. Experimental results for fresh and dry fungal biomass showed a good correlation with Langmuir isotherms. The adsorption rates of CR and MG by of T. virens and T. viride can be more appropriately described using the pseudo-second-order rate. We found an adsorption capacity of 81.82 mg g−1 for T. virens with MG dye. Results show that fresh or dry biomass of T. virens can represent a simple and cost-effective alternative for removing industrial dyes such as CR and MG.

Chemically and thermally treated rice husks were evaluated as a potential decontaminant of toxic Cd (II) in aqueous media. Rice husk (RH), a by-product from rice milling, was chemically treated with HCl and NaOH. Then, thermal treatments to 300, 500, and 700∘ C were applied. The chemical composition and morphological characteristics of RH were evaluated by different techniques. The specific surface area analysis of RH samples by BET nitrogen adsorption method provided specific surface areas ranging from 6 to 14 m 2 /g. SEM, FTIR, and EDX analyses of RH were carried out to determine the surface morphology, functional groups involved in metal binding mechanism, and C/O and C/Si ratios, respectively. The maximum Cd (II) adsorption capacity was 28.27 mg/g at an optimum pH, 6.0. The kinetic studies revealed that adsorption process followed the pseudo-second-order kinetic model.

The behavior of various filamentous fungi in the presence of metals such as Cu, Zn, Ni, Fe, Mn, and V has been widely reported. However, there is little information regarding metals such as Au, Ag and Pt that are not in the form of nanoparticles. The growth of eight filamentous fungi was evaluated at increasing doses of Au, Ag and Pt. The fungi were reactivated in Petri dishes with potato dextrose agar. Subsequently, individual mycelial disks from each strain were inoculated in PDA plates with the following doses of AuCl3, Ag2SO4 and PtCl4: 0, 50, 150 and 300 mg L−1, respectively. The plates were then incubated for 20 days—a period in which the diameter of the colony was measured every 24 h. Au showed the highest toxicity for the tested fungi. All silver doses decreased the growth of most of the fungi, while platinum did not cause any inhibitory effect on the growth of the eight tested fungi. With a simple test, it was possible to observe the effect of precious metals (PMs) on the growth of filamentous fungi and consider their possible biotechnological applications in the recovery of PMs from primary or secondary sources.