Hydrochar washed (1.0, 2.5, 5.0 and 10.0 %) and not washed (10.0%) produced by hydrothermal carbonization using vinasse and sugarcane bagasse was applied in sand, ultisol and oxisol columns, and the release of NO3-, Orthophosphate, SO42-, Total Organic Carbon (TOC), H+ were evaluated for 30 days. These results were compared with the release of these parameters from experiments conducted with anthropogenic soils. The results demonstrated that higher amounts of nutrients were released for the experiments conducted with hydrochar not washed. With higher rates of hydrochar washed, higher the amount of nutrients released. TOC and SO42- were released throughout the experiment, which is beneficial from the agricultural point of view. Low values of orthophosphate and nitrate release in the leachates were observed for ultisol and oxisol due to the clay and iron and manganese oxides contents. Principal components analysis confirmed the observations and demonstrated that SO42- and TOC preferentially influence the oxisol, being that nitrate and pH influenced the columns containing Terra Mulata and sand. The results allow to conclude that it is possible to adjust the application rate of hydrochar in soils with lower fertility in order to increase it as observed for anthropogenic soils.

ABSTRACT Titanate nanotubes (TiNTs) with the chemical composition Na2Ti3O7.nH2O (NaTiNT) were obtained through a hydrothermal method in highly alkaline medium. Protonated titanates nanotubes (H-TiNTs), with the composition H2Ti3O7.nH2O, were prepared by ion exchange reaction through a suspension of Na2Ti3OγnH2O nanotubes in HCl medium, promoting the exchange of Na+ ions by H+. Both Na2Ti3O7.nH2O and H2Ti3O7.nH2O products, as well the TiO2 used as raw material for the nanotubes processing, were used as starting material for the solar cells photoelectrodes sensitized using mesoporphyrin extracted from a precursor of cashew nut shell. Exposing the NaTiNT sample to solar radiation of 1258 W/m2, a short-circuit current density (ISC) of 13 µA/cm2 and an open-circuit voltage (VOC) of 370 mV were registered and, a current density of 7.6 µA/cm2 and a voltage of 256 mV for the prototype cell based on H-TiNTs. A current density of 1.1 µA/cm2 and an open-circuit voltage of 1.6 mV were obtained for the cell using TiO2 as electrode.

Nanoparticles of TiO2 have been the main semiconductor applied in Dye-sensitized solar cells (DSSCs). In this work, titanate nanotubes (NaTiNT) and nanoribbons, were obtained by the hydrothermal method from TiO2 anatase. These materials were deposited on conductive substrate by electrophoresis, with and without thermal treatment, sensitized by ruthenium-based dye and used as work electrode. Exposing those photovoltaic devices to visible radiation, with films before thermal treatment, a short-circuit current density (JSC) of 0.0012 mA/cm2 was observed for the cell with NaTiNT, a current density of 0.0398 mA/cm2 for the cell with Nanoribbons, and a current density of 0.4028 mA/cm2 for the cell with TiO2 as electrode. After thermal treatment, a short-circuit current density of 0.4269 mA/cm2 was observed for the cell with NaTiNT, a current density of 0.0765 mA/cm2 for the Nanoribbons cell, and, finally, a current density of 0.3310 mA/cm2 for the cell with TiO2 as electrode. The new morphological, structural and optical characteristics of these nanoparticles may contribute for the development and research of new generation photovoltaic devices.

Fundamental aspects of the conception and applications of ecomaterials, in particular porous materials in the perspective of green chemistry are discussed in this paper. General recommendations for description and classification of porous materials are reviewed briefly. By way of illustration, some case studies of materials design and applications in pollution detection and remediation are described. It is shown here how different materials developed by our groups, such as porous glasses, ecomaterials from biomass and anionic clays were programmed to perform specific functions. A discussion of the present and future of ecomaterials in green chemistry is presented along with important key goals.