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The dependence of oil and its consequent commercial fluctuation make researchers to seek viable alternatives for their gradual replacement. The present work aims to evaluate the production of biofuels from the slow pyrolysis of the Syzygium malaccense biomass (Malay Apple) through thermogravimetric analysis (TGA-DTG), Fraser-Suzuki deconvolution and chemometric tools of multivariate analysis. Three chemical treatments (sodium hydroxide, sulfuric acid and phosphoric acid) were evaluated, as well as the variation in the heating rate and the consequent effects on the pyrolysis of biomass for the production of biofuels, totaling 16 pyrolysis routes (including the use of biomass no treatment). In the obtained data, multivariate analysis tools were used, looking for groups that presented favorable characteristics for the production of quality biofuels. Heatmap, k-means and SOM analysis indicated the routes that use phosphoric acid treatment and heating rates of 10 or 15 °C/min (Jap10 and Jap15, respectively) as relevant, because they have low lignin contents and high gaseous cellulose and hemicellulose contents.

Lucina pectinata, popularly called Lambreta, is a delicacy very consumed in Bahian cuisine. The shell is composed of nacreous layers formed by keratin, collagen, and elastin, interspersed with layers of calcium carbonate, predominantly calcite, and aragonite phases, which provides protection to the mollusk. As these shells do not readily degrade, provoking environmental imbalance due to their accumulation, this work aims to evaluate the physicochemical and microstructural properties of shells of the species L. pectinata, focusing on the reuse of the solid residue generated by the consumption of this mollusk. The shells were washed, crushed, and subjected to chemical treatment and dried. Subsequently, the physical–chemical and microstructural properties of the samples LN—in nature and LB were treated with sodium hypochlorite. The samples were investigated using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), zero load potential (pHpcz), pH determination, moisture content (%), ash content (%), specific surface area, and pore volume by the BET method, scanning electron microscopy (MEV), thermogravimetric/derivate thermogravimetry (TG/DTG), and differential thermal analysis (DTA). The results revealed that calcite and argonite phases are present in the two samples with high calcium carbonate content (95%) and that thermal decomposition occurs in the range of 575 to 810 °C, producing CaO and CO2. Treatment with sodium hypochlorite (sample LB) promoted leaching in the solid by dragging possible lamellae, which culminated in superficial erosion of solids, resulting in a better cavity and pore distribution profile on the surface, besides increasing the specific surface area in relation to sample LN.

Mercury is a highly toxic substance that is a health hazard to humans. This study aims to investigate powders obtained from the peel of the fruit of Pachira aquatica Aubl, in its in natura and/or acidified form, as an adsorbent for the removal of mercury ions in aqueous solution. The materials were characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis. The infrared spectra showed bands corresponding to the axial deformation of carbonyls from carboxylic acids, the most important functional group responsible for fixing the metal species to the adsorbent material. The thermograms displayed mass losses related to the decomposition of three major components, i.e., hemicellulose, cellulose, and lignin. The adsorption process was evaluated using cold-vapor atomic fluorescence spectrometry (CV AFS) and cold-vapor atomic absorption spectrometry (CV AAS). Three isotherm models were employed. The adsorption isotherm model, Langmuir-Freundlich, best represented the adsorption process, and the maximum adsorption capacity was predicted to be 0.71 and 0.58 mg g(-1) at 25 °C in nature and acidified, respectively. Adsorption efficiencies were further tested on real aqueous wastewater samples, and removal of Hg(II) was recorded as 69.6 % for biomass acidified and 76.3 % for biomass in nature. Results obtained from sorption experiments on real aqueous wastewater samples revealed that recovery of the target metal ions was very satisfactory. The pseudo-second-order model showed the best correlation to the experimental data. The current findings showed that the investigated materials are potential adsorbents for mercury(II) ion removal in aqueous solution, with acidified P. aquatica Aubl being the most efficient adsorbent.

The specific surface area of zirconia, prepared by an aqueous sol-gel route, is affected by aging and by the rinsing solution of the precipitate. The solid aged in mother liquor and rinsed with ammonium hydroxide solution showed the highest value.