Hydroxyapatite (HAp) and hydroxyapatite/multi-walled carbon nanotube (MWCNT) composites were obtained by the co-precipitation method, followed by ultrasound-assisted and microwave radiation and thermal treatment at 250 °C. X-ray diffraction (XRD) confirmed the presence of a hexagonal phase in all the samples, while Fourier-transform infrared (FTIR) spectroscopy elucidated the interaction between HAp and MWCNTs. The photoluminescent technique revealed that HAp and the composite with non-functionalized MWCNTs present a blue luminescence, while the composite with functionalized MWCNTs, under UV-vis radiation shows an intense white emission. These findings allowed presentation of a proposal for the use of HAp and HAp with functionalized MWCNTs as potential materials for optoelectronic and medical applications.

Objective: To quantify the production of total and reducing sugars, as well as bioethanol from sugarcane bagasse (Saccharum spp.) pretreated with Trametes versicolor and 20 % (P/V) NaOH solution. Design/methodology/approach: An experimental 2K design was used to determine the effect of the volume of inoculant added to wild sugarcane bagasse samples (Factor A; 8 and 10 mL), its incubation period (Factor B; 18 and 24 d), and the bagasse weight/ volume of 20% (P/V) NaOH solution (Factor C; 5 and 20%(P/V), on the production of total and reducing sugars during simple saccharification. ANOVA analysis was used to evaluate the significance of these factors. The production of bioethanol was achieved via simple fermentation using a commercial strain of Saccharomyces cerevisiae. Results: It was found that the highest yields of reducing and total sugars were obtained with the use of 10 mL of inoculant solution and with an 18 d incubation period during biological pretreatments. The ANOVA analysis suggests that Factors A and B influence the release of sugars, while Factor C was irrelevant. The bioethanol production registered concentrations of up to 7.3 mg mL-1 for every 5 g of sugarcane bagasse. Limitations/implications: This study focused on how treatments using T. versicolor and NaOH affected the release of sugars. Optimization of bioethanol production needs to be considered subsequently in another study. Findings/conclusions: The results have implications for the use of pretreatments for the production of bioethanol from agro-industrial residues.