Abstract Boron phosphate glasses are known for their unique properties and have been investigated as biodegradable materials for biomedical applications. In this context, the present research studied the characterization of physical, mechanical, and bioactive properties of new boron-phosphate glass in the CaO-P2O5-K2O-B2O3 system produced by the melt-quenching method. The structure and morphology of the material were investigated by FTIR, XRD, DSC, SEM-EDS, laser diffraction, and BET-BJH methods. Additionally, density and Vickers hardness were determined, and its bioactive potential was evaluated by immersion in simulated body fluid (SBF). The results demonstrated higher values of Vickers hardness (7.45 GPa) for the new glass when compared to other glasses. Furthermore, the material exhibited apatite-forming ability after immersion in SBF, which was confirmed by the information obtained through surface analysis. The newly created glass presented a promising potential for applications in tissue engineering.

Cupuaçu husk (CH) is the waste of a common fruit from a native species of the Brazilian Legal Amazon. The current study investigated the influence of ultrasound (US) combined with aqueous, acid, alkaline, and ionic liquid (IL) pretreatments on the chemical and physical aspects of CH and the yield of chemical platforms production, 5-hydroxymethylfurfural (HMF) and furfural (FF), using IL. Scanning electron microscopy, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy were used to feature the raw and pretreated biomass. The highest levels of glucose (9.90 g L-1) were observed in the liquid fraction resulting from the acid + US pretreatment followed by acid hydrolysis. The IL + US pretreatment recorded the best performance in removing lignin. Based on XRD analyses, ultrasound increased crystallinity of all pretreated samples as a result of the removal of cellulose’s amorphous fraction. However, it promoted accessibility to adopted reagents by increasing biomass exposure due to cavitation. The best yields of HMF and FF were recorded from hydrolysis of the solid fraction resulting from the acid + US (12.94%) and alkaline + US (48.84%) pretreatment, respectively. These results indicate satisfactory performance of ultrasound assisted pretreatments to the simplified and economic conversion of biomass into value-added products.

Resumo A casca de arroz é um resíduo abundante no Rio Grande do Sul, Brasil, e pode ser utilizada para produção de sílica pura. As biovitrocerâmicas têm a sílica como principal componente. A biocompatibilidade desses materiais pode ser incrementada adicionando componentes, como SrO. Este trabalho objetivou o uso da sílica proveniente da casca de arroz como um precursor de baixo custo para se obter biovitrocerâmica do sistema 50%SiO2-25%Na2O-(25-x)%CaO-x%SrO (% em mol) via sol-gel e investigar seu potencial como biomaterial. Duas amostras (BGC branco e BGC-5%Sr) foram obtidas e caracterizadas por difração de raios X (DRX), espectroscopia no infravermelho por transformada de Fourier (FTIR) e determinação de carbono elementar por método da combustão. A microscopia eletrônica de varredura (MEV) foi usada para investigar a morfologia das biovitrocerâmicas, enquanto o teste MTT de viabilidade celular foi usado para caracterização in vitro. A sílica obtida apresentou estrutura amorfa e pequena quantidade de carbono. As biovitrocerânicas apresentaram principalmente fases com Si, Ca, Na e Sr na sua estrutura. Ambas as amostras não apresentaram citotoxicidade frente às células mononucleares do sangue periférico (PBMC) e a incorporação de 5% de SrO aumentou a biocompatibilidade.

Abstract Rice husk is an abundant waste at the Rio Grande do Sul, Brazil, and it can be used to produce pure silicon dioxide, which is the main component of bioglass-ceramics. The addition of compounds, such as SrO, can improve the biocompatibility of these biomaterials. Therefore, the goal of this paper was to use rice husk silicon dioxide as a cheap precursor to obtaining bioglass-ceramics of the system 50%SiO2-25%Na2O-(25-x)%CaO-x%SrO (mol%) by sol-gel and investigate its potential use as a biomaterial. Two samples (BGC blank and BGC-5%Sr) were synthesized and characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and elemental carbon analysis by the combustion method. Scanning electron microscopy (SEM) was used to investigate the morphology of the bioglass-ceramics, while MTT assay of cell viability was used for in vitro characterization. The obtained silicon dioxide was amorphous and presented a small carbon content. Also, the bioglass-ceramics showed main phases with Si, Ca, Na, and Sr on their structure. Both samples were not cytotoxic against peripheral blood mononuclear cells (PBMC), and the incorporation of 5% SrO improved biocompatibility.

Cocos nucifera L. is a palm tree of paramount importance in the food and chemistry industries, although over 50% of its biomass is discarded as waste. The aim of the study is to investigate different pretreatments in to coconut husks (CH), based on acid, alkaline, ionic liquid (IL), and peroxidative, in order to produce fermentable sugars. Severity factors were calculated for pretreatments; values ranged from 0.3 to 1.7 for peroxide, from 0.01 to 1.4 for alkaline, from 1.4 to 2.8 for acid and from 2.0 to 3.0 for ionic liquid. Pretreatments were optimized (time and temperature) to maximize the sugar yield and to remove the total lignin after acid hydrolysis. Reducing sugar yield (70%) was higher when CH waste was alkaline-pretreated for 2 h at 76.21 °C. The highest lignin removal rate was recorded when alkaline (21.4%) and peroxide solutions (27.2%) were used. The IL did not increase sugar yield and was not effective in lignin removal. These outcomes were confirmed through infrared spectroscopy, whereas scanning electron microscopy showed increased biomass porosity during alkaline, acid and peroxide pretreatments. The IL showed little and non-significant changes. The crystallinity index notably increased after each pretreatment; besides, it was directly associated with sugar content.

The aims of the current study are to investigate the composition of biomass from baru processing and to explore the feasibility of valuing it through the development of bioproducts such as fermentable sugars, furanics and biochar. Baru (Dipteryx alata Vog.) waste (endocarp and mesocarp) has great energetic potential to produce bioproducts due to its chemical composition. Proximate analyses applied to such waste have found low favorable moisture and ash content in it. Bioproduct characterizations after acid hydrolysis have shown that baru endocarp and mesocarp biomass can enable a range of value-added products in biorefinery concepts such as furfural and 5-hydroximetylfurfural (20.0 and 1.5% yield, respectively), and high sugar content (approximately 19.15 and 38.40%, respectively). Pyrolysis processes also present high biochar content (ca. 48%), with satisfactory characteristics to be used as fuel, as well as calorific value higher than 30 kJ g-1.

Rice husk ashes are a potential source of pollution, thus there is continued interest in its recycling. An environmentally friendly solution is its conversion into products such as aluminosilicates that are designed for use as fertilizer. Aluminosilicates that present a high cationic exchange capacity becomes an excellent material to be used in soil for accumulating and liberating nutrients slowly to the plants. The aim of this study is to investigate the effects of the alkali concentration in the cationic exchange capacity of an aluminosilicate obtained from rice husk ashes. The obtained products were characterized by X-ray diffraction, scanning electron microscopy, atomic absorption spectroscopy, and cationic exchange capacity. The particles that were produced are composed of crystals smaller than 5 μm. The experimental conditions employed in this work produced a semi-crystalline aluminosilicate with a high cationic exchange capacity. The alkali concentration used had an influence on this property.

This work investigates the influence of reaction time (ranging from 12 to 96 h) on the characteristics of zinc stannate (Zn2SnO4) nanoparticles obtained by the hydrothermal method at 200°C. The nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), surface area measurements (BET) and infrared spectroscopy (IR). The results showed that the reaction time influenced the properties of Zn2SnO4 nanoparticles. The product presented a pure crystalline phase with mean particle size about 20 nm and BET surface area ranging from 34 to 43 m².g-1.