ANTHOCYANIN EXTRACTION OF RED DRAGON FRUIT PEELS (Hylocereus polyrhizus) USING MACERATION METHOD

Anthocyanins present in the red dragon fruit peel (Hylocereus polyrhizus) can be used as natural dyes. An extraction procedure can be used to acquire anthocyanins. The maceration method was used to isolate anthocyanin dyes in this analysis. The aim of this study was to see how the solvent ratio affected the total anthocyanin content in the skin of red dragon fruit. This research used laboratory experimental method using descriptive analysis. The solvent ratios used were (1:30, 1:40, 1:50 and 1:60) with a mixture of distilled water with 10% citric acid as the solvent. Parameters observed were total yield, pH, residual solvent content, spesific gravity and total anthocyanin content. The best treatment was found to be red dragon fruit peel with a solvent ratio of 1:30, which produced the highest total anthocyanin content of 4.73 mg/L. This treatment resulted total yield 7.40%, residual solvent content 0.05%, spesific gravity 1.30, and pH 1.05, respectively. It was proven that the more solvent added could linearly decrease the effectiveness of anthocyanin extraction of dragon fruit peel extracts.

Influence of Thermal Annealing on the Sinterability of Different Grades of Polylactide Microspheres Dedicated for Laser Sintering

We present a comparison of the influence of the conditioning temperature of microspheres made of medical grade poly(L-lactide) (PLLA) and polylactide with 4 wt % of D-lactide content (PLA) on the thermal and structural properties. The microspheres were fabricated using the solid-in-oil-in-water method for applications in additive manufacturing. The microspheres were annealed below the glass transition temperature (Tg), above Tg but below the onset of cold crystallization, and at two temperatures selected from the range of cold crystallization corresponding to the crystallization of the α’ and α form of poly(L-lactide), i.e., at 40, 70, 90, and 120 °C, in order to verify the influence of the conditioning temperature on the sinterability of the microspheres set as the sintering window (SW). Based on differential scanning calorimetry measurements, the SWs of the microspheres were evaluated with consideration of the existence of cold crystallization and reorganization of crystal polymorphs. The results indicated that the conditioning temperature influenced the availability and range of the SWs depending on the D-lactide presence. We postulate the need for an individual approach for polylactide powders in determining the SW as a temperature range free of any thermal events. We also characterized other core powder characteristics, such as the residual solvent content, morphology, particle size distribution, powder flowability, and thermal conductivity, as key properties for successful laser sintering. The microspheres were close to spheres, and the size of the microspheres was below 100 µm. The residual solvent content decreased with the increase of the annealing temperature. The thermal conductivities were 0.073 and 0.064 W/mK for PLA and PLLA microspheres, respectively, and this depended on the spherical shape of the microspheres. The wide angle X-ray diffraction (WAXD) studies proved that an increase in the conditioning temperature caused a slight increase in the crystallinity degree for PLLA microspheres and a clear increase in crystallization for the PLA microspheres.

Stability and recovery issues concerning chondroitin sulfate disaccharide analysis

Chondroitin sulfate (CS) is a widely studied class of glycosaminoglycans, responsible for diverse biological functions. Structural analysis of CS is generally based on disaccharide analysis. Sample preparation is a key analytical issue in this case. However, a detailed study on the stability and recovery of CS-derived species has been lacking so far. We have found that for solvent exchange, in general, vacuum evaporation (SpeedVac) is much preferable than lyophilization. Moreover, in the case of aqueous solutions, higher recovery was experienced than in solutions with high organic solvent content. Storage of the resulting disaccharide mixture in typical HPLC injection solvents is also critical; decomposition starts after 12 h at 4 °C; therefore, the mixtures should not be kept in the sample tray of an automatic injector for a long time. The study, therefore, lays down suggestions on proper sample preparation and measurement conditions for biologically derived chondroitin sulfate species.

Effect of operating conditions on the hydrothermal valorisation of sewage sludge

The accelerated population growth, in conjunction with the rapid urbanisation rate, are the principal driving forces behind the augmented volumes of municipal sewage sludge generated worldwide. The traditional approaches of sewage sludge treatment, which include landfilling and agricultural application, are no longer within the realms of possibility due to rigorous regulations, deficiency in the capacity of land available and the environmental and health adversities associated with detrimental constituents of sewage sludge. The population and urbanisation advancements do not only influence the emergent volumes of sewage sludge, but they also instigate fundamental provocations to the global energy demand. The reliance on fossil fuels poses a significant threat, not only to sustainable development, however they are also hugely responsible for the cumulative carbon dioxide and other greenhouse gas (GHG) emissions that deteriorate the environment, trigger global warming and deleteriously impact the livelihood of all life on earth. In line with the quest for sustainable and renewable alternative energy sources, the thermochemical treatment of municipal sewage sludge has a triple advantage of valorising the abundant volumes of the sludge, addressing the injurious nature of conventional fuels to the environment and seeking to bridge the gap as their supply diminishes. This study followed a quantitative approach, with the purpose to convert municipal sewage to valuable bio-oils. The sewage sludge was subjected to hydrothermal liquefaction in 60 ml stainless steel batch reactors, where the effect of temperature, solvent composition, and solvent content were investigated, and all the other process parameters were maintained at a constant. The six temperatures that were explored were 220oC, 250oC, 280oC, 310oC, 340oC, 370oC. The two solvents investigated were de-ionised water (H2O) and ethanol (E) which were applied in the following compositions: 1:0, 1:1 and 0:1 (H2O:E). The five solvent contents investigated were 75%, 80%, 85%, 90% and 95%. The process yielded bio-oils, solid phase and gaseous products and an aqueous phase. Dichloromethane was used as an extraction medium. The obtained results revealed that the temperature, solvent type and solvent content had a significant influence on the yield of bio-oil produced while temperature was the most influential out of the three parameters. When temperatures approached supercritical conditions of water, a notable decline in the bio-oil yields was observed. For each temperature, the bio-oil yields initially increased until about 85% solvent content, and then slightly decreased thereafter. The highest bio-oil yields were achieved at 310oC and the best yields were obtained when the ratio of H2O and E were 1:1. This study found that the optimum operating conditions were obtained at 310oC, 85% solvent content and a 1:1 composition of H2O and ethanol; the bio-oil yields at those conditions was determined to be 40,6 wt%. The bio-oils were contained in the following order of prevalence, fatty acids, aliphatic hydrocarbons, N-containing compounds, O-containing compounds, aromatics and acid esters. Aliphatic hydrocarbons and fatty acids were the dominant functional groups. The following were the most abundant compounds in the 90 runs: heptadecane, pentadecane, eicosane, hexadecane 2,6,10,14-tetramethyl hexadecane and 9-octadecanoic acid.

Organic Aerogels Based on Epoxy Resins: Synthesis and Properties

The aim of this work was to develop methods for the synthesis of organic aerogels based on epoxy resins and to investigate their properties. Aerogels based on DGEBA-epoxy resin were obtained by CO2-supercritical drying of gel samples prepared from acetone solutions of epoxy resin with different amount of catalyst and solvents. As a result, aerogels of different density were obtained; the dependence of density on the solvent content in the samples was revealed. The aerogels were characterized by infrared spectroscopy to define the degree of conversion of the epoxy groups, by SEM to confirm nanoscale morphology of aerogels, as well as by the BET method to determine the specific surface area of the samples and its dependence on the catalyst content and curing conditions.

Starch-Based Aerogels Obtained via Solvent-Induced Gelation

In this work, the ability of several solvents to induce gel formation from amylomaize starch solubilized in dimethyl sulfoxide (DMSO) was investigated. The formed gels were subjected to solvent exchange using ethanol and dried with supercritical carbon dioxide (sc-CO2) to obtain the aerogels. The influence of starch concentration (3–15 wt%) and solvent content (20–80 wt%) on gel formation was also studied. It was demonstrated that the gelation of starch in binary mixtures of solvents can be rationalized by Hansen Solubility Parameters (HSP) revealing a crucial hole of hydrogen bonding for the gel’s strength, which is in agreement with rheological measurements. Only the addition of water or propylene glycol to starch/DMSO solutions resulted in strong gels at a minimum starch and solvent content of 7.5 wt% and 50 wt%, respectively. The resulting aerogels showed comparably high specific surface areas (78–144 m2 g−1) and low envelope densities (0.097–0.203 g cm−3). The results of this work indicate that the HSP parameters could be used as a tool to guide the rational selection of water-free gelation in starch/DMSO systems. In addition, it opens up an attractive opportunity to perform starch gelation in those solvents that are miscible with sc-CO2, avoiding the time-consuming step of solvent exchange.