Valorization of loquat seeds by hydrothermal carbonization for the production of hydrochars and aqueous phases as added-value products

In the framework of circular bio-economy, waste loquat seeds were utilized for the production of two added-value products. The seeds were hydrothermally carbonized at a temperature range of 150-250 °C and time range 2-6 h and the resultant hydrochars and aqueous phases were characterized using various methods. The optimum higher heating value of 30.64 MJ kg-1, ash content of 1.99 wt % and alkali index of 0.05 were achieved for the hydrochar prepared at 250 °C and 6 h, establishing its suitability for energy-related applications. The aqueous phase obtained at 250 °C and 6 h achieved 90% scavenging of the 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical and had a IC50 value of 43.71 μg mL-1. Principal component analysis showed that the production of phenols, ketones, alkenes and organic acids was favored at >200 °C, whereas furans and aldehydes were primarily formed at 150 °C. Conclusively, both added-value products were obtained at the same optimum hydrothermal carbonization conditions of 250 °C and 6 h treatment time. In a bio-refinery context, this has the practical implication that both bio-products be obtained simultaneously, without the need to switch between different temperatures and residence times.

Removal of imipramine using advanced oxidation processes: Degradation products and toxicity evolution

Pharmaceuticals are frequently detected in natural and wastewater bodies, and are very important in environmental toxicology because of their stable nature. Advanced oxidation methods used to remove contaminants are of great benefit, especially removing pharmaceuticals unsuitable for biodegradation. In this study, imipramine was degraded by anodic oxidation and subcritical water oxidation, which are advanced oxidation methods. The determination of degradation products was performed by Q-TOF LC/MS analysis. The genotoxicity and cytotoxicity of the degradation samples were determined by the in vivo Allium Cepa method. Among the anodic oxidation samples, the lowest cytotoxicity was obtained after using 400 mA current, and 420 min of degradation time. No cytotoxic effect was observed in any subcritical water oxidation sample. However, when 10 mM hydrogen peroxide as an oxidant was used at 150 °C and the reaction time was 90 min, the subcritical water oxidation sample showed a genotoxic effect. The results of the study showed that it is crucial to evaluate the toxicity levels of the degradation products and which advanced oxidation methods are preferred for removing imipramine. The optimum conditions determined for both oxidation methods can be used as a preliminary step for biological oxidation methods in the degradation of imipramine.

Subcritical Water Extraction of Onosma mutabilis: Process Optimization and Chemical Profile of the Extracts

The aboveground and root parts of Onosma mutabilis were extracted using subcritical water and the process was optimized with response surface methodology. The composition of the extracts was determined by chromatographic methods and compared to that of conventional maceration of the plant. The optimum total phenolic contents for the aboveground part and the roots were 193.9 and 174.4 μg/g, respectively. These results were achieved at a subcritical water temperature of 150 °C, an extraction time of 180 min, and a water/plant ratio of 0.1, for both parts of the plant. Principal component analysis revealed that the roots contained mainly phenols, ketones, and diols, with the aboveground part mostly alkenes and pyrazines, whereas the extract from maceration contained mainly terpenes, esters, furans, and organic acids. The quantification of selected phenolic substances showed that subcritical water extraction compared favorably to maceration, especially with respect to pyrocatechol (1062 as compared to 10.2 μg/g) and epicatechin (1109 as compared to 23.4 μg/g). Furthermore, the roots of the plant contained twice as much of these two phenolics compared to the aboveground part. Subcritical water extraction of O. mutabilis is an environmentally friendly method that can extract selected phenolics at higher concentrations compared to maceration.