Ultrasonic or Microwave Cascade Treatment of Medicinal Plant Waste

Abstract

In this study, we present a strategy for valorizing lignocellulosic wastes (licorice root and willow bark) that result from industrial extraction of active principles using water as green solvent and aqueous NaOH solution. The wastes were submitted to severe ultrasound (US) and microwave (MW) treatments. The aim of these treatments was to extract the remaining active principles (using water as a solvent) or to prepare them for cellulose enzymatic hydrolysis to hexoses (performed in an NaOH aqueous solution). The content of glycyrrhizic acid and salicin derivatives in licorice root and willow bark wastes, respectively, were determined. The best results for licorice root were achieved by applying the US treatment for 5 min at 25 °C (26.6 mg glycyrrhizic acid/gDM); while, for willow bark, the best results were achieved by applying the MW treatment for 30 min at 120 °C (19.48 mg salicin/gDM). A degradation study of the targeted compounds was also performed and showed good stability of glycyrrhizic acid and salicin derivatives under US and MW treatments. The soluble lignin concentration prior to enzymatic hydrolysis, as well as the saccharide concentration of the hydrolyzed solution, were determined. As compared with the MW treatment, the US treatment resulted in saccharides concentrations that were 5% and 160% higher for licorice root and willow bark, respectively.

Environmental Protection and Superior Recovery of Vegetal Waste and Biomass, Major objectives in the Applied Research Activity

“…From the analysis of the following vegetable wastes: willow bark waste, passionfl ower waste, momordica waste, liquorice waste, mint waste, scrap metalsmith waste and Echinacea waste, by removing soluble lignin, followed by enzymatic hydrolysis of the substrate, high values for reducing sugars were determined for willow bark waste and liquorice waste [3]. These wastes can be used with priority to obtain compost, substrate for fungus-controlled crops or as solid vegetable fertilizer for newly established crops, due to the rich content of nutrients.…”

“…From the analysis of the active compound from licorice waste (glycyrrhizic acid), it was found that, through industrial extraction, the extraction yield of the active principle is 82% [3]. This licorice waste contains 18% active substance and the industrial extraction can be resumed, through a new extraction, by adding a fresh solvent, after which the fractions obtained will be brought together for concentration.…”

Wastewater Treatment with the Natural Sorbents from the Arctic

“…Various modifications reduce water absorption and enhance sorption activity [18,19]. The most popular methods for sorbents modifying and activating are as follows: the heat treatment (different methods of heating, combustion, or hot steam) [20,21]; the methods of physical and chemical influence on the sorbent or a mixture of sorbent and sorbate (microwave irradiation MV, radiation exposure, ultrasonic, and other) [19,[22][23][24][25]; and processing with reagents (solutions of salts, alkalis, or acids), which can be combined with Water 2022, 14, 4009 2 of 10 heating [16,26]. The main criteria for the choice of modification methods are efficiency, economics, safety, and manufacturing.…”