This article was originally published here
J Hazard Mater. September 20, 2021; 424 (Pt A): 127294. doi: 10.1016 / j.jhazmat.2021.127294. Online ahead of print.
Herbal medicine waste (DMD) is a by-product of drug factories, which is mainly landfilled for their environmental concerns. With only the contamination and concerns caused by the COVID-19 pandemic and environmental emissions in mind, the value of herbal medicine waste management and conversion to green products can be understood. In this work, the subcritical water treatment was carried out in batches in a tubular stainless steel reactor in the pressure range 0.792 to 30.0 MPa, varying the temperature (127-327 ° C) and the time (1-60 min) of extraction. This resulted in sources of new and green materials, including organic acids, amino acids and sugars. Surprisingly, at very low extraction times (less than 5 min) and high temperatures (above 277 ° C), about 99% of the HMW was efficiently converted to clean products by subcritical hydrothermal treatment. The results of the hydrothermal extraction after 5 min indicated that at low temperature (127-227 ° C), the total organic carbon in the aqueous phase increased as the residual solid phase decreased, peaking around 220 ° C. vs. Extracts soluble in acetone or the fatty phase appeared above 227 ° C and reached a maximum yield of 21% at 357 ° C. Aspartic acid, threonine and glycine were the main amino acids; glycolic acid, formic acid, lactic acid and acetic acid were obtained as the main organic acids, glucose, fructose and cellobiose were substantial sugars produced from the aqueous phase after 5 min of extraction by hydrothermal subcritical hydrolysis.
PMID: 34592595 | DOI: 10.1016 / j.jhazmat.2021.127294