Chemical structure and characterization of bio-oils isolated from walnut shells by different processes

Abstract

In this study, content analyses of the products obtained by pyrolysis and extraction of walnut shells were performed with some advanced analytical methods such as GS-MS, LC/MS-MS, and FTIR. In LC-MS/MS analyses. The presence of phenolic compounds in the pyrolysis liquid and extract liquid of walnut shells was determined using 41 standards. The obtained LC-MS/MS analysis results were compared, and it was found that the type and amount of phenolic compounds in the extracted liquid were more than the type and amount of phenolic compounds in the pyrolysis liquid. As a result of 41 phenolic standards investigations, the presence of a total of 10 phenolic compounds in liquids was detected and 2 of these compounds were detected in the pyrolysis liquid and 8 in the extracted liquid. As phenolic compounds, catechin (770.75 µg/g extract), hydroxy benzaldehyde (140.78 µg/g extract), and vanillic acid (114.95 µg/g compounds) were detected in the walnut extract. The existence of the compounds was supported by FTIR analyses of liquids obtained as a result of two different processes. By GC-MS analysis, linoleic acid methyl ester (44.01%), stearic acid methyl ester (14.93%), palmitic acid methyl ester (24.67%), linolenic acid and methyl ester compounds were detected in walnut shell extract liquid. GC-MS analysis of the pyrolysis liquid showed that compounds such as stearic acid methyl ester (18.97%), palmitic acid methyl ester (18.10%), o-xylene (12.17%), and o-ethyl toluene (8.14%) were formed as a result of pyrolysis. The findings revealed that walnut shell pyrolysis liquid product and extract contain very different phenolic, acid, and ester compounds. A concrete result was revealed about the use of the products obtained in this study in different areas.