Study on Extracting Lignin from Oil-Tea Camellia Fruit Shells with Deep Eutectic Solvent and Its Structural Characteristics
In order to enhance the value of lignin in oil-tea camellia fruit shells and achieve the high-value utilization of waste resources from Camellia processing.Under the conditions of optimizing the process:oil bath temperature of 160℃,treatment time of 6 hours,solid-liquid mass ratio of Camellia oleifera shell to deep eutectic solvent(DES)of 1∶10,and mass ratio of DES to H2O of 10∶1,four types of DES were used to treat abandoned Camellia oleifera shell,including choline chloride urea(ChCl-U),choline chloride urea H2O(ChCl-U-H),choline chloride urea ethylenediamine(ChCl-U-E),and choline chloride anhydrous oxalic acid(ChCl-OA).The effects of DES on lignin in oil-tea camellia fruit shells were investigated.The extracted lignin structures were analyzed.The results showed that the extraction rate of lignin was the highest after ChCl-U-E treatment,reaching 84.40%.The proton(H+)dissociation from the hydrogen bond donor in DES promoted the cleavage of unstable ether bonds between lignin phenylpropane units,forming small molecular substances and introducing phenolic hydroxyl groups,methoxy groups,and hydroxymethyl groups.The extracted lignin has a lower molecular weight,reduced steric hindrance,and increased activity.The extracted lignin is mainly composed of guaiacyl propane units,with a small amount of p-hydroxyphenyl propane units.The basic unit structure is relatively intact.This study provides a theoretical basis for preparing lignin-based phenol-formaldehyde resins and other aromatic compounds.
oil-tea camellia fruit shellsdeep eutectic solventligninextraction rate
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