HPLC-UV analysis was used to evaluate the enzymatic degradation characteristics of tyrosol acyl esters (TYr-Es) and alkyl gallates (A-GAs). Among various hydrolytic enzymes, TYr-Es can be hydrolyzed by pancrelipase, while A-GAs cannot be hydrolyzed by pancrelipase. Interestingly, carboxylesterase-1b (CES-1b), carboxylesterase-1c (CES-1c) and carboxylesterase-2 (CES-2) are able to hydrolyze TYr-Es and A-GAs, and thus to liberate tyrosol (TYr) and gallic acid (GA). By contrast, the degrees of hydrolysis (DHs) of TYr-Es and A-GAs by CES-1b and CES-1c were significantly higher than those by CES-2. Meanwhile, the DHs of TYr-Es were much higher than those of A-GAs. Especially, the DHs firstly increased and then decreased with the increasing alkyl chain length. Besides, DHs positively correlated with the unsaturation degree at the same chain length. Through regulating carbon length, unsaturation degree and the ester bond structure, controlled-release of phenolic compounds and fatty acids (or fatty alcohols) from phenolic esters will be easily achieved.
Ruibing Bai,Junfeng Wang,Daoguang Wang,Yanqiang Zhang,Junjie Cui
The high acidity of stripping is one of the major problems that hinder the industrialization of the tributyl phosphate (TBP) + FeCl 3 system for lithium extraction from the salt lake brines with high Mg/Li ratio. In this study, a novel solvent extraction system, trialkylmethylammonium di(2-ethylhexyl)orthophosphinate ([N 1888 ][P 507 ]) + TBP + FeCl 3 , was developed to significantly reduce the difficulty of stripping and simplify the extraction process. The conditions of extraction and stripping were systematically studied in the present work. The results showed that Li + extraction efficiency could reach 61% under the optimal extraction parameters and Li + stripping ratio was 90% with a relative mild conditions of O/A = 10:1, [HCl] aq = 1.5 mol·L –1 . Also, combined with experimental results, FT-IR analysis, and UV analysis, the possible mechanisms of lithium extraction and stripping were put forward. Li + was extracted from the aqueous phase through the formation of [Li·2TBP][FeCl 4 ] adduct, meanwhile [N 1888 ][P 507 ] was just slightly involved in the extraction step. In the stripping procedure, the interaction between [FeCl 4 ] − and [Li·2TBP] + might be destroyed, and new possible complexes, [Li·2TBP] + , and [FeCl 4 ·TBP·P 507 ] 2− /[FeCl 4 ·P 507 ] 2− were formed in the organic phase. Additionally, the extraction efficiency of Li + remained above 70% while the organic phase was reused for six cycles. Compared with the traditional system, the addition of [N 1888 ][P 507 ] resulted in a slight decrease of Li + extraction efficiency (about 5%), the stripping acidity significantly reduced from 6 mol·L –1 HCl to 1.5 mol·L –1 HCl. This new extraction system showed a promising performance in selective extracting and easy stripping in lithium separation from the salt lake brines with high Mg/Li ratio.
危险品化学品经营许可证（带存储）