| Luteolin(3',4',5,7-tetrahydroxyflavone,CASRN:491-70-3)is a type of flavonoid which widely exists in many plants.Luteolin has many bioactivities including antioxidant,anti-inflammatory and anti-tumor properties.It can mainly be obtained by two ways.Firstly it can be extracted from natural herbs directly using organic solvents,but only a little amount of luteolin can be obtained.Secondly,it also can be obtained by semi-synthesis by rutin.However,no matter which way mentioned above was used,a large mount organic solvent was used which has bad effects on environment.Room temperature ionic liquids(RTILs)are molten salts which consist entirely of ions,have melting points below 100?and exhibit extremely low vapor pressures below their temperatures of thermal decomposition,good stability and good capacity of solubility.RTILs represent a new kind of liquid materials with unique property profiles which are superior to most organic solvents.In the last decades,RTILs received great interests in different fields.Therefore,we have seeked the possibility to place organic solvent by ionic liquids during the production process of luteolin.The main research contents and results are as follows:(1)"Home-made" equipment was made to measure the solubility of potassium chloride in water at 293-343 K and compared with the published solubility data,the average relative uncertainty was less than 1%.So the"home-made" equipment is reliable to measure solubility data.Solubilities of luteolin in ILs C4mimN03,C4mimBF4,C4mimPF6,C4mimNTF2,C6mimBF4,C6mimPF6 and C4pyBF4 and solubilities of rutin in C4mimN03,C4mimBF4,C6mimBF4 and C4pyBF4 were measured by "home-made" equipment mentioned above.As the solubility data determined shows,with the rising temperature,the solubilities of luteolin and rutin increase in selected ILs;solubilities of luteolin in ionic liquids increases as:C4mimN03>C6mimBF4>C4pyBF4>C4mimBF4>C4mimPF6>C4mimNTF2>C6mimPF6 and solubilities of rutin in ionic liquids increases as:C4mimNO3>C4pyBF4>C4mimBF4>C6mimBF4.Compared with the solubility data of luteolin,solubilities of luteolin in ionic liquids were larger.Solubilities determined were correlated by dual-parameter equation,three-parameter equation and ?h equation successfully.The average relative deviations were lower than 7%.(2)A statistically based optimization strategy is used to optimize the extraction process of luteolin from peanut hull by aqueous solution of C4mimNO3.The effects of concentration of C4mimN03.extraction temperature and solid-liquid ratio on extraction of luteolin were studied by experiments designed by the central composite design(CCD).As the results shows,second order models for concentration of luteolin in extracting solution and extraction efficiency of luteolin are expressed as a function of concentration of C4mimNO3,extraction temperature and solid-liquid ratio;extraction temperature has the largest impact for the two response values;the models obtained give the optimized extraction parameters of solid-liquid ration of 5.00,extraction temperature of 80? and concentration of C4mimNO3 of 56.33%;the confirmatory test with these optimum parameters give the concentration of luteolin of extracting solution of 0.854 mg-mL-1 and extraction efficiency of luteolin of 52.37%.And compared with the predicted values,the relative deviation is 1.3%and 4.6%,respectively.(3)The distribution of luteolin between aqueous solution of C10mimCl and[C12H25(CH3)3N]Cl and ethyl acetate was determined.The effects of the concentration of ionic liquids,extraction temperature,phase ratio,extraction time,the concentration of luteolin and the pH value of the extraction agents on distribution ratio of luteolin were investigated by HPLC.As the results show,the concentration of ionic liquids,extraction temperature and the pH value of the extraction agents have great effects on the distribution ratio.As the results shows,optimum conditions is concentration of[C12H25(CH3)3N]Cl of 30%,extraction time of 2 h,extraction temperature of 303 K,phase ratio of 2 and concentration of substrate of 0.5 mg-mL-1.From the effect results of extraction temperature,we can conclude that the enthalpy values of extraction processes are negative and the whole processes are exothermic when 30%C10mimCl and[C12H25(CH3)3N]Cl were used as extraction agent;however the enthalpy values of extraction processes are positive and the whole processes are endothermic when C4mimBF4 and C4pyBF4 were used as extraction agent;extraction mechanism was simply studied by the comparison of heat effect of two different extraction system.From the effect results of pH value of 30%C10mimCl and[C12H25(CH3)3N]Cl,we can conclude that chemical force is one of the driving forces in this extraction system.(3)Extraction of luteolin by ionic liquid with silver salt complexing with luteolin was initially investigated. |
PDF Full Text Request