本文選題：咖啡因粗品 + 動(dòng)力學(xué)　； 參考：《青島科技大學(xué)》2017年碩士論文

【摘要】：針對(duì)氯乙酸為原料的咖啡因生產(chǎn)過(guò)程中,存在回收、精制工藝復(fù)雜的問(wèn)題,本文從樹(shù)脂結(jié)構(gòu)和官能團(tuán)分析入手,通過(guò)獲得大孔樹(shù)脂對(duì)咖啡因吸附的基礎(chǔ)理論數(shù)據(jù),探討工業(yè)上應(yīng)用的可行性。通過(guò)靜態(tài)吸附及解吸對(duì)比實(shí)驗(yàn),對(duì)6種苯乙烯-二乙烯苯基大孔樹(shù)脂對(duì)咖啡因的吸附性能進(jìn)行篩選,確定XDA-200型大孔吸附樹(shù)脂性能優(yōu)良,實(shí)驗(yàn)獲得最佳的樹(shù)脂用量為60g/L、溶液最優(yōu)pH為6、80%(w/w)的乙醇溶液作為解吸劑。結(jié)合不同溫度、咖啡因濃度下XDA-200型大孔吸附樹(shù)脂的靜態(tài)吸附實(shí)驗(yàn)數(shù)據(jù),發(fā)現(xiàn)其等溫線屬于典型的Ⅱ型吸附等溫線,較低的溫度更利于咖啡因的吸附;通過(guò)對(duì)吸附過(guò)程熱力學(xué)模式和吸附機(jī)理的考察,發(fā)現(xiàn)Freundlich模式可以更好地描述咖啡因在XDA-200型大孔樹(shù)脂上的吸附過(guò)程,該過(guò)程:(1)為多分子層吸附的過(guò)程,且為優(yōu)惠吸附;(2)△G0,△S0說(shuō)明該過(guò)程是自發(fā)的且固液界面處混亂度增大的過(guò)程。(3)△H均大于14kJ/mol,且在8到40kJ/mol之間,說(shuō)明有氫鍵參與的吸附過(guò)程;(4)分析不同溫度下的動(dòng)力學(xué)數(shù)據(jù),二級(jí)動(dòng)力學(xué)模式能夠?qū)υ撐竭^(guò)程更為準(zhǔn)確的描述,該吸附過(guò)程屬于快速吸附類型。通過(guò)粒內(nèi)擴(kuò)散模型對(duì)動(dòng)力學(xué)數(shù)據(jù)的擬合,表明該吸附過(guò)程受到多個(gè)吸附過(guò)程的控制。通過(guò)FTIR和XPS對(duì)吸附前后表面化學(xué)結(jié)構(gòu)分析,O(1s)的解疊圖中,O(1s)的電子結(jié)合能增加了0.5eV;FTIR譜圖中,3446.20cm-1處的酚羥基振動(dòng)峰吸收峰寬度和峰面積均有增加,進(jìn)一步表明該吸附過(guò)程是有氫鍵參與的吸附過(guò)程。考察了單因素對(duì)動(dòng)態(tài)吸附和解吸的影響,對(duì)總傳質(zhì)系數(shù)、傳質(zhì)區(qū)長(zhǎng)度、理論塔板數(shù)、理論塔板高度進(jìn)行了相關(guān)計(jì)算,確定最佳吸附柱床層高度為20cm,最優(yōu)咖啡因進(jìn)料初始進(jìn)料濃度為10mg/mL,最優(yōu)進(jìn)料速度為3BV/h;以濃度為80%的乙醇溶液70℃下解吸,解吸速度為4BV/h時(shí)效率最高,此時(shí)解析率可達(dá)92.10%。將不同樹(shù)脂填充高度(Z)下的動(dòng)態(tài)吸附數(shù)據(jù)以BDST模型進(jìn)行擬合,并分別考察Ct/C0值為0.2、0.6、0.8時(shí)時(shí)間t對(duì)樹(shù)脂填充高度Z的擬合情況,其相關(guān)性系數(shù)均大于0.98以上,表現(xiàn)出良好的相關(guān)性。將Ct/C0等于0.8下的BDST擬合直線對(duì)不同Z下的穿透時(shí)間進(jìn)行計(jì)算,并將該擬合直線所得的參數(shù)預(yù)測(cè)不同咖啡因進(jìn)料速度、不同咖啡因初始濃度下的穿透時(shí)間,模型擬合數(shù)據(jù)與實(shí)驗(yàn)數(shù)據(jù)相差較小,表明BDST模型可以較為準(zhǔn)確的描述XDA-200型大孔吸附樹(shù)脂對(duì)咖啡因溶液的動(dòng)態(tài)吸附過(guò)程。利用XDA-200型大孔樹(shù)脂對(duì)咖啡因粗品的精制工藝進(jìn)行了改進(jìn):將咖啡因粗品配制濃度為11.0mg/m L水溶液,以鹽酸調(diào)節(jié)其pH值至1~2,加入溶液質(zhì)量分?jǐn)?shù)0.5%的活性炭充分?jǐn)嚢韬筮^(guò)濾,調(diào)節(jié)濾液pH至6,完成動(dòng)態(tài)吸附后,解吸液經(jīng)蒸發(fā)、結(jié)晶、干燥后咖啡因的純度在98.74%以上,達(dá)到精品咖啡因的要求。
[Abstract]:In order to solve the problem of complex recovery and refining process in caffeine production with chloroacetic acid as raw material, the basic theoretical data of caffeine adsorption by macroporous resin were obtained from the analysis of resin structure and functional groups. The feasibility of industrial application is discussed. Through static adsorption and desorption experiments, the adsorption properties of six styrene-divinylphenyl macroporous resins for caffeine were screened, and it was determined that XDA-200 macroporous adsorption resin had good properties. The experimental results show that the best resin dosage is 60 g / L and the optimal pH value of the solution is 60 g / L and the optimal pH value is 6 ~ 80 / w) as desorption agent. Combined with the static adsorption data of XDA-200 macroporous adsorption resin at different temperature and caffeine concentration, it was found that the isotherm belongs to the typical type 鈪，

本文編號(hào)：2029091