Cellulose yog ib qho polysaccharide sib xyaw ua ke uas muaj ntau cov glucose units txuas nrog los ntawm β-1,4-glycosidic bonds. Nws yog lub ntsiab lus tseem ceeb ntawm cov phab ntsa cell ntawm cov nroj tsuag thiab muab cov phab ntsa cell ntawm cov nroj tsuag muaj zog txhawb nqa thiab tawv. Vim yog cov saw molecular cellulose ntev thiab crystallinity siab, nws muaj kev ruaj khov thiab tsis yaj.
(1) Cov yam ntxwv ntawm cellulose thiab qhov nyuaj hauv kev yaj
Cellulose muaj cov yam ntxwv hauv qab no uas ua rau nws nyuaj rau yaj:
Muaj crystallinity siab: Cov cellulose molecular saw hlau tsim cov qauv lattice nruj los ntawm cov hydrogen bonds thiab van der Waals forces.
Qib siab ntawm polymerization: Qib ntawm polymerization (piv txwv li qhov ntev ntawm cov saw hlau molecular) ntawm cellulose yog siab, feem ntau yog txij li pua pua mus rau ntau txhiab tus glucose units, uas ua rau kom muaj kev ruaj khov ntawm lub molecule.
Hydrogen bond network: Cov hydrogen bonds muaj ntau nyob nruab nrab ntawm thiab hauv cov cellulose molecular chains, ua rau nws nyuaj rau rhuav tshem thiab yaj los ntawm cov kuab tshuaj dav dav.
(2) Cov tshuaj reagents uas yaj cov cellulose
Tam sim no, cov tshuaj reagents uas paub tias tuaj yeem yaj cov cellulose tau zoo feem ntau suav nrog cov pawg hauv qab no:
1. Cov kua dej Ionic
Cov kua ionic yog cov kua uas muaj cov organic cations thiab cov organic lossis inorganic anions, feem ntau nrog cov volatility tsawg, thermal stability siab thiab adjustability siab. Qee cov kua ionic tuaj yeem yaj cellulose, thiab lub ntsiab mechanism yog los rhuav tshem cov hydrogen bonds ntawm cellulose molecular saw. Cov kua ionic feem ntau uas yaj cellulose suav nrog:
1-Butyl-3-methylimidazolium chloride ([BMIM]Cl): Cov kua ionic no yaj cov cellulose los ntawm kev sib cuam tshuam nrog cov hydrogen bonds hauv cellulose los ntawm cov hydrogen bond acceptors.
1-Ethyl-3-methylimidazolium acetate ([EMIM][Ac]): Cov kua ionic no tuaj yeem yaj cov cellulose ntau hauv qab cov xwm txheej tsis hnyav.
2. Cov tshuaj amine oxidant
Cov tshuaj amine oxidant xws li cov tshuaj sib xyaw ntawm diethylamine (DEA) thiab tooj liab chloride hu ua [Cu(II)-ammonium solution], uas yog ib lub cev muaj zog uas tuaj yeem yaj cellulose. Nws rhuav tshem cov qauv siv lead ua ntawm cellulose los ntawm kev oxidation thiab hydrogen bonding, ua rau cov saw hlau molecular cellulose mos dua thiab yaj tau ntau dua.
3. Lub tshuab Lithium chloride-dimethylacetamide (LiCl-DMac)
Lub LiCl-DMac (lithium chloride-dimethylacetamide) system yog ib qho ntawm cov txheej txheem qub rau kev yaj cellulose. LiCl tuaj yeem tsim kev sib tw rau cov hydrogen bonds, yog li rhuav tshem cov hydrogen bond network ntawm cellulose molecules, thaum DMAc ua cov kuab tshuaj tuaj yeem cuam tshuam zoo nrog cov saw molecular cellulose.
4. Cov kua qaub hydrochloric acid/zinc chloride
Cov kua hydrochloric acid/zinc chloride yog ib qho tshuaj uas tau tshawb pom thaum ntxov uas tuaj yeem yaj cellulose. Nws tuaj yeem yaj cellulose los ntawm kev tsim cov nyhuv sib koom tes ntawm zinc chloride thiab cellulose molecular chains, thiab hydrochloric acid rhuav tshem cov hydrogen bonds ntawm cellulose molecules. Txawm li cas los xij, cov kua no yog corrosive heev rau cov khoom siv thiab muaj kev txwv hauv kev siv.
5. Cov enzymes fibrinolytic
Cov enzymes fibrinolytic (xws li cellulases) yaj cellulose los ntawm kev ua kom cov cellulose lwj mus ua cov oligosaccharides me me thiab monosaccharides. Txoj kev no muaj ntau yam kev siv hauv kev ua biodegradation thiab biomass conversion, txawm hais tias nws cov txheej txheem yaj tsis yog kev yaj tshuaj tag nrho, tab sis ua tiav los ntawm biocatalysis.
(3) Txoj kev ua kom cov cellulose yaj
Cov tshuaj reagents sib txawv muaj cov txheej txheem sib txawv rau kev yaj cellulose, tab sis feem ntau lawv tuaj yeem raug suav hais tias yog ob txoj hauv kev tseem ceeb:
Kev rhuav tshem cov hydrogen bonds: Kev rhuav tshem cov hydrogen bonds ntawm cellulose molecular saw los ntawm kev sib tw hydrogen bond tsim lossis kev sib cuam tshuam ionic, ua rau nws yaj.
Kev so ntawm cov saw hlau molecular: Ua kom cov cellulose molecular saw hlau mos dua thiab txo cov crystallinity ntawm cov saw hlau molecular los ntawm kev siv lub cev lossis tshuaj, yog li ntawd lawv tuaj yeem yaj hauv cov kuab tshuaj.
(4) Kev siv tau ntawm kev yaj cellulose
Kev yaj ntawm cellulose muaj cov ntawv thov tseem ceeb hauv ntau qhov chaw:
Kev npaj cov cellulose derivatives: Tom qab yaj cellulose, nws tuaj yeem hloov kho tshuaj ntxiv los npaj cellulose ethers, cellulose esters thiab lwm yam derivatives, uas yog siv dav hauv zaub mov, tshuaj, txheej thiab lwm yam teb.
Cov ntaub ntawv ua los ntawm cellulose: Siv cov cellulose yaj, cellulose nanofibers, cellulose membranes thiab lwm yam ntaub ntawv tuaj yeem npaj tau. Cov ntaub ntawv no muaj cov khoom siv kho tshuab zoo thiab biocompatibility.
Lub zog biomass: Los ntawm kev yaj thiab rhuav tshem cov cellulose, nws tuaj yeem hloov mus ua cov suab thaj fermentable rau kev tsim cov roj biofuels xws li bioethanol, uas pab ua tiav kev txhim kho thiab kev siv cov zog rov ua dua tshiab.
Kev yaj cellulose yog ib qho txheej txheem nyuaj uas muaj ntau yam tshuaj lom neeg thiab lub cev. Cov kua ionic, cov kua amino oxidant, LiCl-DMAc systems, cov kua hydrochloric acid/zinc chloride thiab cov enzymes cellolytic tam sim no paub tias yog cov neeg sawv cev zoo rau kev yaj cellulose. Txhua tus neeg sawv cev muaj nws tus kheej txoj kev yaj thiab thaj chaw siv. Nrog rau kev kawm tob txog txoj kev yaj cellulose, nws ntseeg tias yuav muaj kev tsim cov txheej txheem yaj zoo dua thiab zoo rau ib puag ncig, muab ntau txoj hauv kev rau kev siv thiab kev txhim kho cellulose.
Lub sijhawm tshaj tawm: Lub Xya Hli-09-2024