Ni dung

Nhm 5Trn M Anh61100145ng Th Hng61101032L Thin Thy Nh61102455Nguyn c Minh Trang61103728L Trn Phng Uyn611041551Tm hiu v pha tnh Silica gel v Alumina trong sc k hp ph20-Oct-141Ni dung1. Silica gelNguyn tc, phng php iu chCu trcPhng php xc nh cu trc ca chtiu kin s dngV d ng dng thc t2. Alumina3. So snh gia Silica gel v Alumina220-Oct-142

320-Oct-14Silica gel

Cng thc phn t: SiO2.nH2O

Silica gel l nhng ht trong sut, c nhiu l xp nh c cng thc phn t SiO2.nH2O, c dng nhiu trong thc tin, v d hp ph nc, lm cht xc tc trong tng hp hu c, ha du c bit l thng dng lm pha tnh trong sc k hp ph, c sc k pha thun v pha o.3Silica gel pha thun420-Oct-14Phng php iu ch

Nguyn liu l silicat natri NaSiO3 c mang i thy gii vi acid (thng l acid H2SO4) to ortho silisic acid (acid yu). Acid c ngng t v polymer ha thu c silica gel t cc ch tiu vt l cn thit nh c cc ht vi kch c ht, th tch l rng trn b mt, din tch b mt, nh yu cu.4

Silica gel pha thun c ch haThay nhm -OH thnh cc nhm chc phenyl, cyano, amino, diol, ci thin tnh phn cc ca pha thun, tnh bn vi cc loi dung mi520-Oct-14Phng php iu chSilica phenylSilica diol520-Oct-146

Phng php iu ch20-Oct-147

Phng php iu ch

820-Oct-14Phng php iu chSilica gel pha oCho silica gel tc dng vi R-Si(CH3)2-Cl bin i silica gel ny thnh loi cht hp ph mi c tnh khng phn cc. Dy alkyl R c th l C-1, C-2, C-4, C-6, C-8, C-18. Trong thc t thng s dng C-8 v C-18.8920-Oct-14Cu trc

Gm 3 nhm chc: Silanol t doSilanol kt hpSiloxaneTm hot tnh: Si-OH Hydrogen bondsSiloxaneIsolatedhydroxylgroupsHot tnh silanol kt hp > silanol t do > siloxane. Silanol kt hp hot tnh cao do c 2 nhm cnh nhau, to lin kt chelate bn.Tm hp ph l ni silanol (Si-OH), c tnh acid, phn cc => d hp ph nhng cht c tnh base, gi cc cht phn cc li trong ct lu hn91020-Oct-14Cu trc

Khi b mt silica hp ph ncHot tnh tm hp ph gimiu chnh hot tnh bng cch iu chnh lng nc

Khi hp ph nc: nc ph hy lin kt hydro ca cc nhm silanol kt hp v to lin kt hydro mi vi cc nhm silanol => gim hot tnh ca tm hp ph10

20-Oct-1411Tuy nhin, khi un nng n nhit cao, khong trn 400oC th silical gel mt hot tnh vnh vin do 2 nhm OH k nhay tch nc, to ni ether, hnh thnh siloxane.11

1220-Oct-14Cu trcSilica gel pha o

B mt silica pha o l nhng nhm chc khng phn cc => gi nhng hp cht km phn cc v dng pha ng phn cc nh nc, methanol12Xc nh din tch b mt v phn b l xp: BET (thng s dng hp ph kh Nit 77K)Phng trnh BET:

SBET = Xm.Am.N.10-18 (m2/g) Xa= hp ph ca Nit (moles/gam cht hp ph)Xm= hp ph n lp ca Nit (moles/gam cht hp ph)C l hng s, N l hng s AvogadroAm khi lng phn t Nit1320-Oct-14Phng php xc nh cu trc

Xc nh s nhm silanol Si-OH: Ph IR1420-Oct-14Phng php xc nh cu trc

Peak (cm-1)Band assignment3700-3550OH stretch silanol groups3400-3500OH stretch hydrogen boded silanol groups4540Combination band OH stretching and bending silanol groups5265Combination band OH stretching and bending water molecules6800-7300Overtones of OH stretch silanol groups and hydrogen bonded silanol groupso cn hng ngoiTable 1. Mid-IR and NIR Band assignments for water adsorbed silicagel samples.1520-Oct-14Phng php xc nh cu trcXc nh s nhm silanol Si-OH: phng php Deuterium exchange (DE)Xc nh nng ca nhm hydroxyl trn b mtDa trn s trao i gia D2O vi nhm -OH trn b mt silica gelDa vo nng [H]/[D] xc nh c s nhm OH1620-Oct-14Phng php xc nh cu trc

Xc nh kch thc ht v kch thc l xp ca silica gel: phng php knh hin vi in t qut (SEM)1720-Oct-14Phng php xc nh cu trc1820-Oct-14

Phng php xc nh cu trcKh nng hp ph nc ca Silicagel

1920-Oct-14Phng php xc nh cu trc20-Oct-1420iu kin s dngSILICA GEL PHA THUNSILICA GEL PHA OCn hot ha trc khi s dngKhng sy qu lu trnh lmmt nhm silanol bt hotTy cht cn phn tch m hot ha silicagel khc nhauKhng cn hot ha trc khi s dngTh t ra gii cc cht: nhm COOH alcol/phenol amin ether/aldehyde cetone hp cht halogen alkanKchthc ccl l 40, 60v 100 , trong Si-60 dng nhiu nht- Khi lng ring xp t 0,4-0,6 g/cm3, nhiu nht l 2,2 g/cm3i vi sc k ch ha s dng trong PTN: thng dng loi c kch thc 15-25 m, 25-40 m hay 40-63 mSilica gel c gn mt chui carbon di thng l 18C (C-18) hay 8C (C-8): SiOSini Carbon20-Oct-1421SILICA GEL PHA THUNSILICA GEL PHA OTu theo vic chn dung mi dng tch cc hp cht base (alkaloid) hay hp cht a du. Phn tch cc cht c phn cc gn vi n. Silica gel l s la chn tt nht lm pha tnh khi phn tch cc cht c khi lngphn t nh (< 2000 Da)Dung dch thn nc c th i quaH thit lp cn bng nhanh chngKh nng tch ca silica gel tt hn khi tm n bng dung dch AgNO3 10-12%, dung dch acid boric, ammoniac, dung dch m phosphateTch tt i vi cc cht phn cciu kin s dng

V d20-Oct-1422V d

20-Oct-1423V d20-Oct-1424

20-Oct-1425Alumina

Cng thc phn t: Al2O3Tn ti dng tinh th mu trng, nhiu l xp, c nhiu kch thc khc nhau: dng bt, dng ht to/nh2520-Oct-1426Phng php iu chMui Al thy gii to kt ta keo trng Al(OH)3 nhit phn to alumina Al2O3Al(NO3)3 + 3NH3 + 3H2O Al(OH)3 + 3NH4NO3

Al(OH)3 Al2O3 + H2O C th iu chnh pH ca dung dch phn ng sn xut ra ht alumina vi b mt c tnh acid, tnh kim, hay trung tnh.

26

20-Oct-1427Phng php iu ch

2820-Oct-14Cu trcTy thuc vo s phn hy nhit ca aluminium hydroxides v oxyhydroxides nhiu trng thi tinh th khc nhau: , , , , , , , -Al2O3 l trng thi bn nhit ng nht ca alumina tt c nhit v cng l sn phm cui cng ca cc nhm oxide sau khi phn hy nhit-Al2O3 li l dng c nng lng b mt thp, din tch b mt cao so vi th tch khi ca tinh th => thch hp lm cht xc tc hay hp ph282920-Oct-14Cu trc

Cu trc ca -Al2O3

Tm hot tnh: Al3+, O2-Hot tnh gim khi Al2O3 ht mAl: lin kt mu vng, O: lin kt mu (s la m k hiu s lin kt, ch a/b k hiu cho ci v tr tng i ca lin kt trong tinh th)

293020-Oct-14Cu trc

Al3+: acid Lewis, in tch dng hp ph cc cht giu electron (nh aren hay alcen)Bng: Nng lng ta ra ca Al khi hp ph COAlIIIAlIVbAlIVaEads-74-46-34O2-: base Lewis hp ph cc cht cho protonKh nng hp ph ca cc tm O: O2b > O2a > O3b > O3a(PDOS technical analysis)Eads l nng lng ta ra khi hp ph, Eads < 0, cng m th qu trnh hp ph din ra cng mnh, kh nng hp ph cng tt

30

Xc nh s nhm -OH xung quanh nguyn t Al: Ph IR

3120-Oct-14Phng php xc nh cu trcCc mu c kim tra trong mi trng chn khng nhit 150C. Ph c ghi tn s 5000-600 cm-1. Mi mu c qut 32 ln phn gii quang ph 4 cm-1. hp th phn nh s thay i trong cc nhm hydroxyl v cc nhm hydroxyl xut hin trong c hai nh hng ngoi v thay i v s lng sng.31

Xc nh kch thc tinh th: phng php knh hin vi in t qut (SEM)3220-Oct-14Phng php xc nh cu trcTo ra nh vi phn gii cao ca b mt mu vt bng cch s dng mt chmin t(chm cc electron) hp qut trn b mt mu. Vic to nh ca mu vt c thc hin thng qua vic ghi nhn v phn tch cc bc x pht ra t tng tc ca chm in t vi b mt mu vt.3220-Oct-1433

Phng php xc nh cu trc

20-Oct-1434Tm ra hnh th mng c s v cc v tr ca nguyn t Al, O: phng php nhiu x tia X XRD Phng php xc nh cu trcChmtia Xnhiu xtrn cc mttinh thcacht rndo tnh tun hon cacu trc tinh thto nn cc cc i v cc tiunhiu x.K thut nhiu x tia X(thng vit gn lnhiu x tia X) c s dng phn tchcu trccht rn,vt liu343520-Oct-14iu kin s dngMun hot ha alumina sy loi b lng nc hp ph i.

Alumina c nhiu c ht, ht cng b kh nng hp ph cng cao.

Trong sc k, c 3 dng alumina: trung tnh, acid, base.

xp ca alumina khong 0,9 g/cm3 n 4,0 g/cm3.3620-Oct-14iu kin s dngAlumina phn tch tt cc cht phn cc yu n trung bnh, thng dng phn tchcc hpcht thm (c ilc mnhvi OH phenol)v cc HC ng phn ca n.

Cn dng tch: hydrocacbon, alkaloid, cht mu thc phm, lipid, vitamin, carotene, acid amin.

tch tt hn ngi ta x l alumina vi cc dung dch acid hoc base.3720-Oct-14iu kin s dngAlumina kim: Khi s dng vi dung mi hu c: hp thu cc cht thm, hydrocarbon bt bo ha, carotenoid, steroid, alcaloid v nhiu loi hp cht t nhin khc.

Khi s dng vi dung mi nc hoc dung dch alcol nc: c tnh trao i cng r nt hn c th hp thu cc hp cht nh: phm nhum c tnh kim, amino acid c tnh kim, cation v c.

3820-Oct-14iu kin s dngAlumina trung tnh: S dng ch yu vi cc dung mi hu c, thch hp tch cc cht d b hng.

Alumina acid: Dng tch cc hp cht c tnh acid hoc trung tnh vi iu kin cc cht ny khng b hy hoi bi acid. Trong mi trng nc hoc alcol, alumina acid c dng nh cht trao i ion

20-Oct-1439V dS dng ct sc k cha alumina trong sc k lng vi mu th plasma nhm xc nh catecholamines.20-Oct-1440So snh Silica gel v AluminaSILICA GELALUMINAGING NHAUu s dng dng oxide.Tm hp ph mnh, s dng nhiu trong sc k hp ph. B mt c nhiu l xp nh, din tch b mt hp ph ln.KHC NHAUc iu ch bng qu trnh ng t hay ngng t t acidBn cht l nhit phn base khng tanTnh hot tnh: nhm silanol (Si-OH), c tnh acid hp ph cc cht c tnh baseTm hot tnh: Al3+ v O2-Al3+: acid lewis hp ph cc cht giu electronO2-: base lewis hp ph cc cht cho proton2 loi: Silica gel pha thun v o3 loi: alumina trung tnh, acid, base20-Oct-1441KHC NHAUC th hot ha hoc khng trc khi s dng (ty theo pha thun hay o)Nhit hot ha loi nc: 120 150oC, trn 300oC lm gim hot tnhHot ha bng cch sy loi ncNhit hot ha loi nc t 400 450oCTng nhit gim hot tnh (do to nhm siloxane)Tng nhit tng hot tnh (trong gii hn cho php) xp t 0,4-0,6 g/cm3, nhiu nht l 2,2 g/cm3 xp khong 0,9 g/cm3 n khong 4,0 g/cm3 C th lm vic trong mi trng nhim ncCh cn mt lng nh nc cng nh hng hot tnh ca AluminaKh nng hp ph mnh hn silica gel nn c th gy cc phn ng ha hc phSo snh Silica gel v Alumina20-Oct-1442Ti liu tham khoHoracio E.Bergnaand William O.Roberts, Colloidal Silica fundamentals and applications , CRC Press Taylors and Francis Group, 2006.S. Musi, N. Filipovi-Vincekoviand L. Sekovani, Precipitation of amorphous SiO2particles and their properties, BrazillianJournal of Chemical Engineering, Vol. 28, No. 01, pp. 89 94, 2011.Takashi Shirai, Hideo Watanabe, Structural properties and surface characteristics on Aluminmun Oxide powders, Nagoya Institute od Technology, 2009.J.B. Peri, A. L. Hensley, The structure of silica gel, Research and Development Department.Karen Davis, Material Review: Alumina (Al2O3), Belgium.The World of Alumina (n.d.), Alumina, modern material with varied applications. Retrieved on December 14, 2002.Larry L. Hench, Stephen Wallace, Structural analysis of water adsorbed in Silica gel, University of Florida, 1994.

20-Oct-1443Cm n thy v cc bn ch lng nghe20-Oct-1444