CHNG 3 - KT QU V THO LUN3.1. Tnh cht l ha ca ht jatropha v du jatropha3.1.1. Kch thc ht jatrophaKt qu o kch thc ca 100 ht jatropha c trnh by trong Ph lc 1. T , xc nh kch thc trung bnh ca ht.100 di (X) trung bnh ca ht:=1,805 (cm)100B rng trung bnh (y) ca ht:=1,560 (cm).100B dy (z) trung bnh ca ht:=0,875 (cm).So snh kch thc ht jatropha trng Bnh Thun - Vit Nam vi ht jatropha trng n trong Bng 3.1.Bng 3.1: So snh kch thc ht jatropha trng Vit Nam v n [41]Vit Namn

di (X) ca ht1,8051,621

B rng ca ht (y) (cm)1,5601,026

B dy (z) (cm)0,7850,775

Cn c vo Bng 3.1 th ht jatropha trng Vit Nam c kch thc trung bnh ln hn so vi ht c trng n . Nguyn nhn y l do ging, iu kin th nhng, kh hu, nh hng n cht lng ca ht.3.1.2. T l khi lng nhn v v htV ht jatropha c mu en, nhn ht c mu trng. Khi lng nhn v v ht c trnh by trong Bng 3.2.Bng 3.2: Khi lng v v nhn ht jatrophaMuKhi lng nhn (g)Khi lng v (g)

1118,72581,275

2120,13079,870

3120,74579,255

4119,18080,820

5122,55077,450

miKhi lng nhn trung bnh:=120,266gamT l khi lng nhn trong ht jatropha:!.100%= 60,13%Khi lng v ht jatropha trung bnh: = 79,734gamT l khi lng v trong ht jatropha: 7 .100% = 39,87%3.1.3. Hiu sut ly trch dua. Phng php soxhletKt qu 5 ln th nghim, trch ly du jatropha bng phng php soxhlet dng dung mi ete du ha sau c trnh by trong Bng 3.3. So snh hm lng du ly trch t ht jatropha trng Vit Nam vi cc nc khc Bng 3.4.Bng 3.3: Kt qu sau 5 ln ly trch du jatropha bng phng php soxhletTh nghimKhi lng ht (g)Khi lng du sau kh lc (g)

114044,15

214047,47

314044,40

414044,36

514044,98

Khi lng du trung bnh sau 5 ln ly trch:44,15 + 47,47 + 44,40 + 44,36 + 44,98 W m=!^!= 45,07 (g)Hm lng du (Hj) c trong ht c tnh theo cng thc 2.1(trang 44):= 45107 100%=%1140Bng 3.4: So snh hm lng du ht jatropha ca Vit Nam v mt s nc [58]Ni TrngVit NamIndonesiaBangladeshn

Hm lng du (%)32,232,032,431,6

Bng 3.4. cho thy hm lng du trong ht jatropha trng Vit Nam cng tng ng vi cc ging jatropha trng cc nc ng Nam v Nam .b. p c hcTrch ly du du bang my p n mt trc vt sau 3 ln thu c kt qu c trnh by trong Bng 3.5.Bng 3.5: Kt qu p du sau 3 th nghimTh nghimKhi lng ht (kg)Khi lng du sau khi lc (kg)

151,11

251,13

351,22

Hm lng du p c tnh theo cng thc 2.2 trang 44 H2 = 1,11 + 1,13 + 1,22.1QQ% = 23,1%Hiu sut p du c tnh theo cng thc 2.3 trang 45:23 1_H, =^-.100% = 71,7%. p 32,2Hm lng du trung bnh c trong ht jatropha curcas L.l 32,2%. Tin hnh ly trch du bng phng php p c hc my p vt mt trc thu c hmlng du 23,1%. iu ny cho thy vi phng php p c hc th hm lng du trong ht cha c ly trch ht Do , cn ci tin thit b p nng cao hiu qu p du.3.1.4. Ch s axtCh s axit ca du sau p c xc nh bng phng php nh phn chun kt qu trnh by trong Bng 3.6.Bng 3.6: Ch s axit ca du sau pLnKhoi lng mau (g)Ch s axit (mg KOH/g du)

12,511,50

22,511,22

Ch s axit trung bnh ca mu du sau khi p:V X+X2 11,50 + 11,22 w ( mu/ AxXb = ~^'*11,36 (mg KOH/g du).So vi cc du nguyn liu khc th du jatropha thuc loi c ch s axit cao (Bng 3.7).Bng 3.7: Ch s axit ca mt s loi du nguyn liu.DuCanolaDunnhDu n qua s dngM c ba saDu ht ngDu ht jatropha

Ch s axit (mg KOH/g du)0,0710,601,074,230,22311,36

Theo cc ti liu, ch s axit ca du jatropha ph thuc vo ging, aieu kin canh tc, th nhng,... Cng nh nhiu loi du thc vt khc, ch s axit c th thay aoi ty theo iu kin v thi gian bo qun (Bng 3.8)Bng 3.8: Ch s axit ca du theo thi gian bo qunThi gianNgay sau khi pSau 6 thngSau 1 nm

Ch s axit (mg KOH/g du)11,3612,2113,23

S thay i ch s axit theo thi gian ca du ht jatropha l khng ng k. iu ny c ngha l du kh bn trong iu kin thng, kh b oxi ha chuyn thnh axit bo t do, thun li cho vic bo qun du v khng gy kh khn trong qu trnh sn xut.Ngoi ra, ch s axit ca du jatropha c th thay i theo k thut p du. Do my p hot ng theo cch sinh nhit do ma st nn phi cn mt lng ht ban u lm nng my. Trong qu trnh p phi theo di nhit ca my p. Nu my p qu nng cn phi tm ngh mt thi gian. Nu khng s gy ra hin tng chy du, lm tng ch s axit ca du jatropha. Thc nghim cho thy vi cc ln p khc nhau du nguyn liu c ch s axit thay i t 8,16 n 13 (Ph lc 2).Du ly trch bng phng php soxhlet thng c ch s axit nh hn phng php c hc p bng my. Ch s axit ca du jatropha c trnh by trong Bng 3.9.Bng 3.9: Ch s axit ca du sau ly trch bng phng php soxhletLnKhi lng mu (g)Ch s axit (mg KOH/g du)

12,58,16

22,58,16

Ch s axit trung bnh ca du jatropha bng phng php ly trch soxhlet dung mi ete du ha l: 8,16 (mg KOH/g du).3.1.5. Ch s it v ch s x phng haKt qu phn tch ch s it v ch s x phng ha ca du jatropha c trnh by trong Bng 3.10Bng 3.10: Ch s x phng ha v ch s it ca daujatrophaCh tiun vPhng php thKt qu

Ch s x phng hamgKOH/gDVNIII PL5:5.10158

Ch s itg ilOOgTCVN 7869:200817

Ch so lt l i lng nh gi mc bt bo ha ca m hay du. Ch s it cao th hin du hay m c cha nhiu axit bo khng no. Ch s du jatropha c xc nh l 17 (g it/lOOg du), thp hn nhiu so vi yu cu du nguyn liu dng sn xut biodiesel ca Chu u theo tiu chun EN 14214 [36] l di 120 (g it/lOOg du). iu ny cho thy rng du nguyn liu jatropha rt thch hp cho vic sn xut biodiesel. V ch s it ca du cao s nh hng n tnh cht ca nhin liu c th nh l: nhit cao, cc axit bo cha no s c kh nng trng hp to thnh polime ca glixerit dn n s hnh thnh cn cacbon v lm gim tnh bi trn ca ng c.Ch s x phng ha ca du jatropha kh cao 158 mgKOH/g du v ch s axit ca du nguyn liu ln s nh hng n qu trnh transeste ha glixerit vi ancol v xc tc kim. Hm lng axit bo trn 1 mg KOH/du d hnh thnh x phng v gy kh khn trong qu trnh tch pha sn phm. Kt qu l lm gim hiu sut ca qu trnh phn ng.3.1.6. Thnh phn axit boKt qu phn tch thnh phn axit bo trong du ht jatropha c trnh by trong Bng 3.11. Bng 3.12 so snh thnh phn axit bo ca du jatropha vi cc du nguyn liu khc.Bng 3.11: Thnh phn axit bo ca du jatrophaThnh phn axit bo% khi lng

Axit Palmitic (c16)15%

Axit Palmioleic (C16:1)1%

Axit Heptadecanoic (Ci7i)1,7%

Axit Stearic (c18)6,9%

Axit Oleic (C18;1)45,3%

Axit linoleic (c18:2)29,7%

Axit linolenic (c18:3)0,2%

Thnh phn axit bo c trong du ht jatropha ch yu l axit bo cha bo ha. Trong , axit oleic chim t l cao nht lm cho biodiesel c sn xut t du ht jatropha c im ng c thp hn so vi cc loi biodiesel c sn xut t m ng vt. Nhc im l khi nhin liu biodiesel trong bung chy, nhit cao c th b polime ha dn n vic ng cn trong bung chy, gy nght h thng bm nhin liu.Bng 3.12: Thnh phn axit bo du jatropha vi cc du thc vt nguyn liukhc.Thnh phn axit boDu jatropha(%)Du c(%)Du hng dng(%)Du nnh(%)

Oleic (C18:1)45,339,221,123,4

Linoleic (c18:2)29,710,166,253,2

Palmitic (Ci6o)15,044,0-11,0

Stearic (c18:0)6,94,54,54,0

Palmitoleic (Ci6i)1,0---

Linolenic (c18:3)0,20,4-7,8

Arachidic (C2oo)--0,3-

Margaric (Ci7o)----

Heptadecanoic (Ci7i)1,7---

Myristic (Ci4o)-1,1-0,1

Lauric (Ci2o)-0,2--

Axit bo no21,949,911,315,1

Axit bo khng no c mt ni i48,039,221,123,4

Axit bo khng no c nhiu lin kt i29,910,566,261,0

bt bo ha ca du ht jatropha c tnh bi cng thc:Z2 + 2x. -y.i2Trong ::l bt bo ha ca du.ai: l hm lng axit bo i ang xt c trong du.Xjl s cacbon ca axit bo khng no i ang xt.il s hiro c trong axit bo khng no i ang xt.Nh vy, bt bo ha trung bnh ca du ht jatropha l:A = 0,01.2 + 0,017.2 + 0,453.2 + 0,297.3 + 0,002.4 = 1,859Thnh phn axit bo trong du ht jatropha ch cha cc axit bo thng thng, khng c s hin din ca cc nhm chc khc trong mch cacbon ca axit, aieu ny rt thun li cho vic sn xut biodiesel. Cc axit bo trong du ht jatropha c mch cacbon t c6 n c18. di mch cacbon v s lng lin kt i trong du u nh hng n tnh cht l ha ca du nguyn liu. Du nguyn liu c t axit bo khng no v nhiu axit bo no l iu kin tt nht cho vic sn xut biodiesel lm nhin liu. Du nguyn liu c nhiu axit bo khng no th to ra este metyl c bn oxi ha thp nh: du nnh, du hng dng. Du nguyn liu c bt bo ha cao th c im ng c ln v tnh cht chy km c th ng rn (du c) nhit thp. Du nguyn liu c tnh cht trn thch hp cho cc vng c kh hu nng. Cn c vo Bng 3.12 cho thy rng: hm lng axit bo c mt lin kt i trong du jatropha 48%, axit bo khng no c nhiu lin kt i 29,9% v axit bo no 21,9%. Thnh phn axit bo khng no c mt lin kt i c trong du ht jatropha cao hn cc loi du khc nh: du c, du hng dng. Axit bo ch yu trong du ht jatropha l: axit oleic, axit linoleic, axit palmitic v axit stearic. Trong , axit oleic chim t l nhiu nht 45,3%, k n l axit linoleic 29,7% . So vi cc loi du thc vt khc th du ht jatropha c hm lng axit oleic cao hn du c, du da, du hng dng, du nnh. Theo tiu chun Chu u hm lng axit linolenic trong du nguyn liu sn xut metyl este ca cc axit bo (FAME) khng c vt qu 12% v axit bo c t 4 lin kt i tr ln khng c vt qu 1%. Cn c vo Bng 3.12 th du ht jaopha ch c hm lng axit linolenic 0,2%, thp hn nhiu so vi du c v du nnh.3.2. Qu trnh este ha h ch s axt ca du3.2.1. nh hng ca t l metanol/duDu nguyn liu c ch s axit 11,98 mg KOH/g du. Mu du mi ln th nghim l 30 gam, metanol c kho st theo t l khi lng t 6% n 12%, xc tc l H2S04 c (1% khi lng du), nhit thc hin phn ng 60c trong bnh iu nhit c khuy t, thi gian thc hin phn ng l 60 pht. Sau khi thc hin phn ng este ha ra sn phm bng nc loi axit H2S04 ra khi sn phm, ri lm khan nc bng Na2S04 khan. Tin hnh xc nh ch s axit bng cch chun theo phng php AOCS Cd 3d-63 (1997). Mi mu c tin hnh 2 ln sau ly kt qu trung bnh, kt qu th nghim c th hin trong Bng 3.13 v Hnh3.1.Bng 3.13: Kt qu chui th nghim thay i t l khi lng metanol/du (xc tcH2SO4 1%, 60c, 60 pht)T l khi lng metanol/ du (%)Ch s axit (mg KOH/du)

62,91

81,35

100,75

120,45

6789101112T l khi lng metanol/du (%)5050505C 3322110 1PS/HOXSSnCQ} mlo0 2U

Hnh 3.1: S ph thuc ca ch s axit du jatropha sau giai on 1 theo t l metanol/du (xc tc H2S04 1%, 60c, 60 pht)Trong iu kin th nghim nh nhau khi tng lng metanol ln th qu trnh chuyn ha axit bo t do thnh metyl este c hiu sut cng ln v ch s axit ca du thu c cng thp. V phn ng este ha l phn ng thun nghch nn khi tng hm lng metanol th cn bng chuyn dch theo chiu to ra este cng nhiu, tc l hiu sut ca qu trnh chuyn ha cng ln. Trong khong hm lng metanol kho st th 12% cho ra sn phm du jatropha c ch s axit thp nht.3.2.2. nh hng ca nng xc tc H2SO4Cc th nghim kho st nh hng ca hm lng xc tc H2S04 c thc hin vi cc mu 30 gam du (ch s axit 12,2 mg KOH/g du), khi lng metanol 3,66g (tng ng vi t l khi lng 12%) nhit 60oc trong thi gian 60 pht v hm lng xc tc H2S04 thay i 1%;1,2%; 1,25%; 1,5% khi lng/du. Mi th nghim tin hnh 2 ln v ly kt qu trung bnh. Kt qu th nghim c th hin Bng 3.14 v Hnh 3.2.Bng 3.14: Kt qu chui th nghim thay i t l khi lng ^SOVdu (t l khi lng metanol/du 12%, 60c, 60 pht)T l khi lng H2SO4/ du (%)Ch s axit (mg KOH/g du)

1,000,69

1,200,53

1,250,57

1,500,82

Hnh 3.2: Anh hng ca t l khi lng H^SCVdu.Trong iu kin thay i t l xc tc H2S04 th hu nh ch s axit ca du jatropha sau x l thay i khng ng k. V H2S04 ng vai tr l cht xc tc nn khng nh hng n chuyn dch cn bng m lm cho phn ng nhanh chng t trng thi cn bng. t l xc tc l 1,2% th ch s axit h c l thp nht, tuy nhin do hin tng x phng ha nn thi gian ra sn phm rt lu.3.2.3. nh hng ca thi gian thc hin phn ng este haTin hnh th nghim vi thi gian thay i t 20 - 70 pht. Khi lng mu du l 30 gam, ch s axit ca du l 12,21; t l khi lng metanol/du l 12%, t l khi lng xc tc H2S04/du l 1%. Kt qu th nghim c trnh by Bng3.15 v Hnh 3.3.Bng 3.15: Kt qu chui th nghim theo thi gian phn ng este ha.(t l khi lng metanol/du 12%, t l khi lng H2S04/du 1%, 60C)Thi gian (pht)Ch s axit (mg KOH/g du)

202,59

301,68

401,11

501,15

601,07

700,84

l-S/H XB[ DBS :9. quHI slo 0 ,

Trng H Khoa hc T nhin - Lun vn Thc s Ha hc - 2010UBtp UIB TIBS JQQ B01J 9S9SUBJ Sun UBqd U9p DB onx Bo ujonq quy quH

Nguyn Mng Hong#% 4nBp/HOKN[ Bttii OIPI 311SIeII60Z/0

Hiu sut (HBDF)%0S090Z.0806s -I - - Y I

HObN[ anx no Su^Jiq quy010-3I BH s OBII UBA uni-U9IU ni oq BOI^ HQ Sumith nghim c trnh by Bng 3.18 v Hnh 3.7. Sn phm sau phn ng yn tch pha 8 gi, tch lp glyxerin v ra sn phm, tin hnh sc k bn mng ta thu c kt qu hnh 3.8.Bng 3.18: Cc thng s phn ng transeste ha iu kin mNa0H:n^u = 0,75%,60c, 60 pht.T l mol metanol/duThigiantchpha(gi)Khilngglixerol(gam)Thtchncra(ml)KhilngBDFtrcra(g)Khi lng BDF sau ra v lm khan(g)Hiu sut phn ng transeste ha (%) HbdfM t sn phm

5:185,1220028,7722,6175,02Mu vng hi m

6:185,5520029,2723,0376,42Mu vng hi m.

7:186,5920028,3323,0076,32Mu vng hi m

8:1107,5520028,3622,8675,85Mu vng m

9:1107,8822528,5322,8575,82Mu vng nht

T l mol metanol/du% aH) ns