nghiên cứu khả năng hấp thụ một số kim loại nặng.pdf

S ha bi Trung tm Hc liu i hc Thi Nguyn http://www.lrc-tnu.edu.vn

- 5 -

MC LC

Trang

DANH MC CC BNG ......................................................... 7

DANH MC CC HNH V, TH ...................................... 8

M U................................................................................... 9

Chng 1. TNG QUAN

1.1. nh hng ca s nhim kim loi nng ti sc kho con

ngi ............................................................................... 11

1.1.1. Ch ........................................................................... 11

1.1.2. Crom........................................................................ 12

1.1.3. ng ........................................................................ 12

1.1.4. Mangan .................................................................... 12

1.1.5. Niken ....................................................................... 13

1.2. Qu trnh hp ph ............................................................. 13

1.2.1. Hin tng hp ph .................................................. 13

1.2.2. Hp ph trong mi trng nc ................................ 14

1.2.3. ng hc hp ph ..................................................... 15

1.2.4. Cn bng hp ph - Cc phng trnh ng nhit hp

ph........................................................................... 16

1.3. Gii thiu v vt liu hp ph - B ma .............................. 19

1.4. Mt s phng php nh lng kim loi .......................... 22

1.4.1. Phng php th tch ................................................ 22

1.4.2. Phng php trc quang ............................................ 23

Chng 2. THC NGHIM V KT QU

2.1. Thit b ho cht ................................................................. 27

2.1.1. Thit b..................................................................... 27

2.1.2. Ho cht ................................................................... 27


- 6 -

2.2. Ch to v kho st mt s c trng cu trc ca vt liu

hp ph ............................................................................ 28

2.2.1. Ch to vt liu hp ph ............................................ 28

2.2.2. Mt s c trng cu trc ca VLHP ......................... 29

2.3. nh lng cc kim loi ...................................................... 31

2.3.1. Dng ng chun xc nh Cr(VI) ........................... 31

2.3.2. Dng ng chun xc nh Ni2+

............................... 32

2.3.3. Dng ng chun xc nh Mn2+

............................. 33

2.3.4. nh lng Pb2+

........................................................ 34

2.3.5. nh lng Cu2+

....................................................... 34

2.4. Kho st kh nng hp ph ca VLHP v nguyn liu .......... 35

2.5. Kho st cc yu t nh hng n kh nng hp ph ca

VLHP ................................................................................ 36

2.5.1. nh hng ca thi gian ........................................... 36

2.5.2. nh hng ca pH .................................................... 39

2.5.3. nh hng ca nng - Cn bng hp ph .............. 41

2.6. Th x l nc thi cha Cr(VI) ........................................ 45

KT LUN....................................................................................... 47

DANH MC CNG TRNH CNG B ..................................... 49

TI LIU THAM KHO .................................................................. 50


- 7 -

DANH MC CC BNG

Trang

Bng 1.1 Nng gii hn ca mt s kim loi trong nc thi cng

nghip v nc cp sinh hot............................................. 13

Bng 1.2 Mt s ng ng nhit hp ph thng dng .................... 16

Bng 1.3 Thnh phn ho hc ca b ma ......................................... 20

Bng 2.1 Th t cc dung dch dng ng chun xc nh Cr(VI) ... 31

Bng 2.2 S liu dng ng chun xc nh Cr(VI) ........................ 32

Bng 2.3 Th t cc dung dch dng ng chun xc nh Ni2+

....... 32

Bng 2.4 S liu dng ng chun xc nh Ni2+

............................ 33

Bng 2.5 Th t cc dung dch dng ng chun xc nh Mn2+

..... 33

Bng 2.6 S liu dng ng chun xc nh Mn2+

........................... 34

Bng 2.7 So snh kh nng hp ph ca nguyn liu v VLHP

i vi Cr(VI), Ni2+

, Mn2+

, Pb2+

v Cu2+

............................. 35

Bng 2.8 nh hng ca thi gian n kh nng hp ph ................. 36

Bng 2.9 Thi gian t cn bng hp ph i vi mi ion kim loi .... 39

Bng 2.10 nh hng ca pH n kh nng hp ph .......................... 40

Bng 2.11 nh hng ca nng n kh nng hp ph................... 42

Bng 2.12 Dung lng hp ph cc i v hng s Langmuir ............. 45


- 8 -

DANH MC CC HNH V, TH

Trang

Hnh 1.1 ng ng nhit hp ph Langmuir ................................. 19

Hnh 1.2 th s ph thuc ca Ccb/q vo Ccb ................................ 19

Hnh 1.3 Hnh nh cc thnh phn ho hc chnh ca b ma ............ 21

Hnh 2.1 Ph hng ngoi ca nguyn liu ........................................ 29

Hnh 2.2 Ph hng ngoi ca VLHP ................................................ 30

Hnh 2.3 nh SEM ca VLHP v nguyn liu.................................. 31

Hnh 2.4 ng chun xc nh Cr(VI) ........................................... 32

Hnh 2.5 ng chun xc nh Ni2+

............................................... 33

Hnh 2.6 ng chun xc nh Mn2+

.............................................. 34

Hnh 2.7 S ph thuc ca dung lng hp ph theo thi gian .......... 38

Hnh 2.8 S ph thuc ca dung lng hp ph vo pH dung dch .... 41

Hnh 2.9 S ph thuc ca dung lng hp ph vo nng ban u

ca cc ion........................................................................ 43

Hnh 2.10 ng ng nhit hp ph Langmuir i vi Cr(VI) .......... 43

Hnh 2.11 S ph thuc ca Ccb/q vo Ccb ca Cr(VI)......................... 43

Hnh 2.12 ng ng nhit hp ph Langmuir i vi Ni2+

.............. 44

Hnh 2.13 S ph thuc ca Ccb/q vo Ccb ca Ni2+

............................ 44

Hnh 2.14 ng ng nhit hp ph Langmuir i vi Mn2+

............. 44

Hnh 2.15 S ph thuc ca Ccb/q vo Ccb ca Mn2+

........................... 44

Hnh 2.16 ng ng nhit hp ph Langmuir i vi Pb2+

.............. 44

Hnh 2.17 S ph thuc ca Ccb/q vo Ccb ca Pb2+

............................ 44

Hnh 2.18 ng ng nhit hp ph Langmuir i vi Cu2+

............. 45

Hnh 2.19 S ph thuc ca Ccb/q vo Ccb ca Cu2+

............................ 45


- 9 -

M U

Do s pht trin khng bn vng m hin nay vn nhim ngun

nc ang tr thnh vn nn ca nhiu quc gia. nc ta, qu trnh pht

trin cc khu cng nghip, cc khu ch xut gp phn tng trng kinh t,

thc y u t v sn xut cng nghip, gp phn hnh thnh cc khu th

mi, gim khong cch v kinh t gia cc vng... Tuy nhin, bn cnh s

chuyn bin tch cc v kinh t l nhng tc ng tiu cc n mi trng

sinh thi do cc khu cng nghip gy ra. Thc t, hin nay rt nhiu nh my

cc khu cng nghip vn hng ngy thi trc tip nc thi c cha cc ion

kim loi nng vi hm lng vt qu gii hn cho php ra mi trng. Hu

qu l mi trng nc k c nc mt v nc ngm nhiu khu vc ang

b nhim kim loi nng nghim trng.

C nhiu phng php khc nhau c nghin cu v p dng

tch loi cc kim loi nng ra khi mi trng nc. Mt trong cc phng

php ang c nhiu ngi quan tm hin nay l tn dng cc ph phm

nng nghip, cng nghip lm vt liu hp ph cc ion kim loi [3,19,20].

Phng php ny c u im l s dng ngun nguyn liu r tin, sn c v

khng a thm vo mi trng cc tc nhn c hi khc.

Mt trong cc ngun ph phm cng nghip c khi lng ln nc

ta l b ma. B ma vi thnh phn chnh l cc xenluloz v hemixenluloz

rt thch hp cho vic nghin cu bin i to ra cc vt liu hp ph tch

loi cc ion kim loi nng.

Xut pht t nhng l do trn, chng ti chn ti: Nghin cu kh

nng hp ph mt s ion kim loi nng trn vt liu hp ph ch to t b

ma v thm d x l mi trng.


- 10 -

Vi mc ch , trong ti ny chng ti nghin cu cc ni dung

sau:

1- Ch to vt liu hp ph t b ma.

2- Nghin cu kh nng hp ph ca vt liu hp ph i vi Cr(VI),

Ni2+

, Mn2+

, Cu2+

v Pb2+

trong mi trng nc.

3- Th x l mt mu nc thi cha Cr(VI) ca x nghip m in

qun i bng vt liu hp ph ch to c.


- 11 -

CHNG 1

TNG QUAN

1.1. nh hng ca s nhim kim loi nng ti sc kho con ngi

hm lng nh mt s kim loi nng l cc nguyn t vi lng cn

thit cho c th ngi v sinh vt pht trin bnh thng, nhng khi c hm

lng ln chng li thng c c tnh cao. Khi c thi ra mi trng, mt

s hp cht kim loi nng b tch t v ng li trong t, song c mt s hp

cht c th ho tan di tc ng ca nhiu yu t khc nhau. iu ny to

iu kin cc kim loi nng c th pht tn rng vo ngun nc ngm,

nc mt v gy nhim. Cc kim loi nng c mt trong nc, t qua

nhiu giai on khc nhau trc sau cng i vo chui thc n ca con ngi.

Khi nhim vo c th, kim loi nng tch t trong cc m, tc ng n cc

qu trnh sinh ha (cc kim loi nng thng c i lc ln vi nhm -SH-

SCH3 ca enzim trong c th, v th cc enzim b mt hot tnh, cn tr qu

trnh tng hp protein ca c th). ngi, kim loi nng c th tch t vo

ni tng nh gan, thn, xng khp gy nhiu cn bnh nguy him nh ung

th, thiu mu, ng c,...[1,13,18]. Di y l tc ng ca mt s kim loi

nng n con ngi.

1.1.1. Ch

Ch thng c s dng trong cng ngh sn xut pin, c quy, sn

xut n v tm bo v phng x,

Ch l mt trong nhng nguyn t rt c hi i vi con ngi v

ng vt. N xm nhp vo c th sng ch yu qua con ng tiu ha, h

hp, Khi mi ngy tip xc mt lng ch cao (>10mg Pb/ngy) trong vi

tun s gy nhim c nng. n 1g Pb/ln s cht ngay. Cc hp cht hu c

cha ch c c tnh cao gp hng trm ln so vi cc hp cht v c. S


- 12 -

nhim c ch c th gy ra nhiu bnh nh: gim tr thng minh; cc bnh v

mu, thn, tiu ha, ung th,[1,9,13,16].

1.1.2. Crom

Nc thi t cng nghip m in, cng nghip khai thc m, nung t

cc nhin liu ha thch, l cc ngun gy nhim crom. Crom c trong

nc thi thng gp dng Cr(III) v Cr(VI). Cr(III) khng c nhng

Cr(VI) rt c hi i vi c th ngi, n gy nguy him cho gan, thn v

ng h hp; gy ra cc bnh v rng, ming, kch thch da,...[1,9,13,16].

1.1.3. ng

ng l nguyn t cn thit cho c th con ngi, nhu cu hng ngy

ca ngi ln khong 0,033 - 0,050mg/kg th trng. Tuy nhin, nu hm

lng ng trong c th ln th c th s b nhim c v c th gy mt s

bnh v thn kinh, gan, thn; lng ln ng hp th qua ng tiu ho c

th gy t vong [1,9,13,16].

1.1.4. Mangan

Mangan l mt trong cc nguyn t vi lng cn thit cho sc kho con

ngi trong qu trnh sinh trng v pht trin. Do mangan c hp th rt t

qua ng rut nn hu nh khng ai b ng c do n hoc ung thc phm

c cha nhiu mangan hn nhu cu cn thit (2 - 5mg/ngy). Tuy nhin, ng

c mangan vn c th xy ra, gy ri lon hot ng thn kinh vi biu hin

rung git kiu Parkinson. Cng c mt s trng hp ng c mangan l do

ngun nc ung b nhim nng mangan do r r t bi chn pin, c quy

vo ngun nc sinh hot, ung thuc c cha mangan liu cao v ko di,

hoc do tm hi nc khong c nhiu mangan thng xuyn [1,9,13,16].


- 13 -

1.1.5. Niken

Niken c s dng nhiu trong cc ngnh cng nghip ho cht, luyn

kim, in t, V vy, n thng c mt trong nc thi. Niken vo c th

ch yu qua con ng h hp, n gy ra cc triu chng kh chu, bun nn,

au u; nu tip xc nhiu s nh hng n phi, h thn kinh trung ng,

gan thn; cn nu da tip xc lu di vi niken s gy hin tng vim da,

xut hin d ng,[1,9,13,16].

Bng 1.1. Nng gii hn ca mt s kim loi trong nc thi cng

nghip v nc cp sinh hot. [12]

Stt Tn ch tiu Gi tr gii hn (mg/l)

Nc thi cng nghip Nc cp sinh hot

1 Hm lng ch 0,10 0,01

2 Hm lng crom

0,05 0,05

3 Hm lng ng

2,00 1,00

4 Hm lng mangan 0,50 0,50

5 Hm lng niken

0,20 0,10

1.2. Qu trnh hp ph

1.2.1. Hin tng hp ph

Hp ph l s tch ly cht trn b mt phn cch cc pha (kh rn,

lng rn, kh lng, lng lng). Cht c b mt, trn xy ra s hp ph

c gi l cht hp ph; cn cht c tch ly trn b mt cht hp ph gi

l cht b hp ph.

Ngc vi qu trnh hp ph l qu trnh gii hp ph. l qu trnh

i ra ca cht b hp ph khi lp b mt cht hp ph.

Hin tng hp ph xy ra do lc tng tc gia cht hp ph v cht

b hp ph. Ty theo bn cht lc tng tc m ngi ta phn bit hai loi hp

ph l hp ph vt l v hp ph ha hc [2,7,11].


- 14 -

1.2.1.1. Hp ph vt l

Cc phn t cht b hp ph lin kt vi nhng tiu phn (nguyn t,

phn t, cc ion) b mt phn chia pha bi lc lin kt Van Der Walls

yu. l tng hp ca nhiu loi lc ht khc nhau: tnh in, tn x, cm

ng v lc nh hng.

Trong hp ph vt l, cc phn t ca cht b hp ph v cht hp ph

khng to thnh hp cht ha hc (khng hnh thnh cc lin kt ha hc) m

cht b hp ph ch b ngng t trn b mt phn chia pha v b gi li trn b

mt cht hp ph. hp ph vt l, nhit hp ph khng ln [2,7,11].

1.2.1.2. Hp ph ha hc

Hp ph ha hc xy ra khi cc phn t cht hp ph to hp cht ha

hc vi cc phn t cht b hp ph. Lc hp ph ha hc khi l lc lin

kt ha hc thng thng (lin kt ion, lin kt cng ha tr, lin kt phi

tr). Nhit hp ph ha hc ln, c th t ti gi tr 800kJ/mol.

Trong thc t s phn bit hp ph vt l v hp ph ha hc ch l

tng i, v ranh gii gia chng khng r rt. Trong mt s qu trnh hp

ph xy ra ng thi c hp ph vt l v hp ph ha hc [2,7,11].

1.2.2. Hp ph trong mi trng nc

Trong nc, tng tc gia mt cht hp ph v cht b hp ph phc

tp hn rt nhiu v trong h c t nht l ba thnh phn gy tng tc: nc ,

cht hp ph v cht b hp ph. Do s c mt ca dung mi nn trong h s

xy ra qu trnh hp ph cnh tranh gia cht b hp ph v dung mi trn b

mt cht hp ph. Cp no c tng tc mnh th hp ph xy ra cho cp .

Tnh chn lc ca cp tng tc ph thuc vo cc yu t: tan ca cht b

hp ph trong nc, tnh a hoc k nc ca cht hp ph, mc k nc

ca cc cht b hp ph trong mi trng nc.


- 15 -

Trong nc, cc ion kim loi b bao bc bi mt lp v cc phn t

nc to nn cc ion b hidrat ho. Bn knh ( ln) ca lp v hidrat nh

hng nhiu n kh nng hp ph ca h do lp v hidrat l yu t cn tr

tng tc tnh in. Vi cc ion cng in tch th ion c kch thc ln s

hp ph tt hn do c phn cc ln hn v lp v hidrat nh hn. Vi cc

ion c in tch khc nhau, kh nng hp ph ca cc ion c in tch cao tt

hn nhiu so vi ion c in tch thp.

S hp ph trong mi trng nc chu nh hng nhiu bi pH. S

thay i pH khng ch dn n s thay i v bn cht ca cht b hp ph

(cc cht c tnh axit yu, baz yu hay trung tnh phn li khc nhau cc gi

tr pH khc nhau) m cn lm nh hng n cc nhm chc trn b mt cht

hp ph [2,7,11].

1.2.3. ng hc hp ph

Trong mi trng nc, qu trnh hp ph xy ra ch yu trn b mt

ca cht hp ph, v vy qu trnh ng hc hp ph xy ra theo mt lot cc

giai on k tip nhau:

- Cc cht b hp ph chuyn ng ti b mt cht hp ph - Giai on

khuch tn trong dung dch.

- Phn t cht b hp ph chuyn ng n b mt ngoi ca cht hp

ph cha cc h mao qun - Giai on khuch tn mng.

- Cht b hp ph khuch tn vo bn trong h mao qun ca cht hp

ph - Giai on khuch tn trong mao qun.

- Cc phn t cht b hp ph c gn vo b mt cht hp ph - Giai

on hp ph thc s.

Trong tt c cc giai on , giai on no c tc chm nht s

quyt nh hay khng ch ch yu ton b qu trnh hp ph [2,7,10,11].


- 16 -

1.2.4. Cn bng hp ph - Cc phng trnh ng nhit hp ph

Qu trnh hp ph l mt qu trnh thun nghch. Cc phn t cht b

hp ph khi hp ph trn b mt cht hp ph vn c th di chuyn ngc

li pha mang. Theo thi gian, lng cht b hp ph tch t trn b mt cht

rn cng nhiu th tc di chuyn ngc tr li pha mang cng ln. n mt

thi im no , tc hp ph bng tc gii hp th qu trnh hp ph

t cn bng.

Mt h hp ph khi t n trng thi cn bng, lng cht b hp ph

l mt hm ca nhit , p sut hoc nng ca cht b hp ph:

q = f (T, P hoc C) (1.1)

nhit khng i (T = const), ng biu din s ph thuc ca q

vo P hoc C (q = fT(P hoc C)) c gi l ng ng nhit hp ph.

ng ng nhit hp ph c th c xy dng trn c s l thuyt, kinh

nghim hoc bn kinh nghim ty thuc vo tin , gi thit, bn cht v

kinh nghim x l s liu thc nghim [2,7,11].

Mt s ng ng nhit hp ph thng dng c nu bng 1.2.

Bng 1.2. Mt s ng ng nhit hp ph thng dng [11]

ng ng nhit hp ph

Phng trnh Bn cht s hp

ph

Langmuir .

1 .m

v b p

v b p=

+ Vt l v ha hc

Henry .v k p= Vt l v ha hc

Freundlich 1. nv k p= , (n>1) Vt l v ha hc

Shlygin-Frumkin-Temkin 1

ln .ov C p

v am

= Ha hc

Brunauer-Emmett-Teller (BET)

( )

( )11.

. .o m m o

Cp p

v p p v C v C p

-= +

-

Vt l, nhiu lp


- 17 -

Trong cc phng trnh trn, v l th tch cht b hp ph, vm l th

tch hp ph cc i, p l p sut cht b hp ph pha kh, op l p sut hi

bo ha ca cht b hp ph trng thi lng tinh khit cng nhit . Cc

k hiu , , ,a b k n l cc hng s.

Trong ti ny, chng ti nghin cu cn bng hp ph ca VLHP

i vi mt s ion kim loi nng trong mi trng nc theo m hnh ng

ng nhit hp ph Langmuir.

Phng trnh ng nhit hp ph Langmuir c xy dng da trn cc

gi thuyt:

1) Tiu phn b hp ph lin kt vi b mt ti nhng trung tm xc nh.

2) Mi trung tm ch hp ph mt tiu phn.

3) B mt cht hp ph l ng nht, ngha l nng lng hp ph trn cc

tiu phn l nh nhau v khng ph thuc vo s c mt ca cc tiu phn

hp ph trn cc trung tm bn cnh.

Phng trnh Langmuir xy dng cho h hp ph kh - rn c dng:

m

v b.p

v 1+ b.p= (1.2)

Trong :

- v, vm ln lt l th tch cht b hp ph, th tch cht b hp ph cc i.

- p l p sut cht b hp ph pha kh.

- b l hng s.

Tuy vy, phng trnh ny cng c th p dng c cho qu trnh hp

ph trong mi trng nc. Khi c th biu din phng trnh Langmuir

nh sau:

cb

cb

maxK.C

q = q1+ K.C

(1.3)


- 18 -

Trong :

- Ccb l nng cht b hp ph trng thi cn bng.

- q, qmax ln lt l dung lng hp ph v dung lng hp ph

cc i.

- K l hng s Langmuir.

Khi nng cht b hp ph l rt nh (K.C > 1) th q qmax. Tc,

dung lng hp ph s t mt gi tr khng i khi tng nng cht b hp

ph. Khi b mt cht hp ph c bo ha bi mt n lp cc phn

t cht b hp ph.

Phng trnh (1.3) cha hai thng s l qmax v hng s K. Dung lng

hp ph cc i qmax c mt gi tr xc nh tng ng vi s tm hp ph

cn hng s K ph thuc cp tng tc gia cht hp ph, cht b hp ph v

nhit . T cc s liu thc nghim c th xc nh qmax v hng s K bng

phng php ti u hay n gin l bng phng php th.

Vi phng php th, phng trnh (1.3) c vit thnh:

cbcb

max max

C 1 1.C

q q .K q= + (1.4)

T s liu thc nghim v th s ph thuc ca Ccb/q theo cbC .

ng ng nhit hp ph Langmuir v th s ph thuc ca Ccb/q vo Ccb

c dng nh hnh 1.1 v hnh 1.2.


- 19 -

T th s ph thuc ca Ccb/q vo Ccb d dng tnh c qmax v

hng s K (max

1OM

K.q= ;

max

1tg

q= ).

Phng trnh ng nhit hp ph Langmuir c dng n gin, cho php

gii thch kh tha ng cc s liu thc nghim [2,7,11].

1.3. Gii thiu v vt liu hp ph - b ma

Nc ta nm trong vng kh hu nhit i, rt thun li cho ngnh ma

ng pht trin. Nin v sn xut ma ng 2006 - 2007, din tch ma c

nc l 310,067ha, sn lng ma thu hoch t khong 17 triu tn. Theo

quy hoch pht trin ma ng n nm 2010, sn lng ng sn xut

trong c nc phn u t 1,5 triu tn [22, 23].

Pht trin sn xut ma ng l mt nh hng ng n. Tuy nhin,

cc nh my sn xut ng cng thi ra mt lng khng nh b ma. Theo

tnh ton ca cc nh khoa hc, vic ch bin 10 triu tn ma lm ng

sinh ra mt lng ph thi khng l: 2,5 triu tn b ma. Trc y 80%

lng b ma ny c dng t l hi trong cc nh my sn xut ng,

sinh ra 50.000 tn tro [22]. Tuy l ph thi nhng trong tro v b bn li c

O

a

M

cbC

q

Ccb

q

O Ccb

Hnh 1.1. ng ng nhit hp ph Langmuir

Hnh 1.2. th s ph thuc ca Ccb/q vo Ccb


- 20 -

nhiu cht hu c. Cc cht ny sau s l nguyn nhn gy nhim mi

trng v nhim ngun nc rt nng. B ma cng c th c dng lm

bt giy, p thnh vn dng trong kin trc, cao hn l lm ra furfural l

nguyn liu cho ngnh si tng hp. Trong tng lai khi m rng ngy cng

gim, ngun nguyn liu lm bt giy, lm si t cy rng gim i th b ma

l nguyn liu quan trng thay th.

B ma chim khong 26,8 - 32% lng ma p. Trong b ma cha

trung bnh khong 50% l nc, 48 49% l x (trong ch yu l

xenluloz v hemixenluloz) 1 2% l ng [14,21]. Ty theo loi ma v

c im ni trng ma m cc thnh phn ho hc c trong b ma kh (x)

c th bin i. Hm lng % cc thnh phn ho hc chnh ca b ma c

ch ra trong bng 1.3.

Bng 1.3. Thnh phn ho hc ca b ma [14]

Thnh phn % khi lng

Xenluloz 40 50

Hemixenluloz 20 25

Lignin 18 23

Cht ho tan khc (tro, sp, protein, ) 3 5

Xenluloz: Xenluloz l polisaccarit do cc mt xch -glucoz

[C6H7O2(OH)3]n ni vi nhau bng lin kt 1,4-glicozit. Phn t khi ca

xenluloz rt ln, khong t 10000 150000u.

Hemixenluloz: V c bn, hemixenluloz l polisaccarit ging nh

xenluloz, nhng c s lng mt xch nh hn. Hemixenluloz thng bao

gm nhiu loi mt xch v c cha cc nhm th axetyl v metyl.

Lignin: Lignin l loi polyme c to bi cc mt xch phenylpropan.

Lignin gi vai tr l cht kt ni gia xenluloz v hemixenluloz.


- 21 -

S phn b xenluloz, hemixenluloz v lignin trong b ma c ch

ra trong hnh 1.3.

Hnh 1.3. Hnh nh cc thnh phn ho hc chnh ca b ma [22]

Vi thnh phn chnh l xenluloz v hemixenluloz, b ma c th

bin tnh tr thnh vt liu hp ph tt. Trn th gii c mt s nh

khoa hc nghin cu bin tnh b ma lm vt liu hp ph x l mi

trng, nh cc nh khoa hc Braxin, n , Malaixia,[19,20]. nc

ta cng c nhng cng trnh nghin cu s dng b ma lm vt liu hp

ph, tuy nhin nhng nghin cu mi ch dng s dng b ma th [3].

Trong ti ny chng ti ch to vt liu hp ph t b ma bng cch dng

anhydrit succinic hot ha b ma.

Lignin

Hemixenlulz

Xenluloz


- 22 -

1.4. Mt s phng php nh lng kim loi

C nhiu phng php khc nhau c dng nh lng cc kim

loi. Trong ti ny chng ti s dng phng php th tch nh lng

ch v ng; phng php trc quang nh lng crom, niken v mangan.

1.4.1. Phng php th tch

Phn tch th tch l phng php phn tch nh lng da trn s o

th tch ca dung dch thuc th bit chnh xc nng (dung dch chun)

cn dng phn ng ht vi cht cn xc nh c trong dung dch cn phn

tch. Da vo th tch v nng ca dung dch chun dng tnh ra hm

lng cht cn xc nh c trong dung dch phn tch.

Da theo bn cht ca phn ng chun , phng php phn tch th

tch c phn loi lm cc loi sau:

- Phng php chun axit baz (Phng php trung ha).

- Phng php chun kt ta.

- Phng php chun to phc.

- Phng php chun oxi ha kh.

nh lng Cu2+

v Pb2+

chng ti s dng phng php chun

to phc vi thuc th l EDTA.

EDTA (axit etylen iamintetraaxetic, H4Y) l thuc th c ng dng

rng ri trong phng php chun to phc . Phng php chun s

dng EDTA lm thuc th c gi l phng php chun complexon.

Ngi ta thng dng EDTA di dng mui inatri Na2H2Y, thng gi l

complexon III (nhng vn quen quy c l EDTA). EDTA to phc bn vi

cc cation kim loi v trong hu ht cc trng hp phn ng to phc xy ra

theo t l 1:1.

n+ 4- (n-4)M Y Y+ (1.5)


- 23 -

Cc php chun complexon thng tin hnh khi c mt cc cht to

phc ph duy tr pH xc nh nhm ngn nga s xut hin kt ta hidroxit

kim loi. xc nh im dng trong chun complexon, ngi ta thng

dng mt s loi thuc th nh: eriocrom en T (ET-OO), murexit, 1-(2-

piridinazo) 2- naphtol (PAN), 4-(2-piridinazo) rezoxin (PAR ),[4,6,17].

1.4.1.1. Nguyn tc ca php chun nh lng ch bng EDTA

Pb2+

to phc bn vi EDTA pH trung tnh hoc kim, song cng rt

d thy phn, do trc khi tng pH ta cho Pb2+

to phc vi tactrat ri mi

tin hnh chun , ch th l ET-OO [4,6,15,17].

1.4.1.2. Nguyn tc ca php chun nh lng ng bng EDTA

Da trn phn ng to phc bn ca Cu2+

vi EDTA:

2 2 22

2 24 2 4

+ - - +Cu +H Y CuY +2H

+ - -CuH Ind +H Y CuY +H Ind

Ch th l murexit 1% trong NaCl, pH =8 [4,6,15,17].

1.4.2. Phng php trc quang

1.4.2.1. Nguyn tc

Phng php trc quang l phng php phn tch c s dng ph

bin nht trong cc phng php phn tch ha l. Nguyn tc chung ca

phng php phn tch trc quang l mun xc nh mt cu t X no , ta

chuyn n thnh hp cht c kh nng hp th nh sng ri o s hp th nh

sng ca n v suy ra hm lng cht cn xc nh X.

C s ca phng php l nh lut hp th nh sng Bouguer-

Lambert-Beer. Biu thc ca nh lut:

oIA lg LCI

= = (1.6)

Trong :

- Io, I ln lt l cng ca nh sng i vo v ra khi dung dch.


- 24 -

- L l b dy ca dung dch nh sng i qua.

- C l nng cht hp th nh sng trong dung dch.

- l h s hp th quang phn t, n ph thuc vo bn cht ca cht

hp th nh sng v bc sng ca nh sng ti ( ( ) = f ).

Nh vy, hp th quang A l mt hm ca cc i lng: bc

sng, b dy dung dch v nng cht hp th nh sng.

( )A = f ,L,C (1.7)

Do , nu o A ti mt bc sng nht nh vi cuvet c b dy L

xc nh th ng biu din A = f(C) phi c dng y = a.x l mt ng

thng. Tuy nhin, do nhng yu t nh hng n s hp th nh sng ca

dung dch (bc sng ca nh sng ti, s pha long dung dch, nng H+,

s c mt ca cc ion l) nn th trn khng c dng ng thng vi mi

gi tr ca nng . V biu thc 1.6 c dng:

( )b

xA = k..L. C (1.8)

Trong :

- Cx: nng cht hp th nh sng trong dung dch.

- k: hng s thc nghim.

- b: hng s c gi tr 0 < b 1 . N l mt h s gn lin vi nng Cx.

Khi Cx nh th b = 1, khi Cx ln th b < 1.

i vi mt cht phn tch trong mt dung mi xc nh v trong mt

cuvet c b dy xc nh th = const v L = const. t K = k..L ta c:

b

A = K.C (1.9)

Vi mi cht c ph hp th phn t vng UV-Vis, th lun c mt gi

tr nng gii hn Co xc nh, sao cho:

- Vi mi gi tr Cx < Co: th b = 1, v quan h gia hp th quang A

v nng Cx l tuyn tnh.


- 25 -

- Vi mi gi tr Cx > Co: th b < 1 (b tin dn v 0 khi C x tng) v quan

h gia hp th quang A v nng Cx l khng tuyn tnh.

Phng trnh (1.8) l c s nh lng cc cht theo php o ph

hp th quang phn t UV-Vis (phng php trc quang). Trong phn tch

ngi ta ch s dng vng nng tuyn tnh gia A v C, vng tuyn tnh

ny rng hay hp ph thuc vo bn cht hp th quang ca mi cht v cc

iu kin thc nghim, vi cc cht c ph hp th UV-Vis cng nhy, tc

gi tr e ca cht cng ln th gi tr nng gii hn Co cng nh v vng

nng tuyn tnh gia A v C cng hp [5,17].

1.4.2.2. Cc phng php phn tch nh lng bng trc quang

C nhiu phng php khc nhau nh lng mt cht bng phng

php trc quang. T cc phng php n gin khng cn my mc nh:

phng php dy chun nhn mu, phng php chun so snh mu,

phng php cn bng mu bng mt Cc phng php ny n gin,

khng cn my mc o ph nhng ch xc nh c nng gn ng ca

cht cn nh lng, n thch hp cho vic kim tra ngng cho php ca cc

cht no xem c t hay khng. Cc phng php phi s dng my quang

ph nh: phng php ng chun, phng php dy tiu chun, phng

php chun trc quang, phng php cn bng, phng php thm,

phng php vi sai, Ty theo tng iu kin v i tng phn tch c th

m ta chn phng php thch hp. Trong ti ny chng ti s dng

phng php ng chun nh lng cc cation kim loi.

Phng php ng chun: T phng trnh c s A = k.(Cx)b v

nguyn tc, xy dng mt ng chun phc v cho vic nh lng mt

cht trc ht phi pha ch mt dy dung dch chun c nng cht hp th

nh sng nm trong vng nng tuyn tnh (b = 1). Tin hnh o hp th


- 26 -

quang A ca dy dung dch chun . T cc gi tr hp th quang A o

c dng th A = f(C), th A = f(C) gi l ng chun.

Sau khi c ng chun, pha ch cc dung dch cn xc nh trong iu

kin ging nh khi xy dng ng chun. o hp th quang A ca chng

vi iu kin o nh khi xy dng ng chun (cng dung dch so snh,

cng cuvet, cng bc sng) c cc gi tr Ax. p cc gi tr Ax o c

vo ng chun s tm c cc gi tr nng Cx tng ng [5].

1.4.2.3. nh lng Cr(VI), Ni2+

, Mn2+

bng phng php trc quang

a) nh lng Cr(VI)

Trong mi trng axit, Cr(VI) phn ng vi 1,5-diphenylcacbazit to

thnh mt phc cht mu tm thch hp cho vic nh lng Cr(VI) theo

phng php trc quang. Hm lng Cr(VI) c xc nh theo cng hp

th mu ca phc cht bc sng = 540nm vi cuvet 1cm [12,17].

b) nh lng Ni2+

Ion Ni2+

trong mi trng amoniac yu c mt cht oxy ha mnh s

to thnh vi dimetylgyoxim mt phc mu , cng mu t l vi nng

niken. Phng php ny c th p dng xc nh niken trc tip nng

t 0,25,0mg/l. hp th mu ca phc c o bc sng

= 520nm , cuvet 1cm [12,17].

c) nh lng Mn2+

Dng kali pesunfat v cht xc tc l ion Ag+ trong mi trng axit

oxi ha Mn2+

n MnO4-. Hm lng MnO4

- c xc nh bng phng

php trc quang vi my trc quang vng UV-Vis bc sng = 540nm

vi cuvet 1cm [12,17].


- 27 -

CHNG 2

THC NGHIM V KT QU

2.1. Thit b, ha cht

2.1.1. Thit b

- My quang ph hp th phn t UV 1700 Phamaspec (Shimadzu - Nht

Bn), my quang ph hng ngoi IR Prestige 21 (Shimadzu - Nht Bn).

- My lc, my nghin bi, my khuy t, my o pH, t sy, cn in t

bn s,

- B sohxlet thu tinh; cc loi pipet, buret, bnh tam gic, cc, bnh nh

mc; chn s

2.1.2. Ha cht

Cc ha cht c dng l cc ha cht c tinh khit phn tch hoc

tinh khit ha hc.

2.1.2.1. Chun b cc dung dch gc [8,12]

a) Dung dch Cr(VI) 1000mg/l: Ha tan 2,8285g K2Cr2O7 ( sy kh

1000C) trong nc ct sau nh mc n 1000ml.

b) Dung dch Ni2+

1000mg/l: Ho tan 4,9533g Ni(NO3)2.6H2O trong 20ml

dung dch HNO3 10%, un nh cho tan ht, nh mc ti vch.

c) Dung dch Mn2+

1000mg/l: Ha tan 2,7480g MnSO4 ( nung 500oC)

trong 10ml axit sunfuric 1:4. Thm nc ct n 1000ml.

d) Dung dch Pb2+

0,01M: Ha tan 3,3121g trong 20ml dung dch HNO3

10% un nh cho tan ht, cho vo bnh nh mc 1000ml thm nc ct ti

vch.

e) Dung dch Cu2+

0,01M: Ha tan 2,4160g Cu(NO3)2.3H2O vo nc ri

cho vo bnh nh mc 1000ml, thm nc ti vch.

Cc dung dch c nng thp hn c pha ch t dung dch gc.


- 28 -

2.1.2.2. Chun b cc cht ch th, thuc th [8,12]

a) Dung dch 1,5-diphenylcacbazit 0,1% trong ru etylic: Ha tan 0,5g

1,5-diphenylcacbazit trong 100ml ru etylic 950, cho vo bnh nh mc

500ml, thm nc ti vch. ng dung dch trong bnh thy tinh mu v bo

qun trong t lnh.

b) Dung dch dimetylgyoxim 1,2%: Ha tan 1,2g dimetylgyoxim tinh

khit trong axeton v pha thm nc ct n 1000 ml.

c) Dung dch AgNO3 10%: Ho tan 104g AgNO3 trong nc ct, cho vo

bnh nh mc 1000ml, thm nc ct n vch.

d) Dung dch K2S2O8 bo ha: Ha tan K2S2O8 trong 1000ml nc ct n

khi K2S2O8 thm vo khng tan c na, lc ly phn dung dch.

e) Dung dch EDTA 0,01M: Ha tan 1,8612g EDTA trong nc ct, cho

vo bnh nh mc 500ml, thm nc ct n vch. Bo qun trong bnh thy

tinh mu nu.

f) Thuc th eriocrom T en (ET-OO) 0,02% trong NaCl: Trn u 0,02g

ET-OO trong 9,98g NaCl khan.

g) Dung dch kali natri tartrat 1M: Ha tan hon ton 28,222g

KNaC4H4O6.4H2O trong nc, cho vo bnh nh mc 100ml v nh mc ti

vch.

2.2. Ch to v kho st mt s c trng cu trc ca vt liu hp ph

2.2.1. Ch to vt liu hp ph

B ma c x l s b bng cch ngm trong nc ct 3 - 4 gi, ra

sch sau sy kh 1000C trong 24 gi. B ma kh c nghin nh bng

my nghin bi, ry v ra bng nc ct nng trong 1gi, sy kh 1000C.

Cui cng bt b ma c ra bng h dung mi n-hexan : etanol (1:1) trn

h thng sohxlet trong 4 gi, sy kh thu c nguyn liu.


- 29 -

Tip theo nguyn liu c hot ho bng anhydrit succinic trong mi

trng pyridin. Ra nguyn liu thu c ln lt bng ru etylic 950, nc

ct cui cng l ru etylic 950; lc, sy 80

0C trong 30 pht. Nguyn liu

thu c tip tc c trn vi dung dch NaHCO3 bo ha, khuy u trong

30 pht; lc, ra ln lt bng nc ct, ru etyilic 950 chng ti thu c

vt liu hp ph (VLHP) [19].

2.2.2. Mt s c trng cu trc ca VLHP

2.2.2.1. Ph hng ngoi ca VLHP

Cu trc ca VLHP c phn tch qua ph hng ngoi ca VLHP v

so snh vi ph hng ngoi ca nguyn liu. Kt qu c ch ra hnh 2.1

v hnh 2.2.

Hnh 2.1. Ph hng ngoi ca nguyn liu


- 30 -

Hnh 2.2. Ph hng ngoi ca VLHP

So snh ph hng ngoi ca nguyn liu b ma trc v sau khi x l

bng anhydrit succinic thnh VLHP cho thy c s dch chuyn cc nh hp

th 1728,66cm-1

, 1711,30cm-1

c trng cho dao ng ha tr ca nhm

cacbonyl C = O (hnh 2.1) sang cc nh 1724,80cm-1

, 1713,23cm-1

(hnh 2.2)

vi cng mnh hn. iu ny chng t anhydrit succinic acrylat ha

nhm hydroxyl ca b ma to ra mt lin kt este v gii phng mt nhm

chc axit cacboxylic [19].

2.2.2.2. nh SEM ca VLHP

kho st c im b mt ca VLHP, chng ti tin hnh chp

nh knh hin vi in t qut (SEM) b mt ca VLHP v nguyn liu. Kt

qu thu c c ch ra trong hnh 2.3.


- 31 -

(a) Nguyn liu (b) VLHP

Hnh 2.3. nh SEM ca VLHP v nguyn liu

Qua nh SEM ca VLHP v nguyn liu c th thy b mt VLHP xp

hn nhiu so vi b mt ca nguyn liu

2.3. nh lng cc kim loi

2.3.1. Dng ng chun xc nh Cr(VI)

Chun b 6 bnh nh mc dung tch 50ml, nh s t 0 n 5 v ln

lt cho vo mi bnh cc dung dch theo bng 2.1.

Bng 2.1. Th t cc dung dch dng ng chun xc nh Cr(VI)

Mu Dung dch (ml)

0 1 2 3 4 5

Dung dch Cr(VI) chun 2mg/l 0,0 0,5 1,0 5,0 10,0 25,0

H2SO4 1:1 0,5 0,5 0,5 0,5 0,5 0,5

H3PO4 c 0,1 0,1 0,1 0,1 0,1 0,1

1,5-diphenylcacbazit 0,1% 2,0 2,0 2,0 2,0 2,0 2,0

Nc ct ti vch

Lc u cc bnh nh mc, yn 10 pht ri o hp th quang A

ca dy dung dch chun bc sng = 540nm vi cuvet 1cm. T hp


- 32 -

th quang o c dng ng chun xc nh Cr(VI). Kt qu c ch ra

bng 2.2 v hnh 2.4.

Bng 2.2. S liu dng ng chun xc nh Cr(VI)

Stt Nng

(mg/l)

hp th quang A

1 0,02 0,002

2 0,04 0,013

3 0,20 0,088

4 0,40 0,203

5 1,00 0,504

Hnh 2.4. ng chun xc nh Cr(VI)

2.3.2. Dng ng chun xc nh Ni2+

Ly 6 bnh nh mc dung tch 100ml, nh s t 0 n 5 v ln lt

cho vo mi bnh cc dung dch theo bng 2.3.

Bng 2.3. Th t cc dung dch dng ng chun xc nh Ni2+

Mu

Dung dch (ml) 0 1 2 3 4 5

Dung dch Ni2+

chun 1mg/l 0,0 2,5 5,0 10,0 20,0 50,0

Nc brom bo ho 10,0 10,0 10,0 10,0 10,0 10,0

Amoniac 12,0 12,0 12,0 12,0 12,0 12,0

Dimetylgyoxim 1,2% trong axeton 4,0 4,0 4,0 4,0 4,0 4,0

Nc ct ti vch

o hp th quang A ca dy dung dch trn vi cuvet 1cm bc

sng = 520nm . T i lng hp th quang o c dng ng chun

xc nh Ni2+

. Kt qu c ch ra bng 2.4 v hnh 2.5.


- 33 -

Bng 2.4. S liu dng ng chun xc nh Ni2+

Stt Nng (mg/l)

hp th quang A

1 0,025 0,002

2 0,050 0,006

3 0,100 0,063

4 0,200 0,133

5 0,500 0,346

Hnh 2.5. ng chun xc nh Ni2+

2.3.3. Dng ng chun xc nh Mn2+

Ly 6 bnh nh mc dung tch 100ml, nh s t 0 n 5 v ln lt

cho vo mi bnh cc dung dch theo bng 2.5.

Bng 2.5. Th t cc dung dch dng ng chun xc nh Mn2+

Mu

Dung dch (ml) 0 1 2 3 4 5

Dung dch Mn2+

chun 5 mg/l 0,0 0,5 1,0 2,0 5,0 10,0

Nc ct 50,0 49,5 49,0 48,0 45,0 40,0

Axit sunfuric c 1,0 1,0 1,0 1,0 1,0 1,0

Bc nitrat 10% 1,0 1,0 1,0 1,0 1,0 1,0

Kali pesunfat bo ha 10,0 10,0 10,0 10,0 10,0 10,0

Nc ct ti vch

Lc u mi khi thm cc dung dch, yn 45 pht ri tin hnh o

hp th quang A ti bc sng = 540nm vi cuvet 1cm. T hp th

quang o c dng ng chun xc nh Mn2+

. Kt qu c ch ra bng

2.6 v hnh 2.6.


- 34 -

Bng 2.6. S liu dng ng chun

xc nh Mn2+

Stt Nng (mg/l)

hp th quang A

1 0,02 0,006

2 0,05 0,016

3 0,10 0,030

4 0,20 0,066

5 0,30 0,098

Hnh 2.6. ng chun xc nh Mn2+

2.3.4. nh lng Pb2+

Dng pipet ly chnh xc 10ml dung dch Pb2+

vo bnh tam gic dung

tch 250ml. Thm 20ml nc ct, 5ml dung dch KNaC4H4O6 1M, lc u ri

thm 5ml dung dch m amoni v mt t ch th ET-OO. un nng nh n

khong 500C v tin hnh chun Pb

2+ bng EDTA 0,01M. Chun n

khi dung dch chuyn t mu sang mu xanh th ngng chun . Ghi th

tch EDTA chun . Nng Pb2+

(mol/l) c tnh theo cng thc:

2+EDTA

0,01.VC

Pb 10= (2.1)

2.3.5. nh lng Cu2+

Dng pipet ly chnh xc 10ml dung dch Cu2+

cn xc nh vo bnh

tam gic dung tch 100ml. Thm 5ml dung dch NH4Cl 5% v dng dung dch

NH3 1N chnh pH dung dch n 8. Chun Cu2+

bng EDTA 0,01M cho

n khi dung dch chuyn t mu vng nht sang mu tm th ngng chun

. Ghi s ml EDTA chun . Nng Cu2+

(mol/l) c tnh theo cng

thc:

2+EDTA

0,01.VC

Cu 10= (2.2)


- 35 -

2.4. Kho st kh nng hp ph ca nguyn liu v VLHP

Ly 6 bnh tam gic dung tch 100ml, cho vo 3 bnh mi bnh 0,5g

VLHP v 3 bnh cn li, mi bnh 0,5g nguyn liu; thm vo mi bnh 50ml

dung dch cha ion kim loi c nng xc nh. Tin hnh lc trn my lc

trong 120 pht, lc thu ly phn dung dch. Xc nh nng ion kim loi

cn li trong dung dch. Dung lng hp ph q (mg/g) v hiu sut hp ph H

(%) ca VLHP v nguyn liu i vi mi kim loi c xc nh theo cng

thc:

( )o ocb cbC -C .50 C -Cq1000.0,5 10

= = (2.3)

o cb

o

C -CH .100

C= (2.4)

Trong : Co, Ccb l nng ca ion ban u v sau khi hp ph (mg/l).

Cc kt qu c ch ra trong bng 2.7.

Bng 2.7. So snh kh nng hp ph ca nguyn liu v VLHP i vi

Cr(VI), Ni2+

, Mn2+

, Pb2+

v Cu2+

Ion

Nguyn liu VLHP

Co

(mg/l)

Ccb

(mg/l)

H

(%)

q

(mg/g)

Co

(mg/l)

Ccb

(mg/l)

H

(%)

q

(mg/g)

Cr(VI) 105,00 83,13 20,83 2,19 105,20 39,00 62,93 6,62

Ni2+

100,00 33,54 66,46 6,65 100,40 1,67 98,34 9,87

Mn2+

97,05 70,05 27,82 2,70 97,00 11,86 87,77 8,51

Pb2+

2380,50 2297,70 3,48 8,28 2380,50 2080,35 12,61 30,01

Cu2+

633,60 614,40 3,03 1,92 633,60 307,20 51,52 32,64

Kt qu bng 2.7 cho thy c nguyn liu v VLHP u c kh nng

hp ph cc ion kim loi: Cr(VI), Ni2+

, Mn2+

, Pb2+

v Cu2+

. Tuy nhin, so

snh dung lng hp ph cng nh hiu sut hp ph ca VLHP v nguyn

liu i vi mi ion kim loi chng ti nhn thy kh nng hp ph ca


- 36 -

VLHP tt hn nguyn liu rt nhiu. iu ny ph hp vi nhng kt qu

c ch ra mc 2.2.2 v mt s c trng cu trc ca VLHP.

2.5. Kho st cc yu t nh hng n kh nng hp ph ca VLHP

2.5.1. nh hng ca thi gian

Ly 7 bnh tam gic dung tch 100ml, nh s t 1 n 7 v ln lt

cho vo mi bnh 0,5g VLHP v 50ml dung dch cha ion kim loi c nng

xc nh. Tin hnh s hp ph trong cc khong thi gian khc nhau: t

10 120 pht vi Cr(VI), Pb2+

, Ni2+

v t 5 90 pht vi Mn2+

, Cu2+

. Xc

nh nng ca ion kim loi cn li sau mi khong thi gian . Cc kt

qu c ch ra trong bng 2.8, hnh 2.7.

Bng 2.8. nh hng ca thi gian n kh nng hp ph

Ion Thi gian (pht) Co (mg/l) Ccb (mg/l) H (%) q (mg/g)

(1) (2) (3) (4) (5) (6)

Cr(VI)

10 240,00 107,00 55,42 13,30

20 240,00 101,50 57,71 13,85

30 240,00 96,00 60,00 14,40

45 240,00 97,00 59,58 14,30

60 240,00 96,50 59,79 14,35

90 240,00 94,00 60,83 14,60

120 240,00 94,00 60,83 14,60

Ni2+

10 168,40 4,08 97,58 16,43

20 168,40 3,38 97,99 16,47

40 168,40 4,00 97,62 16,53

60 168,40 2,86 98,30 16,56

80 168,40 2,80 98,34 16,56

100 168,40 2,80 98,34 16,56

120 168,40 2,78 98,35 16,56


- 37 -

(1) (2) (3) (4) (5) (6)

Mn2+

5 88,00 21,70 75,34 6,63

10 88,00 11,30 87,16 7,67

20 88,00 10,80 87,73 7,72

30 88,00 10,70 87,84 7,73

45 88,00 10,00 88,64 7,80

60 88,00 10,00 88,64 7,80

90 88,00 9,60 89,09 7,84

Pb2+

10 2691,00 2359,80 12,31 33,12

20 2691,00 2318,40 13,85 37,26

40 2691,00 2256,30 16,15 43,47

60 2691,00 2173,50 19,23 51,75

80 2691,00 2173,50 19,23 51,75

100 2691,00 2173,50 19,23 51,75

120 2691,00 2173,50 19,23 51,75

Cu2+

5 633,60 458,88 27,61 17,6

10 633,60 311,68 50,84 32,21

20 633,60 300,80 52,53 33,28

30 633,60 298,88 52,69 33,39

45 633,60 302,08 52,36 33,17

60 633,60 300,80 52,53 33,28

90 633,60 300,80 52,53 33,28


- 38 -

0

10

20

30

40

50

60

0 20 40 60 80 100 120 140Thi gian (pht)

q (

mg/g

)

Cr(VI)

Ni2+

Mn2+

Pb2+

Cu2+

Cr(VI)

Ni2+

Mn2+

Pb2+

Cu2+

Hnh 2.7. S ph thuc ca dung lng hp ph theo thi gian

T cc kt qu bng 2.8 v hnh 2.7, chng ti thy:

- Vi Cr(VI): Trong khong thi gian kho st (10120 pht), t 10 n

90 pht u dung lng hp ph Cr(VI) ca VLHP tng nhanh, t 90 pht tr

i dung lng hp ph tng chm v tng i n nh. Do , chng ti cho

rng thi gian t cn bng hp ph i vi Cr(VI) l 90 pht v chn khong

thi gian ny nghin cu tip theo i vi Cr(VI).

- Vi Ni2+: Trong khong thi gian kho st (10120 pht) dung lng

hp ph ca VLHP i vi Ni2+

thay i khng nhiu (16,4316,56mg/g).

Tuy nhin, chng ti thy sau 60 pht dung lng hp ph l tng i n

nh. Do , chng ti cho rng thi gian t cn bng hp ph i vi Ni2+

l

60 pht v chn khong thi gian ny nghin cu tip theo i vi Ni2+

.

- Vi Mn2+: Trong khong thi gian kho st (590 pht), t 45 pht tr

i dung lng hp ph Mn2+

ca VLHP tng chm v tng i n nh. Do

, chng ti cho rng thi gian t cn bng hp ph i vi Mn2+

l 45 pht

v chn khong thi gian ny nghin cu tip theo i vi Mn2+

.


- 39 -

- Vi Pb2+: Trong khong thi gian kho st (10120 pht), t 10 n 60

pht u dung lng hp ph ca VLHP i vi Pb2+

tng nhanh, t 60 pht

tr i dung lng hp ph tng chm v tng i n nh. Do , chng ti

cho rng thi gian t cn bng hp ph i vi Pb2+

l 60 pht v chn

khong thi gian ny nghin cu tip theo i vi Pb2+

.

- Vi Cu2+: Trong khong thi gian kho st (590pht), t 5 n 10 pht

u dung lng hp ph Cu2+

ca VLHP tng nhanh, t 10 n 20 pht tip

theo dung lng hp ph tng chm v sau 20 pht dung lng hp ph Cu2+

l tng i n nh. Do , chng ti cho rng thi gian t cn bng hp

ph i vi Cu2+

l 20 pht v chn khong thi gian ny nghin cu tip

theo i vi Cu2+

.

Thi gian t cn bng hp ph i vi mi ion kim loi c ch ra

bng 2.9.

Bng 2.9. Thi gian t cn bng hp ph i vi mi ion kim loi

Ion Cr(VI) Ni2+

Mn2+

Pb2+

Cu2+

Thi gian t cn bng (pht) 90 60 45 60 20

Qua bng 2.9 chng ta thy vi mi ion thi gian t cn bng hp ph

l khc nhau. iu ny hon ton hp l bi kh nng hp ph ca VLHP vi

mi ion l khc nhau. Ngoi tr Cr(VI) tn ti dng anion, cc ion Ni2+

,

Mn2+

, Pb2+

v Cu2+

tuy c cng in tch nhng c kch thc khc nhau nn

tng tc gia chng vi cc tm hp ph trn b mt VLHP l khc nhau.

2.5.2. nh hng ca pH

Ly 5 bnh tam gic dung dch 100ml, nh s t 1 n 5 v ln lt

cho vo mi bnh 0,5g VLHP v 50ml dung dch cha ion kim loi c nng

xc nh cc gi tr pH khc nhau (C th: Cr(VI) t 1,357,33; Ni2+

t

1,476,24; Pb2+

t 1,004,94; Cu2+

t 1,805,21). pH ca cc dung dch c


- 40 -

iu chnh bng dung dch HNO3 10% hoc dung dch NaOH 0,1N. Tin

hnh s hp ph trong khong thi gian cn bng i vi mi ion xc nh

c mc 2.5.1, xc nh nng ca ion cn li trong dung dch. Cc kt

qu thu c c ch ra trong bng 2.10 v hnh 2.8.

Bng 2.10. nh hng ca pH n kh nng hp ph

Ion pH Co (mg/l) Ccb (mg/l) H (%) q (mg/g)

Cr(VI)

1,35 223,00 98,00 56,05 12,50

2,21 223,00 105,00 52,91 11,80

3,00 223,00 106,20 52,38 11,68

4,34 223,00 110,79 50,32 11,22

5,07 223,00 111,00 50,22 11,20

6,21 223,00 105,91 52,91 11,80

7,33 223,00 113,00 49,33 11,00

Ni2+

1,47 184,80 16,43 91,11 16,84

2,40 184,80 8,87 95,20 17,59

4,06 184,80 4,44 97,60 18,04

5,10 184,80 3,70 98,00 18,11

6,24 184,80 7,11 96,15 17,77

Pb2+

1,00 2670,30 2370,15 11,24 30,02

2,16 2670,30 2297,70 13,95 37,26

3,06 2670,30 2194,20 17,83 47,61

4,06 2670,30 2152,80 19,38 51,75

4,94 2670,30 2090,70 21,71 57,96

Cu2+

1,80 633,60 612,30 3,36 2,13

2,30 633,60 366,90 42,09 26,67

3,02 633,60 300,8 52,53 33,28

3,90 633,60 298,67 52,86 33,49

5,21 633,60 299,73 52,69 33,39


- 41 -

0

10

20

30

40

50

60

70

0 1 2 3 4 5 6 7 8

pH

q (

mg

/g)

Cr(VI)

Ni

Pb

Cu

Cr(VI)

Ni2+

Pb2+

Cu2+

Hnh 2.8. S ph thuc ca dung lng hp ph vo pH dung dch

Cc kt qu bng 2.10 v hnh 2.8 cho thy khong pH ti u cho s

hp ph ca VLHP i vi mi ion kim loi: Cr(VI) pH=12; Ni2+

pH=56,

Pb2+

pH=45 v Cu2+

pH=45. Ring i vi Mn2+

chng ti ch kho st

khong pH t 12.

2.5.3. nh hng ca nng - Cn bng hp ph

2.5.3.1. nh hng ca nng

Ly 5 bnh tam gic dung tch 100ml, nh s t 1 n 5 v ln lt

cho vo mi bnh 0,5g VLHP v 50ml dung dch cha ion kim loi vi cc

nng khc nhau xc nh (C th: Cr(VI) t 102,00739,00 mg/l; Ni2+

t

56,00754,00mg/l; Mn2+

t 88,00450,00mg/l; Pb2+

t 252,542424,60mg/l;

Cu2+

t 60,80632,53mg/l). Tin hnh s hp ph trong khong thi gian v

pH ti u vi mi ion kim loi xc nh c mc 2.5.1 v 2.5.2, xc

nh nng ca ion kim loi cn li trong dung dch. Kt qu c ch ra

trong bng 2.11 v hnh 2.9.


- 42 -

Bng 2.11. nh hng ca nng n kh nng hp ph

Ion Co (mg/l) Ccb (mg/l) H (%) q (mg/g)

Cr(VI)

102,00 38,30 62,45 6,37

184,00 86,50 52,99 9,75

326,00 157,50 51,69 16,85

398,00 202,00 49,25 19,60

739,00 442,00 40,19 29,70

Ni2+

56,00 0,38 99,32 5,56

192,00 11,60 93,96 18,04

293,00 22,74 92,24 27,03

412,00 61,00 85,19 35,10

754,00 162,00 78,51 59,20

Mn2+

88,00 7,40 91,59 8,06

185,00 16,60 91,03 16,84

260,00 24,60 90,54 23,54

375,00 37,60 89,97 33,74

450,00 59,30 86,82 39,07

Pb2+

252,54 182,16 27,87 7,04

606,51 459,54 24,23 14,70

1211,00 945,99 21,88 26,50

1800,90 1500,80 16,66 30,01

2442,60 2074,10 15,08 36,85

Cu2+

60,80 18,13 70,18 4,27

162,13 50,13 69,08 11,20

312,53 105,60 66,21 20,69

478,93 215,47 55,10 26,35

632,53 297,60 52,95 33,49


- 43 -

0

10

20

30

40

50

60

70

0 500 1000 1500 2000 2500 3000Nng ban u Co (mg/l)

q (

mg/g

)Cr(VI)

Ni

Mn

Pb

Cu

Cr(VI)

Ni2+

Mn2+

Pb2+

Cu2+

Hnh 2.9. S ph thuc ca dung lng hp ph vo nng ban u ca cc ion

Cc kt qu bng 2.11 v hnh 2.9 cho thy trong khong nng

kho st vi mi ion: Cr(VI) t 102 n 739mg/l; Ni2+

t 56 n 754mg/l;

Mn2+

t 88 n 450mg/l; Pb2+

t 252,54 n 2442,6mg/l; Cu2+

t 60,8 n

632,53mg/l, khi tng nng , dung lng hp ph ca VLHP i vi cc kim

loi u tng; cn hiu sut hp ph gim dn.

2.5.3.2. Cn bng hp ph

T cc kt qu thu c chng ti nghin cu cn bng hp ph vi

mi ion kim loi theo m hnh ng ng nhit hp ph Langmuir.

a) Crom

0

5

10

15

20

25

30

35

0 100 200 300 400 500

Ccb (mg/l)

q (

mg

/g)

Hnh 2.10. ng ng nhit hp ph

Langmuir i vi Cr(VI)

y = 0.0201x + 6.1641

R2 = 0.956

0

5

10

15

20

0 100 200 300 400 500

Ccb (mg/l)

Ccb

/q (

g/l

)

Hnh 2.11. S ph thuc ca Ccb/q vo

Ccb ca Cr(VI)


- 44 -

b) Niken

0

10

20

30

40

50

60

70

0 50 100 150 200

Ccb (mg/l)

q (

mg

/g)


Langmuir i vi Ni2+

y = 0.0153x + 0.4165

R2 = 0.9292

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0 50 100 150 200Ccb (mg/l)

Ccb

/q (

g/l

)


Ccb ca Ni2+

c) Mangan

0

10

20

30

40

50

0 20 40 60 80

Ccb (mg/l)

q (

mg/g

)


Langmuir i vi Mn2+

y = 0.0113x + 0.7887

R2 = 0.9283

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

0 20 40 60 80

Ccb (mg/l)

Ccb

/q (

g/l

)


Ccb ca Mn2+

d) Ch

0

10

20

30

40

0 500 1000 1500 2000 2500

Ccb (mg/l)

q (

mg

/g)


Langmuir i vi Pb2+

y = 0.0165x + 22.774

R2 = 0.9779

0

10

20

30

40

50

60

0 1000 2000 3000

Ccb (mg/l)

Ccb

/q (

g/l

)

Hnh 2.17. S ph thuc ca Ccb/q

vo Ccb ca Pb2+


- 45 -

e) ng

0

5

10

15

20

25

30

35

40

0 50 100 150 200 250 300 350

Ccb(mg/g)

q (

mg/l

)


Langmuir i vi Cu2+

y = 0.0184x + 3.6563

R2 = 0.9635

0

2

4

6

8

10

0 100 200 300 400Ccb (mg/l)

Ccb

/q (

g/l

)


Ccb ca Cu2+

T m hnh ng ng nhit hp ph Langmuir i vi mi kim loi,

chng ti tnh c cc gi tr dung lng hp ph cc i qmax v cc h s

Langmuir K vi mi kim loi:

Bng 2.12. Dung lng hp ph cc i v hng s Langmuir

Ion Cr(VI) Ni2+

Mn2+

Pb2+

Cu2+

Dung lng hp ph cc i qmax (mg/g)

49,75 65,36 88,50 60,61 54,35

Hng s Langmuir K 0,0033 0,0367 0,0143 0,0007 0,0050

2.6 . Th x l nc thi cha Cr(VI)

Mu nc c ly ti b thi ca phn xng m in, x nghip m

in qun i cha qua x l. Nc thi c ly v bo qun theo ng

TCVN 4574-88.

- Dng c ly mu: chai polyetylen sch.

- Mu ly xong c c nh bng 5ml HNO3 c.

Ly ba bnh tam gic dung tch 100ml, nh s cc bnh t 1 n 3, cho

vo mi bnh 50ml nc thi v 0,5g VLHP. Tin hnh hai ln s hp ph


- 46 -

trong cc iu kin thi gian v pH ti u cho s hp ph Cr(VI) xc nh

c. Xc nh nng Cr(VI) cn li trong dung dch. Kt qu thu c:

- Nng Cr(VI) trong nc thi: 326mg/l.

- Nng Cr(VI) cn li sau mt ln hp ph: 303mg/l. Gim 7,06% so

vi nng ban u.

- Nng Cr(VI) cn li sau hai ln hp ph: 290mg/l. Gim 11,04% so

vi nng ban u.

Nh vy, sau hai ln hp ph kt qu cho thy VLHP c kh nng tch

loi Cr(VI) trong nc thi v nu tin hnh lin tip nhiu ln th c th lm

gim hm lng Cr(VI) trong nc thi ti gii hn cho php.


- 47 -

KT LUN

1. ch to c VLHP t b ma v kho st mt s c im cu trc v

b mt ca VLHP.

1.1. Kho st cu trc VLHP qua ph hng ngoi ca VLHP cho thy cc

phn t anhydrit succinic este ha cc nhm hydroxyl trn b ma.

1.2. Kho st c im b mt ca VLHP qua nh SEM cho thy b ma

sau khi hot ha c cu to xp hn so vi b ma khi cha hot ha.

2. kho st kh nng hp ph ca nguyn liu v VLHP i vi Cr(VI),

Ni2+

, Mn2+

, Pb2+

v Cu2+

. Kt qu cho thy c nguyn liu v VLHP u hp

ph c cc ion kim loi ny trong dung dch. Tuy nhin, kh nng hp ph

ca VLHP i vi cc ion kim loi ny l tt hn nhiu so vi nguyn liu.

3. nghin cu nh hng ca mt s yu t n s hp ph ca VLHP i

vi Cr(VI), Ni2+

, Mn2+

, Pb2+

v Cu2+

. Kt qu thu c cho thy:

3.1. Thi gian t cn bng hp ph:

- Cr(VI): 90 pht.

- Ni2+

: 60 pht.

- Mn2+

: 45 pht.

- Pb2+

: 60 pht.

- Cu2+

: 20 pht.

3.2. Khong pH ti u:

- i vi Pb2+

v Cu2+

: pH=45.

- i vi Ni2+

: 56.

- i vi Cr(VI) : 12.

3.3. Nng ban u: Trong cc khong nng kho st vi cc ion

kim loi, khi nng ion kim loi tng dung lng hp ph ca

VLHP i vi cc ion kim loi tng.


- 48 -

4. Xc nh c dung lng hp ph cc i ca VLHP i vi Cr(VI),

Ni2+

, Mn2+

, Pb2+

v Cu2+

. C th dung lng hp ph cc i ca VLHP i

vi cc ion kim loi l:

- Cr(VI): 49,75mg/g.

- Ni2+

: 65,36mg/g.

- Mn2+

: 88,50mg/g.

- Pb2+

: 60,61mg/g.

- Cu2+

: 54,35mg/g.

5. th x l mt mu nc thi cha Cr(VI) ca nh my m in qun

i. Kt qu cho thy VLHP c kh nng tch loi Cr(VI) trong mi trng

nc.


- 49 -

DANH MC CNG TRNH CNG B

Hong Ngc Hin, L Hu Thing, Nghin cu kh nng hp ph ion

Ni2+

trong mi trng nc trn vt liu hp ph ch to t b ma v ng

dng vo x l mi trng, Tp ch Khoa hc v Cng ngh i hc Thi

Nguyn, s 2 (46), tp 2, nm 2008, trang 118 121.


- 50 -

TI LIU THAM KHO

Ting Vit

1. L Huy B (ch bin) (2000), c hc mi trng, Nxb H Quc gia TP.

HCM

2. L Vn Ct (2002), Hp ph v trao i ion trong k thut x l nc v

nc thi, Nxb Thng k, H Ni.

3. Trnh Ngc Chu, Triu Th Nguyt, V ng (2001), Nghin cu

kh nng s dng mt s ph phm nng nghip hp th mt s ion

kim loi nng trong nc thi, Tuyn tp cc cng trnh khoa hc, Hi

ngh khoa hc ln th hai - ngnh Ho hc, trng H Quc gia H Ni.

4. Nguyn Tinh Dung (2002), Ha hc phn tch, phn III: Cc phng

php nh lng ho hc, Nxb Gio dc, H Ni.

5. Trn T Hiu (2003), Phn tch trc quang ph hp th UV-Vis, Nxb i

hc Quc gia H Ni, H Ni.

6. Trn T Hiu (2004), Ha hc phn tch, Nxb i hc Quc gia H Ni,

H Ni.

7. Nguyn nh Hu (1982), Gio trnh ha l, Nxb Gio dc, H Ni.

8. P.P. Koroxtelev (1974), Chun b dung dch cho phn tch ho hc

(Ngi dch: Nguyn Trng Biu, Mai Hu ua,), Nxb Khoa hc v k

thut, H Ni.

9. Hong Nhm (2001), Ha v c tp ba, Nxb Gio dc, H Ni.

10. Trn Vn Nhn, H Th Nga (2005), Gio trnh cng ngh x l nc

thi, Nxb Khoa hc v k thut, H Ni.

11. Trn Vn Nhn, Nguyn Thc Su, Nguyn Vn Tu (1998), Ha l tp

II, Nxb Gio dc, Hi Phng.

12. Tiu chun Vit Nam: TCVN 5945-2005, TCVN 5502-2003, TCVN 4573-

88, TCVN 4574-88, TCVN 4577-88, TCVN 4578-88.


- 51 -

13. Trnh Th Thanh (2001), c hc, mi trng v sc kho con ngi,

Nxb i hc Quc gia H Ni.

14. H S Trng (2005), C s ho hc g v xennluloza, tp 1, Nxb Khoa

hc v k thut, H Ni.

15. Lm Minh Trit, Dip Ngc Sng (2000), Cc phng php phn tch

kim loi trong nc v nc thi, Nxb Khoa hc v k thut, Tp H Ch

Minh.

16. Nguyn c Vn (2004), Ha v c tp 2: Cc kim loi in hnh, Nxb

Khoa hc v k thut, H Ni.

Ting Anh

17. David Harvey (2000), Modern Analytical Chemistry, McGraw-Hill, The

United States of America..

18. Jaakko Paasivirta (1991), Chemical E toxicalog, Lewis Publishers.

19. Osvaldo Karnitz Jr, L.V.A. Gurgel, J.C.P. de Melo, V.R. Botaro, T.M.S.

Melo, R.P.de Freitas Gil and L.F. Gil (2007), Adsorption of heavy metal

ion from aqueous single metal solution by chemically modified sugarcane

bagasse, Bioresource Technology, 98, 1291-1297.

20. Umesh K. Garg and Dhiraj Sud (2005), Optimization of process

parameters for removal of Cr(VI) from aqueous solutions using modified

sugarcane bagasse, Electronic Journal of Environmental, Agricultural

and Food Chemistry, 4(6), 1150-1160.

21. Yong-Jae Lee (2005), Oxidation of sugarcane bagasse using a

combination of hypochlorite and peroxide, B.Sc., Chonnam National

University.

Cc trang web

22. http://www.thanhthanhcong.com.

23. http://faostat.fao.org.

nghiên cứu khả năng hấp thụ một số kim loại nặng.pdf

Documents