Nghiên cứu chế tạo hệ thống phân tích dòng chảy xách tay sử dụng các điện cực chọn lọc ion làm Detector xác định các ion chứa Nitơ có trong nước thải Phú Dưỡng

Trong ban bao cao cua de lai nay chung toi trinh bay mot nghien cuu che tao va ung dung dien cue mang long su dung lam detector cho he FIA ket hop vai bp tham tich khi de phuc vu cho xac

DAI HOC QUOC GIA HA NOI

TRUCING DAI HOC KHOA HOC TlT NHIEN

D^ T.AI:

NGHIEN ClTL CHE T.AO HE THONG PH.AN TICH DONG CHAY XACH TAY Sir DUNG CAC DIEN Cl/C CHON LOG ION LAM DETECTOR XAC DINH CAC ION CHlTA NITO CO TRONG

NlTOC THAI PHU DLONG

TfiN D^ T A I :

*'Nghien cicu che tqo he thong phdn tich dong chdy xdch tay su dung cdc dien cue chon loc ion lam detector xdc dinh cdc ion chua nitatrong nuac thaiphu duffng"

MA S O : QT-97-06

CHU TRI Dfi TAI:

PGS PTS Phani Hung Viet, Gidm doc trung tdm Hod hoc Moi truang - Tru&ng Dai hoc Khoa hoc tu nhien - Dai hoc Quoc gia Ha Noi

C A C C A N B O P H O I H O P :

- ThS Do Phiic Qudn, Trung tdm Hod hoc Moi tru&ng, DHKHTN HN

- ThS Duang Hong Anh Trung tdm Hod hoc Moi tru&ng, DHKHTN HN

BAO CAO TOM TAT

1 Detai:

• Ten de tai : ''Nghien cioi che tqo he thong phdn tich dong chdy xdch tay su dung cdc

dien cue chon loc ion lam detector xdc dinh cdc ion chua nita trong nuac thai phu duang''

• Ma so: QT-97-06

2 ChiJ tri de tai:

• PGS.PTS Pham Hung Viet Giam doc trung tam Hoa hoc Moi truang - Truang dai hoc

Khoa hpc tu nhien - Dai hoc Quoc gia Ha Npi

3 Cac can bo tham gia:

• ThS D6 Phuc Quan Trung tam Hoa hpc Moi truang, DHKHTN HN

• ThS Duong Hong Anh Trung tam Hoa hoc Moi truang, DHKHTN HN

4 Muc tieu va npi dung nghien cihi:

Ung dung thiet bi de kiem ira cac mSu nuac \'a nude thai

5 Cac ket qua dat dirac:

• Nghien cuu che tao mang long chon loc ion nitral [14.15] gom c6:

- 3 % ionphore cho Nitrat (tetraoctylamonibromua)

- 30% PVC

- 67% o -NPOE (o-Nitrophenyioctyl ete)

Dp doc dien cue 58 mV/dec trong khoang tuyen linh tu 10' den lO""^ M/1 va he so

chon Ipc ion doi \6i cac anion gay anh huang toi qua irinh phan tich cua dien cue hau

hei nho han 10"

Khao sat cac dit^u kien lam \'iec cua dien cue trong dong chay la dem photphat 10"^

M pH = 2,8 va loc dp 2.3 ml/phiit

• Che tao bp th^m tich khi tren ca so cac vat lieu bang nhua Teflon eo ty le dien tich be mat so vai the' tich kenh dan Idn han so vai cac bo thim tich thong thuang khae (24.6em"') (hinh 2.2) diing ket hap vcd he FIA, phuc vu cho qua trinh phan tich ion nirit

• Tren ca so he FIA-ISE chpn loc ion nitrat, da khao sat cac dieu kien chuyen hoa NO

-> NOx -> NO3" thong qua qua trinh trung gian chuydn hoa thanh NOx

Dung dieh chat mang la muoi KH2PO4 nong do 10"^ M/1 vai pH=2,8 trong do c6 chua 0,1% Wt H2O2 va NaN03 nong dp lO'-M/l

Dung dieh axit hoa la H3PO4 nong dp 5.10'M/l

Toe dp dong chat mang la 2,3ml/phut

The' tich vong miu 500|il

• Che tao duac dien cue chpn Ipc ion amoni mang long tren eo so ionophore nonaclin/monactin[16] bao gom:

- 3 % ionphore cho amoni (nonactin/monactin)

- 30% PVC

- 67% o- NPOE (octo-Nitrophenyloctylele)

- KT4C1PB 70% irpng luang so vai ionophore

• Khao sal cac dit^u kien lam viec ciia dien cue amoni trong he FIA ket hap vai bo iham tich khi {dong chuyen hoa NH4' -> NH, la dung dieh NaOH, pH=:12; dong chuyen

hoa NH;,^ NH4* la dem Tris pH = 7,2) dt tang do chpn loc ciia phep phan lich, tu do

ma rpng kha nang dp dung cua dien cue cho xac dinh ion amoni trong nuac thai Dien cue lam viec tuyen linh trong khoang tu 10' den lO""* mol/1 NH4^ vai dp doc la 53,2 mV/dee

• Ky thuat phan lich su dung cue chpn Ipc ion la dan gian, nhanh, nhay va chinh xac

cao Tren co so ket hap voi ky thuat FIA va bp tham lich khi cho phep tang dp chpn

cac phep do thir nghiem cho mot so miu thue le da dupe tien hanh va cho ket qua dang tin cay va nit ngan thai gian phan tich

6 Tinh hinh kinh phi ciia de tai:

• Tong kinh phi dupe cap la 12 irieu dong tu nguon kinh phi nghien cuu co ban ciia DH

Quoc gia Ha npi di thue hien de tai trong 2 nam

BRIEF REPORT

1 Title of project:

'^Development of portable flow injection system with ion selective sensors as detector to study nitrogen-containing ions in eutrophical wastewater^'

VNU Hanoi Research grand number: QT-97-06

2 Name of investigator: Ass Prof Dr Pham Hung Viet, Director, Center of

Environmental Chemistry, Hanoi University of Science, VNU Hanoi

Design and fabrication of gas dialysis chamber to enhance selectivity and sensitivity of polentiometric method used ion selective liquid membrane electrodes

Application of FIA/ISE in conjunction with flow through gas dialysis chamber to determination of nitrogen-containing ions in groundwater and v.astewater in Hanoi area

5 Results of Research Project

Nitrate ion liquid membrane component:

3% Tetraocthylammonium bromide

30% High molecular PVC

67% Plaslicizer o-NTOE (oclo -nitrophenyloctylete)

Dynamic slope value of the nitrate liquid membrane electrode: ^% mV/decade

Dynamic range of linearity showed from 10"^ M/1 to 10'' M/1

Almost selectivity coefflcient value for foreign anions K^",, ^o be determined by mean

of SSM in the range from 10" to 10^

Flow injection analysis condition: Phosphate buffer (pH=2.8, 10~ M/1) and flow rate

2.3 ml/min

Design and fabrication of gas dialysis chamber from PTFE with available wider channels (a ratio surface area to volume of channel is 24.6 c m ' ) improves the

efficiency of gas transfer and thus the detection capabilities of system

Condition of FIA -ISE conjunction with flow though dialysis chamber for nitrite determination:

Carrier solution: 10'^ M/1 phosphate buffer, pH=2.8 containing 0.1% wi H.O, and 10"' M/INO3

Oxidation solution N O / ^ NO,: 5.10' M/l H,P04

Flow rate of carrier solution: 2.3 ml/min

Sample loop volume: 500 fil

Ammonium liquid membrane component:

3% nonactin/monactin

30% High molecular PVC

67% Plaslicizer o-NPOE (oeto -nitrophenyloctylete)

70 % wi/wt KT4CIPB to nonactin

Investigation of working condition of ammonium electrode in FIA system conjunction with NH- dialysis chamber:

Carrier solution; NaOH pH=l2

Trap solution: TRIS buffer, pH=7.2

Tins FIA system approach has been application for determination of nitrate, nitrite and ammonium in natural water and domestic wastewater

Ha not, ngay thang nam 1999 XAC NHAN CUA

BAN CHU NHlfiM KHOA

CHU TRI D £ T A I

U ?Tl A;^^^^^^/^^^'^''''^^'^^^'""""^^*-^

XAC NHAN CUA TRUING

I MO DAU

Su phat trien cua khoa hpc, cong nghe va dai song hien dai doi hoi cac nha phan tich hpc phat tri^n, phdi hap nham sang tao nhung ky thual, phuang phap phan tich moi cho kha nang thue hien cac phep do vdi toe dp cao, xac dinh nhung luang vet va sieu vet cac chat vai dp lap lai va dp chinh xac ngay cang Ian [1,2] De dap ung nhimg yeu eau do bat dau tir nhung nam 60 cua the ky nay, cac nha phan tich da co nhimg y tuang va co gang nghien cufu tim ra nhung ky thuat mcd nham tien hanh mot each ban tir dong de dong nhat cac thao tac phan tich dac biet lien hanh cac phan ung kho thue hien trong cac phong thi nghiem binh thuang [3-9], vi du cac phan ung tao nhimg phuc mau co dp hap thu thay doi theo thai gian, cac phan ung xuc tac can duac tien hanh trong didu kien nghiem ngat cac phan ung xay ra khong hoan loan, cac phan ung diang cac thuoc thu oxy hoa - khir khong b6n trong khong khi Mat khae, trong nhieu truang hap nguai la can tien hanh dong thai

nhieu phan xxng phan tich mot each dong thai hoac thue hien cac phan ung noi tiep nhau

mot each nghiem ngat, sir dung cac chat che khae nhau theo nhimg thu tu nhat dinh trong mot he phan ung Nhung ky thuat tren ro rang la kho thue hien dupe bang tay su dung cac dung cu thong thuang va neu phai thue hien thi tat phai nhan nhung ket qua co dp chinh xac va dp lap lai thap De phan tich nhung lucmg vet trong cac doi tircmg phuc tap nguai la con muon ket hap cac phuang phap tach, cac phuang phap lam giau co hieu qua cao nhu

chiet bang dung moi huu co, trao dOi ion vai cac phucmg phap do quang hpc va dien hoa

trong mot thiet bi phan tich boat dong tu dong [10-13] Thue hien nhung y tuang tren, cac nha phan lich da che tao duac nhung thiet bi boat dong ban tu dong ghep vai cac may do quang hoac may do dien hoa de phan tich trong nhiing truang hap rieng va sang tao ra nhung may phan lich hoac phuang phap mai nhu sac ky long hieu nang cao phuang phap dien di mao quan v\'

Trong ban bao cao cua de lai nay chung toi trinh bay mot nghien cuu che tao va ung dung dien cue mang long su dung lam detector cho he FIA ket hop vai bp tham tich khi de phuc vu cho xac dinh mot so chi lieu ion nitrat, nitril va amoni trong nuac va nuac thai sinh boat cua thanh pho Ha npi Nha ap dung ky thuat mai nay cac thao tac phan tich dupe thue hien thuan tien lap lai va nil ngdn thai gian phan lich miu Cac tin hieu phan lich thu dupe dual dang pie thuan tien cho qua trinh dinh luang

n PHUONG PHAP NGHlfiN CtfU

Theo nhiem vii cua da tai la nghien cuu ung dung dien cue chpn Ipc ion lam detector trong he thong phan tich dong chay nham xac dinh chpn Ipc cac ion chua nita trong moi truang, cac buac khao sat tien hanh sau day :

Che tao mang va dien cue chpn Ipc ion nitrat

Che tao mang va dien cue chpn Ipc ion amoni

- Che tao bp tham tich sir dung mang tham khi teflon

Khao sat cac dieu kien lam viec cua dien cue trong irang thai tInh va trong he FIA

- Khao sat cae dieu kien lam viec cua he thong dong chay ket hap vai bp tham tich khi Ung dung he thong dong chay xac dinh ham luang cua cac ion nitrat, nitril va amoni trong mot so miu nuac va nuac thai

2.1 Dung cu va hoa chat

2.1.1 Hoa chat

Tat ca cac dung dieh d6u dupe chuan bi tu cac loai hoa chat tinh khiet phan tich (loai p.a) cua hang Fluka, Bucks, Thuy sy hoac hai loai tinh khiet hoa hpc, pha bang nuac cat hai lan Dual day la cac loai hoa chat chinh dupe su dung trong qua trinh nghien cuu:

Tetrahidrofuran (THE)

Amoni sunphat: (NH4) 2SO4

Bac sunphat Ag2S04

- Axit: H3PO4, HCl, H2SO4 axil boric, axil xitric

- Dung dich NaOH

- Cac muoi v6 co: NaCl, KH2PO4, Na3HP04, Na.PO, NaOAc, NaHCO;, NaBr Nal,

NaSCN NaNO., NaNO,, NH4CI, MgCL, LiCl, NaCl, BaCU, KCl, Na,B40, KMn04 K2Cr207, H2O2

Vat lieu mang cua hang Fluka, Buchs, Thuy Sy

Dung dieh dem MES (2-morpholinoethanesulfonie acid)

TRIS (Tris(hydroxymethyl)aminomelhane),

2.1.2 Dung cu thi nghiem

Dien cue so sanh Ag/AgCl tiep xuc kep Hang Orion Research My

Bom Mini-Micro Ismatee 4 kenh My

- Van bom mau Rheodyn Model 5020, My

May do Digital Ion pH meter 692 Metrohm Thuy sT

- Bp tu ghi Kipp & Zonen BD 40 Ha lan

Tliiet bi lav mau nuac mat Kemmerer, Mv

2.2 Che tao mang va dien circ chon loc ion

2.2.1 Chuan bi dung moi

De hoa tan cac thanh phan mang chung toi sit dung dung moi tetrahydrofuran khan, tinh khiet Do dac tinh cua THF co kha nang hap thu hai nuoc trong khong khi va da bi peroxit hoa trong didu kien binh thuang, nen trong THF thucmg co lin lupng nho nude va peroxit,

VI vay can phai chung eat THF truac khi sii dung Qua trinh chung cat duac tien hanh nhu sau :

Cho THF vao binh cau ba eo the tich 500 ml Cho them KOH vao binh chung cat de' lam

kho loan bp nuac lan trong THF Dun hoi luu 1,5 gia trong dieu kien eo dong khi Nita d6

phan buy loan bp luang peroxit, sau do cat lay 1/3 lupng THF ban dau thi ngung qua trinh cat THF dupe giu trong Ip sach, dung gia'y nhom bpc lai va dupe bao quan noi kho rao

Vi THF doc va de no nen phai chung eat trong tu hot va iranh ngpn lira

2.2.2 Che tao mang va dien ciic

Mang long chpn loc ion g6m 3 thanh phan chinh : thanh phan chpn loc ion (chat irao doi ion long hoac chat tao phuc vai ion trung tinh), chat deo hoa va hcfp chat cao phan tu PVC

CO long khoi luang la 200 mg Ngoai ra tiiy theo tijng loai mang cu tha co ih6 cho them

cac thanh phan phu nham muc dieh ue che cac ion la trong qua trinh do cac dung dieh co cuang dp ion lan Cac thanh phan mang duac hoa tan hoan loan bang 2 ml THF (khan, linh khiet) trong mot Ip thuy linh pyrex, sau do rot dung dich mang vao vong ihiiy tinh duang kinh 24 mm dai tren tam kinh sach (rua bang xa phong, nuac cat, etanol, axelon va

say kho) Di cho dung moi bay hai sau 24 gia la se thu dupe mot mang long chpn loc ion

CO dp day khoang 0,2 mm Diing mui khoan cat mot mang co duong kinh 5 mm lap vao than dien cue van nang sau do luyen dien cue 24 gio trong dung dich npi truac khi sir dung

Tlianh phan ciia mang chpn loc ion nitrat [14.15] gom co:

- 3 % ionphore cho Nitrat (tetraoctylamonibromua)

- 30% PVC

- 67% o -NPOE (o-Nitrophenyloctyl ete)

Thanh phan ciia mang chpn Ipc ion amoni [16] bao g6m:

- 3 % ionphore cho amoni (nonactin/monactin)

- 30% PVC

- 67% o- NPOE (octo-Nitrophenyloctylete)

- KT4C1PB 70% trong lucfng so vai ionophore

[CH3(CH2),]4NBr

(TOAB)

Tetra Octyl Amoni Bromua

(o-NPOE) o-Nitro phenyl Octyl Ete

Hinh 2.1 : Cong thue ciia cac thanh phan sir dung trong che tao mang long

2.3 Che tao bo tham tich [17]

Bp tham tich khi la mot bp phan gom 2 kenh dan dupe ngan each bang mot mang tham khi CO kich thuoc 16 mang xac dinh Trong Ihi nghiem nay chiing toi dung loai mang microporous polytetrafluoroethylen (duang kinh 16 mang co 0,2 um) Mot vong dem cao

su CO tinh tra vt mat hoa hpc de giii cho mang tham khi a vi tri c6 dinh De tang hieu qua

cho viec van chuyein khi qua mang, Ihiet bi buong tham khi dupe che tao sao cho moi

kenh ciia thiet bi nay co ty le dien tich be mat so \ai the tich buong lan han so \ a i cac

thiet bi thong thuang khae (24.6cm ' so vai 16.3cm' i V6 thiet bi buong tach duac che tao bans vat lieu nhua Teflon (hinh 2.2)

Hinh 2.2 So do thiet ke bo thaim tich khị

2.4 Khao sat cac dieu kien lam viec ciia cac dien cue [18,19]:

2.4.1 Khao sat dieu kien lam viec cua dien cue mang long chon loc ion nitrat

- Xay dung duong lam viec va xac dinh he so chpn loc cua dien cue chpn loc ion nitral va cac diau kien do trong dong chaỵ

He so chpn Ipc cua dien cue duac xac dinh theo phuang phap dung dich rieng: cac dung

dich NO;,HCO/ CP, Br -, I " NO,', SỐ duac pha trong dung dich dem Tris 0,01 M/1,

^ Xac dinh do pH va ham luang chat oxy hoa trong dong chat mang

Sii duns dung dich nitrit 10"^ M/1 trong cac dong chat mang co dp pH va cac ham luang chat oxy hoa khae nhau, so sanh chiau cao ciia cac pic tuang ung da chon dieu kien lam viec sao cho dp nhay ciia phep do la cue dai

* Xac dinh thai gian ciia phan ung chuyen hoa

Thai gian phan ung a day dupe tinh la khoang thai gian tij khi dong van thu nhat den khi

bat dau dong van thu hai Bam dung dich Nitrit tai mot nong dp nhat dinh, thay d6i thai gian phan ung, khao sat ke't qua do thi do de tim thai gian phan ling phu hap nhat

* Xac dinh toe dp bam dong chat mang oxy hoa

Ghi the'cua dung dich miu Nitrit a mot nong dp (10 M) trong diau kien toe dp bam dong chat mang khae nhau So sanh chieu cao va dp rpng cua pic do toe dp bom gay ra, tu do chpn toe dp bam thich hap

* Xac dinh dp pH va loai chat axit hoa

Kha nang chuyen hoa tir nitrit thanh NO;^ rat phu thuoc vao loai chat axit hoa va dp pH cua no Tien hanh ghi the cua dung dich Nitrit vai cac loai chat acid boa co dp pH khae nhau Tim ra chat acid boa va dp pH thich hcfp

* Xac dinh he so chpn Ipc ciia dien cue doi vai cac ion can sau khi da qua bp thaim tich

Di khao sat dac tinh ciia dien cue Nitrat trong he Chiing toi lien hanh do he so chon Ipc

ciia dien cue doi voi cac ion can sau khi da qua thiet bi mang tham

2.4.2 Khao sat dieu kien lam viec ciia dien cue mang long chon loc ion amoni

- Khao sat dien cue do a trang thai tinh

Xay dung duang lam x'lec ciia dien cue amoni trong cac dung dich dem khae nhau :

Dem MES CO pH = 5.5

Dem Tris co pH = 7,2

Dem borat pH = 9,0

Xac dinh he so chpn Ipc ciia dien cue

Ha so chpn loc ciia dien cue amoni duac xac dinh theo phuang phap dung dich rieng Cac

dung dich muoi riang biat cua cac cation, nong do O.IM dupe pha trong dem Tris pH - 7,2

nong dp 0.01 M/1

- Khao sat dien cue do trong he FIA

Tren co so ket qua ciia phan do tinh, chiing toi sir dung cac dung dich dem khae nhau da khao siit lam chat mang cho he FIA Cac dung dich amoni co nong dp tu 10"^ M den 10"^

M dupe bam lan lugt vao he thong

Ngoai ra cac yeu to kliac cung duac khao sat

- Khao sal he FIA ghep vai bo tham tich khi

Sau khi khao sal cac yeu to Iran, chung toi tien hanh buac tiep theo, gdn them mot bo tham tich khi amoni da tang do chpn Ipc va kha nang ung dung thue le ciia he thong

2.4.3 Khao sat dieu kien phan tich miu thue te

- Diau kien lay miu va bao quan miu

Xir ly sa bp miu tru6e khi phan tich

III K^T QUA VA THAO LUAN

3.1 Khao sat cac dieu kien lam viec cua dien cue nitrat

Doi vol cue chpn Ipc ion cac ya'u to quan trpng nhat la khoang tuya'n tinh, dp doc va dp chpn loc do'i v6i cae ion ngoai Cac ka't qua thu dupe cho thay dien cue nitrat mang long co

do doe la 58mV/dec va dap ling nhanh (5 giay) trong khoang nong dp cua ion nitrat tir 10"' den 10'M/1 [20]

8.5 - 59.1 Ig[N03-] (1) 11.0 - 55.7 Ig[N03-] (2)

Hinh 3.1 : Duong lam viae ciia dien cue nitrat mang long vai

cac chat trao doi ion khae nhau

300 EMF (mV)

200

100

16.0

U.O" 55.7 IglNOj-] (1) 8.5 - 59.1 Jg[N03-] (2) -15.0 - 52.2 Ig[N03] (3)

Hinh 3.2 : Duong lam \'iec cua dien cue nitrat mang long \'ai

cac chat deo hoa khae nhau

Qua khao sat mot so loai chat trao doi ion long tren co sa muoi amin bac 4 vai cac mach hidrocacbon eo dp dai khae nhau chung toi co nhan xet vai chieu dai maeh R=C8 thi linh

dp ciia cha't trao doi ion long la nhanh nhat (thong qua viec do thai gian dap ung ciia dien cue) va CO dp doe va khoang tuyen tinh lan nhat Ngoai ra nhan to lam moi truang van chuyen cua cac chat trao dOi ion long cung v6 cung quan trpng Vai chat deo hoa la o-NPOE mang thu dupe co mau trong (kha nang hoa tan cac chat trao d6i ion long tot), con khi sir dung cac chat deo hoa khae mang co mau due

Bang 3.1 : Ket qua xac dinh he so chpn loc cua dien cue nitrat bang phuang phap dung

dich rieng (nong dp ion cua cac dung dich 10"' M/1, do tinh va do trong dong chay FIA)

aj,max (M/1) 10' 1.4xl0' 5.0x10"^

7.8x10^

9.8xl0' 1.74 1.23 3.5 2.1x10' 3.5x10' 5.3xl0'

l 4 x l 0 '

Do trong trang thai dong chav

(FIA) E(mV)

59 -44 -12

a, (MA)

1.9x10"' 6.5x10'"^ 7.2x10"' 1.7x10"' 1.7 2.6 3.5 2.2xl0' 2.2x10' 7.24xl0' 1.4x10'

Tix ket qua xac dinh ha so ebon Ipc ciia dien cue chung toi nhan thay cac anion gay anh

huang manh la SCN ' I ' Br', NO " va CI ' va OH 7 Do co dp ma hoa cao ion I", SCN'

CO tha hoa tan true tiep vao pha mang ma khong can den sir tuang tac vai cac chat trao dOi ion Tuy nhian nong dp ciia cac ion gay anh huang manh nay trong thuang rat nho do vay

su anh huang do chung gay ra khong dang ke Cac ion halogen co he so chon loc nho han, nhung do nong dp ciia chiing trong moi iruong lai gap nhieu tram lan n6ng dp ciia

ion nitrat vi vay phai lien hanh buac xii ly so bp bang ket tiia bac truac khi xac dinh nitrat

Ca ion anh huang khae bang bian phap phan buy bang axit sunfamic hoac thay doi pH

ciia dung dich chuna ta c6 the loai bo hoan loan anh huang ciia chiing

Sau khi do kiem tra trong trang thai tinh chiing toi da thir nghiem do trong dong chay

FIA voi cac dieu kien da dupe nghian ciiru cho dap ung tot nhat : loai thanh phan pH va loc dp ciia dung dich chai mang cho he FIA la dam photphat 10'^ M pH = 2.8 va toe do 2.3 ml/phiit

3.2 Khao sat dieu kien phan tich nitrit su dung he FIA voi dien cue chon loc ion nitrat ket hop voi bo tham tich khi

3.2.1 Chon chat oxy hoa

Hien nay, dien cue mang long chpn Ipc ion nitrit Iran ca sa su dung din xuat cua vitamin B12 da bat dau nghien cuu che tao [21] Dien cue mang long loai nay co dp chpn Ipc rat cao v6i ion nitrit, tuy nhian gia thanh ciia vat lieu mang con rat cao Trong phan nay chiing toi trinh bay mot phuang phap gian tiep xac dinh nitnt khae do theo nguyan tac

khir nitrit thanh khi NO,, sau do chuyen boa NO, thanh NO/ va xac dinh bang cue nitral

Nitrit trong moi truang a xit tao thanh NO, se khuech tan qua mang tham khi \a dupe bay trong dong chat mang chua chat oxy hoa Chiing toi da thu nghiem sir dung 3 loai chat oxy hoa la KMn04, K2Cr207, H.O tat ca deu dupe pha trong dem photphat Ca KMnOj

va K2Cr207 deu to ra kha nang oxy hoa rat tot, nhung do tinh oxy hoa manh cua chiing nen gay ra nhieu tra ngai eo tha lam hong mang Khi sir dung chat oxy hoa H^O., chiing toi nhan thay rang khong gap tra ngai nhu trong hai truang hcfp tren

Qua trinh oxy hoa mau xav ra nhu sau

Bang ket qua sau day se chi ra nong dp thich hcfp ciia chat oxy boa va dp pH ciia dong chat mang (theo chiau cao ciia pie dupe tinh bang em)

Bang 3.2: Su phu thuoc ciia kha nang oxy hoa vao pH \a ham luang ciia chat oxy hoa

2,6

3,1 3,5 3.3

2,8

3.3 4,2 4.0

3,0

3.0 3,1 2.9

3,2

2.7 3.0 2.5

Tren ca sa nghian cuu \an da toi uu hoa he ihdng chiing toi sir dung dam phot phat 0,005M pH 2,8 chiia 0.1% H.O va NaNO; 10"' VI Viec tham lupng nho nitrat co y nghia

lam tang toe do can bang ciia dien circ va tang do nhay lai cac nong dp nitrit thap

3.2.2 Xac dinh thdi gian cua phan ixng chuyen hoa

Thai gian cua phan ung chuyen hoa dupe xac dinh la khoang thai gian ka tir liie bam miu den khi dong van thu hai Khao sat thai gian phan ling thich hcfp quyet dinh den dp chuyan hoa cua qua trinh Bang ket qua dual day cho ta thay khoang thai gian thich hap

la 2,0 phiit

Bang 3.3: Sir phu thuoc cua dp chuyen hoa vao thai gian oxy boa NO,

Thai gian oxy hoa (phut)

Cdc dieu kien xdc dinh nitrit bang su dung he FIA ket hap vai bo tham tich khi :

Dung dieh chat mang la muoi KH2PO4 nong dp 10"^ M/1 vai pH=2,8 trong do eo chua 0,1% Wt H2O2 va NaNO, nong d6 10"'M/1

- Dung dich axit hoa la H,P04 nong dp 5.10''M/1

Toe dp dong chat mang la 2,3ml/phut

The tich vong miu 500|il

Dp nhay may ghi 50mV

Toe dp giay may ghi Imm/phiit

Hinh ?f3 : Tin hiau FIA ciia dung dich chuan mint xac dinh bang dien cue nitrat

ket hap vai bo tham tich

10

Tinh chpn Ipc cao ciia he thong phu thupe vao kha nang khuyech tan cua cae khi boa tan trong dong chat mang qua mang teflon cua bp tham tich va dp chpn Ipc ciia detector chpn loc ion nitrat Ket qua thue nghiem cho thay cae ion HCO3", F', CI", Br" khong gay anh huang tai qua trinh phan tich NO2", ngoai trir truang hcfp cua ion 503'' la co anh huang ro ret Trong he thong, ion S03^" chuyan hoa thanh khi SO2 va khuech tan tuang toi manh qua mang teflon va gay anh huang tai qua trinh dien cue Tran thue te vai ham luang sunphit trong moi trucmg thucfng nho han 10"^ M/1 do do khong gay anh huang den phep xac dinh nitrit

3.3 Khao sat cac dieu kien lam viec cua dien cue amoni

3.3.1 Khao sat dien cue amoni do tinh:

Su ton tai cua ion amoni trong dung dich rat phu thuoc vao pH ciia dung dich do do vay khao sat su anh huang ciia pH dung dieh tai phep do dian the ciia ion nay la cin thiet Cac dung dich dem (nong dp 10"' M/1) co pH khae nhau dupe lua chpn nhu sau : dem MES pH

= 5,5; dem Tris pH = 7.2 va dem Borat pH = 9.0 Ket qua dupe the hien trong hinh 3.4

Hmh 3.4 : Duong lam viec ciia dien cue amoni do trong dam vai cac pH khae nhau

I- dam TRIS (pH-7.2): 2 - dam MES (pH=5.5); 3 - dam Borat fpH=9)

Tu ket qua thu duac chung loi nhan thay trong dam Borat pH==9.0 dien cue dap ung cham gia tri the khong on dinh do trong dem Borat pH ciia dung dich cao lam thay d6i can bang NHj"" — > NH; lach ve phia NH-, gay anh huang den the can bang dien cue

Khi do trong dem MES pH = 5.5 va dem Tns pH = 7.2 ihi dien cue boat dong tot ban gia tri the 6n dmh nhung dien circ do trong dem Tns co do doc \'a khoang tuyen tinh mo rpng ban, co tha dai den giai han phat hien 5.10" M/l cua ion amoni

I I

Qua cac ke't qua khao sat tren chiing toi nit ra ket luan dian cue boat dong tot trong dem

Tris pH =7,2

Sau khi tim duac dung dich dem va pH thich hap doi vai cue amoni, chiing toi da xac

dinh he so chpn Ipc cua dien cue theo phuang phap dung dich riang, ket qua thu dupe

trinh bay trong bang sau:

Bang 3.4 : He so chpn Ipc ion cua dien cue amoni mang long va phan tram sai so cue dai

doi voi nong dp 10"' M/l cua cac dung dich ion ngoai dupe do a trang thai tinh

Sai so cue dai Pg (%)

-_-0.014 0.030

0.40 20.00

0.03 0.03 1 0.01

Til bang ka't qua he so chpn Ipc, cho ta thay ion K^ va

chpn Ipc ion amoni, va cung tu bang tran cho thay khi

amoni thi sai so gay ra la 0,4% doi vai truang hcfp Na

cac ion khae co he so chpn Ipc K^^^ j deu tij 10"' den

phep do N H / deu nho ban 0,04% Nhu vay dien cue

tuang doi cao doi vai mot so cation trir truang hop ciia

tham khao nong dp K^ va Na^ trong mau moi truang th

sai so do anh huang ciia chiing gay ra chiing toi tien

Na^ gay anh huang manh den cue hai ion nay ciing nPng dp vai ion

^ va 20% doi vai K* Con doi vai

10 '^, sai so do chiing gay ra trong chiing loi che tao co dp chpn Ipc

2 ion K" va Na* Theo cac tai lieu uang kha cao Vi vay da iranh cac hanh khao sat theo phuang phap dong chay

3.3.2 Khao sat cue amoni do trong he thong FIA

Lua chon chat mang:

Til ket qua thu dupe khi khao sal dien ciJc a trang thai tinh ta su dung dien cue ebon loc

ion amoni lam detector trong he thong dong chay

Nhu phan tren da thay pH boat dong toi uu ciia dien cue la 7.2 do do khi lua chpn dong

chat mang ta sir dung mot so dem thong thuang co kha nang dem trong khoang nay nhu:

Tris-HCl pH=7,2; phot phat(KH2P04 va Na.HPO, ) pH=7.5: xitrat pH=6,7 Sau day la ket

qua thu dupe:

12

^^idnnm&

Hinh 3.5 Tin hieu FIA khi sir dung cac loai dem khae nhau lam chat mang

Ket qua cho thay vai dem phot phat duang nan khong on dinh, duang lam viec khong dap ung yau cau

Khi sii dung chat mang la dem phot phat a pH==7.5 thi co the tuyen tinh trong khoang tii

lO'"* den 10''M nhung khi do dp doc thap (45,8mV/dec), do thanh phan ciia dem co chua

cac ion kali va natri

Tir cac ket qua thu dupe chiing loi thay dem phot phat khong thich hap lam chat mang vi tin hieu xau, duang nen khong dupe Ihang, dp doc khong cao va khoang tuyen linh hep Con doi vai hai loai dem xitrat va dem Tris, thi dem Tns cho tin hieu tot han dp doc cao ban (53,lmV/dec) nhung thai gian tra lai duang nan keo dai (khoang 3 phut) Trong truang hcfp dem xitrat, tuy thai gian tra lai duong nen nhanh (khoang1.5 phut) pic gpn ban nhung tin hieu do thap va co khoang tuyen tinh nho han (chi lai nPng dp lO^M) Do

do viec toi uu hoa cac dieu kien lam viec trong he FIA can duac tiep tuc nghien cuu ky

han Hian nav chiino toi lam duns lai a viae co the su duns duns dich dem Tris lam chat

mang cho he FIA nham xac dinh chpn Ipc ion amoni

Xdc dinh he so chpn loc cua dien cue trong ddng chdy:

Sau khi tim dupe chat mang thich hap chiing toi lien hanh do dp can tra ciia cae ion trong dong chay Cac cation khae nhau vai nong dp O.IM lan luot dupe bam vao he ket qua thu dupe a bang sau:

Bang 3.5: Ha so chpn Ipc ion ciia dien cue amoni mang long \'a phan tram sai so cue dai

doi vai nons do 10"' M/l ciia cac duns dich ion ngoai duac do irons dong chav

chonioc Kj j Sai so cue dai P^ (%)

—

0.010 0.020 0.160 15.850 0.001 0.006 0.002

13

So sanh ket qua vira thu dupe vai ket qua a trang thai tinh, chiing toi nhan thay trong dong chay dp chpn loc tuy co cao ban nhung vin bi Na"*" va K "^ gay sai so lan (0.16 % do Na"*"

va 15,85 % do K"*" gay ra) Qua do ta thay rang, vin chua the xac dinh true tiep amoni tir cae mau theo phuang phap dong chay

Vi vay, tren ca sa tham khao tai lieu nuac ngoai, ciing vai nhung ket qua thu dupe a Iran

chiing toi chuyen sang huang nghian cuu mai la xac dinh ham lupng amoni bang he FIA

CO gan bp tham tich khi

3.3.3 Khao sat trong he FIA co g^n bp tham tich khi

Tu nhOng ket qua thu duge trong he FIA thong thuang va nghian cuu tai lieu tham khao [ ] chiing toi buac dau nghian cuu dap ling ciia dien cue trong he FIA co gan bp tham tich khi v6i dong hap thu khi la dem Tris pH = 7,2

Lua chon pH cho phdn i(ng chuyen hod

Amoni trong dung dich ton tai can bang sau:

Di can bang chuyan dich ve phia trai (tao NH3) thi can phai tang pH ciia dung dich thanh

moi truang kiam Trong truang hcfp nay, chiing toi da diing dung dich NaOH co pH khae nhau cho phan ling chuyen hoa va dong thai lam dong van chuyen mau den bp tham tich Sau day la tin hieu FIA va duang lam viec cua dien cue khi diing NaOH co pH khae nhau cho phan ung chuyen boa

—.-*. ^ ^

Hinh 3.6 : Tin hiau FIA kei hap voi bo tham lich khi

Hinh 3.7 : Duong lam viec cua FIA ket hap vai bp thaim lich khi a cac pH khae nhau

Tii do thi Iran ta thay rang: vai pH = 12 dian cue lam viae lot nhat nghIa la phan ung chuyen hoa Iriat da nhai Neu pH cao ban nua se dan den qua trinh thuy phan cac cation kim loai kiem lh6, gay tac mang ngan can qua trinh tham khi Vay pH tot nhat cho phan ling chuyen boa la 12

Xdc dinh ihZyi gian chuyen hod

Thai gian chuyen hoa cung chinh la thai gian ke' lu khi dong van ihu nhat den khi dong van thu hai) bao gom :

4- Thai gian chuyen boa tii NH ^ thanh NH3 duai tac dung ciia NaOH (dian ra a kenh

duai)

+ Thai gian NH3 tham qua mang de lan kanh tran

+ Thai gian chuya'n hoa tir NH3 thanh NH + (dian ra a kenh Iran)

Chiing toi sir dung nong do NH "^ (10"^M) da khao sat Ket qua thu duac trong bang sau:

Bang 3.6 : Anh huang cua thai gian den chuyan boa den dp nhay (nong do dung dich

amoni sir dung trong khao sat nay la 10"' M/l)

Thai gian (phiit) 1.0

The(mV) 88.2

2.0 89.7

2.5

95

3.0 96.8

3.5

94

4,0 92,5

Tij do ta thay rang thai gian cho su chuyen hoa lan nhat la 3 phiii

Xdc dinh he so chon loc:

Trong he nay, qua trinh xac dinh NH4+ khong bi Na"^ va K+ gay anh huang nhung neu nong dp Ca^"*" va Mg^"^ lan se bi thuy phan, tao ket lua dang huyan phu (do pH cao cua moi truang), lam tac mang, can tra qua trinh tham khi Trong truang hap nay, dung dich chat chuyen hoa (NaOH) can cho tham EDTA (nong dp 0,0IM) de tao phuc ben, ngan khong

cho Ca '^ va Mg "^ thuy phan

Anh huang cua toe do bam vd the tich vdng mau :

Ngoai cac yeu to quan trpng nau Iran, khi thay dPi cac vong miu co tha tich khae nhau \'a diau chinh toe dp bam khae nhau chiing toi cung nhan dupe cac dp nhay khae nhau Gia tri lua chpn phii hcfp cho he phan tich nay nhu sau :

-I- Toe dp bam kanh tran : 1,5 ml/phiit

-I- Toe dp bam kenh duai: 1,0 ml/phiit

-I- The lich vong miu la : 100 \x\

3.4 iTng dung do mkn moi truang nude va nuoc thai

Hien nay so dan a thii do Ha noi co khoang Iran 1,5 irieu nguai Vai han 250 nha may lan

va trung binh khoang 1000 co so san xuat nho, 20 benh vien va nhiau vien nghien cuu

khae Lucng nuac thai hang nam cua Ha npi ca 120 irieu m' dupe thai ra chii yeu tii 4 khu cong nghiep chinh nam a phia nam thanh phd da la ngu6n gay o nhiem anh huang true tiep tai nguon nuac khu vuc Ha npi Cac khu cong nghiap nay chu yeu nam rai rac chung quanh huyen Thanh tri bao gom 33 nha may Idn nhu :

• Khu cong nghiep Van dian: nha may boa chat, nha may pin, nha mayphan bon phot phat, nha may muc

• Khu cong nghiep VInh tuy: Cac nha may dat nhu: Nha may del 8-3 nha may dat Ha npi, nha may Hong ha

• Khu cong nghiep Minh khai va Giap bat: Khu che bien thue pham (6 nha may), nha may khoa Minh khai nha may cha' tao may a Mai dong

• Vai nha may a khu cong nghiep Thuang dinh cac benh vien va cac phong thi nghiam Ion nhu: Thanh nhan Bach mai va Viet x6 cung dang thai nuoc ra song To lich va Kim nguu

Nguon nuac thai a cac benh vien \'a cac phong thi nghiem nghian ciiu thuang c6 chua nhihig sinh vat gay benh nhieu hoa chat co doc tinh Nuoc thai sinh boat cung nhu nuac thai cong nghiep la nhung doi tuang co chua nhieu ion co nita Lucng nuoc do dupe thai true tiep vao cac kanh, muang, ao, ho da tan dung cac chai dinh duong trong nuac thai da nuoi ca Dong thai tir cac ngu6n nuac nay chung cung co tha duac diing da bam tuai cho hoa mau

Chinh VI vay chung toi tien hanh lay miu a mot so nha may nuac Iran dia ban Ha noi cung nhu mot so diam tren he thong thoat nuac nham thu nghiam kha nang ung dung cua thiet bi phan tich dong chay sir dung cue chon Ipc ion phuc vu phan tich cac ion v6 co chua nita

16

3.4.1 Lay mSu va bao quan mkn [22] :

Ngoai viec lay miu nu6c ngim a cac nha may nu6c phuc vu cho viec khao sat thi cae

miu sit dung cho viec phan tich con dupe lay tai mot so diem doc theo cac con song, ao,

dim ca chLi yeu la khu vuc thupe huyen Thanh tri Miu dupe lay bang thiet bi lay miu

nu6c a dp sau 0,5 met v6i the tich khoang 1 lit va dupe axit boa ngay lap tuc bai 5ml axit

sunfuric dac doi voi muc dich phan tich N H / , con doi vai phan tich NO3" va NO2 thi miu duac bao quan bang eloroform da ban cha' sir chuyan boa cua cae vi sinh vat Tat ca cac miu nay dupe dung trong chai thuy tinh 1 lit mau nau va dupe bao quan a 4'^C trong phong thi nghiem

3.4.2 Xac dinh ham lugng cac ion amoni eo trong mau nuoc ngam:

De khao sat viec xac dinh ham lucng cac ion v6 co co chua nita trong moi truang buac

diu chiing toi thu nghiem tia'n hanh xac dinh ham luang ion amoni co trong nuac ngim tran dia ban Ha npi bing dien cue chpn Ipc ion amoni mang long vira che tao a tran Dong thai so sanh ket qua thu dupe vai viec xac dinh bang dien cue khi amoniac thuang mai do

MI che tao

a) Xdc dinh ham luang cdc ion amoni co trong man nuac ngdm hang dien cue mang long:

Viae xac dinh nong dp ion amoni co trong nuoc ngam dupe thue hien theo phuang phap iham Npi dung ciia phuang phap do nhu sau:

Do hai gia in the ciia dung dich miu truac khi tham (E,) va sau khi tham (E.) mot the tich

Va dung dich chuan N H / n6ng dp Cs vao dung dich miu tha tich Vo va nong dp chua biet Cx Khi do taco:

Vo + Va

Cac miu dung trong viae khao sat dupe lay lu cac nha may nuac nam tran dia ban Ha npi nhu : Nha may nuac Mai dich nha may nuac Phap Van nha may nuac Ha dinh nha may nuac Yan phu, nha may nuac Tuang mai nha may bia Heniger

Tien hanh do gia tri the E, truac khi them 0.25ml NH.Cl O.IM va gia in the E sau khi tham 0,25ml NH4CI O.IM roi tinh nong dp theo phuang phap them nau chuan ta thu duac ket qua nhu sau :

- »

uimBi '

Gia tri the do duac tinh bang mV

•52.9

19.1

13.9

Sau -75.0 -75.5 -75.1 -75.2 -54.5 -54.8 -54.1 -54.5 20.7

12.3

HaDmh Truac -79.2 -79.8 -79.6

-79.5

-56.3 -55.5 -56.4

•56.1

23.4

10.2

Sau -81.3 -80.9 -80.9

•81.0

-56.5 -55.8 -56.3

•56.2 24.8

9.3

YanPhu Truac -96.0 -96.1 -95.7

-95.9

-59.7 -59.9 -59.3 -59.7 36.2 4.7

Sau -99.4 -99.8 -99.2

•99.5

-60.7 -60.9 -60.4 -60.7 38.8

4.1

TuangMai Truac

-88.6 -88.6 -88.0

-88.3

-58.9 -59.1 -58.4 -58.8 29.5 6.9

Sau -91.1 -90.7 -91.3

-91.0

-60.6 -60.8 -60.1

-60.5

30.5 6.5

Do miu a nha may nuac Mai Dich va May Bia Heniger nam ngoai khoang tuyen tinh cua dien cue nan chiing toi khong dua cae gia tri do dupe ciia chiing vao phin ket qua

Di danh gia tinh diing din va tinh kha ihi ciia phuang phap buac tiep theo chiing 161 xac

dinh ham lucfng ion amoni trong nuoc ngam ciia cac miu Iran bing dien cue nhay khi

NH^ thuang mai do My che tao sau do so sanh vai kei qua vira thu dupe a tran

b) Xdc dinh ion amoni trong nUac ngdm hang dien cue nhay khi theo phuang phap {hem tieu chuan

Do the ciia dung dich miu tuang lu nhu Iran Gia tri E, la the do dupe truac khi tham NH4CI con E la gia tri the sau khi iham 0,2 ml NH4CI O.IM Sau do tinh nong dp theo phuang phap tham ta thu dupe ket qua sau:

Cac gia tri the do dupe linh bans mV

Sau 40.2 39.5 39.7 39.8 28.2 28.6 28.7 28.5 11.3 11.7

Ha Dinh Truac 41.3 41.7 41.9 41.6 27.9 28.5 28.8 28.4 13.2 9.5

Sau 48.6 47.8 48.3 48.0 33.6 33.9 34.4 34.0 14.0 8.8

Yen Phu Truac 58.3 57.8 58.5 58.2 35.4 35.2 34.8 35.1 23.1 4.4

Sau 60.6 60.5 59.8 60.3 35.9 35.1 35.4 35.4 24.9 3.8

Tuang Mai Truac 50.3 51.1 50.5 50.6 32.6 32.8 33.3 32.9 17.7 6.4

Sau 53.2 52.5 52.7 52.8 33.7 33.6 34.2 33.9 18.9 6.0

So sanh hai ket qua thu dupe ta c6 :

Ha Dinh

Truac 9.5 10.2 6.9

Sau 8.8 9.3 5.4

Yan Phu

Truac 4.4 4.7 6.4

Sau 3.8 4.1 7.3

Tuang Mai

Truac 6.4 6.9 7.2

Sau 6.0 6.5 7.7

Qua cac ka't qua tran ta thay :

Ham lupng amoni trong nude ngam a mot so khu vuc tai Ha Npi la rat cao vucft qua qui

dinh cho phep (3 mg/l) Cae ket qua do dupe giiia dian cue amoni mang long \'a dien cue

nhay khi NH3 sai lech nhau khong dang ka, chiing to viec xac dinh amoni trong nude

ngim bang dien cue amoni mang long la co the thue hian dupe

Tuy nhien khi xac dinh amoni nitrat, nitrit trong nuac thai ihi kho khan ban nhiau so vai

phan tich nuac ngam hoac nude mat do thanh phan cua nude thai sinh boat co chua rat

nhiau chat khae nhau

Vi vay chiing toi lien hanh budc tiep theo la ap dung xac dinh nong do ciia cac ion vo ca

chira nita co trong nuac thai a khu vuc song To lich, song Kim nguu cung nhu cac ao nuoi

ca a huyen Thanh iri

Viec xac dinh ham lucng cac ion vo co co chiia nita nhu N0-\ NH/ NO bang thiei bi

phan tich dong chay dupe thii nghiem trong phong ihi nghiem irons vong 24 gia sau khi

lay miu Ket qua thu duac nhu sau:

Diem lav miu

5.5

8.3

5.5

6.3 5.0 3.8 3.3 5.1

Ion amoni (mg/l) 20.7 20.7 21.2 24.6 29.7 30.2 28.1 14.0 13.1 12.8

Ion nitril (mg/l) 2.9 3.2 2.6 6.4 4.4 : 3.4 !

1

3.8 1 2.3

1.7 1 1.5

19

KET LUAN

Tren day chung toi da trinh bdy loan bg cdc ket qua nghien cihi cua de tai nghien eihi che tao vd itng dung dien cue chon Ipc ion ket hap vai phuc vu eho qua trinh phdn tich cdc ion chua nita trong thue pham vd moi tru&ng Day la mot linh vuc phdn tich hien dai vd

CO tinh thi^c tiin rat cao De tai nay da gop phdn quan trpng vao su phat trien ede phucmg phap phdn tich dien hod cua nuac ta Theo npi dung da trinh hay, de tai da gidi quyet cdc van de sau :

L Nghien cuu che tqo mang long chpn Ipc ion nitrat khdo sdt ede dac tinh cua dien cue nhu dp doc dien cue, khoang tuyen tinh vd he so chpn Ipc ion doi vai ede anion gay anh huang tai qua trinh phdn tich cua dien cue

2 Khdo sdt cdc dieu kien lam viec cua dien cue trong dong chdy ve ede yeu to nhu thanh phdn, nong dp, pH vd toe dp eita dong chdy

3 Che'tqo bp tham tich khi tren ca so cdc vat lieu trong nuac diing ke't hap vai he FIA phuc vu cho qua trinh phdn tich ion nirit

4 Tren ca sa he FIA-ISE chpn Ipc ion nitrat da khdo sdt cdc dieu kien chuyen hod NO2 -^ NOx -^ NO^ thong qua qua trinh trung gian chuyen hod thanh NOx

5 Che tqo duac dien cue chon loc ion amoni mang Idnq tren af so ionophore nonactin/monactin

6 Khdo sdt cdc dieu kien lam viec cua dien cue amoni trong he FIA ket hap vZ/i ho (ham tich khi (dong chuyen hod NH/ -^ NHj Id dung dich NaOH, pH=I2: dong chuyen hod NHj-^ NH/ id dem Tns pH = 7.2) de tang dp chon loc ciia phep phdn tich tir do

ma rpng khd nang dp dung eiia dien cue eho xdc dinh ion amoni trong nuac thdi Dien cue lam vice tuyen tinh trong khodng tic W' den 10'^ moll I NHA ^'<^^ do doc Id 53.2 mVldec

7 Trong cdc loqi phuang phdp phdn tich ihi phuang phdp su dung cue chon Ipc ion Id dan gidn nhat, nhanh nhay vd chinh xdc cao Tren ea sa ket hap vai k-y thuat FIA vd

bp tham tich khi cho phep tang dp chpn cdc phep do thu nghiem cho mot so mdu thuc

te da duac tien hanh vd cho kei qiid ddng tin cay vd nil ngdn thai gian phdn tich

20

TAI LIEU THAM KHAO

[I] T E Edmonds

Chemical sensing in the environment: the challenge to the analytical

chemist,

Trends in Analytical chemistry, Vol.4, No 9, 1985

[2] Michael T Riebe and Daniel J Eustace

Process Analytical Chemistry an Industrial Perspective

Analytical chemistry Vol.62, No 2 January 15 1990

13J Liliana Ilcheva and Karl Cammann

Flow Injection Analysis of Chloride in Tap and Sewage Water Using

Ion-Selective Electrode Detection

FreseniusZAnal Chem 322 (1985), 323-326

(4J Application short note

Determination of the sum of nitrite and nitrate hy flow

injection analysis

TecatorASTM 12/1984

[5J Flow injection analysis from test tube to Integrated Microcondiiits

Analytical chemistry Vol.55, No II September 1983

16J Bernard Rocks and Clifford Rileay

Flow injection Analysis : A New approach to quantitative measurements in clinical chemistry,CLIN Chem 28/3, 409-421 (1982)

[7] Medical and Biological Applications of Electrochemical Devices Edited hy J

Koryta; Chapter 21980 John Wiley and Sons Ltd

[8/ W E van der linden

Flow injection analysis: the manipulation of dispertion

Trends in Analytical chemistry, Vol.1, No 8, 1982

[9] W E van der linden

Miniaturisation inflow infection analysis Practical limitations from a

theoretical point of view

Trends in Analytical chemistry Vol.6, No 2 1987

1101 Von P Collet

Being ziir Bestimmungvon Nitrit und Nitrat in Lenhensmitteln

Deusche Lebensmittel - Rundschau / 79 Jalirq ' Heft II i 1983

/Ill Andre Schmitt Louise Buttlie and Ro^er LBJIOW i Depanment of Applied

Biology.Umversity of Hull, Hull HV 67RX-(zKr

An intergraie Reduction method for the Determination rfUrca as

Ammoni in Fresh water samples,

Analxtica Chimica 254 i 1993) 249-255

: i