luẬn vĂn

TRNG H CNG NGHIP H NI HA

KHOA CNG NGH

MC LC

Contents MC LC.............................................................................................. 1 M U ................................................................................................ 4 PHN I: TNG QUAN ....................................................................... 5 CHNG I: TNG QUAN V NC ............................................. 5 1.1.NC .............................................................................................. 5 1.2.NC MT .................................................................................... 6 1.3.NC THI ................................................................................... 6 1.4. KHI QUT V NHIM NC ........................................... 8 1.5. NHIM NC MT ................................................................ 9 CHNG 2: TNG QUAN V PHOTPHO TNG S ............... 11 2.1.KHI NIM .................................................................................. 11 2.2.PHN LOI PHOTPHO ............................................................. 11 2.3.TNH CHT CA PHOTPHO ................................................... 12 2.4.VAI TR CA PHOTPHO ......................................................... 12 2.5.THC TRNG NHIM PHOTPHO HIN NAY ................ 13 2.6.NGUYN NHN GY NHIM ............................................. 13 2.7.NH HNG CA PHOTPHO TNG ................................... 14 2.7.1. nh hng i vi mi trng t ......................................... 14 2.7.2.nh hng i vi mi trng nc ....................................... 15 2.7.3.nh hng i vi con ngi ................................................... 17 CHNG 3: TNG QUAN V PHNG PHP PHN TCH QUANG PH HP TH UV-VIS .............................................................. 18 3.1.PHNG PHP TRC QUANG .............................................. 18 3.1.1.Khi nim.................................................................................... 18 3.1.2.Phn loi ..................................................................................... 18 3.2.PHNG PHP PT QUANG PH HP TH UV-VIS ......... 18 3.2.1. nh lut v s hp th nh sng ............................................ 18 GVHD: Nguyn Th Thoa SVTH: Th Thoa Page 1


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3.2.2. Cc nguyn nhn gy ra s sai lch nh lut Lambert - Beer ......................................................................................................................... 21 3.2.3. Cc phng php nh lng trong quang ph hp th phn t ..................................................................................................................... 22 3.2.3.1.Phng php dy tiu chun ( PP thang mu )..................... 22 3.2.3.2. Phng php cp i ( hay PP chun so mu )............... 24 3.2.3.3. Phng php cn bng (PP t l so snh). ............................ 25 3.2.3.4. Phng php ng chun ................................................... 26 3.2.3.5. Phng php thm chun ...................................................... 28 3.2.3.6. Phng php vi sai ................................................................. 28 CHNG 4: CC PHNG PHP PHN TCH PHOTPHO TNG S ....................................................................................................... 30 4.1. PHNG PHP CHUN TRUNG HA (hm lng ln) ......................................................................................................................... 32 4.2. PHNG PHP KHI LNG (khi hm lng ln) .......... 32 4.3. PHNG PHP TRC QUANG ............................................. 33 PHN 2: KT QU THC NGHIM ............................................ 35 CHNG 1: CHUN B ................................................................... 35 1.1. NGUYN TC ............................................................................. 35 1.2. DNG C - HA CHT ............................................................ 35 1.2.1. Dng c ...................................................................................... 35 1.2.2. Ha cht ..................................................................................... 36 1.2.2.1. Axit H2SO4 30% ...................................................................... 36 1.2.2.2. K2S2O8 ...................................................................................... 36 1.2.2.3. Dung dch Vanadat Molipdat .............................................. 36 1.2.2.4. Dung dch HCl long (dd ra) ............................................... 36 1.2.2.5. Dung dch ch th phenolphtalein .......................................... 36 1.2.2.6.Than hot tnh.......................................................................... 36 1.2.2.7. Dung dch chun PO43- ( 50mg PO43- - P/l ) .......................... 36 1.3. LY MU BO QUN MU ................................................ 37 1.4.CHUN B MU .......................................................................... 37 1.4.1 Lc s b ..................................................................................... 37 1.4.2 Thy phn axit s b ................................................................. 38 GVHD: Nguyn Th Thoa SVTH: Th Thoa Page 2


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CHNG 2: KHO ST CC IU KIN TI U .................. 39 2.1.KHO ST BC SNG TI U (max) ................................ 39 2.2. KHO ST THI GIAN TI U ............................................ 39 2.3. KHO ST pH TI U............................................................. 40 2.4. KHO ST LNG THUC TH......................................... 40 2.5. KHO ST KHONG NNG TUYN TNH ................. 41 2.6. KHO ST ION CN TR ...................................................... 42 2.7. DNG NG CHUN ........................................................... 42 CHNG 3: O MU THC ......................................................... 43 3.1.PH MU...................................................................................... 43 3.2.O MU ........................................................................................ 43 3.3.TNH TON KT QU .............................................................. 43 3.4. SAI S - X L KT QU THC NGHIM ........................ 43 KT LUN .......................................................................................... 44 TI LIU THAM KHO .................................................................. 45

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M UHin nay mi trng tr thnh vn chung ca ton nhn loi v c c th gii quan tm.Nm trong khung cnh chung ca ton th gii, c bit l khu vc Chu -Thi Bnh Dng, Chu Phi, mi trng Vit Nam ca chng ta hin nay ang xung cp tng ngy,nguy c mt cn bng sinh thi.C rt nhiu vn hin nay rt c quan tm l s cn kit cc ngun ti nguyn, ph rng...lm nh hng ti cht lng cuc sng v s pht trin bn vng ca t nc. Hin nay vn nhim nc rt c quan tm.Trong qu trnh sinh hot hng ngy, di tc pht trin nh hin nay con ngi v tnh lm nhim ngun nc bng cc ha cht, cht thi t cc nh my, x nghip. Cc n v c nhn s dng nc ngm di hnh thc khoan ging sau khi ngng khng s dng khng bt kn cc l khoan li lm cho nc bn chy ln vo lm nhim ngun nc ngm. Cc nh my x nghip x khi bi cng nghip vo khng kh lm nhim khng kh, khi tri ma, cc cht nhim ny s ln vo trong nc ma cng gp phn lm nhim ngun nc. Hm lng Pht pho tng trong nc cng l nguyn nhn gy nhim nc. Vic nghin cu, tm hiu pht pho tng ng vai tr quan trng v t ta c th tm c bin php x l lm sch mi trng nc. Xut pht t thc t , ni dung n chuyn ngnh ca em l: Phn tch hm lng phot pho tng trong nc song m - x Ty Tu T Lim H Ni. Em hy vng vi nhng kt qu thc nghim thu c s cho thy r hn v tnh hnh nhim hin nay ca sng m. GVHD: Nguyn Th Thoa SVTH: Th Thoa Page 4


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PHN I: TNG QUANCHNG I: TNG QUAN V NC1.1.NC

Cc loi ngun nc dng cp nc cung cp nc sch, c th khai thc t cc ngun nc thin nhin ( thng gi l nc th) ti nc mt, nc ngm,nc bin. Nc mt: bao gm cc ngun nc trong cc h cha, sng sui. Do kt hp t cc dng chy trn b mt v thng xuyn tip xc vi khng kh nn cc c trng ca nc mt l: - Cha kh ho tan, c bit l oxy. - Cha nhiu cht rn l lng ( ring trng hp nc trong cc ao, m, h, cha t cht rn l lng v ch yu dng keo); - C hm lng cht hu c cao. - C s hin din ca nhiu loi to. - Cha nhiu vi sinh vt. Nc ngm: c khai thc t cc tng cha di t. Cht lng nc ngm ph thuc vo cu trc a tng m nc thm qua. Do vy nc chy qua cc tng a tng cha ct hoc granit thng c tnh axit v cha t cht khong. Khi chy qua a tng cha vi th nc thng c cng v kim hydrocacbonat kh cao. Ngoi ra, cc c trng chung ca nc ngm l: - c thp; - Nhit v thnh phn ho hc tng i n nh; - Khng c oxy, nhng c th cha nhiu kh H2S, CO2,... - Cha nhiu cht khong ho tan, ch yu l st, mangan, canxi, magie,flo - Khng c s hin din ca vi sinh vt. GVHD: Nguyn Th Thoa SVTH: Th Thoa Page 5


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Nc bin: thng c mn rt cao. Hm lng mui trong nc bin thay i tu theo v tr a l: khu ca sng, gn hay xa b. Ngoi ra nc bin thng c nhiu cht l lng, ch yu l cc phiu sinh ng - thc vt.1.2.NC MT

Nc mt cng do ma cung cp. mt s ni th do hin tng tan tuyt to ra. Thng gm cc loi sau: Nc sng: thng c lu lng ln, d khai thc, cng v hm lng st nh. Nhng hm lng cn cao, nhiu vi trng nn gi thnh s l t. N thng c s thay i ln theo ma viet nam nhit , lu lng, mc nc. Nc sui: ma kh rt trong, lu lng nh, ma l lu lng ln, c nhiu ct si. Nc h, m: tng i trong tuy nhin chng c mu kh cao do nh hng ca rong, ru v cc thy sinh vt.1.3.NC THI

Nc qua s dng gi l nc thi. Nc thi thot ra t nh my, bnh vin, phng th nghim, nh my, cc c s sn xut th cng ca lng ngh, cc c s chn nui, trng trt,... chy qua mt h thng cng nhng khng qua x l thng vo sng, h lm they i cht lng nc b mt, gy ra nhim cho mi trng nc. Cc biu hin ca s thay i cht lng nc dn n tnh trng nhim mi trng nc. C th nhn bit s nhim ny bng trc gic, song nhn bit chnh xc phi xc nh hm lng c th cc cht ha tan. Bng trc gic c th thy c cc cht c hm lng tng i cao c hm lng ha tan trong v nc thi c nhng biu hin c trng: GVHD: Nguyn Th Thoa SVTH: Th Thoa Page 6


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c: nc thi khng trong sut. Cc cht rn khng tan to ra cc huyn ph l lng. Cc cht lng khng tan to dng nh tng l lng hoc to vng trn mt nc. S xut hin ca cc cht keo lm cho nc c nht. Mu sc: nc t nhin khng c mu. S xut hin mu trong nc thi rt d nhn bit. Mu ca cc cht ha hc cn li sau khi s dng tan theo ngun nc thi. Mu c sinh ra do s phn gii ca cc cht lc u khng c mu. Mu xanh l s pht trin ca to lam trong nc. Mu vng l biu hin c s phn gii v chuyn i cu trc sang cc hp cht trung gian ca cc cht hu c. Mu en biu hin ca s phn gii gn n mc cui cng ca cc cht hu c Mi: nc t nhin khng c mi. Mi ca nc thi ch yu l do s phn hy cc hp chat hu c trong thnh phn c cc nguyn t N, P, S... V: nc t nhin khng c v v trung tnh vi pH=7. Nc c v chua l do tng axit ca nc (pH7). V mn cht l do mt s mui v c ha tan, in hnh l NaCl c v mn, mui ca Mg c v cht Nhit : ty theo tng ma nhit ca nc s theya i. Nc b mt vit Nam dao ng t 14,30C - 33,50C.Ngun gc gy nhim nhit chnh l nhit ca cc ngun nc thi t cc b phn lm lnh ca cc nh my. dn in: cc mui v c ha tan trong nc to thnh cc ion, ;m cho nc c kh nng dn in. dn in ca nc ph thuc vo nng v kh nng linh ng ca cc ion. V


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vy kh nng dn in ca nc cng phn nh mc nhim mi trng nc. nhn bit chnh xc phi xc nh hm lng c th cc cht ha tan, cc ch tiu khc nh COD, BOD, tng Nit, tng phot pho, canxi tng, st, mangan...1.4. KHI QUT V NHIM NC

nhim nc l s suy thoi cht lng nc c o bi cc tiu chun sinh hc, ha hc v vt l. S suy gim ny c nh gi da theo vic s dng nc, khng ng tiu chun, v sc khe cng ng hay tc ng sinh thi. T sc khe cng ng hay quan im sinh thi, cht nhim l nhng cht vt qu gii hn cho php m gy hi n cc i sng ca sinh vt. Nh vy, lng d ca kim loi nng, cht ng vi phng x, photpho, nit, natri, v nhng nguyn t cn thit khc, cng nh vi rt, vi khun gy bnh, tt c u l cht gy nhim. Mt vi cht c th l cht nhim trong mt giai on ring bit mc d n khng gy hi nhng giai on khc. V d, d Natri nh l mui khng gy nguy him, nhng i vi mt s ngi trong ch n king li hn ch ly vo v mc ch y hc. Nhng vn lin quan n nhim nc rt nhiu. c bit l thi gian lu tr v s lng lu tr nc trong nhiu giai on ca chu k nc.V d, nc sng c thi gian lu tr trung bnh khong 2 tun. V th, khi b nhim (khng lin quan n nhn t trm tch di y sng, l kt qu ca mt qu trnh di), m lin quan n chu k ngn v nc s mau chng thot khi mi trng sng. Mt khc s nhim tng t s a vo h hoc bin, ni m thi gian lu tr s di hn v kh gii quyt vn nhim hn. Nc mt, khng ging nh nc sng, c thi gian lu tr di (hng trm nm ti hng nghn nm). V th s di chuyn ca cht nhim t nc mt l mt qu trnh rt chm v s phc hi rt tn km v kh khn. GVHD: Nguyn Th Thoa SVTH: Th Thoa Page 8


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S nhim nc c th c ngun gc t nhin hay nhn to: -S nhim c ngun gc t nhin l do ma, tuyt tan, gi bo, l lt Nc ma ri xung mi nh, mt t, ng ph th, khu cng nghip ko theo cc cht bn xung sng, h hoc cc sn phm ca cc hot ng sng ca sinh vt, k c xc cht ca chng. S nhim ny gi l nhim din. -S nhim nhn to ch yu do x nc thi t cc khu dn c, khu cng nghip, hot ng giao thong vn ti, thuc tr su, phn bn trong nng nghip vo mi trng nc. Theo thi gian,cc dng gy nhim c th din ra thng xuyn hoc tcthi do s c ri ro. Theo bn cht ca cc tc nhn gy nhim, ngi ta phn bit: nhim v c, nhim hu c, nhim ha cht, nhim vi sinh vt, c hc hay vt l ( nhim nhit hoc do cc cht l lng khng tan), nhim phng x. Theo phm vi thi vo mi trng nc, ngi ta phn bit: nhim im ( nhim t mt ming cng thi nh my ) v nhim din (v d nhim t mt v trn du trn mt vng bin). Theo v tr khng gian, ngi ta phn bit: nhim sng, nhim h, nhim bin, nhim nc mt, nhim nc ngm1.5. NHIM NC MT

S nhim nc mt xy ra khi c qu nhiu dng cht c hi trong nc, nhiu hn kh nng ca h sinh thi cho php, s dng hoc di chuyn cht nhim, hoc bin i n thnh dng t c hi hn. Nc nhim c pht tn t ngun tp trung ( nhim im) hoc c khuch tn t cc ngun khng tp trung ( nhim din). Cc ngun gy nhim tp trung:


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Cc ngun gy nhim ri rc v hn hp, nh l cc ng dn ra sng sui t cc khu cng nghip hoc th. Thng thng, ngun gy nhim t khu cng nghip c kim sot trong khu x l v c iu chnh bng giy php. Trong cc thnh ph lu i thuc vng ng bc v h ln ca M, phn ln cc ngun gy nhim c ra t cc h thng cng kt hp h thng dng chy ca nc l v rc t cc khu th. Trong lc ma ln, dng nc chy mnh trong thnh ph vt qu sc cha ca h thng cng lm cho nc dng ln v trn ra ngoi, lm pht tn cht nhim ln tng nc mt. Mt nguyn tc quan trng ca vic hn ch cht nhim l nc t cc ngun khc nhau th khng nn ha ln vo nhau. Chng phi c tch nhau ra theo cc mc ch a nh trc. V d, dng cht thi nng nghip c cha nhiu nitrat v thuc tr su nn c gi xa dng nc chy phc v cho nhu cu s dng th. y l vn quan trng nht ca h thng phn phi nc trn din tch rng cung cp cho nhiu ngi s dng khc nhau theo cc yu cu cht lng nc khc nhau. Cc ngun gy nhim khng tp trung: Cc ngun gy nhim khng tp trung khuch tn v khng lin tc. Chng b nh hng bi cc nhn t nh vic s dng t, kh hu, thy h, a hnh, thc vt t nhin, v a cht. Cht nhim t ngun khng tp trung hay dng chy nhim rt kh kim sot. Nhng ngun gy nhim khng tp trung ph bin thnh ph l t nhng con ng, cc cnh ng c cha cc loi cht nhim, v t cc kim loi nng, cc cht ha hc, v trm tch. Khi chng ta ra xe trn ng li xe vo nh, cht ty ra v du trn b mt s chy xung cng ra knh rch, gp phn gy nhim dng chy. Dng chy b nhim cn c to ra khi phun thuc tr su cho cy trng, sau dng chy chy vo sng sui hoc thm nhp vo nc mt lm nhim bn nc ngm. Tng t, nc ma v dng chy t nh my v GVHD: Nguyn Th Thoa SVTH: Th Thoa Page 10


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bi kho l nhng ngun nhim khng tp trung. Nhng ngun nhim khng tp trung ngoi thnh th lin quan ti nng nghip, lm nghip v khai thc khong sn.

CHNG 2: TNG QUAN V PHOTPHO TNG S2.1.KHI NIM

Tng lng photpho bao gm ortho photphat + poly-photphat + hp cht photpho hu c trong ortho photphat lun chim t l cao nht. Photphat c th dng ha tan, keo hay rn. Trc khi phn tch cn xc nh dng tn ti ca photpho. Nu ch xc nh orth-photphat (mc ch kim sot qu trnh kt ta photpho) th mu cn c lc trc khi phn tch. Tuy nhin nu phn tch photpho tng (kim sot gii hn thi) th mu phi c ng nht v sau c thy phn.2.2.PHN LOI PHOTPHO

Pht pho tn ti di ba dng th hnh c bn c mu: trng, v en. Cc dng th hnh khc cng c th tn ti. Ph bin nht l pht pho trng v pht pho , c hai u cha cc mng gm cc nhm phn b kiu t din gm 4 nguyn t phtpho. Cc t din ca pht pho trng to thnh cc nhm ring; cc t din ca phtpho lin kt vi nhau thnh chui. Phtpho trng chy khi tip xc vi khng kh hay khi b tip xc vi ngun nhit v nh sng. Phtpho cng tn ti trong cc dng a thch v mt ng hc v nhit ng lc hc. Chng c tch ra nhit chuyn tip -3,8 C. Mt dng gi l dng "alpha", dng kia gi l "beta". Phtpho l tng i n nh v thng hoa p sut 1 atm v 170 C nhng chy do va chm hay nhit do ma st. Th hnh phtpho en tn ti v c cu trc tng t nh graphit GVHD: Nguyn Th Thoa SVTH: Th Thoa Page 11


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cc nguyn t c sp xp trong cc lp theo tm lc gic v c tnh dn in.2.3.TNH CHT CA PHOTPHO

Pht pho l mt nguyn t c nhiu trong t nhin di dng qung. sinh vt, P c vai tr quan trng, c nhiu trong xng ng vt di dng caxi phtphate, trong no, lng trng,di dng hp hu c.. Phootpho l 1 kim, nguyn t lng 31, t trng 1,83, im nng chy 94oC, im si 278oC, khng tan trong nc, tan trong dung mi hu c. L mt cht rn, d gy nhit thng, mm d un, c ba dng th hnh l trng (vng), v phootpho pryromorphic2.4.VAI TR CA PHOTPHO

Pht pho l mt yu t cn thit cho cuc sng. Sinh vt sng, bao gm c con ngi, s hu mt s lng nh v yu t ny rt quan trng trong qu trnh sn sinh nng lng ca t bo. Trong nng nghip, pht pho khai thc t cc m c s dng rng ri ch bin lm phn bn gip tng nng sut cy trng. Pht pho cng s dng cng nghip khc. Phtpho l nguyn t quan trng trong mi dng hnh s sng bit. Phtpho v c trong dng phtphat PO43- ng mt vai tr quan trng trong cc phn t sinh hc nh ADN v ARN trong n to thnh mt phn ca phn cu trc ct ty ca cc phn t ny. Cc t bo sng cng s dng phtphat vn chuyn nng lng t bo thng qua ansin triphtphat (ATP). Gn nh mi tin trnh trong t bo c s dng nng lng u c n trong dng ATP. ATP cng l quan trng trong phtphat ha, mt dng iu chnh quan trng trong cc t bo. Cc phtpholipit l thnh phn cu trc ch yu ca mi mng t bo. Cc mui phtphat canxi c cc ng vt dng lm cng xng ca chng. Trung bnh trong c th ngi cha khong gn 1 kg phtpho, v khong ba phn t s nm trong xng v rng di


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dng apatit. Mt ngi ln n ung y tiu th v bi tit ra khong 1-3 g phtpho trong ngy trong dng phtphat. Theo thut ng sinh thi hc, phtpho thng c coi l cht dinh dng gii hn trong nhiu mi trng, tc l kh nng c sn ca phtpho iu chnh tc tng trng ca nhiu sinh vt. Trong cc h sinh thi s d tha phtpho c th l mt vn , c bit l trong cc h thy sinh thi, xem thm s dinh dng tt v bng n to2.5.THC TRNG NHIM PHOTPHO HIN NAY

D tha pht pho t cc cnh ng v bi c ngoi cc thnh ph xung cc ao, h, sng, sui l nguyn nhn chnh to pht trin, sau chng i vo cc ngun nc v lm gim cht lng nc. nhim pht pho gy nguy him cho c v cc loi thy sinh khc cng nh cc loi ng vt v con ngi, nhng sinh vt sng ph thuc vo ngun nc sch. Trong mt s trng hp, d tha pht pho cn gip to c pht trin, gy ra mi e da trc tip n sinh mng con ngi v ng vt. D tha pht pho trong mi trng l mt vn ch yu cc nc cng nghip, phn ln Chu u, Bc M v mt s khu vc Chu . cc khu vc khc, c bit l chu Phi v Australia, t rt ngho pht pho, gy ra mt s mt cn bng dinh dng. Tr tru thay, t nhng ni nh Bc M, khu vc m phn bn vi pht pho c s dng ph bin nht, li c rt nhiu thnh phn ny.2.6.NGUYN NHN GY NHIM

Hp cht photphat c tm thy trong nc thi hay c thi trc tip vo ngun nc mt pht sinh t: Tht thot t phn bn c trong t Cht thi t ngi v ng vt GVHD: Nguyn Th Thoa SVTH: Th Thoa Page 13


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Cc ha cht ty ra v lm sch Vic s dng pht pho trn ton th gii, mt loi phn bn quan trng trong nng nghip hin i phn ln, mt nhm nh nghin cu cnh bo rng kho d tr pht pho th gii s sm khan him v vic s dng qu mc trong mt th gii cng nghip ha l nguyn nhn hng u s nhim ca cc h, sng, sui nh hin nay.2.7.NH HNG CA PHOTPHO TNG

2.7.1. nh hng i vi mi trng t Hin nay, nng nghip nc ta phi s dng phn ha hc v thuc tr su, c di vi khi lng ngy cng ln. y l xu th tt yu bi l phn ha hc v thuc tr su, tr c di c tc dng quyt nh n 40-50% mc tng sn lng cy trng hng nm. Vn t ra y l cn c cc bin php hu hiu nhm hn ch mt c hi ca nhng ha cht y i vi mi trng sng v sc khe con ngi. C hng trm loi ha cht tr dch hi v phn ha hc c a vo nc ta. Theo nhiu nh nghin cu, trong khong hn 120 ha cht tr su bnh thng dng th c ti 90 cht c hi, 33 cht gy t bin di truyn, 22 cht gy d dng khuyt tt, 14 cht gy u c v ung th cho cc loi ng vt mu nng. Ni chung, hu ht cc loi phn ha hc v ha cht tr dch bnh, c di t nhiu u gy c cho ngi v gia sc. Mi loi ha cht c tnh cht ha l khc nhau nn c ch gy c cng khc nhau. C th chia lm hai loi: Loi c mnh, cp tnh nguy him v loi gy c t t, tch ly dn, gy tc hi mn tnh cho ngi. Nhm c pht-pho phn hy tng i nhanh trong t, cy, trong c th ngi v ng vt... Khi b nhim c nng, s nh hng r rt n h huyt p, h hp, lm thay i chc nng ca h thn kinh, lm tn thng chc nng bi tit ca thn v qu trnh trao i cht trong c th. Nu nhim c GVHD: Nguyn Th Thoa SVTH: Th Thoa Page 14


KHOA CNG NGH

nhm Clo hu c, s tc ng mnh n h thn kinh, gy co git c, lm nhp tim v h tiu ha ri lon. 2.7.2.nh hng i vi mi trng nc Kh nng tn ti ca phosphat sinh hc hon ton ph thuc vo pH: - pH thp (mi trng axit): phospho gn cht vi cc ht st v to thnh cc cht tng hp khng tan vi ion st (v d Fe(OH)2H2PO4) v nhm (Al(OH)2H2PO4). Do s xut hin ca ion Fe3+ v nhm trong t, ca cn lng v nc, nn lng phospho ha tan rt thp trong iu kin axit. Khi mi trng khng c oxy, phospho c c nh l cc phc hp st khng tan, c th gii phng Fe3+, gim thnh Fe2+ v to thnh sunfit st. - Trong iu kin pH cao (mi trng kim): phospho hnh thnh cc hp cht khng ho tan khc nht l canxi (v d hydroxyapatite Ca10(PO4)6(OH)2). Trong iu kin hiu kh c Ca, Al v ion Fe th phosphat tan nhiu nht pH = 6-7. Photpho l ngun dinh dng quan trng cho thc vt v to. Trong nc, cc hp cht photpho tn ti 4 dng: Hp cht v c khng tan, hp cht v c c tan, hp cht hu c tan v hp cht hu c khng tan. Nng cao ca photpho trong nc gy ra s pht trin mnh ca to, khi to cht i qu trnh phn hy k kh lm gim lng xi ha tan trong nc v iu ny gy nh hng c hi vi i sng thy sinh. Nit v photpho l hai nguyn t c bn ca s sng, chng c mt hu ht trong mi hot ng lin quan n s sng vo trong nhiu ngnh cng nghip, nng nghip. Khi thi 1 kg nit di dng hp cht ha hc v mi trng nc s sinh ra 20 kg COD; cng nh vy, khi thi 1 kg P s sinh ra 138 kg COD. Trong GVHD: Nguyn Th Thoa SVTH: Th Thoa

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KHOA CNG NGH

ngun nc giu cht dinh dng (N,P) thng xy ra cc hin tng: to v thy sinh pht trin mnh to nn mt ln vo ban ngy hoc khi nhiu nng to quang hp mnh. quang hp, to hp th kh CO2 hoc bicacbonat (HCO3) trong nc v nh xi. pH ca nc tng nhanh, nht l khi ngun nc c pH thp (tnh m thp do cn bng H2CO3 HCO3- - CO32-) vo cui bui chiu; pH ca mt s ao, h giu dinh dng c th t gi tr trn 10. Nng xi tan trong nc thng siu bo ha, ti 20mg/l. Song song vi qu trnh quang hp l qu trnh h hp (phn hy cht hu c to nng lng, ngc vi qu trnh quang hp) xy ra. Trong khi h hp, to v thc vt thy sinh tiu th xy thi ra CO2 - l tc nhn lm gim pH ca nc. Trong cc ngun nc, nu hm lng N > 30 - 60 mg/l, P > 4-8 mg/l s xy ramhin tng ph dng. Vo ban m hoc nhng ngy t nng, qu trnh h hp din ra mnh m gy hin tng thiu xi v lm gim pH ca nc. Do vy, vo bui sng thng xi trong nc cn kit v pH rt thp. Hin tng ph dng cng xy ra h sinh thi bin, c bit vng ca sng hay cc vnh kn hoc cc vng bin kn. To n hoa gy ra hin tng thy triu v phn hy h sinh thi thy sinh. V d, trong sut ma du lch trn th gii c khong 200 triu ngi du lch cng vi 85% nc thi khng c x l t cc thnh ph ln thi ra bin s gy nhim bin nhiu ni. C cht v gy nhim trm tch.


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KHOA CNG NGH

2.7.3.nh hng i vi con ngi y l nguyn t c c tnh vi 50 mg l liu trung bnh gy cht ngi (phtpho trng ni chung c coi l dng c hi ca phtpho trong khi phtphat v orthophtphat li l cc cht dinh dng thit yu). Th hnh phtpho trng cn c bo qun di dng ngm nc do n c hot ng ha hc rt cao vi xy trong kh quyn v gy ra nguy him chy v thao tc vi n cn c thc hin bng kp chuyn dng do vic tip xc trc tip vi da c th sinh ra cc vt bng nghim trng. Ng c mn tnh phtpho trng i vi cc cng nhn khng c trang b bo h lao ng tt dn n chng cht hoi xng hm. Nut phi phtpho trng c th sinh ra tnh trng m trong y t gi l "hi chng tiu chy khi". Cc hp cht hu c ca phtpho to ra mt lp ln cc cht, mt s trong l cc k c. Cc este floro photphat thuc v s cc cht c thn kinh c hiu lc mnh nht m ngi ta bit. Mt lot cc hp cht hu c cha phtpho c s dng bng c tnh ca chng lm cc thuc tr su, thuc dit c, thuc dit nm v.v. Phn ln cc photphat v c l tng i khng c v l cc cht dinh dng thit yu. Khi photpho trng b a ra nh sng mt tri hay b t nng thnh dng hi 250 C th n chuyn thnh dng photpho , v n khng t chy trong khng kh, do vy n khng nguy him nh photpho trng. Tuy nhin, vic tip xc vi n vn cn s thn trng do n cng c th chuyn thnh dng photpho trng trong mt khong nhit nht nh v n cng ta ra khi c c tnh cao cha cc oxit photpho khi b t nng.


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KHOA CNG NGH

CHNG 3: TNG QUAN V PHNG PHP PHN TCH QUANG PH HP TH UV-VIS3.1.PHNG PHP TRC QUANG

3.1.1.Khi nim Phn tch trc quang l tn gi chung ca cc phng php phn tch quang hc da trn s tng tc chn lc gia cht cn xc nh vi nng lng bc x thuc vng t ngoi, kh kin hoc hng ngoi. Nguyn tc ca phng php trc quang l da vo lng nh sng b hp thu bi cht hp thu tnh hm lng ca cht hp thu. 3.1.2.Phn loi Phng php hp th quang: phng php ny da trn vic o cng dng nh sng b cht mu hp thu chn lc Phng php pht quang: da trn vic o cng dng nh sng pht ra bi cht pht quang khi ta chiu mt dng nh sng vo cht pht quang. Phng php o c: phng php ny da trn vic o cng dng nh sng b hp thu hoc b khuch tn bi h keo c iu ch t cht cn phn tch.3.2.PHNG PHP PT QUANG PH HP TH UV-VIS

3.2.1. nh lut v s hp th nh sng (nh lut Lambert Beer). Khi chiu 1 dng sng qua dung dch cht hp th nh sng th cht ch hp th chn lc 1 s tia ty theo mu sc ca cht. nh lut: Nu chiu 1 chm sng n sc c cng l Io qua 1 dung dch c b dy l b (cm) v nng l C (mol/l) th sau khi ra khi dung dch n b hp th 1 phn nn cng ch cn li l I t ( It < Io ) v pt ca nh lut l: GVHD: Nguyn Th Thoa SVTH: Th Thoa Page 18


KHOA CNG NGH

It 10 bC IoTrong : C l nng ban u g/L, mg/L, mol/L, mmol/L b l chiu dy ca cuvet (cm) l h s hp th phn t gam.N c trng cho bn cht

ca cht hp th nh sng v sng nh sng n sc chiu vo dung dch khi nng ca cht hp th l mol/l. Cc i lng thng dng trong phng php trc quang. - truyn qua (T Transmittance) hay gi l truyn quang, truyn sut l t s gia hai cng tia chiu l ra I v tia n I0, k hiu l T. truyn qua T ph thuc vo . T l i lng khng c th nguyn, khng c tnh cng. truyn qua biu th trong sut ca dung dch mu kho st ng vi bc sng cho . truyn qua T = i lng lg dch (A) :It Io

I0 gi l mt quang D hay hp th quang ca dung It I0 = bC It

A= lg

A ph thuc tuyn tnh vo C ca cht phn tch. A v T l 2 i lng khng c th nguyn. T c gi tr t 100% - 0% hay t 1 0; A c gi tr t 0- .


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KHOA CNG NGH

100

T (%)

50

0 0 1 2

C,l 3

A= lg

I0 = bC It

T=

It bC = 10 Io

ng dng tnh cht cng tnh ca A Tnh cng ca mt quang hay hp thu A A = AA + AB = 1bC1 + 2bC2

Mt quang o c khi cht tan ho tan trong mt dung mi l mt quang tng cng ca dung dch . A = AX + Adm A phn nh ng AX th Adm rt nh ( 0). tho mn iu kin ny, ta nn chn dung mi c ph hp thu rt xa ph hp thu ca cht tan. GVHD: Nguyn Th Thoa SVTH: Th Thoa Page 20


KHOA CNG NGH

Nu trong hn hp gm nhng cu t cng hp th nhng chng khng c tng tc ha hc vi nhau. Ta c th xc nh nng ca cc cu t theo h thc sau : A= A1 + A2 + ...+ Ai + ...+ An. Dung dch mu tun theo nh lut hp thu c bn nu tho mn cc iu kin sau C s trng kht cc ng ph - i vi cc dung dch c nng khc nhau. th biu din s ph thuc A C khi b = const l mt ng thng i qua gc to . Khi pha hai dung dch 1 v 2 sao cho C1b1 = C2b2 th cng t ta s c A1 = 1bC1 = A2 = 2bC2 Cc ng ph A - vi nng Cn khc nhau u c cng max th biu din mi quan h gia truyn qua T v lgC c im un nm gi tr T = 0.368 3.2.2. Cc nguyn nhn gy ra s sai lch nh lut Lambert - Beer Mc n sc ca nh sng ti. nh sng khng n sc thng dn n lch m. Cht mu hp thu cc i max v ch max mi c s tuyn tnh gia Aimax Ci v th Aimax Ci l mt ng thng, khi mt quang l cc i. Mc n sc cng ln, kh nng tun theo nh lut Lambert Beer cng ln. Nng ln ca dung dch kho st: Nng ca dung dch ln s xy ra tng tc in, i lng thay i, thng thng khi tng nng dung dch, gi tr gim. S sai lch khi nh lut Lambert Beer thng l sai s m. S trng hp hoc kh trng hp phn t, s solvat ho hay hydrat ho xy ra khi thay i nng cht hp thu; s to thnh cc hp cht trung gian, phc ph, cc hp cht ng phn, to h keo hay s c mt ca cc GVHD: Nguyn Th Thoa SVTH: Th Thoa Page 21


KHOA CNG NGH

cht in ly mnh, pH u c kh nng lm thay i hp thu ca dung dch, lm sai lch khi nh lut Beer. Ph hp th. ng biu din s ph thuc ca hp thu A hoc vo di sng (hay tn s sng ) gi l ph hp thu ca cht kho st. Ph hp thu ca phn t l ph m gm mt hoc mt s m hp thu, mi m u c dng ng phn b xc sut chun v khc nhau bi cng hp thu v bc sng cc i max ca m. Trong trng hp n gin phn t ch c mt tm mang mu th ph A = f() ch c mt gii ph c dng i xng hnh chung. 3.2.3. Cc phng php nh lng trong quang ph hp th phn t 3.2.3.1.Phng php dy tiu chun ( PP thang mu ) a) Nguyn tc. - Chun b: Ngi ta chun b 10-15 ng so mu (ng nghim c ng knh v cht lng thy tinh nh nhau).Sau ly vo mi ng nghim nhng lng dd tiu chun ca cu t cn phn tch,pha long n th tch nh nhau,thm vo c dy nhng lng thuc th bng nhau v tin hnh mi ch ha cn thit nh nhau chuyn cu t X thnh hp cht c mu.dd phn tch cng c chun b nh trn.

-Pha dy tiu chun:


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KHOA CNG NGH

S ng dd Dd chun Pha long Lng thuc th R pH Lng mui

1 0

2 0,1

3 0,2

4 .

. 10 0,9

15 1,4

dd ptch X(mg/ml)

n th tch nh nhau Lng trong c dy nh nhau pH c dy nh nhau Nh nhau

b) Cch o. Ngi ta em so snh mu ca dd phn tch vi mu ca dy dd chun,dd phn tch c mu bng mu ca dd tiu chun no th hm lng cht X bng chnh hm lng ca cht trong dd tiu chun. Nu mu ca dd phn tch nm gia 2 dd mu tiu chun no th hm lng cht X c tnh bng trung bnh cng hm lng X 2 dd mu tiu chun .Nu mun chnh xc hn th s lp dy dd chun c nng chun bin thin trong khong nng 2 dd mu m dd phn tch c mu nm gia. c) u nhc im: - u im: + C th s dng xc nh c cc dd m s hp th a/s khng tun theo nh lut Lambert-Beer. + PP n gin,nhanh,khng phi cn my mc. - Nhc im: + chnh xc khng cao. + dd chun khng bn mu do phi pha li thng xuyn.Vic la chon mu phi tht chnh xc v rt cng phu.


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KHOA CNG NGH

3.2.3.2. Phng php cp i ( hay PP chun so mu ) a) Nguyn tc. Ly 2 cc so mu c nh s v t cnh nhau, dd tiu chun cht cn phn tch X vo cc 1,ch ha vi thuc th v pH cn thit chuyn phi t thnh hp cht c mu.Cc 2 ch ha 1 lng dd mui,axit ging nh cc 1,pha long n th tch ca dd trong 2 cc l nh nhau.Sau va khuy (c th dng my khuy) va nh dd tiu chun ca phi t X n khi mu 2 cc bng nhau.PP ny cn gi l pp chun so mu. b) Cch o. Gi V1 v V2 l th tch dd cn xc nh ly vo cc 1 v th tch cht tiu chun X cn thm cc 2 c mu ca cc 2 bng nhau.Gi T1 v TX l chun mg/ml ca dd tiu chun v dd cn phn tch.Vy lng cht cn xc nh s c tnh bng CT sau:

T X ( mg / ml ) c) u nhc im. -u im:

V2 .T1 V1

+ Gii hn nng rng,ph thuc vo kh nng mt quan st. + S hp th nh sng khng tun theo L Lambert-Beer.Vic xc nh nhanh v c th xc nh c nhiu mu. - Nhc im: + Mc sai s do mt ngi quan st do c s khc nhau gia cng mu ca dd 1 v dd 2. + Khng p dng cho mi phn ng to mu c.


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KHOA CNG NGH

3.2.3.3. Phng php cn bng (PP t l so snh). a) Nguyn tc. Chun b 2 bnh nh mc 1 v 2, vo bnh 1 mt lng dd chun X c nng Ca , bnh 2 ng dd cn phn tch c nng l Cx. Thm vo c 2 bnh lng thuc th,lng axit v ch ha trong cc k ging nhau chuyn ton b lng cht X thnh hp cht c mu.Sau nh mc 2 bnh c th tch ging nhau. b) Cch tin hnh. Cch 1: Dng 1 ng hnh tr (sc k tho). 2 dd 1 v 2 vo 2 ng hnh tr c kha 1 v 2,c y phng,chiu dy ging nhau.Sau quan st mu t trn xung.Dng kha iu chnh 2 cht lng trong 2 ng n khi no mu ca 2 ng hnh tr ging nhau.c chiu cao b 1,b2 ca dd 2 ng v tnh Cx theo CT: b1Ca= b2Cx. Cch 2: Dng my o quang ph o cng hp th nh sng ca dd 1 v dd 2 trong 2 ng vi cng 1 loi cuvet c chiu dy b(cm) cng 1 bc sng c cc gi tr nh sau: Dd 1: Aa= bCa Dd 2: Ax = bCx Cx= Ca. Ax/ Aa c) u nhc im. - u im: chnh xc tng i cao. - Nhc im: + Khng th xc nh c hng lot mu. + Sai s do mt quan st. + Mc sai s do thnh phn hn hp ca cc dd cn phn tch c th s ln cc hp cht khc. GVHD: Nguyn Th Thoa SVTH: Th Thoa

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KHOA CNG NGH

3.2.3.4. Phng php ng chun - Khi tin hnh phn tch hng lot mu pp ng chun s cho php phn tch v tnh ton kq nhanh. - Cch tin hnh: Pha ch 1 dy dd chun ri tin hnh o mt quang A. Cch pha ch dd tiu chun: Bnh M 0 Dung dch Dd tiu chun X (mg/ml) Lng th pH nh mc C (mg/ml) A (D) thuc 0 a b c d e f k Vmu 1 2 3 4 5 6 . 10 Mu

Nh nhau trong c dy Bng nhau trong c dy 0 0 C1 A1 C2 A2 C3 A3 C4 C5 C6 C10 A10 Cx Ax

Sau khi pha dd tiu chun chng ta v th biu din s ph thuc ca A vo C. Sau khi lp th , pha ch dd cn xc nh trong nhng k ging nh khi xc nh ng chun ri em o gi tr mt quang Ax ( Cng 1 dd so snh,cng 1 cuvet,cng 1 bc sng) ri a vo th xc nh Ax.


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KHOA CNG NGH

A

A AX

Cx u nhc im: - u im:

C (mg/ml)

+ ng chun c dng trong 1 thi gian di,khi dng c th iu chnh li. + C th xc nh hng lot mu. + kt qu kh chnh xc. - Nhc im: + S hp th nh sng phi tun theo L Lambert-Beer. + kq chnh xc ph thuc vo my. + i vi nhng mu c thnh phn phc tp th ng chun s b sai s.


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KHOA CNG NGH

3.2.3.5. Phng php thm chun Ly 1 lng dd cht phn tch c nng l Cx,sau khi thm thuc th hin mu nhng k ti u,em o mt quang trn my bc sng ti u c gi tr Ax. A= bCx. Ly 1 lng dd cn phn tch,thm vo 1 lng dd chun ca cht cn xc nh c nng l Ca , ngi ta thc hin phn ng mu v em o mt quang c gi tr Atc . Atc= b(Cx + Ca) T ta tnh c Cx . u nhc im: - u im: + Loi tr c nh hng ca cc ion l c trong dd cht ptch. + C th x c hm lng cht X trong dd c nng nh. + Kim tra lp ca pp. - Nhc im: + Khng th tin hnh phn tch hng lot mu c. + S hp th nh sng cng phi tun theo L Lambert-Beer. 3.2.3.6. Phng php vi sai Nguyn tc: Phng php vi sai l mt bin dng ca phng php so snh. Trong phng php ny, dung dch so snh chnh l 1 trong cc dd chun (dd tiu chun c nng thp nht hoc cao nht) Nu ly dung dch tiu chun c nng thp nht lm dd so snh th C0< CX, gi l phng php vi sai nng ln). Nu ly dung dch tiu chun c nng cao nht lm dd so snh th C0 > CX, gi l phng php vi sai nng nh). Nu kt hp c hai chiu th gi l phng php vi sai 2 chiu. GVHD: Nguyn Th Thoa SVTH: Th Thoa

Page 28


KHOA CNG NGH

PP vi sai nng ln. Phng php tnh: Pha 3 dd gm: dd chun c nng Ca, dd cha cht cn xc nh CX, dd so snh c nng C0. o mt quang ca dd chun v dd nghin cu so vi dd so snh (dd c nng C0), ta c: Ax = Ax A0 = l(CX Co)>0 Atc = Atc A0 = l(Ctc Co)>0 Cng thc tnh:C X = C0 + A'X (C tc - C0 ) A'tc

PP vi sai nng nh. Phng php tnh: Pha 3 dd gm: dd chun c nng Ca, dd cha cht cn xc nh CX, dd chun c nng C0. o mt quang ca dd chun Ca so vi dd so snh (dd c nng C0) v dd chun C0 so vi dd so snh (dd c nng CX), ta c: A0/x= A0 AX= l(C0 CX)>0 Atc = Atc A0 = l(Ctc C0)>0 Cng thc tnh:C X = C0 A'X (C tc - C0 ) A'tc

Lu : Phng php ny c dng nng cao chnh xc ca php phn tch trong nhng trng hp sau: Xc nh lng ln cc cht. Loi tr nh hng cn tr ca tp cht l.


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KHOA CNG NGH

Loi tr nh hng ca thuc th d do n cng hp thu t nhiu bc sng ti u. Loi tr nh hng ca nn ni chung. i khi phng php vi sai cn c dng cho nhng dd nng ln v khng tun theo nh lut LamBert - Beer.

CHNG 4: CC PHNG PHP PHN TCH PHOTPHO TNG S Photpho trong nc v nc thi thng tn ti dng orthophotphat (PO43-, HPO42-, H2PO42-, H3 PO4) hay polyphotphat Na3(PO3 )6 v photphat hu c. Orthophotphat c th xc nh bng phng php so mu vi thuc th l NH4MoO4 v SnCl2, cn polyphotphat v photphat hu c cn chuyn ha thnh orthophotphat qua phn ng vi axit sau xc nh bng phng php so mu. Lng phospho tn ti di dng orthophosphate c th c o bng nhng phng php trng lng, th tch, so mu. Phng php trng lng c s dng khi hm lng phospho hin din ln, nhng iu ny khng xy ra trong thc t. Phng php th tch c s dng khi nng nng phosphat ln hn 50mg/L nhng nng ny rt him gp trong trng hp nc si hay chuyn ha k kh nhng cht ni. Phng php ny gm: kt ta, lc, lm sch kt ta v chun . Phng php ny tn nhiu thi gian. Phng php so mu o nc v nc thi c th c tha mn vi mt chnh xc cao. GVHD: Nguyn Th Thoa SVTH: Th Thoa Page 30


KHOA CNG NGH

C ba phng php so mu c s dng xc nh orthophosphat, chng c cng bn cht vi nhng nguyn tc trn nhng khc nhau ch l n c thm vo mt s nguyn t t nhin to mu. Yu t ha hc cn thit nh: ion phosphat kt hp vi ammonium molypdat trong iu kin acid thnh molypdophosphat PO43- + 12 (NH4)2MoO4 + 24H+ (NH4)3PO4.12MoO3 + 21 NH4 + 12 H2O Khi hin din mt lng phosphat ln, trng thi ca molypdophosphat s l nhng kt ta mu vng c th lc v o bng phng php th tch. nng phosphat thp hn, to thnh nhng ht keo mu vng s c xc nh hm lng bng phng php so mu . Vi nng phosphat di 30mg/ L, mu vng ca ht keo khng th nhn bit r v iu ny c ngha l cn phi pht trin theo mt hng khc. Mt cch khc ci thin l thm vanadium hnh thnh dng phc hp vanadomolypdophosphoric acid c mu vng r, cho php phn tch phospho vi hm lng di 1mg/L hoc nhng khong thp hn. Lng molypdenum cha trong ammonium phosphomolypdate cng c gim to nhng sn phm c mu xanh t l tng ng vi lng phosphate hin din Mt lng tha ammonium molypdate khng b gim i v do khng can thip vo qu trnh. Ascorbic acid (C6H6O6) hay thic clorua c th s dng nh mt nhn t kh. Hp cht mu c to thnh l mu xanh molypdeum hay xanh heteropoly. Thic clorua cng c s dng nh mt nhn t c th c m t qua phng trnh: (NH4)PO4 + 12MoO3 + Sn2+ molypdenum + Sn4+


Page 31


KHOA CNG NGH

4.1. PHNG PHP CHUN TRUNG HA (hm lng ln)

Nguyn tc: Trong mi trng axit HNO3 6 M, ion PO43- phn ng vi thuc th Nitro - Molipdic sinh ra phc mu vng Photpho - Molipdat H7[P(Mo2O7)6]. Lm mui kt ta ny trong 60 pht. Sau lc kt ta qua giy bng xanh v ra kt ta bng dung dch NH4NO3 1% cho sch ht axit. Ri ra kt ta bng mt lng d chnh xc (30-40 ml) dung dch NaOH 0,1M, c thm 10 ml formalin ( trung ha n pH = 7) v ch th phenolphtalein. Khuy cho tan ht. Sau chun lng d NaOH bng dung dch HCl 0,02M. Ri t lng NaOH tiu tn ha tan kt ta chng ta s tnh c hm lng ion PO43- trong mu.PO43- + 12 MoO42- +27 H+ H7[P(Mo2O7)6] + 10H2O

Cng thc tnh: (mg/ml) PO43- =

4.2. PHNG PHP KHI LNG (khi hm lng ln)

Nguyn tc : Trong mi trng m (NH3/ NH4) pH = 7-8, ion PO43- tc dng vi hn hp (NH4Cl/MgCl2) s sinh ra kt ta tinh th MgNH4PO4. Lm mui kt ta trong 60-70 pht, sau lc kt ta qua giy bng xanh v ra sch kt ta bng dung dch (NH3/NH4NO3 1%, pH = 8). Sau nung kt ta 900oC n khi lng khng i v cn dng Mg2P2O7 ta s tnh c hm lng PO43-. Nhng cc ion Ca (II), Mn(II), Pb(II).. c nh hng v trong iu kin ny cc ion ny cng kt ta c mt phn c dng tng t Mg(II). Mg2+ + PO43- + NH3 + H+ MgNH4PO4.6 H2O2MgNH4PO4.6 H2O Mg2P2O7 + 2NH3 + 7 H2O


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Cng thc: % PO43= f 1004.3. PHNG PHP TRC QUANG

Nguyn tc: Trong mi trng axit HNO3 6M, ion PO43- phn ng vi thuc th Nitro - Molipdic sinh ra phc mu vng Photpho - Molipdat H7[P(Mo2O7)6]. Phc ny khi phn ng vi cht kh , v d SnCl 2 (hay axit Ascorbic) s to ra phc mu xanh Molipden hp th quang cc i ti = 690 nm. o hp th quang v bng phng php ng chun ta s xc nh c hm lng ca PO43 Phc phn ng vi SnCl2 Gii hn o n 7 g P/L bng cch tng chiu dy cuvet Nng thp nht c th pht hin c: Nng thp nhtc th pht hin c khong 3 g P/L. nhy ti 0,3010 v thay i 0,009. Khi o hp th quang: Sau 10 pht, nhng trc 12 pht, dng thi gian gia cc ln nh nhau trong tt c nhng ln xc nh, o mu ti 690 nmv so snh vi mt Cuvet chun, s dng nc ct lm mu chun. dy cuvet ph hp cho khong nng nh sau: Khong nng P (mg/ml) 0,3 - 2 0,1 - 1 0,007 - 0,2 GVHD: Nguyn Th Thoa SVTH: Th Thoa Chiu dy Cuvet (cm) 0,5 2 10 Page 33


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Lun lun chy mu trng v thuc th vi nc ct. Bi v u tin mu tng dn tng mc v sau mt dn, gi cho thi gian bng nhau gia cc ln cho mu v chun. Chun b t nht mt ng chun vi tng t mu hoc mi ngy thc hin phn tch. Mu Cuvet chun c th chch khi ng thng vi nng cao hn 0,3 nng 2,0 mg/L Sau ta xy dng ng chun vi dy dung dch chun c nng nm trong khong nng trn. T ta s xc nh c hm lng PO43-. Cc yu t nh hng Silica v asenate ch nh hng nu mu b un nng. Cc anion gy nh hng gm: arsenate, fluoride, thorium, bishmuth, sulfide, thiosulfate,thiocyanate, hoc nng molybdate qu cao. Mu xanh to bi st khng nh hng ti kt qu nu hm lng st nh hn 100mg/L. Sulfide gy nh hng nhng c th loi b bng cch cho oxy ha vi nc Brm. Cc ion sau khng gy nh hng n kt qu ngay c khi nng ln ti 1000mg/L nh l Al 3 + , Fe 3 + , Ca 2 + ,Ba 2 + ...Nu HNO3 cdng trong phng php Phc phn ng vi cht kh l axit Ascorbic Gii hn thp nht c th xc nh c: xp x 10 g P/L. Cch tin hnh: Lm tng t nh trn. dy cuvet ph hp cho khong nng nh sau: Khong nng P (mg/ml) 0,3 - 2 0,15 - 1,3 0,01 - 0,25 Chiu dy Cuvet (cm) 0,5 1 5


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Yu t nh hng: Arsenates (As V) phn ng vi molydate to mu xanh tng t nh mu xanh to vi PO43-. Nng 0.1 mg As/L gy nh hng ti phng php xc nh PO43Cr (VI) v NO 2-nh hng ti khong 3% nng thp hn 1 mg/L v nh hngkhong 10-15% khi nng 10 mg/L. Na 2 S v silicate khng gy nhhng khi nng t 1 10 mg/l. Ngoi ra ta c th tin hnh o quang s dng thuc th vanadat molipdat to phc mu vng bn. phng php ny s c nghin cu k hn ti phn thc nghim di y

PHN 2: KT QU THC NGHIMTin hnh phn tch thc nghim theo phng php trc quang s dng thuc th l vanadate- molipdate. CHNG 1: CHUN B1.1. NGUYN TC

Trong dung dch orthophosphat, di iu kin axit amoni molipdat phn ng to thnh axit herteropoly v molybdophotphoric axit. Khi c mt vanadium to thnh axit vanadomolybdophosphoric c mu vng. Cng mu ny t l viet nami nng photphat trong dung dch1.2. DNG C - HA CHT

1.2.1. Dng c Pipet cc loi: 0,1 ;0,2 ; 0,5 ; 1 ; 2 ; 5 ;10 ; 25 (ml) Bnh nh mc: 50 ; 100 ; 250 ; 500 (ml) Bnh tam gic 250ml GVHD: Nguyn Th Thoa SVTH: Th Thoa Page 35


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Phu lc, giy lc Bp in My quang ph UV/VIS Cuvet thy tinh Cn phn tch bn s T sy Bnh ht m

1.2.2. Ha cht 1.2.2.1. Axit H2SO4 30% Ha 30ml H2SO4 c vo khong 60ml nc ct sau nh mc n vch 100ml 1.2.2.2. K2S2O8 Ha tan 5g K2S2O8 vo 100ml nc ct ( lm hng ngy ) 1.2.2.3. Dung dch Vanadat Molipdat Dung dch A: ha tan 12,5g amonimolipdat (NH4)6Mo7O24.4H2O trong 150ml nc ct Dung dch B : ha tan 0,625g amonivanadat NH4VO3 trong 150ml nc ct un si, ngui thm 175ml axit HCl c. Sau trn dung dch B lm ngui n nhit phng vo dung dch A ri nh mc ti vch 1 lt. 1.2.2.4. Dung dch HCl long (dd ra) 1.2.2.5. Dung dch ch th phenolphtalein 1.2.2.6.Than hot tnh 1.2.2.7. Dung dch chun PO43- ( 50mg PO43- - P/l ) Ha tan 219,5 mg KH2PO4 trong 1l nc ct


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1.3. LY MU BO QUN MU

Nu cc dng P tan c lm ring bit, th ngay sau khi thu mu phi lc ngay.Bo qun bng ng lnh hoc di -100C. Trong mt s trng hp khc, 40 mgHgCl2/l c th c thm vo mu, c bit khi mu phi bo qun lu phn tch. CH : -HgCl2 l cht nguy hi, cn phi c nhng bin php phng nga thch hp,vic s dng n khng c khuyn khch. -Khng thm bt c axit no hoc CHCl3 khi cha phn tch cc dng P. -Nu ch phn tch tng P, thm H2SO4 hoc HCl npH

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