J O U R N A L O F SCIENCE O F H N U E DOI 10.18173/2354-1059.2015-0006 Natural Sci. 2 0 1 5 , Vol. 60, No. 4, pp. 41-46
This paper is available online at http,//stdb.hnue.edu.vn
HAP PHU VA GIAI HAP ION La'* VA Nd'* TRONG DUNG DICH BANG NHlTA TRAO DOI ION POLY(HVDROXAMIC AXIT)
DUOC TONG HOP TREN CO S 6 ACRYLONITRIL Hoang Thi Phucmg' Trinh Dire Cong", Nguyen Thj My Hoa", Nguyen Tien Diing", Nguyen Thi Kim Giang" va Nguyen The Hiiu"'
Vien Hda hoc. Vten Hdn lain Khoa hoc vd Cdng nghe Viil Nam 'Khoa Hda hoc, Truang Dgi hoc Su phgm Hd Ndi Khoa Cdng nghi Hoa hoc, Tru&ng Dai hgc Cdng nghiep Hd Ndi T6ni tat. Qua trinh hap phu ciia ion La^" va Nd"" dupc xac dinh bang phucmg crlnh dang nhiet hap ph^ Langmuir vdi dp hap phu cue dai cua La"'' va Nd'"" tuong iing la 210 52 va 190.47 mg/g t^i pH = 6. Bang each xu li het cac ion kim loai trong polyme sau khi giai hap bang dung moi HCI O.IN thi kha nang hap phy ciia poly(hydroxamic axit) co the duac phuc hoi Sau 5 chu ki hap phu- giai hap thi kha nang hap phu cua poly(hyd!'oxamic axit) van tu'ong doi cao
Tir khda: Hap phu, poly(hydroxamic axit), lantan, neodym.
1. Mffdau
Ciing vdi su phat trien khoa hpc va cdng nghe, cac tinh nang uu viet cua cac nguyen td dat hiem (NTDH) ngay cang d u p c kham pha, ling dung vao ddi sdng trong nhieu ITnh vuc khac nhau nhu: che tao spi cap quang, vat lieu tir, vat lieu gdm sieu dan, vat lieu cho cdng nghiep dien tu, vat lieu hat nhan, tao mau cho thuy tinh, vat lieu mai bdng va thiet bi quang hpc, San xuat chat xiic tac trong cdng nghe xii H khi thai, cdng nghe xuc tac hda dau va tdng hpp huu ca, che pham dinh dudng kich thich sinh trudng cho cay trdng va mang lai hieu qua kinh te cao trong ndng nghiep, gom sieu dan [1-4],
Cd nhieu p h u a n g phap de tach cac nguyen td Dat hiem tu tinh quang dat hiem nhu chiet long - long, chiet sieu tdi h a n , p h u o n g phap quang boa, p h u a n g phap ket tua. trao ddi ion [1-2]....Viec tach cac ion kim loai khac nhau bang kT thuat trao ddi ion tren c o sd cac polyme da dupc su dung tu lau. Trong dd, cd cac polyme chiia cac nhdm chiic dac biet n h u amino axit, axit photphonic, ammo photphonic, axit cacboxylic [5, 6]. De tach mdt sd nguyen td dat hiem da va dang dupc nhieu nha khoa hpc tren the gidi quan tam nghien ciru.
Copolyme polyacrylonitril d u a c tdng hpp tit monome acrylolitril bang phuong phap tning hop huyen phu ngupc sau dd thiiy phan bang dung dich H2SO4 5 0 % va bien tinh bang hydroxyamin tao tbanh p o l y ( h y d r o x a m i c axit) ( P H A ) . P o l y m e nay chiia n h d m c h u c h y d r o x a m i c axit ( - C O N H O H ) cd kha nang tao pbiic cang cua vdi nbieu ion kim loai dat hiem, kim loai nang [3,4].
Trong nghien ciiu nay nhdm tac gia da tien hanh nghien ciiu qua trinh hap phu. giai hap cua ion La^* va Nd'* trong dung djch bang polyme chiia nhdm chirc nang hydroxamic axit (-CONHOH) dupc tong hpp tren c a sa acrylonitril va qua trinh hap phu, giai hap hai nguyen to dat hiem nay trong dung dich.
Ngay nhan bai: 23/1/2015. Ngay nhan dang. 27/4/2015.
Tac gia lien lac: Tnnh Due Cong, dia chi e-mail: congvhh@gmail,c
-1 - 5 I ^ i W _ - ^ * ^ 1 H. T. Phucmg.T. D, Cdng, N, T. M. Hda. N. T, Dung, N. T, K, Giang va N. T Hiiu * 2. Noi dung nghien cihi
2.1. Thurc nghiem 2.1.1. Hoa chat va vat li|u
- Dung djch chuSn La(N0i)3, Nd(N0i)3, dung mdi, hda chit trong phan tich nhu NaOH, HCI, CH3COOH, CHjCOONa, axit oxalic (tinh kliifit phan tich Trung Qudc).
- Polyme chiia nhdm chiic hydroxamic axit (PHA) dupc tdng hpp tu acrylonitril bang phuong phap thing hpp huyen phu ngupc vdi sir cd mat ciia chat tao ludi Divinyl benzen (DVB) 7%; chat khoi mao la azobisisobutyronilrile (AIBN) 1%; chat boat dpng be mat gelantin 0.3%. Sau dd polyme tao thanh dem thiiy phan trong 24h biing dung dich H2SO4 50% va bien tinh b3ng dung dich NH2OH.HCI 4 M. Poly(hydroxamic axit) tong hpp cd ham luong nhdm chiic nang -CONHOH la 9,12 mmol/g.
Quan sat anh SEM cho th5y hat cd dang hinh cSu kich thudc 100 - 300 fim. So dd phan ung trimg hpp dupc mo ta trong Hinh 1,
CK-
^ DVB _ C H , - C K - C E - C H : -
Hinh 1. Sff do tdng hcfp PHA tu acrylonitril 2,1,2, Phinmg phap tien hanh
* Qud trinh hdp phu
Dung dich ion La ' va Nd'* voi nong dp khac nhau duac dinh muc bjng dung dich chuan La(N03), va Nd(N03)] 1 g/L voi dung mai la dem axetat 0,5 M, axit CHjCOOH 0,1 M va nuoc cat 2 lin dl ducrc pH thich hop. Lay 0,15g PHA cho vao cac c6c chiia 50 mL dung djch ion La'* va Nd'* co ndng do dSu la 500 mg/L rdi khuiy trin may khuay tir tai 25°C vcri t6c dp khong dai. Sau khi kit thuc qua trinh hdp phu, Ipc lly dung dich va x4c dinh ndng do ion kim loai dit hiim con lai bing phuang phap pha hap thy njjuyen tii AAS.
Dung lupng hap phu duac tinh theo cong thiic;
^ ( C „ - Cri,).F
. ' "" (1) trong do: q, la dung lupng hap phu tai thai diem can bang (mg/g hoac mmol/g), Co la nSng dp kim loai
trong dung dich ban dau (mg/L hoac mmol/L), C,b la n6ng do kim loai trong dung dich tai thoi dijm cto b k g (mg/L hoac mmol/L), V la the tich dung dich kim loai hip phu (1), m la khii luong chit lupng hap phy (g).
Hdp phu vd giai hdp ian La^^ vd Nd'' trong dung dich bdng nhira trao doi ion poly(hydroxamtc axil)...
* Qua trinh giai hap phg
Chat hap phu bao boa dupc dua vao 50 mL dung dich HCI 0.1 N va khuay Sau nhirng khoang thdi gian khac nhau, lay miu va xac dinh dp h^p phu can b5ng cua PHA. Chat hap phu dupc rua bang nudc cat tdi pH trung tinb sau dd lam kbd trong chan khdng d 65"C den khdi lupng khong ddi.
* Qud trinh tdi sinh chat hap phu
Lay 0,15 g chat hap phu cho vao cac cdc chua 50mL dung dich ion La'' 500 mg/L va Nd^' 500 mg/L. Sau thdi gian 90 phiit lay mau va tien hanh giai hap b^ng dung djch HCI 0,1 N. Tien hanh 5 chu ki bip pbu ya giai hap lien tiep bang 0,15 g chit hip pbii tren Sau mdi chu ki, xac dmh phan tram kim loai bi hap phu, phan tram kim loai dupc giai hap va khoi lupng chat hap phu bj hao hut.
* Xdc dinh dung lucmg hdp phu cue dgi theo md hinh hdp phu ddng nhiet Langmuir Tien hanh qua trinh bap phu vdi ndng dp ban dau cua ion kim loai La'' va Nd'" khac nhau 100, 200, 300, 400, 500 va 600 mg/L, nbiet dp 25''C, pH = 6, tbdi gian bip pbu 90 phut. Tir ket qua thu duoc xay dung phucmg trinb dang nbiet Langmuir cd dang:
" bCcb
q'-^-^^^-r^ <2)
Trong dd: q^ la dung luong hap phu tai thdi diem can bang, q™, la dung lupng hip phu cue dai, b la hang sd, Ccb la ndng dp kim loai trong dung dich tai thdi diem can bing.
De xac dinh cac hang sd trong phuong trinh dang nhiet Langmuir cd the chuyen phuong trinh ve dang phuang trinb dudng tbang:
Cct 1 ^ 1
Day la phuong trinh dudng bieu dien su phu thudc C^Jq^ vao Cj,. Tu phuang trinh dudng thang nay xac dinh dupc hang sd qm« va b trong phuong trinh tir he sd gdc cua dudng thang va ngoai suy dd thi tdi Ccb = 0.
2.2. Ket qua va thao Iuan
2.2.1. Nghien ciru anh hirdng ctia pH den qua trinh hap phu
Ket qua khao sat cho thay trong khoang ndng dp dau cua hai ion kim loai La'" va Nd'" la 500 mg/L, thdi gian dat can bang hap pbu 5h, nbiet dp SO^C, dung mdi la dem axetat 0,5 M, khoi lucmg polyme la 0,15 g thi kha nang hap phu ciia PHA la tdi uu. Tuy nhien, trong qua trinh hip phu va giai hap pH la mdt trong nhung yeu td quan trpng anh hudng rat ldn den kha nang bap phu - giai bap ciia vat lieu PHA. Ket qua nghien ciru anh huang cua pH den qua trinh hap phu La'' va Nd''" bing PHA dupc trinh bay trong Hinh 2.
_
II)
3.
"c.
^^
-
250 200 150 100 50 0
\d(IIl) La(IlI)
3 4 5 6 -
pH
Hinh 2. Anh hu&ng cua pH den qud trinh hap phu La'^ vd Ni^* bang PHA-AN
H. T. Phuong.T. D, Cong, N. T, M. Hda, N T. Dung, N. T. K. Giang va N. T HiJu Khi pH > 7, mdt phan ion kim loai dat hiem La'' va Nd'* bj ket tua d dang huyen phu la lung trong dung dich va mdt sd bam tren b£ mat PHA. De xac dinh mdt each chinh xac luang loii kim loai da hip phy \ko PHA, lupng kk tiia bam tren bd mat PHA dupc Ipc va nia lai bang nudc cat. Lupng nudc thu hoi sau rda dupc gom cung vdi hdn hpp dung djch - ket tiia sau hip phii. Lupng ket tua trong dimg djch dupc hda tan bing each dieu chinh pH cua dung dich xudng < 6 trudc khi xac djnh lupng ion kim loai cdn lai sau hap phu,
Tli Hinh 2 cho thiy, khi pH tang thi dp hip phy cua PHA tang va dp hap phy cao nhit ciia La'* va Nd'* tucmg img tai pH = 6. Vdi pH tir 6 - 7 dp hap phy giam vj trong dung dich bit dau xuat hien sir kSt tua ciia ion kim lozii gay can trd qua trinh hap phu ciia ion bing nh^a PHA. Do vay chi nghien ciiu qua trinh hap phy vdi moi trudng pH < 7.
2.2.2. D$ h4p phu ciia La(ni) v^ Nd(III) theo mo hinh d^ng nhi^t Langmuir
Tren CO sd cac diSu kien tdi uu ve thdi gian, ndn^ dp ion kim loai dat hiem liic dSu, pH, dung moi da tim duoc d tren tien banh qua trinb hSp phu vdi ndng dp La'* va Nd'* ban dau khac nhau. Cac dfl lieu hip phu dupc phan tich theo md hinh ding nhiet hap phy Langmuir. Dang tuyen tinh ciia phuong trinh Langmuir dupc chi ra trong Hinh 3.
1.2 jy = 0.00475x-r 0.31337
R= = 0.99854 1.2
0 9 0.6 0.3
0 ' - - 0
y
50
= 0 0 0 5 2 5 x - 0 . 3 3 8 4 2 . » R- = 0 . 9 9 8 9 1 / ^
^^
100 150 ; CtbCmg/l)
(a) (b) Hinh 3. Dgng tuyin tinh ciia phuomg trinh Langmuir ddi v&i (a) La(lH) vd (b) Nd(IH)
Cd the thiy ring md hinh hap phy dang nhiet Langmuir md ta kha chinh xac sir hip phu ciia La'*va Nd'* Ien poly(hydroxamic axit) dupc tdng hpp tren ca sd acrylonitril. Dung lupng hap phu cyc dai qnw, ciia polyme ddi vdi La'* va Nd'* lin lupt la 210,52 va 190,47 mg/g va hing sd b trong trudng hpp La'* la 0,31337 va 0,33842 ddi vdi Nd'*.
2.2.3. Qua trinh giai hap phy ciia ion La(III) va Nd(lU) theo thoi gian
pk nghien ciiu qua trinh giai hip, chung toi tiln hanh thi nghiem nhu sau: liy 0,15 g nhya PHA dS hip phu bao hda dua vao cdc chua 50 inL dung dich axit HCI 0,1 N va khuiy d nhiet do phdng. Sau nhCfng khoang thdi gian khac nhau, liy mau va xac djnh ham luong ion kim Ioai trong dung djch. Su phu thudc cua lupng kim loai dupc thu hdi tbeo thdi gian xir li dupc bidu diln tren Hinh 4 va 5.
Ket. qua cho thay kim logi dupc giai hap tang nhanh theo thdi gian d giai doan diu, sau dd ti6p tyc tang diu khi keo dai thdi gian va luang ion dupc giai hip phy gin nhu hoan toan khi sii dyng dung moi rua giai la HCI 0,1 N. Nhu vay, cd the sd dyng dung dich HCI 0,1 N lam dung mdi trong qua trinh nia giai thu hdi ion La'* va Nd'* do su tuang tac cua ion hai kim loai nay bing PHA la su tao hen ket phuc ciia nhdm -CONHOH vdi ion kim loai nen khi rua giai bing dung mdi cd mdi trudng axit thi hieu qua thu hoi ion tot hon.
Hdp phifva gidi hdp ion La^' vdNd" trong dung d]ch bdng nhifa trao doiion poly (hydroxamic axit) ...
15 30 45 60 Thdi gian (phut) Hinh 4. Anh hu&ng cua th&i gian
t&i qud trinh gidi hap La * (CB= 500 mg/L, q,= 136,55 mg/g) 2.2.4. Qua trinh tai sinh, tdi sir dung chat hap phu PHA
Sau khi giai hap, chat hap pbu dupc tai sii^ bang each rua bang nudc cat den pH trung tinh, say khd trong chan khdng den 65"C den khoi lupng khdng ddi va tiep tuc thyc hien 5 chu ki hSp phy - giai hap nhu tren. Ket qua dupc trinh bay trong cac Bang 1 va 2.
Thai gian (phtil) Hinh 5. Anh hu&ng cua th&i gian
t&i qud trinh gidi hdp Nd^*
(Co = 500 mg/L, q^= 126,72 mg/g)
So chu kl 1 2 3 4 5 (Nong a
So chu ki
1 2 3 4 5
Bdng 1. Khd ndng tdi sd" dung chdt hdp ph KhS nang
mg/g 136,55
136,02 134,19 132,12 129,51
hap phu 100
%
99,6 98,2 96,7 94,8
Luong kim lo^i dir^'c giai hap (mg/g)
136,10 135,13 133,24 130,42 128,11
« PHA ddi vdi La'*
Khoi lirong chat hap phij sau khi tai sinh (g)
0,60 0,593 0,580 0,569 0,558 0 La'* Co= 500 mg/L, luang chdt hdp phu 0,15 g tuo
Bdng 2. Khd ndng tdi su' dung chdt hap ph Kha nang hap phu
mg/g 126,72 125,42 123,1 121,98 120,19
100
%
98,9 97,1 96,2 94,8
Luang kim loai duac giai bap (mg/g)
126,12 124,01 122,45 120,42 119,01
ng ung vdi q,. - 136,55 mg/g) t PHA ddi vdi Nd""
Khoi lu-o'ng chat h4p phu sau Ithi tai sinh (g)
0,589 0,580 0,571 0,564 0,551
(Ndngdd Nd^'^ C,i= 500mg/L, lugng chdt hdp phii 0J5g luang ung v&iq^= 126,72 mg/g) Kit qua cho thiy kha nang hap [ihu cua PHA gi^m din sau cac chu ki hap phu - ^iai hip, tuy nhien van d mirc cao. Kha nang tbu hdi kim loai bang dung mdi HCI 0,1 N cung giam dan, mpt ti le nhd kim loai khdng dupc thu hdi bdi qua trinb tai sinh cd le la do chiing dupc lien ket qua cac tucmg tac manh han va do dd hieu qua hip phu giam din theo cac chu ki. Ngoai ra, sau mdi chu ki khdi Iupng chit hap phu cQng bj suy giam rapt lupng nhd do cac thao tach Ipc, rua, trong qua trinh hip phy.
H T. Phuang T D. Cong. N, T. M. Hoa, N T. Dung. N. T. K. Giang va N. T Hftu 3. Kk luan
Chung tdi da nghien cuu, khao sat mdt sd yeu td ndng dp ion kim loai ban diu, pH cua dung dich, dung moi, thdi gian hip phy den qua trinh hap phy La'' va Nd'* bing polyme chtta nhdm chiic nang hydroxamic axit dupc tdng hop tir acrylonitril. Tir do, dua ra dieu kien tdi uu cho qua trinh bap phy:
ndng dp ion kim loai liic dau la 500 mg/L, dung mdi la d?m axetat 0,5 M, tbdi gian hap phu la 5h, pH ctia dung dich bang 6 vdi La'* va Nd'\
Qua trinh bap phy cua ion La'* va Nd'' !en PHA dupc nghien ciru bing phuang phap gian doan, Ap dung md hinb hap phu dang nhiet Langmuir xac dinh dupc dung lupng bip pbu cue dai q^n, ciia La" va Nd'* lin lupt la 210,52 mg/L va 190,47 mg/L, tuong irng. Chat hap phu PHA-AN dupc giai hap va tai sinh bang dung dich HCI 0,1N, kha nang tat sinh cua polyme tuang ddi cao.
TAI LIEU THAM K H A O
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ABSTRACT
Adsorption and desorption of La(in) and Nd(III) ions from aqueous solutions by poly(hydroxamic acid)
The adsorption of La'* and Nd'* ions conformed to the linear form of the Langmuir adsorption isotherm. The adsorption capacities for La'* and Nd'* were found to be 210.52 mg/g and 190.47 mg/g at pH = 6, respectively. When treating the metal ion loaded polyme with 0.1 N HCI, it is possible to recover all of the La(lll) and Nd{Ill) from this polyme. After 6 cycles of adsorption-desorption, the adsorption capacity of hydrogel is still high.
Keywords: Poly(hydroxamic axit), lantan, neodym.
