TAP CHi H 6 A HQC T. 50(3)327-331 T H A N G 6 N A M 2 0 1 2
NGHIEN CLTU KHA NANG HAP PHg KIM LOAI B6UG SI> Dl^NG
TRO COA V 6 KHOAI TAY Bill Thj L§ Thuy
Tru&ng Dgi hgc Mo Dja chit, Dong Nggc, Tit Liim, Hd Ngi Din Tda sogn 29-11-2011
Abstract
The adsorption of Cu(II) ion from aqueous solutions using potato peels charcoal, which are normally discarded as solid waste was investigated. The study on influence of various parameters such as solid liquid ratios, solution concentration, temperature and pH was carried out. The adsorption yield of 98.5% was reached at pH 6 and Cu(ll) solution concentration 190 mg/I. The copper adsorption was found to follow the Langmuir and Freundlich isotherms.
The maximum adsorption capacity of potato peels charcoal of 53.9 mg/g was determined from Langmuir isotherm equation.
Keywords' Adsorption, Cu(II), potalo peels charcoal.
l.MdDAU
Kim loai nang Id cac nguyen to cd khoi lugng nguyen tii tir 63,5-200,6 vd khdi lugng rieng Idn ban 5,0 [1], Cling vdi su phdt triin nhanh chdng ciia cac nganh cdng nghiep nhu mg, Iuy?n kim, phan bdn, thupc da, giay, dugc... nguon nudc thdi cd chiia cac kim loai nang true tiep va gidn tiep gdy d nhiem mdi trudng ngdy cang tang. Khdng nhu cac tap chdt hiru CO, kim loai nang khdng phan huy sinh hpc ma tich ty lai trong ca the sdng. Rat nhilu kim loai ndng cd dpc tinh cao vd la tac nhan gay ung thu. Cac kim logi ddc trong nudc thai cdng nghidp bao gdm: kem, ddng, niken, thiiy ngan, cadimi, chi vd crom.
Hap thu mdt lugng du dong vdo ca the se dan den dau dau, ryng tdc, tang nhjp tim, budn ndn, hdng than vd gan. Ddng thdi nd ciing gay ra cac van de ve tam Iy nhu: hoat dpng bat thudng cua nao, trdm cam, tam than phan liet, lugng ldn ddng hap thy qua dudng tieu hod cd the gdy tu vong [2]. Td chiic Y te The gidi khuyen cao ndng dp tdi da ciia ion Cu trong nudc udng la 1,5 mg/l [3]. Mpt so kim loai nang khac cung dac biet nguy hilm doi vdi sire khoe con ngudi vd su an toan cua h? sinh thdi. Vi the can phai logi bd chiing trong nudc thdi. Cdc phuang phap truyen thdng de loai bd kim logi nang bao gdm;
tham th3u ngugc, xu ly dien hda, trao ddi ion [4].
Cdc phuong phdp nay cd the lam gidm ion kim logi nang nhimg khdng cd hieu qud cao do bj ban chi bdi khodng pH, gid thanh vat lieu vd chi phi van hanh cao. Trong nhiing nam gdn day, cd nhieu nghien ciiu tap chung vdo viec sir dyng cac chat hap phu re til" M ,'f>,-: ^h"i "? r,?c k'm lo^l nan^ trong
dung djch nudc. Mpt so chat hap phy nhu mim cua, oxit silic, oxit sdt, tro biin thai, bd cay oliu, keo vd CO, than hoat tinh da dupe nghien cdu diing ldm chat xii ly cac chat thai chiia nhieu Cu * [5-10].
Trong nghien ciiu nay, Cu^* trong dung dich nudc dugc xii ly diing tro ciia vd khoai tay vdi myc dich tgn dyng nguon nguyen li$u hdp phy re tiin, san cd trong nudc vd giam chat thai gdy d nhiem mdi trudng. Ngodi ra, dpng hpc cua qua trinh vd dnh hudng cua cac dilu kien tien hdnh cung dugc nghien cuu.
2. THU'C NGHIEM 2.1. Chuan bi chat hap phu
Vd khoai tdy dugc rda de logi bd het tgp chat ban, trdng lai bdng nudc cat that sach rdi ngdm trong nudc cat khoang 3 gid. Mau thu dugc dem sdy d 100°C trong 3 gid, nung d 700°C trong 2 gid; sau do idy mdu ra dem nghien nhd, say va su dyng lam chat hdp phu.
2.2. Qua trinh tach ion Cu^^
bdng chat hap phu
trong dung dich
Thi nghiem dugc thuc hien trong binh cau cd lap may khudy, sinh han hdi luu va nhiet ke. Dung dich CUSO4 vd chdt hdp phu dugc dua vdo binh cau, sir dyng cdc dung dich NaOH 0,1 M vd HNO3 0,1 M dl dilu chinh dg pH cua hdn hgp ve cdc gia \x\ nghien ciru (I-I5). Hon hgp dupe khudy vol toe dp 150 vdng/phiit d nhiet do vd thdi gian nghien ciiu.
TCHH, T. 50(3), 2012
Sau khi kit thuc qud trinh, dCing gi^y Ipc dl lpc tdch ch4t hdp phy vd dung djch, cQng c6 thi dimg phuang phdp li tdm dl tdch. Dung djch thu dugc dem chudn dp de xdc djnh nong dg ion kim logi cdn Igi trong dung djch.
PhiTOTig phdp chuSn dO de xdc djnh nfing d^ Ion Cu^^ trong dung djch sau hkp ph\f
Trong nghien cim ndy, phuang phdp chu^n dp iot dupe ddng dl xdc djnh nong dp ion Cu^' trong dung djch. ,Cdc phdn iing ca bdn bao gom:
2Cu^' + 4 r = 2 C u I + l2
I2 thodt ra dupe chudn dg bdng dung djch Na2S20.i theo phdn ling sau:
2 NajSjOj + I2 = 2Nai + Na2S406
Chat chi thj diing d phan img ndy Id ho tinh bpt [11,12].
2.3. Tdi sinh chat hSp phy
Chat hdp phy sau khi sir dyng dugc nia bang nudc cat vd cho vdo binh cdu 3 cd, cho them vdo 100 ml dung dich HCl I M, khudy Irong 60 phiit.
Sau dd sir dyng gidy Ipc de tdch lay tro sau khi da nha hdp phu, dem say khd vd nghien nhd de dimg cho thi nghipm tai hap phu nhiing Idn sau 3. KET QUA VA THAO LUAN 3.1. Dac trung tinh chat cua chat hap phi^
Tro thu dugc sau khi nung dugc xac dinh mpt sd tinh chat vat Iy. Dien tich be mat cua mdu khoang 0,6 mVg. Su hdp phy bj anh hudng bdi cdc tinh chdt hda ly ciia chat hap phy va chat bi hap phy. Anh SEM (hinh 1) d cdc dp phan giai khac nhau cho thay cdc hgt phan bd tuong ddi ddng deu khoang 2-3 pm.
Bid Thf L? Tfitiy ciru dl tim ra cdc thdng so t6i uu trong vung khio sdt.
3.2.1. Anh hu&ng ctia khSi lugng chdt hap phif Ciic thi nghi§m dugc thgc hi?n d cime dieu ki?n vdi khAi lugng chdt h4p phy thay doi. Ket qud dugc trinh bdy d hlnh 2.
Hinh I: Anh chyp kinh hien vi dien tir quet cua mau chdt hap phu (tro vd khoai tay) 3.2. Anh hudng cua mpt so yeu to den qud trinh hap phu
Cdc yeu td anh hudng den c^ua trinh hdp phu nhu: khdi lugng chat hap phu, nong dp dung dich chat hap phy, thdi gian, nhi?t dp va pH dugc nghien
Khoi lupng chdt hdp phy (g/lOOmI dd) Hinh 2: Anh hudng cua khdi lugng chat hap phg
den qud trinh hap phy ([Cu^*] = 190 mg 1. 20 phut. 2 0 T , pH = 6) Ket qud d hinh 2 cho thdy nen diing lupng diit hdp phy td 1 g/lOO ml dung dich de thvc h i ^ hq) phy ion ddng. Voi khoi lugng chat gid tri cao nhat Khi khdi lugng chat hap phy tang dan thi lupng ion kim logi ddng dugc hap phy tren bl mgt chat hSp phy cung tdng dan. Tuy nhien, tdng lugng chat hip phy dan den tdng chi phi nen trong cac thi nghiem tiep theo, lugng chdt hap phy sii dyng deu la I g/100 ml dung djch C\r'
3.2.2. .Anh hir&ngcita nongdg dung dich bihapphii.
Khi ndng dg ciia dung djch chiia Cu'' tdng tii 95 mg 1 den 380 mg I thi hipu sudt qud trinh hap phy gidm nh? tir 9S"(> xudng cdn '?5"o. Dieu nay la phi hgp vi dung lugng hap phy cua chdt hap phu la co dinh.
Nong do Cu^^ (g/100 ml dd) Hinh 3: Anh hudng cua ndng dp dung dich Cu^^d™
hieu suat hdp phy (1 g chat hdp phy/100 ml dung dich, 20 phut, 20*'C, pH = 6)
rCHH,T. 50(3), 2012
D I so sdnh vd ddnh gid khd ndng hdp phy ciia
;hat hap phy d cdc dieu ki?n khdc nhau, trong todn bO nghi6n cuu ndy cdc thf nghidm deu sd dyng dung djch chiia Cu^* 190 mg/l.
2.3.3. Anh hir&ng ciia thai gian
Khi tdng dan thdi gian thi hi^u suat hdp phy tdng vd dgt c\rc dgi Id 98,5% d 20 phut, sau dd hi^u suat khdng thay doi chung td qud trinh dd dgt tdi cdn bang (hinh 4). Vi vgy, tM&i gian hap phy toi uu Id 20 phut.
Nghien ctru khd ndng hdpph\i...
nhipt dg thdp han 20''C thi cdn phdi ldm Ignh nudc thdi. Dilu ndy khdng thugn Igi trong thyc te. Do do, nhi^t d$ hgp phii cho qud trinh hap phy td 20°C.
3 2.5 Sy dnh hu&ng cua pH
Qud trinh hap phy ion Cu^* dugc nghien cuu d mdi trudng cd pH thay doi tir H14 (hinh 6). Kit qud cho thay pH = 6 Id toi uu de thu dugc hi^u suat hap phy Idn nhdt (98,5%). Kit qud tuang ty cung thu dugc khi nghien cuu sy hap phy ion Ni^^ bdng tro vd khoai lay [13]. 6 pH thap han sy hap phy ciia ion Cu"' gidm do bl mdt cua chat hap phy bj proton hda va xdy ra sy hap phy cgnh tranh giira cdc ion H*^ vd cdc ion Cu'"" [14]. Cdc ion H* phan iing vdi nhdm chirc mang dipn dm tren be m^t chat hap phy lam hgn che so lugng cac nhdm chuc danh cho su hap phy ion dong [13]. Tuy nhien, khi pH > 6 cd sy tao thdnh kit tua hidroxit dong vd cac phiic ciia ddng vdi ion OH" ldm can trd sy hap phy ion dong len be m$t chat hdp phy [5, 15]. Dilu nay din din sy gidm hipu suat hap phy.
Thdi gian hdp phy, phiit Hmh 4: Anh hudng cua thdi gian hap phy din hi^u
suat hap phy (1 g chat hap phy /lOO ml dung djch, ([Cu^1 = 190 mg/I, 20^0, pH = 6) 3.2.4. Anh hu&ng cua nhi^l dg
Anh hudng ciia nhiet do dugc nghien curu trong khoang 20-40''C (hinh 5). Kit qua cho thay hieu sudt hap phu giam khi tang nhi?t dp. Dieu ndy phii hgp vdi nhiet dpng hpc, hdp phu la qua trinh tda nhiet, do dd nhiet dp cang tang thi qua trinh hap phy cdng giam vd qud trinh gidi hdp ldng.
"
^
phu hip
p 3
£ m
60 40 20
fl
• - ^ " ^ ' ^ • — ^ _
Nhiel do h^p phy, °C Htnh 5: Anh hudng cua nhiet dp den hieu sudt hap
phy (Igchdthdpphu/lOOml dung djch, [Cu^*] = 190 mg/l, 20 phut, pH = 6) Tuv nhipn d | thirc hien aud trinh hdo phu d
pH ciia dung dich nghien ciiu Hmh 6: Anh hudng ciia pH din hieu suat hdp phu
20 phiit (1 g chdt hap phy/100 ml dung dich, [Cu^*] = 190 mg/I, 20 phut, 20°C) 3.2.6. Tdi sir dung chdt hdp phu
Khd nang ldi sii dung chat hap phy Id mot tinh chat quan trpng. Day cac thi nghiem dugc thuc hien d ciing dilu kien su dung lai chat hap phy sau khi nhd hdp phy. Qua trinh dugc lap lai ba ldn, thu dugc ket qua d bang 1.
Hieu suat hdp phy gidm dan khi sd Ian hap phu tdng cd thi la do qua trinh nha hap khdng hoan loan.
Tuy nhien, hieu sudt hap phu chi giam nhe chung td chdt hdp phu co kha nang tdi su dyng cao.
3.3. Sir hap phu ddng nhiet
Tinh chdt dac trung cho qua trinh hap phy thudng dugc nghien curu bdng each sii dyng mpt sd
T C H H , T . 50(3), 2012
m o hinh h a p phy dSng nhi?t. M o hinh p h 6 bi^n nhat trong s o c i c m o hinh n i y l i m 6 hlnh L a n g m u i r v i m o hlnh Freundlich.
Bdng 1. K h i nfing t i i sir d g n g chSt h^p phy ([Cu^*]= 1 9 0 m g / l , l g c h S t h a p p h g / l O O m l d u n g
djch, 20°C, 20 phiit, pH = 6) L^n h^p phg
1 2 3
H S H P , % 98,4737 96,5541 96,3513
D0 HP, mg/g 18,4617 18,3189 21,6552
3 . 3 . S ^ h a p p h y d d n g n h i f t
Tinh chdt ddc trung c h o qud trinh h a p phy t h u d n g d u g c nghien ciiu bdng cdch s d d y n g mpt so md hinh hap phy ddng nhi?t. M d hinh pho bien nhat trong s o cdc m d hinh ndy Id m d hinh Langmuir vd m o hinh Freundlich.
3.3.1. Md hinh hdp phu ddng nhi^l Langmuir
Phucmg trinh d a n g nhiet L a n g m u i r cd dgng:
( I )
C - 1 C,
T r o n g dd: Ce: n d n g d p can bdng cua ion kim logi c d n Igi trong dung dich (mg/l),
Qe: lugng kim logi bj hdp p h u len mpt d o n vj khdi lugng ciia chat hdp phy (mg/g),
b: hdng sd L a n g m u i r (I/mg),
Qma^: khd n a n g hap phu c u e dai ciia chat hdp phy (mg/g).
M d hinh hap p h y d a n g nhi?t Langmuir t u o n g ling vdi m d hinh hdp p h y d a n ldp. Ket q u a nghien c u u qud trinh h a p p h y theo m d hinh ddng nhipt Langmuir d u g c trinh bdy d hinh 7,
Hinh/: lyid hinh hdp phy ddng nhiet L a n g m u i r (I g chat hap p h y / 1 0 0 ml d u n g dich, 20''C, 2 0 phut
pH = 6)
C o the thdy rdng p h u a n g trinh d d n g nhiet hdp
Biti Thi L4 lU^
phy Langmuir md td khd chinh xdc s^ hdp p h u ^ Cu^' I6n tro vd khoai tdy. Dilu ndy cd dugc thi his qua h$ s6 tucmg quan R^ cda qud trinh hoi qui ( 1 ^ 0,986). Dilu ndy cOng chihig td rdng Cu^' d u g c l ^ phy don ldp tr£n v$t ti^u hdp phy.
Tir Ah thj cd thi tfnh dugc cdc gid trj sau:
J - - 0 , 0 1 8 8 =>Qm„ = 53,I9mg/g
— ! — = 0,1683 =o b = 0,111 t/mg bQ.„„
Vi^c so sdnh gid tr[ Qm»% cua tro vd khoai tdyi^di Q,„ax ciia cdc chat hap phy ri tiin trong cdc nghi&i ciru khdc dugc thi hicn trong bdng 2.
Bdng 2: Khd ndng hdp phg dong trSn cdc chdt h^
phy khdc nhau
Chat hap phy
Vff lua mi
Cacbon ho^t tinh tu v6 trau
C$n biomass Mim cua Tro xuong Chi
Chat thai cong nghiep ch6 Hematit
Oxit sit Bentonit Vo cay thong Dolomit thien nhien Cacbon ho^t tinh tir ba cij cai ducmg (300°C) Vo cay phi Brazin Tro vo khoai I;i\ trong nghien ciru niy
Khi ning hap ph^j
(Q™,) (mg/g) 10,84 3,92 3,00 0,05 100 11,35 11,29 0,244 98 4 14,16 1.02 40,8 19,4 53,19
Tai lieu tham khio [16]
[171 [18]
[5]
(191 [20]
[21] 1 f211 1 [211 [211 [211 [211 [21]
[21]
4.4 2 .\lo hinh hdp phg ddng nhi^t Freundlich
l o g Q , = logKf + - l o g C , (2) T r o n g d d : C^ Id n o n g d g c a n b d n g c u a ion kim lo?i cdn lgi t r o n g d u n g dich (g/g).
Qe Id l u g n g k i m loai bi h a p p h y Ien mpt don vj khdi l u g n g ciia chdt hap phy ( g / g ) .
Kf v a n Id h a n g s o ddc t m n g c h o s u chdt hap phv vd chdt b | h a p p h y d nhiet d p n g h i e n ciiru.
M d hinh h a p p h y d d n g nhi?t Freundlich la mo hinh d a n g nhipt t h y c n g h i e m thudn tuy. Ket gua nghien c u u q u d trinh h a p p h y t h e o m d hinh dang nhipt Freundlich d u g c trinh b a y d hinh 8.
Tir dd thj ta cd:
- = 0 , 5 8 5 2 = > n = 1,71.
T C H H , T. 50(3), 2 0 1 2
l o | K , = 1,3493 => K , = 1 0 " ™ = 2 2 , 3 5 Ket qua thu dug-c c h o thay, q u i trinh hap phg Cu * bang than ciia v o khoai tay c u n g d u p e m 6 t i phu hop boi m o hlnh h a p phu d i n g nhiet Freundlich.
G i i trj 1/n nhd chirng tb v j t li$u hap phy c h e t j o dugfc phii hgrp d e h a p p h y ion Cu^*
oe ,
O-S 0.4
—
§ 0 3 0.2 1 4^^"^
1 1 0,1 — 0 0 -
0 10
Ce
y O O I S S n ' O i e s i R'- 0^98£„*iB=^
ts 20
Hinh 8: M d hinh hap p h y ddng nhigt Freundlich (I g c h d t h d p p h y / I O O m l d u n g d j c h , 20''C, 2 0 p h u t ,
p H = 6) 4. KET LUAN
Ket qud nghien c i m b u d c ddu c h o thay, cd the su dung tro ldm tir vd khoai tdy d e loai ion Cu^* trong dung dich n u d e thdi. C d the loai d u g c 9 8 , 5 % Cu^"^
trong dung djch chira 190 mg/l d p H = 6 trong thdi gian 20 phut. Qua trinh hdp p h y tuan theo md hinh Langmuir vd Freudlich. C h a t hap phu de k i l m va giam d u g c chat thdi trdnh 6 nhiem mdi t r u d n g . TAI LIEU T H A M K H A O
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Nghiin ciru khd ndng hdp phu...
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Lien h^: Biii T h i L ^ T h i i y
T r u d n g Dgi h p c M d - D j a chat Ha N d i D d n g N g g c , Tir L i e m , H a N p i
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