Tgp chi phdn tich Hoa, Ly vd Sinh hgc - Tap 19, So 4/2014
NGHIEN CUtl HAP PHU MAU METYLEN XANH BANG V.^T LIEU BA CHE
Den toa sogn 29-4- 2014
B6 Tra Huong, Trin Thuy Nga Tru&ng Bgi hgc Sit phgm - Dgi hgc Thdi Nguyin
SUMMARY
ADSORPTION ATUDIES ON THE REMOVEL OF COLOR OF METHYLEN BLUE USING MATERIAL TEA WASTE
The potentiality of tea waste for the adsorptive removal of methylene blue, a cationic dye, from aqueous solution was studied. Batch kinetics and isotherm studies were carried out under varying experimental condirions of contact time, initial methylene blue concentration, adsorbent dosag, pH... The nature of the possible adsorbent and methylene blue interactions was examined by the FTIR technique.The pHp^ of the adsorbent was estimated by titration method and a value of 5,23 was obtained.
Anadsorption-desorption study was carried out resulting the mechanism of adsorption was reversible and ion-exchange. Adsorption equilibrium of tea waste reached wirhin 2 hfor merhylene blue. The extentofthe dye removal increased with increasing initial dye concentration. The equilibrium data in aqueoussolutions were well represented by rhe Langmuir isotherm model. The adsorption capacity of methyleneblue onto tea waste was found to be as high as 178,57 mg/g. Tea waste appears as a very prospective adsorbent for the removal of methylene blue fi'Om aqueous solution.
Keywords: Adsorption; tea waste; isothermal Langmuir; methylene blue; cationic dye.
1. MCJ DAU deu su dung pham mau va son de tao mau DSc dilm ndi bat cua nudc thai det cho cac san pham. Nudc thai cua cac nhugm la chiia mdt ndng do cao chit mau nganh cdng nghiep nay nlu khdng dugc liiru CO bin vi sinh. Nhiing hgp chit mau xii ly hoac chua dugc xir ly triet dl cd thi la nhiing chit d nhilm de nhan thiy nhit chira cac hgp chat hilu ca dgc hai khi thai bdi mau sac cua chung. Hau het cac vao cac ngudn nudc tu nhien nhu sdng nganh cdng nghiep nhu det, giay, m an... sudi se lam nhiem dgc mdi trudng nudc 27
va pha hiiy canh quan mdi trudng tu nhien. Do dd viec tim ra phuang phap nhim loai bd chung ra khdi mdi trudng nudc cd y nghia het siic to ldn. Hien nay cd nhilu phuang phap khac nhau da dugc nghien ciru va ap dung de tach loai cac hgp chit hilu CO ra khdi mdi trudng nudc nhu cac phuang phap vi smh, phuong phap dien hda. phuong phap hda hgc, cac phuong phap lien quan din UV hay ozon, phuang phap hap phu. Trong dd phuong phap hip phu dugc lira chgn va mang lai ket qua cao.
Uu diem ciia phuong phap ia tan dung cac phu pham ndng nghiep, cdng nghiep lam vat lieu hip phu de xir ly ngudn nudc d nhiem. Hon nfia ngudn nguyen Heu nay re tien, san cd va khdng dua Ihem vao mdi trudng cac tac nhan ddc hai khac.[l-9].
Bai bao nay trinh bay ket qua ngliien ciru sy hap phu cac chat mau hilu ca (dung metylen xanh lam vi du) trong mdi trudng nudc ciia vat heu hip phu chl tao til ba che.
2. THUC NGHIEM 1. Hoa chat
Nudc cit hai lin, dung dich NaOH, HCI, NaCl, metylen xanh (MB). Tit ca hoa chat diu cd do tinh khilt PA.
2. Che tao tao vat lieu hap phu ba che (VLHP)
Ba che dugc thu thap tir cac hg gia dmh, cac hang quan dugc nia vdi nudc cit nhieu lan de loai bd tat ca cac hat bui ban. Sau dd dem dun sdi vdi nudc cit dl loai bd caffein, taimin .... Tilp tuc nia lai bing nudc cit nhilu lin cho din khi nudc nia khdng cdn mau, rdi dem siy khd d 95°C trong 16 gid, sau do dugc nghiin nat va ray din kich thudc 180 - 300/m. va dugc bao \e U-ong binh hut am de su duna
3. Phirong phap nghien ciru Dac diem be mat, hinh thai hgc ciia viit lieu hap phu dugc xac dinh qua phd hdng ngoai FT-IR. kinh hien vi di|n tir quet SBM.
Dien tich be mat rieng cua vat lieu ba che dugc xac dinh theo phuang phap BET.
Xac dinh ndng do trudc va sau khi hip phu ciia metylen xanh (MB) bing phucmg phap do quang.
4. Phuvng phap nghiSn ciru thirc nghiem
* Nghien ciru khd nang hap phu MB cua VLHP
- The tich cua metylen xanh la 30 ml vdi ndng do va pH xac dinh (dung dung dich HNO3 loang va dung dich NaOH de dieu chinh pH).
- Lugng vat lieu hap pliu la 0,05 g - Cac thi nghiem dugc tien hanh d nhi^t do phdng
(25 ± 1°C), hdn hgp hip phu dugc lac bang may lac vdi tdc dd 200 vdng/phiit.
+ Khao sat thdi gian dat cSn bing hip phu.
+ Khao sat anh hudng cua pH + Kliao sat anh hudng ciia khdi lugng vat lieu.
+ Khao sat anh hudng ciia nhiet dp (25°C, 35°C, 45°C, 55°C).
+ Khao sat anh hudng ciia ndng do diu din sir hip phu MB cua VLHP.
- Dung lugng hap phu tinh theo cdng thiic:
m
Trong do: V la thi tich dung djch (1).
m la khoi lugng chit hip phu (g), Co la ndng do dung dich ban diu (mg/l), Cd, la ndng do dung dich khi dat can bing hip phu (mg/l), q la dung lugng hip phu tai thdi diem can bing (mg/g).
- Dung lugng hip phu cue dai dugc xac dinh theo phuong trinh hap phu Langmuir dang tuyen tinh:.
q 1^ qm..-b Trong dd: qmax la dung lugng hip phu cue dai (mg'g),_
b la hang sd Langmuir.
* Nghien citu hip phu MB cUa VLHP Can 0,05g VLHP vao 12 eclen cd dung tich 100ml, danh sd thii ty tir 1 - 12; cho tiep vao mdi eclen 30ml dung dich MB cd ndng do la 23,66 mg/l (da dugc xac dinh chinh xac ndng do ) cd pH = 8,50, lac trong 120 phut, d nhiet do phdng ( ~ 25''C ) vdi toe do lie 200 vdng/phiit. Sau dd liy 1 mlu, tiln hanh li tam xac dinh lai ndng do MB. Vdi 11 mau cdn lai, dimg dung dich NaOH 0,1M va HCI 0,IM de dieu chinh pH ciia cac dung dich den cac gia tri tuong img la 8,50;
8,10; 7,50; 6,50; 6,0; 5,50; 4,50; 4,00;
3,20; 2,30; 1,50. Sau dd tiln hanh lie trong 120 phiit, d nhiet do phdng (~25°C ) vdi tdc do lac 200 vdng/phiit. Lay mau li tam va xac dinh lai ndng do MB sau khi hip phu.
6. Thuoc nhugm metylen xanh (MB) Metylen xanh (MB) la mdt chit mau thugc hg thidzin, phan ly dudi dang cation MB* la CeHigNjS*:
Hinh 1: Pho FT-IR ciia VLHP Phan tich quang phd hdng ngoai cua VLHP (hinh 1) cho thiy van phd rdng d 3413,42cm'', dai dien cho nhdm -OH.
Van phd d tin sl 2925,79 cm'' cho thiy su hap thu ciia nhdm C-H no. Tai tan sd 1731,35 cm'' cd mdt van phd cd the gan cho nhdm cacbonyl C=0 (cacboxylic).
Dai hap thu cd tan sd tir 1657.12 cm'' tuang ling vdi su hap thu cua nhdm C^O keo dai hen hgp vdi NH. Cac van phd quan sat thay d 1534, 35cm' tuong ling vdi nhdm amin bac hai. Sy hdp thu ciia nhdm CH3 ddi xiing dugc chi ra tai van phd 1374,46cm-'. Van phd quan sat thay d 1060,41cm-' cd the gan cho sy hap thu ciia nhdm C -O. Do dd, cd the ndi rang cac loai nhdm chiic tren cd kha nang tham gia hap phu pham nhudm [2,4].
3. KET QUA VA THAO LUAN 3.1. Ket qua khao sat d^c diem be mat cua (VLHP)
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Hinh 2: Anh SEM cm VLHP: g tru&c khi hdp phu metylen xanh; b, sau khi hap phu
metylen xanh
YAX qua chup anh SEM ciia VLHP truac
\ a sau hap phu dupc chi ra trong hinh 2 cho thay be mat VLHP truoc khi hap phu metylen xanh. co hinh dang ong.
xop. Sau khi hap phu be mat VLHP min, khong xop. Dieu nay chiing to metylen xanh da hap phu tren b^ mat VLHP.
Dien tich be mat rieng ciia VLHP da dupc xac dinh theo phuang phap BET la 0,3394 m^/g
3 J£. Khao sat anh huong pH
Hinh 3: Do thi dnh hu&ng cOa pH din qud trinh hdp phu MB ci'ui VLHP Til ket qua dupc chi ra a hinh 3 ta th5\- klii pH tang hieu suat hap phu \ a dung luang hap phu ddu tang. Trong khoang pH tir 2.51 - 5,83, khi tang pH dung luong hap phu ciia VLHP tang nhanh. trong khoang pH tir 5.83 - 8.61 dung luong hip
phu ciia VLHP lang cham \a. trong khoang pHtu 9.17^ 10.14 ca hieu su^th^jAura dung lupng hap phu d ^ gjam. Dieu nay CO the giai thich nhu sau: khi gia tri pH <
pEl^zc bl inat VLHP tich dien duong do co sir hap phu ion H*^. E)6ng thai nhom amin (NH) CO trong VLHP nhan H* va mang dien tich duong theo jAuong Irinh sau:
R R I + I . TW-NH+H =T1^'-NH2*
Vi vay, xuit hien luc day giiia thuic nhugm cation \a hk mat chit hap phu.
Ngoai ra, d pH thap ban ndng do cila H~
ldn xay ra su hap phu canh tranh vdi cac thudc nhudm cation tich dien duong tai cac tnmg tam hap phu. Do dd, d gia tri pH thap, hieu xuat hap phu la rit thip. 0 gia tri pH > pHpjc bl mat VLHP tich dien am do hap phu OFT, mat khac cac nhdm cacboxylic (-COOH) cd trong VLHP tham gia phan irng theo phuong trinh sau:
TW - COOH -> TWCOO~ + H*
TW-COOH+OH- -^TWCOO- +H,0 Trong dd: TW la
VLHP
Xuit hien lyc hiit tinh dien giila VLHP mang dien tich am va diudc nhugm mang dien tich duong Nen tai cac gia tri pH ldn, hieu xuit hip phu ldn. Do vay, chiing tdi lya chgn pH hap phu tdt nhit dli vdi dung dich MB la khoang pH =8. Gia tri nay dugc su dung cho cac thi nghiem tiep theo.
3.3. Khao sat anh hirdng ciia nhiet do Ket qua dugc chi ra d hinh 4.
30
\. /
Hinh 4: Dd thi biiu dien suphit thugc cOa hieu sudr hdp phu MB vdo nhiir do Ta thay khi tang nhiet do thi hieu suit hap phu giam. Dieu nay cd thi giai thich nhu sau: Do hip phu la qua trinh tda nliiSt cho nen khi tang nhi^t do, can bing hap phu chuyen dich theo chilu nghich tlic lam tang ndng do chat bi hip phu trong dung dich va din din lam giam hieu suat va dung lugng hap phu cua qua trinh hap phu.
3.4. Khao sat dung lupng hap phu Ket qua khao sat can bang hap phu theo md hinh ding nhiet hap phu Langmuir cua VLHP dugc the hien trong hmh 9 cho thay md hinh dang nhiet hap phu Langmuir md ta kha tit sy hip phu ciia VLHP ddi vdi MB va xac dinh dugc dung lugng hip phu cyc dai qm»i=
178,57 mg/g va hing so b = 0,096
ZZ^
7^
Hinh 5: Su phu thugc cita Ccb /q vdo Cd doi vai su hdp phu MB 3.5. Nghien ciru giai hap phu
Hinh 6: Do rhi rhe hien qud trinh gidi hdp phu MB cua VLHP Nghien ciiu giai hap cho thay khi giam pH hieu suat hap phu giam. Ndng do can bang cila metylen xanh d pH bing 8,50 la 0,86 mg/l, Ndng do metylen xanh sau giai hip tang 0,86 - 22,86 mg/l khi lam giam pH tir 8,50 - 1,5. Dilu nay cd thi dugc giai thich nhu sau: (3 pH thap, cac proton nhieu, xay ra sy hap phy canh tranh cac cation MB+ nen day cac cation MB+ ra khdi bl mat VLHP.
4. KET LUAN
1. Da che tao thanh cdng vat lieu hip phy tir ba che.
2. Da xac dinh dugc dac diem be mat, mdt sd nhdm chuc cua VLHP qua anh hiln vi dien tu quet va phd hdng ngoai.
3. Khao sat dugc mdt sd ylu td anh hudng din kha nang hap phu metylen xanh ciia VLHP theo phuong phap hip phu tinh cho ket qua:
+ pH hap phu tdt nhit ddi vdi metylen xanh la 8.
+ Klii tang nhiet dd tir 25°C - 55''C thi hieu suat hip phy metylen xanh giam.
4. Qua trinh hap phy metylen xanh dugc thyc hien bdi co che trao ddi ion.
5. Qua trinh hap phy ciia metylen xanh tren VLHP tuan theo phuang trinh ding nhiet hap phu Langmuir va xac dinh
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dugc dung lugng hap phu cyc dai ddi vdi metylen xanh q„a.\= 178,57 mg/g, hing sdb= 0,096.
Nhu vay viec su dung VLHP ba che de hip phu MB cho kit qua tit. Cac ket qua thu dugc se la ca sd cho dinh hudng nghien ciru nhim irng dung VLHP trong viec xir ly ngudn nudc bi d nhiem.
TAI LIEU THAM KHAO 1. K.G. Bhattacharyya, A. Sharma,
"Kinetics and thermodynamics of methylene blue adsorption on Neem (Azadirachta indica) leaf powder"". Dyes Pigments, 65, pp 51-59 (2005).
2. Md. Tamez Uddin, Md. Akhtarul Islam, Shaheen Mahmud, Md.
Rukanuzzaman, "Adsorptive removal of methylene blue by tea waste" Journal of Hazardous Materials, 164, pp 53-60 (2009).
3. N. Dizadji; N. Abootalebi Anaraki,
"Adsorption of chromium and copper in aqueous solutions using tea residue" Int.
J. Environ. Sci. Tech., 8 (3), pp 631-638 (2011).
4. P. Panneerselvam, Norhashimah Morad, Kah Aik Tan, 'Magnetic nanoparticle (Fe304) impregnated onto tea waste for the removal of nickel(n) from aqueous solution", Joumal of
Hazardous Materials 186, pp 160-168 (2011).
5]. R N. Nasuha, B.H. Hameed, Azam T.
Mohd Din, "Rejected tea as a potential low-cost adsorbent for the removal of methylene blue". Jounuil of Hazardous Materials, 175, pp 126-132 (2010).
6. S. Senthilkumaar, P.R. Varadarajan, K. Porkodi, CV. Subbhuraam,
"Adsorptionof methylene blue onto jute fiber carbon: kinetics and equilibrium studies", J.Colloid Interf Sci. 284, pp 78-82 (2005).
7. T Celal Durana, Duygu Ozdesa, Ali Gundogdub, Mustafa Imamogluc, Hasan Basri Senturk, "Tea-industry waste activated carbon, as a novel adsorbent, for separation, preconcentration and speciation of chromium" Analytica ChimicaActa 688, pp 75-83 (2011).
8. V. Vadivelan, K.V. Kumar,
"Equilibrium, kinetics, mechanism, and process designfor the sorption of methylene blue onto rice hush", J.
Colloid Interf. Sci. 286, pp 90-100 (2005).
9. Xiaopmg Yang, XiaonmgCui,
"Adsorption characteristics of Pb (II) on alkali treated tea residue" Water Resourcesand Industry, 3, pp 1-10 (2013).
