Báo cáo " Nghiên cứu khả năng tạo phức của ortho-este tetra azophenylcalix[4]aren (TEAC) với Th(IV) "

Tgp chi Hoa hgc, T. 47 (6), Tr. 739 - 744, 2009 NGHIEN CQU KHA NANG TAO PHLfC CUA TETRA (TEAC) V6l TH(IV) Den Tda soan 3-3-2009 TRAN QUANG HIEU', LE V A N T A N ' , NGUYEN NGQC TUAN' 'Bg mon Hoa - Khoa Dai hgc Cong nghe Sdi Gdn ^Trudng Dai hgc Cong Nghiep Tp. Ho Chi Minh 'Wien Nghien cifu Hgt nhdn Dd Lat A simple, sensitive and selective method was developed for the of Thorium based on between Tetra azophenyl (TEAC) and Th(lV). In acid media, TEAC formed a 1:1 complex with Th(IV). Beer's law was obeyed in the range 2.5x10'- mol.l' of Th(N). The limited of detection was l.OxW" moi i'. This result could be applied for of Thorium in various samples, soil and waste samples. Thorium. I - GlOl THIEU Trong nhiing nam gan day, ITnh vuc hoa hgc sieu phan tir phat trien rat nhanh chdng va cd nhilu ling dung quan trgng trong phan tfch [1, 2]. Mot trong nhirng hudng nghien ciiu dugc cac nha hoa hgc quan tam la tao ra cac hgp chat chiia cac nhdm mang miu dua tren chit gdc Tir day, da cd nhilu cdng trinh nghien cihi dugc cdng bd vl phiic cua cac din xuat vdi cac ion kim loai nhu Ca'* [3] Ni-"[4], Cr'15, 6], Ba'* [7] hoac chilt cac ion kim loai bing din xuit [8 - 11]. Tuy nhien, phirc chit ciia din xuit vdi cac ion ciia nguyen to nhdm dit hiem ft dugc nghien ciiu. TTiori la nguyen td phdng xa tu nhien, sd thir tu 90 trong bang tuin hoan, cd nhilu irng dung trong linh vuc hat nhan. Ham lugng Tliori trong cac miu phan tfch dugc xac dinh bing nhilu phuang phap khac nhau nhu tao phiic miu vdi thudc thir Asenazo (III) [13, 16], hoac vdi thud'c thir [19]! I. Hien nay, phucmg phap phan tfch thudng dugc sir dung la phan tfch kfch boat natron (NAA) [14, 15], khd'i phd- cao tan cam iing plasma (ICP-MS) [17, 18] hoac quang phd phat xa-cao tin cam iing plasma [20]. Trong bai bao nay, chiing tdi gidi thieu kha nang tao phirc chgn lgc ciia thud'c thir tetra (TEAC) vdi ion Th(IV) va kha nang irng dung trong phan tfch. 11 - THUC NGHIEM 1. Hoa chait Cac hoa chat sir dung trong thf nghiem diu dam bao do tinh khilt phan tfch. - Axit nitric HNO3 ndng do 65%; metanol (MeOH), axeton nitri! (MeCNj, (PA) Merck. 739 (RA) dugc cung cip bdi ca quan nang luang nguyen tir qud'c t l (IAEA); P^NO,) . (RA); Cr(N03)3; CH3COOH; NaOH rin; NaNOj rin; axit picric; bromua (RA) Merck. 2. Thiet bj - May quang phd UV-VIS hai chiim tia Lambda 25 ciia hang Perkin Elmer (My). - Miy phd cdng hudng tir 'H-NMR DPX 400 va phd 'C-NMR Bruker FT-NMR 600 Mz (Diic); Phd FT-IR dugc do tren may FT-IR 1000 ciia hang Perkin Elmer (My). - May cit nudc 2 lin ciia hang Hamilton (Anh); Can phan tfch Afcoset, do nhay 10"̂ gam (An Do), may do pH Thermo Orion- 290 (My). - Cae dung cu thiiy tinh: pipet eac loai tir 1 - 25 ml, dng dong, binh dinh mdc, binh tam giac, cd'c, pheu chilt cic loai, pheu lgc, chen platin, loai 1 - 25 |il, 50 )al, 100 |rl, 500 î l, 1000 p.\, cac binh, Ig (PE) dung miu.. . dugc mua tir hang Merck. 3. Pha dung dich chuan Thud'c thir 5,1 hay ggi theo ten thudng la tetra (TEAC) (xem hinh 1) dugc tdng hgp bing each cho tac dung vdi khi cd mat ciia d nhiet do thap. San phim dugc tinh chi de dat do tinh khilt phan tfch; thanh phin va ca'u true duac xac dinh bing cac phuang phap FT-lRil2] . EtO,C' 'CO,Et I I r OH OH OH HO Thudc thir TEAC - Dung dich chudn TEAC: Can chfnh xac 0,1126 gam thudc thir TEAC rdi cho cd'c 50 ml, them tir tir dung dich hdn hgp gdm MeOH:H20 740 (7:3 vl the tfch) khuay diu. Sau dd chuyin vao binh dinh miic 100 ml, dinh miic tdi vach thu dugc dung dich thudc thir cd ndng do 10' M. - Dung dich chudn Th(IVj: Can chfnh xac 0,5602 g tinh khiet cho vao cd'c thiiy tinh 100 ml. Sau dd them nudc cit hai lin rdi hoa tan. Chuyen dinh lugng vao binh dinh mirc 1000 ml rdi them nudc cit hai lin din vach ta dugc dung dich chuan Th(IV) 10"̂ M. Cac dung dich cd ndng do loang han dugc pha tir dung dich gd'c niy. - Cic dung dich dem cd pH = 3 - 6 dugc pha tir dung dich CH3COOH 0,1 M va NaOH 0,1 M. - Cac dung djch UO2'*; Eu'*; La'*; Pb"*, Or'*, Ni-*, Fe'*, Sm'*... dugc pha tir mudi nitrat tucmg ling. Ill - KET QUA v A THAO LUAN 1. Pho hap thu - Dung dich thudc thif: Diing cho 200 )il thud'c thir TEAC vao binh dinh mii:c 10 ml, sau dd them 2 ml dung dich dem axetat, them dung dich hdn hgp (7:3 vl the tfch) tdi vach, thu dugc dung dich thud'c thir ndng do 2.10"^M, khao sat phd hap thu ciia dung dich nay, dung dich so sinh la nudc cit. - Dung dich nghien cifu: Cho 200 \x\ thudc thir TEAC lO 'M vao binh dinh miic 10 ml, sau dd them 2 ml dung dich dem axetat cd pH = 4,5, d ip tuc cho them 200 |il dung djch Th(IV) 10' M, dinh miic bing dung dich hdn hcfp (7:3) tdi vach, khi dd ndng dd ciia TEAC va th(IV) la 2.10-'M. Dung dich chuyin din tir miu vang sang mau hdng. Sau khi miu dn dinh, chiing tdi tien hanh do phd hip thu, dung dich so sinh la nudc cat. Trong mdi trudng axit, phd hip thu ciia thud'c thir TEAC dat gia tri cue dai tai budc sdng 385 nm. Gia tri nay phii hgp vdi budc nhiy ciia electron n -^n vi cua electron n -^n ciia nhdm -N=N-. Kit qua nay cung rit phii hgp vdi cac cdng trinh lien quan da dugc cdng bd trudc day [ 3 - 6 ] . Phd ha'p thu ciia he xuat hien 2 pic tai cic budc sdng 376 nm va 520 nm (dudng b). Do ddi pic hip thu cue dai ciia he so vdi thud'c thir TEAC d dang tu do len de'n 135 nm, la mdt tin hieu td't d l tiln hanh nghien ciiu cac dilu kien ldi uu. Vi vay, d cac thi nghiem sau chung tdi do dd hap thu quang tai budc sdng 520 nm. 5 0 0 7 0 0 W a v e l e ng h t (n m ) Hinh 2: Phd cua thudc thir TEAC va he tai pH = 4,5 (a) Phd ciia TEAC 2.10 ' M vai phong so sanh la nudc cat; (b)Ph6 cua phiic 2.10-M tai pH = 4,5 vdi phong .so sanh la nuoc cat 2. Anh hudng cua pH va dung mdi tdi phd haip thu ciia he Chiing tdi khao sat anh hudng ciia pH den phd hip thu eiia he Gii tri pH anh hudng rat nhilu den qua trinh tao phiirc ciia ion kim loai. Trong mdi trudng kiim cac ion nguyen td dit hilm va phdng xa thudng uu tien cho qua trinh tao phiic hydroxo hoac tao kit tiia khi ndng do cac ion dii ldn. Vi vay, chiing toi chgn mdi trudng axit de nghien ciru. Chuan bi cac dung dich nghien ciiu tucmg tu nhu tren va dieu chinh pH ciia he thay ddi tir 2,5 - 6 bing each sir dung dung dich dem natri axetat, cac gia tri pH diu dugc kiem tra lai bang may do pH. Do do hip thu quang eiia he tai budc sdng 520 nm, dung dich so sanh la nudc cit. Kit qua dugc biiu thi tren hinh 3. Mat do quang ciia he gia tri cue dai trong khoing pH = 4 - 5. Vi vay, chiing toi ebon khoang gia tri pH niy de tiln hanh cac nghien ciru tilp theo. pH Hinh 3: Su phu thudc ciia mat do quang vao pH 741 toi da tien hinh khao sat phd ha'p thu ciia he trong nhilu loai dung mdi khac nhau nhu axeton nitril, tetra hydro furan, hoac cac dung mdi niy vdi nudc. Ke't qua cho thay trong dung mdi hdn hgp MeOH -i- H2O vdi ti le 7:3 vl the tfch thi do hap thu quang ciia he tai budc sdng 520 nm dat gia tri cue dai. Vi vay, chiing tdi chgn he dung mdi niy de tien hanh cic nghien cuu sau. 4. Anh hudng cua ndng do Th(IV) De khao sat inh hudng ciia ndng do ion Th(IV) de'n phd hap thu ciia he chiing tdi chuan bi cac dung dich tuong tu nhu tren nhung giir nguyen ndng do thudc thir TEAC la 2.10"^ M tai pH - 4,5, cdn ndng do ion Th(IV) tang tu 0,25.10-5 M- 15 I Q - ' M . Chiing tdi tien hanh do do hap thu quang eiia he, dung dich so sanh l i nude cit. Kit qui dugc trinh biy trin hinh 4. Nhin vao dd thi ta thiy khi tang din ndng do ion Th(IV) thi mat do quang tai pic tai 520 nm tang din. Tren ca sd dd, chiing tdi da xay dung dd thi biiu thi khoing tuye'n tfnh cua ndng do Th(IV) vi do hip thu quang (A) tai budc sdng 520 nm, bang tfnh toan thdng ke, dudng bieu dien ed phuang trinh: A = 0,248x C(10-' mol/1) -^0,020 (R^ = 0,990, n = 7). Hinh 4: Phd hap thu ciia he TEAC- Th(IV) khi thay ddi ndng do ion 'M Tir ( a ) ^ (n) : 0; 0,25; 0,5; 0,75; 1; 1,5; 2,0; 2,5; 5,0; 7,5; 10; 12,5; 15 4. Anh hudng cua thdi gian De khao sat do bin mau ciia he theo thdi gian, chiing tdi tao dung dich nghien ciiu tuang tu nhu tren va do do hip thu quang ciia he tai budc sdng 520 nm, dung dich so sanh la nude cit trong khoing thdi gian tir 5 - 80 phiit. Chiing tdi nhan thiy mau ciia he chuyen tir vang sang hdng dam sau thdi gian khoang 1 phiit va dn dinh trong khoang thdi gian 5-90 phiit sau khi cho them ion kim loai vao dung dich thud'c thir. 5. Khao sat thanh phan ciia he De khio sat thanh phan ciia he, chiing tdi sir dung phuang phap day ddng phan tir gam: Chuin bi 9 dung dich nghien ciru vdi cac dilu kien tdi uu nhu tren, sao cho ndng do TEAC giam din tir lO'^M - 10'* M cdn ndng dd ion Th(IV) tang din tir l O ' M - lO'^M, nghla la tdng ndng do ludn bing 2.10-'M. Gia tri pH ciia he dugc cd dinh l i 4,5. Sau khi he dn dinh, do do hip thu quang ciia cac dung dich, diing nudc cat lam dung dich so sanh tai budc sdng 520 nm. Kit qua dugc trinh bay tren hinh 5. Tir kit qua niy cho thiy khi =1:1 thi do ha'p thu quang dat gia tri cue dai, tucmg ung vdi ke't luan la phirc cd thanh phan 1:1. 6. Anh hudng ciia su cd mat cac ion kim loai khac Chiing tdi tiln hanh khio sit anh hudng cua mdt sd ion kim loai khic de'n kha nang tao phirc ciia TEAC vdi ion Th(IV). Dung dich cac ion 742 dugc pha che tir dung dich mudi nitrat tuang ling. Sau dd tao dung dich nghien ciiu tai pH = 4,5 tucmg tu tren sao cho ndng do eiia TEAC va ion kim loai M"* la 2 .10 'M. De dn dinh rdi do phd hip thu cua timg he. Kit qui dugc trinh bay d hinh 6. Tir phd nay cho thiy d dilu kien tao phiic ciia Th(IV), cac ion nhu UO2-*, Eu'*i La'*, Sm'*... hiu nhu khdng tao phiic vdi thud'c thir. 0 3D - , | o 2 5 - s < 0.20 - 0.15 - 0 1 0 - 0 05 - 0 . 0 . 0 2 - 0 i 0 6 H 0 8 - 1 .0 Hinh 5: Thanh phin ciia he theo phucmg phap he ddng phan tir gam vdi [TEAC] -H Th(IV) = 2.10 'M 0.8 - , 0 1 0.4 - 0.2 - 0.0 - 1 1 3 0 0 4 0 0 ^ T E A C - T h ( I V ) / \ ^ T E A C - U O j * " (^ / V ^ ^ ^ ^ ^ TEAC-Eu*' ^ ^ , / ^ ^ ^ ' ^ \ ^ ^ ^ T E A C - L a ' ' ^ ^ 5 ^ ^ < ^ ^ ^ ^ ' \ ^^^^^^ T E A C - S m ' ' \ ^ ^ ^ ^ ; ^ ^ \ , ^ V \ ^ ^ ' ^ ^ ^ E A C 500 6 0 0 7 0 0 W a v e l e n g h t ( n m ) Hinh 6: Anh hudng cua cac ion kim loai din phii:c TfAC-Th* Kha ndng tach chiet La'y 5 binh djnh miic 25 ml, lin lugt cho vao mdi binh 125 p\ dung dich chuin TEAC 10'M, them 5 ml dung djch dem axetat cd pH = 4,5. Sau dd them 125 \x\ dung dich Th(IV) 10 'M, dinh mirc bing dung mdi hdn hgp (7:3), ndng dd cua TEAC vi ion Th(IV) khi dd la E)e yen 5 phiit, chuyen dung dich vao phlu chiet 100 ml. Cho lin lugt vao mdi phlu chilt 5ml dung mdi /7-hexan, lae that ki trong 20 phiit. Kit qua cho tha'y dung mdi chilt khdng thay ddi. Khi dting mdt lugng du bromua phirc cung khdng bj chilt. Ngugc lai khi sir dung mdt lugng axit picric cho vio pheu chiet lic diu thi dung mdi chie't chuyen sang mau hdng va phd ha'p thu eiia he sau khi chiet ed hai pic cue dai tai budc sdng 375 nm va 520 nm. Kit qua niy kha phu hgp vdi cdng trinh ma Ashok Kumar da 743 cdng bd khi diing ion picrat dl chilt cdng hgp phiic chit -Rh'* [9]. IV- KET LUAN 1. Da tim dugc phdc chit mdi giira TEAC vi Th(IV) trong mdi trudng axit ylu, gidi han phat hiln la LIO'*" mol/1. Phd hap thu ciia phiic cd cue dai tai budc sdng 520 nm, thanh phin ciia phiic la 1:1. 2. 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