IV. KHAO SAT,THIET L~P QUI TRiNH TACH VA XAC DINH THUYNGAN:
1.Khao sat nguyen t8 can:
Qua trinh do 75As (eo dinh nang lU<;Jng la 559 KeV) tren h~ ph6 k@ gamma bi ean tr6 b6i 122Sb (eo dinh nang IU<;Jng la 563 KeV), 82Br (eo dinh nang IU<;Jng la 554 KeV); 24Na (eo dinh nang IU<;Jng la 511 KeV). Viv~yphai ti@n hanh Xlily hoa d~ lo~i bo eae nguyen t6 can tr6 tren. ChUng tOi ti@n hanh taeh arsenb~ngcaeh k@t tua d6ng thdi FeAs04vdi Fe(OH)3 trong moi trlldng bazo dU<;Jet~o b6i NH40H. Nhung ehi lo~i bo dU<;Je Na+ va B(. Con Sb5+eoth~ t~ok@t tua FeSb04nhu arsen. D~khao anh hu6ng eua Sb5+ehung toi ti@n hanh xlily hoa sau khi ehi@ux~.
Chuftn bi 7 e6e eo dung tich 250ml dU<;Je danh s6 thtl hj, Iftn IU<;Jt eho vao m6i e6e 100ml nude cftt hai Iftn, 5illdung dieh ehuftn Img/ml AsH. Lfty eaethitieh khae nhau eua dung dieh Img/ml Sb5+; dung dieh Img/ml Na+ va dung dieh Img/ml B( . Ti@n hanh qui trinh phan tieh trong diiuki~nnhu da neu 6 phftn phuong phap nghien etIu ta dU<;Je k@t qua nhu sau :
*Bang V.l:Kit quakhGo sat slj anh hllong cLlaSb5+, Na+, Br- din qua trinh tach As3+
s6III dung djch s6III dung djch s6III dung djch Di~ntich dinh STT
Im~/mlSbs+ Im~/mlNa+ Im~/ml Br- (xun~)
I 0 0 0 1734 - - - --- --- ---'----11---"-'-=---'--- 2 10 10 10 1722 - - - ---_._---_.__.__._---..-.-,--".-" " " - _.._._.__.._._._----_..__.. 3 --- -20 -- -- ---1----"--'-'-'----20 20 1586 4 30 40 40 1648 --- --- --- --- --- ---- - - ' - 5 40 60 60 1497 ------ 6 60 100 100 1515 1 - - - --- --- --- - - - - 7 80 200 200 1542
Nh4n xel :B~ng cach t'!-o k~t tua d6ng thdi FeAs04 vdi Fe(OH)3 trong m6i tntdng NH40H, sau do dung h~ khV KIIHCI d~c va (N2HS)HS04, chi~t b~ng CCI4 chung t6inh~n th~y r~ngcac nguyen td trenh~unhu kh6ng anh hUdngd~n qua trinh xac dinh arsen
2. Xac djnhhi~usufi! tach:
L~y 5m~u gi~ylQc nho <1>=lcm. Tftm vao m6i m~u gi~y Sill dung dich As co n6ng di) Img/ml, vai giQt dung dich FeCI3 Img/ml, vai giQt NH40H .D~kh6, dong goi b~ngtuiPE.Demchi~u x'!- trongdi~u ki~nda neuph~n phuong phap nghien cUu. Do va ghidi~ntich dinh d€ xV Iy (So).
Cho 5m~utren vao 5 cdc danh sd thu tlj tuong ung. Ti~n hanh qui trinh phan tich arsen nhu da neu trongph~nphuong phap nghien cuu. Do va ghidi~n tich dinh d€ xV Iy(Sl)'
(T~td m~udUQcchi~u x'!-va dophd. L~y di~n tich dinh tl).i 559 KeV d€ xac dinh ham IUQng A s . ) ' -
*Bang V.2:Kit qua tfnh hi¢u sudt'tach arsen
STT Sn(xun~) S,(xun~) Hieu suftt(%)
e--J ~9_3_4 '-'1'-7-'.-33'-- ~ 85,2 _ __~ 12~~______ _ _ !§§L +__ 85,7 _ _ _ _3 }_~~() _ _ 17_3~ 1---'-87'-",2=--- 4 2071 1765 85,2 1--- --- ----...,1---'-'--'--- 5 1883 1574 83,4
Nh4n xel : Tu k~t qua th\fCnghi~m chung t6i nh~n thfty r~ng hi~u suftt tach arsen dl).thi~u suM kha cao (trung binh 85,3%).K~tqua nay phu hQp vdi mi)t sd c6ng trinh da c6ng bd tnfdc day (khoang 85- 90%).[28]
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