HOA CHE BIEN DAU KHI ~4 KY THUAT TONG TRO OIEN HOA LTNG DUNG TRONG D A N H GlA KHA NANG BAO VE CHONG AN MON CUA CAC LOP PHU HUU CO PGS TS Nguyen Thi Le Hien Viin Dau khi Viit Nam Tdm t i t Sdn phu hij[.]
HOA - CHE BIEN DAU KHI ~4 KY THUAT TONG TRO OIEN HOA LTNG DUNG TRONG D A N H GlA KHA NANG B A O VE CHONG AN MON CUA CAC LOP PHU HUU CO PGS.TS Nguyen Thi Le Hien Viin Dau Viit Nam Tdm t i t Sdn phu hijfu cd Id mdt cdc phUdng phdp hdu hiiu de bdo vi chdng dn mdn, nhdt Id cde cdng trinh d trUdng bien nhU: gidn khoan, cdu cdng, tdu thuyin vd dUdng dng van chuyen xdng ddu Viic ddnh gid nhan chinh xdc chdt lUdng cua cdc Idp phu Id vdn di rdt quan trpng cho phep Ida chpn hi phu phu hap cho cdng trin logi dcde mdi trUdng Idm viic khdc Trong do, tdng trd dien hda Id phuang pbdp bdu hiiu deddnh gid qud t dn mdn kim logi, hiiu qud cdc chdt Uc ehi chdng dn mon cdng nhukhd ndng bdo vi kim logi eda cdc ldp phu dd [2] vd cdch diin [3,47 Bdi bdo gidi thiiu nguyin tdc Idm viic eua phuang phdp tdng trd dien hda vd dp dung tro ddnh gid khd ndng bdo vi chdng dn mdn cua Idp sdn phu hOtued trin bi mat kim logi Tdng trd dien hoa Tdng trd didn hda l i phUOng phip nghien eUu khdng phi huy mau, dupe sd dung de nghidn cdu ddng hpc v i CO che eie qui trinh didn hda xiy trdn be mat phan chia pha giUa kim loai/dung dieh dien ly [1 ] Nhd phdp duqc tien hanh che dp ddng tUtan sd eao den tan sd thap cho phep phin tich cic qui trinh khac tham gia vio cq ehe phin Ung, die bidt eae hing sd thdi gian die trung eho cic qui trinh rat khie La phUOng phip nghidn cdu hidn dai eho phdp thu duqc nhieu thdng tin vdi ehinh xic eao, tdng trd didn hoa d i duqe sd dung de nghidn cUu vat lieu va eie qui trinh an mon dien hda tai nhieu nUde trdn the gidi Tuy nhien, cic phan tich qua trinh xiy trdn be mat phan chia pha nham giai thieh ca chl phin Ung trdn co sd cic phd tdng trd thu duqc cdn rat han ehe 1.1 Tdng trd diin hda ddi vdi binb diin hda hi diin cUe Cic qui trinh didn hda thudng duqc tien hanh nghidn eUu binh didn hda he didn ciic, duqc nhung dung dieh chat dien ly (dung djch nghien eUu) (Hinh 1) Oidn cue lim vide duqc chl tao bang vat lieu can nghien eUu, didn ciic ddi la platinum hoic graphite v i didn cue so sanh l i didn cUc calomel bio hda KCI (Hg/Hg^CI^'KCI J Vl mat nguydn tie, thiet bi potentiostat cho phep ddng didn di qua didn cUc lim vide v i dien cUc ddi, thdng qua dung djch dien ly Oidn cue so sanh ed didn t h i tidu ehuan khdng ddi ddng vai trd nhu dien cue ehuan d l xae djnh didn t h i 52 l-SO 5^013 eua didn ciic lam vide Binh didn hda didn ciic ed t h i duqc the hidn bang so mach diln nhU Hinh 1.1.1 Diin trd dung dich Trdn thUe t l , thudng tdn tai ddng diln rat nhd I, qua didn cue RE va WE, dd didn t h i i p d i t (hoae duqc) nhd potentiostat (hoic von kl) E, khdng bing didn thi thuc E cua dien cue lim vide: E, = E -I- R3.I, Trong dd R3.I, die trUng eho sup the Cl Tren sodd mach diln Hinh 2, ta ed: l = l, + l, (R3 + R,).l, = Rj.lj • ^ l , = I.Rj/(R, + Rj-l-R3) -*E = E + \.H^.R^/{R^ + R^-^R^} R^ = Rj R3/(R, -I- Rj -I- R3) duqe gpi l i diln trd dung djch "=> E, = E -I- R^.l vdi R^.l duqc gpi l i sut t h i Ohm Gia tn diln trd dung djch R^ dupe xic dinh nhd tdng trd dien hda 1.1.2 Diin dung Idp kip Ddng didn chay binh diln hda gdm phin: Ddng didn Faraday (I,) duqe tao bdi phin Ung di^n hda cd t h i dien d diln cue lim vi|c PETROVIETNAM Potentiostat WE RE •y WE Hinh I.Hi diin hda Ddng di^n dung (1^ l i ddng didn tich lidn quan den su tdn tai cda didn dung Idp didn tieh kdp C^ (cd gii tri tU 10 - lOOnF/cm') v i gii tri cda didn dung C^ phu thudc vio didn t h i i p d^t, bin chit diln eUc lim vide v i ndng dd cic chit ho^t ddng trdn b l mat diln cue Ddng diln dung 1^ = dq/dt = C^ dE/dt, vdi q l i didn tich cda tg dl|n '2 C£ Hinh Sa dS mgch diin cua hi diin hda Tacd:E|=E + R^.I, •^E=E,-R^J Thay E vio phuong trinh trdn ta ed: Al = (AE,-R^.Al)[(1/Z,) + icoC,] 1=(AE/Al-R^)[(1/Z,) + i(oCJ - • Z = AE/Al = R^ + /[(I /Z,) + i(o C J 1.1.3 Xdc djnh tdng trd diin hda (Z) vd tong trd Faraday (Z) Tdng trd diln hda Z = AE/Al Tdng trd Faraday Z,phu thudc vio eie dai luqng lidn quan din qui trinh di|n hda Khi biit ddng Faraday I, v i dl|n t h i thi/e E eua diln eUc lim vile, ta cd: Z, = AE/Al, Phin tich tdng trd niy dUdi dang mach didn tuong duong eho thiy tdng trd Faraday I, duqc ndi song song vdi didn dung Idp kdp C^ v i toin bd duqc mie ndi tilp vdi didn trd dung dich R^ (Hinh 3) Cd Re Ddng dl|n tdng I chay qua binh didn hda gdm: I, v i 1^ l = l, + C,dE/dt Tuyin tinh hda phuong trinh niy v i vin dung biln ddi Laplace, ta ed: Al = Al,+ i(oC,AE Al = AE/Z, +1(0 C, AE = AE [(1/Z,) +1(0 CJ OI|n t h i E phuong trinh trin dai dl|n cho di|n t h i thuc cua dl|n ci/c, dd phdp dua g i i trj diln t h i E^ dl|n t h i i p d i t d di|n ci/c Hinh Sadd mgch diin tuang duang cOa binh diin hda hi di Oidn trd dung djch R^ duqc xic djnh trin giin 66 tdng trd d t i n sd cao Z, khdng phu thudc vio R, v l C^ m i chl liln quan din qui trinh dl^n hda nhit Vdl mdt co c h l cho trudc, Z, cd t h i duqc thllt lip nhd phuong trinh ddng hqc bilu diln v i phin tich cic bilu diln niy thinh mdt mach dl|n tuong duong die trung cho Z^Td dd, cd t h i suy phuong trinh tdng trd di|n hda Z v l mach diln tuong duong, Bi«ai-80 5/2013 53 I HOA - C H i BIEN D A U KHI Nhin chung cie tinh toin niy 6ugc thiie hidn vdi gia thilt v l CO c h l phin Ung Cie tinh toin tdng trd eho mdt co chl nio dd cho phep vd cie phd tdng trd ly thuyet m i eac phd niy duqe so sanh vdi phd thUe nghidm v i dinh gii duqc tinh ehinh xie cua gii thilt 1.2 Nguyin tdc tong trd dien hda Chon mdt trang thai tinh (E^ IJ trdn dudng eong phin cue d l nghien cUu Xung quanh the E^ i p dit mdt didn t h i xoay chilu hinh sin ed bidn dp AE v i tan sd gdc (0 = 27rf len didn ciic lim vide (E