Tap chi Khoa hoc DHQGHN, Khoa hpc Tu nhien va Cong nghe, TJp 29, So 4 (2013) 16-23
Nghien ciiu ta g dung vat lieu Fe** nano de xu ly nitrat trong nude
Nguyen XuSn Huan\ Nguyen Nhu Quynh^
^Khoa Mdi tnrdng, Tneang Dai hoc Khoa hoc Txr nhien. DHQGHN, 334 Nguyen Trai, Thanh Xuan, Ha Npi, Viet Nam^
^Trucfng Dai hoc Khoa hoc va Cong nghi Ha Noi, 18 Hoang Qude Viet, Cdu Gidy, Ha Noi, Viet Nam Nhan ngay 05 thtag 8 nam 2013
Chinh sua ngay 19 fliangS nim 2013; chap nhan dang ngay 20thang 12 nam 2013 Tom tat: l/ng dyng vat heu Fe“ nano (nZVI) trong xii IJ 6 nhilm moi tnrcmg la mot hiidng quan tSm mdi cua nhita nha khoa hoc tren the gioi. Bdo cao nay nghien cihi fog dyng v?t lieu Fe” nano duoc nhdm tac gia tir chd tao btag phuemg phap khii pha long boi NaBH^ de xii 6 nhi^m nitrat va nghita cfo cSc ylu t6 anh hufog ton hieu qua xii If nhu thai gian, pH nong d5 nitrat ban dJlu.
Dac tuih vat liSu duoc xdc dmh bSng phuong phap ph6 nhieu xa tia X. kmh hien vi dien tu truyin qua TEM, kinh hi6n vi dien ni qu6c (SEM) va phuong phap Brunauer Emmett Teller (BET). PhSn tich ndng d$ mtrat con lai sau khi xu li bing phuong phip so m&u quang di|n tat bucrc song X = 430nm. KSt qua phan tfch nhilu xa tia X cho thSy, v4t lieu Fe“ nano dugc che tgo la kha thuan nhat, dll c6 duy nhat hi|u fog cua Fe® (20 = 44,7). V^t li#u Fe® nano c6 dien tich b i m |t lieng la 60mVg. dufog kinh 10 - 18,6 nm. Hieu qua xu b' dat 98,9% nude 6 nhiem nitrat c6 n6ng do ban dSu la 30 mg N-NOs'/L trong 40 phdt tai pH 2 v^ ty 1| vat lieu hap phu Fe® nano la 1 g/L.
Tic khoa. Fe® nano, vSt lieu, xu IJi, nitrat, nude.
1. Mo’ dSu
Phu duOng la sir gia tang lugng nitrat va phot phat trong cac thtiy virc gSy ra su tang trudng ciia cic loai thuc vat bac thap (tao, vi tao...) va tao ra nhung bien d6ng Idn trong he sinh th ^ nude, Ifoi cho chat lugng nude bi suy gifoi va 6 nhilm [1]. Vi v |y , viec nghiSn cmi lam giam ham lugng nitrat trong nude nham xu ly phu duong, ngan chan sir phdt trien cua tao doc dang dugc cho la hudng nghien ciru mang y nghia thuc tien cao can dugc khuyin khich hien nay. De xir ly nitrat c6 nhieu phuemg phap khde
nhau da duoc dp dung nhu; phuemg phap trao ddi ion, Igc tham thfo ngugc, sinh hoc va phuemg phdp khir nitrat...[2]. Mot trong nhung hudng nghien ciiu mdi hien nay dang dugc rSt nhieu nha khoa hoc trong nude va.tren th i gidi quan tim dd la edng nghe su dung sat nano (Fe°
nano) de xii ly nitrat.
2. Nguyen lieu va p hu on g phap 2.1 Nguyen lieu
Tac gia li8n he DT. 84-983665756 E-mail' [email protected]
- FeS04.7H2O - Bohidrua (NaBlL)
N.X.Huan, N.N Quj/nh/TapcMKJioahgcDHQGHN, KJwahocTunhiinva Congnghe, Tap 29, So 4 (2013) 16-23 17
- Etanol 100 % - Polyacrylamid (PAA)
- C ic mau nu6c bi gay nhilm nitrat nhan t?io voi c&c nong dp tir 30 - 70 mg N-NOa'/L 2.2. PhiKTng phdp nghien cihi
2.2.1. Phucmg phdp dieu c h i vqt lifu Fe°
nano [3]
Vat li^u nZVI diroc dieu d ie bang phucmg phdp khii pha long thdng qua sir khii muoi FeS0*.7H20 bang natri borohydrat (NaBHj) khi c6 mat cua chat ph3n tin Polyacrylamid (PAA). Cu thd:
Budc 1: c a n 4g FeS04.7H20 h6a tan trong 50mL nude c it trong binh tarn giac 150 mL.
LSc hSn hpp tren may lie 20 phut vdi toe do 150 v6ng/phut dupe dungdich A.
Budc 2: c a n 0,1 g Polyacrylamid (PAA) h6a tan trong 1000 mL nude du<7c dung dich PAA c6 nong d§ 0,01%, de dung djeh nay qua dim.
Budc 3: Can 2g NaBHj hda tan trong ISmL nude cat trong binh tarn giac 100, sau dd thSm 2mL dung djeh ch& phin tdn PAA 0,01% da duoc chuan bj d budc 2 vd khuay tit trong 5 phut vdi toe do 300 v6ng/phiit, dupe dung djeh B.
Budc 4 ’ Nho tu tu dung djeh B vao binh chda dung djeh A tren may khuay cir vdi toe do nho giot khoang 5 mL/phut. K it tiia m lu den ciia Fe° nano dupe hinh thinh, su dung cac thanh nam ch§m d i tdeh Fe“ nano ra va rua sach 3-4 Ian bSng con. Sau do v |t lieu Fe° nano dupe dua v^o binh htit am phpi khd v^ bao quan d i su dpng cho ede thi nghiem xu 1^ nitrat.
2.2.2. Phucmg phdp kiim ira dde imh ciia vdt H4u B-nZVI
Sau khi lira chon dupe ede dieu kien tot nhat de dieu che v3t lieu Fe° nano, vat lieu tao
thanh dupe kiem tra dac tinh thong qua phucmg phap phan ti'ch nhilu xa tia X (XRD) tren may do nhieu xa tia X (D5005, Bruker, Due) chup anh tren kinh hien vi dien tu quyeeets (SEM, JSM-5410LV), kinh hien vi dien tu tniyen qua (TEM) va phan ti'ch dien tich b l mat riSng theo phuong phap Brunauer Emmett Teller (BET) tren may BET Micrometries Gemini VO.
2.2.3. Phucmg phdp b6 tri thi nghiem khao sat kha nang xii ly ciia FeO nano vdi nude bi gdy nhiem nitrat nhan tao
Vdi muc dich xdc dinh co' che xir 1;^ ciia Fe°
nano doi vdi mtrat, nghien cuu da b6 tri thi nghiem cho Fe® nano tdc dung true tiep vdi nitrat dupe gay nhilm nhdn tao trong nude cat (khdng bi tdc dong bdi cac yeu to kbdc). Sau dd Ian lupt thay doi then gian xii If, nong d6 nitrat ban ddu, pH ciia dung djeh vd phan ti'ch nong dp nitrat con lai sau xu IJ'.
- Khdo sat anh hu&ng cua th&i gian Hut 50mL dung dich nitrat c6 nong dp 50 mg N-NOa'/L vao 4 binh tarn giac cd dung tich 100 mL, dieu chinh v l pH 2. Cin chi'nh xdc 0,05g Fe® nano (tuong ung ty IS Fe° nano/ dung dich can xu ly la 1 g/L) cho Ian lupt vao 4 binh tarn giac trSn. Ldc tren may lac vdi tdc dp 250 vdng/phiit trong c^c khoang thdi gian khde nhau la: 10, 20, 40 va 60 phut. Ly tarn Vdi tdc dp 2.500 vdng/phiit de gpi lay phSn dung djeh.
Xdc djnh nong dp nitrat trong dung djeh sau phan ling bang phucmg phdp so mau quang dien tai budc song X = 430nm.
- Khdo sal anh hu&ng cua pH
Hut 50 mL dung dich nitrat cd ndng dd 50 mg N-NO3 /L vao 4 binh tam gidc cd dung ti'ch 100 mL. Dieu chinh gia tri pH cua cac dung dich trong binh tam giac ve 2, 4, 6 va 8 bang
18 N.X. Huan. N.N. Quynb /Tap dii Khoa hoc DHQGHN, Khoa Itpc Tie nhiin va Cong nghe, Tap 29, So 4 ilOll) 16-23
dung dich H2SO4vk NaOH tigu chuan O.OIN.
B6 sung vao m6i binh lam giac tren 0,05g Fe°
nano (tirong ijmg ty le Fe® nano/ dung djch can xii ly la 1 g/L). L ie tren mdy 15c voi t6c dp 250 v6ng/phut trong thoi gian 40 phiit. Ly tim voi l6c do 2.500 vong/phut de gan lay phan dung djch. Xac djnh nong dp nitrai trong dung djch sau phan ung.
- Khao sdT anh Huang cua nong do nitrai ban ddu
Hut lin lupt 50mL dung djch nitrat c6 cac nong dp 30, 40, 50, 60 v5 70 mg N-NOj’/L vao 5 binh tam gidc c6 dung tfch 100 mL. C5n chinh xac 0,05g Fe° nano (tuong ung ty le Fe®
nano/ dung djch can xu 1^ la 1 g/L) cho v5o cac binh tam giSc tren. l i e tren m iy 15c voi toe d^
250 vong/phut trong thoi gian 40 phdt. Ly tam voi tdc dp 2.500 vong/phut d i gan !5y phin dung djch. X5c dinh n6ng dp nitrat trong dung djch sau phan umg.
3. K it qua va thao lu^in
3.1. Mot s6 dge diem, tinh chdt cua vat lieu Fe°
nano
3.1.1. K it qua nghiin cuu pho nhieu xg tia X cua Fe° nano
Hinh 1. Pho nhieu xa tia X ciia Fe'’ nano Dira tren pho nhieu x? tia X, c6 the nhan
thay hieu ung dac tnm g ciia Fe® nano xu5t hien VOI cuong dp Ion va kh6ng xuat hipn c5c pic phu khac, dieu n5y cho thay vat lieu Fe® nano dupe che tao la kha thuan khiet va khong bi oxi hoa trong khdng khf 6 nhiet dp ph6ng thanh
Fe'* hoac Fe®* K8t qua nghien cuu nay da khac phuc dupe nhung kh6 kh5n trong vife bao quan Fe® nano trong moi truong chin kh6ng hoac trong khl nito ciia cac t5c gia kh5c [4-6].
3.1.2. K it qua chiip dnh SEM, TEM vat lieu r e nanor- 0
N.X HuSn, N.N. Quynh /Tap chi Khoa hoc DHQGHN, KJmhpcTienhii)i va C6ng nghi, Tap 19, SSi (2013) 16-23 19
Hinh 2. Anh SEM v^t li^u Fe“ nano. Hinh 3. Anh TEM vat lipu Fe“ nano
Qua anh TEM cua v$t lieu thu du^c cho thay: Wch thucfc hat trong khoMg tir 10 - 18,6 nm (mmg binh 16,7 nm), cac hat c6 s\r phan biet ro rin g va khong c6 sir ket dam lai voi nhau lim cho dien tich be mat cang loti. Cac tinh the sit c6 Mnh cau va noi vdi nhau thanh chudi, tao thanh mang luoi. Kieu lien ket thanh chudi nay la do su tuong tic gi&a cac kim loai CO tir d'nh vdi nhau. So vcd ki'ch thudc cac hat sit nano thu dirge tCr nghien oru cua Zhang (nam 2006) [4] la 10 - 100 nm; cua Yang-hsin Shih, Chung-yu Hsu, Yuh-fan Su (nim 2011) la 50- 80 nm [5] thl kich thirdc hat nano thu dirge la khd nhd.
3.1.3. K it qua xdc dinh dien rich be mat Dien ti'ch be mat cd anh Inrdng rat Idn tdi hieu qua xCr ly, dien n'ch be mat cin g Ion kha nang tiep xuc cang cao do v^Ly hieu qua xir ly cing cao. Ket qua do di?n tich be m il cua vat
lieu Fe“ nano theo phirong phap Brunauer Emmett Teillor (BET) l i 60 mVg. So vdi phueng phap che tao sat nano cua Sun v i nnk (2006) thi dien tich be mat la 12,82 mVg [4] v i theo phuotig phap dieu che cua Hwang v i nnk ia 46,27 m’/g [5] thi phuotig phip dieu chd niy cho ket qua dien tich bd m it cua hat Fe° nano cao hot! tir 1,3 ddn 4,7 Ian.
3.2. Ket qua khdo sat khd ndng xie I'} cua Fe°
nano v&i nu&c bi gay nhiim nitrat nhdn tao 3.2.1. Anh hudng cua thai gian den hieu qudxicly
Vdi ndng do nitrat trude xu ly 50 mg N- NOj'/L, ndng do fuong ung ciia pha rin/pha long (Fe® nano/duDg dich cin xu ly) = 1 g/L thi ket qua phin ti'ch v i hieu qua xir ly nitrat sau cac khoang ihdi gian 10, 20,40 va 60 phut dugc the hien d Hinh 4.
20 N X. Huan, N.N. Qui/nh /Tap chi Khoa hoc DHQCHK Khoa hoc Tic nhiin va Cong nghi, T ^ 29, So 4 (2013) 16-23
■ Nongdonstrat con lai (maN'l)
—Hicii suafxitly mtral QC\TJ08:20»8 BTNArr
Hinb 4. Nong dp niirat sau xvr va hi^u suSt xir nitrat bdi Fe® nano theo then gian.
Ket qua nghiSn curu o Hinh 4 cho thay, hieu suat xij ly nitrat bdi Fe® nano tang d in theo thdi gian va tang nhanh nhit a 10 phut dlu tign, hieu suat dat 71,36% va nong dp nitrat con lai la 14,32 mg N-NO3 /L. Sau 20 phiit hieu suat xii la 78,76%, sau 40 phut hipu suit xii l;y dat 85,30% nong dp nitrat c6n Ipi 1& 7,35mg/l va
sau 60 phut hipu suat len den 93,41%, nong dp nitrat con lai 1^ 3,29mg/L.
3 2.2. Anh hu&ng cua p H dung dich den hieu qua x u I'y
Ket qua khao sdt anh huong cua cua pH dung djeh den hieu qua xur ly nitrat dupe the hien d Hinh 5
Hinh 5 Nong dp nitrat c6n iai sau xii ly higu suit xu ly theo pH.
N.X. HuSn, N.N. Quj/nh /Tap chi KJwa hoc DHQGHN, Khoa hoc Tu nhm va Cdng nghl 29, Sff4 (2013) 16-23 21
Ket qua nghien ciiu a Hinh 5 cho thay, Meu suat xii ly nitral bing Fe® nano giam d in khi pH ling. Tai pH 2 hieu su it xu ly dat gia tri cao nhat la 86,17%. tai pH 4 hieu suit xu ly giam xuong c6n 78,60% va khi pH 8 hieu suit chi c6n 49,07% va u6ng d$ sau phan ling l i 25,47 mg N-NOs'/L. Co c h i khu nitrat cua vat li?u Fe° nano la do Fe® nano cho dien ni e, nitrat se nhin e va chuyin ihanh dang nitrit, sau do nitrit s i tilp tiic bi khii thanh amoni, amoni se la sin phim cuoi cung cua qua trinh khii nitrat v i mot lu^ng nho khi nito cung dupe hinh thanh [6],
C ic phan m g ciia nitrat v i Fe® nano diln ra theo cac phuong trinh sau:
Fe®->Fe-* + 2 e ( l) Fe° + 2 H ,0 ^ Fe^" + H, + 20H ' (2) Fe® + NOj' + 2H* ^ Fe^* + NO.’ + H ,0 (3) Fe® + NO,- + 8H* ^ 3Fe‘* + ME,* + 2H2O (4) 4Fe® + NO3- + 1 0 H "^ 4Fe^* + N E * + SHjO (5) 4Fe® + NO3- + 7 H ,0 4Fe(OH), + NH4* + 20H- (6)
3Fe® + NOj- + H2O ^ FejOi + N , + 2 0H ' (7) 5Fe° + NO3- + 12H* -> 5Fe^* + N2 + 6H2O (8) 2,28Fe® + NOj' + 0,75Fe^* + NOj' + 2,25H20
I,19Fe3O4 + NH4* + 0 ,5 O E (9 )
Nhimg nghien cthi ve q u i trinh khu nitrat ciia v |t li|u Fe® nano deu cho thay sin phim cuoi Cling cua phan ung la amoni, c6 th i c6 nito va khong phat hien thiy nitrit. Theo c ic nghien ciiu ciia Cheng (1997) [7], ciia Alowitz va Scherer (2002), ciia W esterhoff (2003), Liao va cic c$ng su (2002) cung chi ra rin g viec b6 sung dung djeh axit c6 th i thde diy cho qua trinh khii nitrat ciia Fe® nano. T it ca cic nghiin ciiu tren deu dua den ket luin rin g sir dung dung djeh co g ii tri pH < 4 l i diiu kien thich hop cho loai bo nitrat bang Fe® nano. C ic tic gia Huang va Zhang [8] da tien hanh nghiin cihi v6i nong do nitrat la 50 mg N-NOs'/L, tai pH bing 2 thi 95% lupng nitrat dupe lo?ii bo chi trong khoang 30 phiSt. Nhu viy, kSt qua nghien ciju v l anh huong cua pH tcri hieu suit ciia q u i trinh xir 1}^ nitrat bang Fe® nano ciia nhom tic gia l i hoin to in phu hop voi ly thuyet va ket qua thuc nghiem cua cac n h i nghiin cuu tren the gidi da thuc hien truoc day.
3.2.3. Anh htrong cua nong dg nitrat ban ddu den hieu qua xir ly
K it qua nghiSn cihi anh huong ciia nong dd nitrat ban d iu d in hiiu qua xir 1^ bing vat lieu Fe® nano dupe the hien 6 Bang 1.
Bang 1. Lupng niiral dupe xuly tren Ig vit li^uFe°nano v i hieu suit x phy ihudc vio nong dp nitrat ban dau
STT
Nong dp nitrat ban dau (mgN/I)
Nong dp nitrat sau xu ly (mgN/1)
Lupng nitrat dupe x iiiy/lgvit lipu
Qt (mgN/g)
Hieu suit xu
ly mtrat(%) QCVN 08: 2008/
BTNMT
A, B,
1 30 0,33] 29,669 98,90
2 40 2,928 37,072 92,68
3 50 8,966 41,034 82,07 5mgN/l 15mgN/l
4 60 14,563 45,437 75,73
5 70 27,688 42,312 60,45
Ket qua nghien o h i t ^ Bang 1 cho thiy, trong cung dieu Men thbi gian v i khoi lupng vat lieu su dung de xu 1}?, neu tang nong dp nitrat ban dau thi hieu qua xir 1^ se giam dan.
Vdi nong dp nitrat ban dau l i 30 mg N-N03'/L
thi sau 40 phut hieu qua xu ly dat 98,90 %. Khi ting nong dp nitrat truoc xu ly len 40, 50, 60 va 70 mg N-NOs'/L thi hieu qua xu ly giam xuong tuong ling con 92,68; 82,07; 75,73 v i 60,45 %.
22 N.X. Huan, N.N. Quynh /Tap ch KIwa hoc DHQGHN, Khoa hoc Tir nhicn va Cong ngite, TSp 29, So 4 (2013J 16-23
aN onjdd niiril sau'ar 1^ mgl.
-QCVN08 c?iB2
- — QCVN0g,cplA2
f ™ .
Ndng do nitrat tnidc 1^. mg/L
H3nh 6. N6ng do oitrat c6n sau xii IJ boi Fe° nano tuong ling v6i cac n6ng dp mlrat ban dau khac nhau.
Ket qua nghiSn cmi tai hinh 6 cho thay, voi ty le v |t lieu Fe*’ nano sir diing/the tich dung djch c&n xii Ik 1 g/L; then gian xu ly la 40 phdt; tai pH 2 vk nong dp 6 nhilm nitrai ban diu < 60 mg N-NOj'/L thi n6ng d6 nitrat con lai sau xii Ij? dal tieu chuan QCVN 08:2008/BTNMT (cot B2) - Quy chuan ky thuat quoc gia ve chat luong nurdc mkt, kp dung cho ckc boat d$ng giao thdng thuy vk cic muc dich khac v6i yeu cau nude chat lupng thap. Voi nong dp 6 nhilm mtrat ban dau < 40 mg N- NOs'/L thi nong dp nitrat con lai sau xir ly dat Ueu chukn QCVN 08;2008/BTNMT (cot A2) - Quy chuan ky thuat quoc gia ve chat luong nude mkt, kp dung cho muc dfch cip nude sinh boat nhung phai ap dung cong nghe xCt 1;^ phii hop; bao ton dong thuc vat thuy sinh, hoac cac muc dich sir dung nhu loai B 1 vk B2.
4. Ket Iu|n
Sir dung phuong phkp khii mudi skt (H) bang NaBH, khi c6 sir dung chit phan tan la PAA CO the dieu che dupe ckc hat Fe° nano kha dong nhat, cd kich thude nho tir 10 - 18,6 nm
(trung blnh 16,7 nm), cd dien tfch be mkt Idn (60 mVg) vk dac bi$t cd the lam kho va bao quan d nhiet dp phong.
Hipu qua xir ly nitrat ciia vat lieu Fe'* nano la rat nhanh (71,36%) trong iO phut dku cua quk trinh xir ly, nong dp nitrat giam tir 50 xuong 14,32 mg N-NO3 /L. Hieu suat xii 1^ tang cham d in trong khoang thdi gian tir 10 d in 60 phkt.
Tm pH 2 thi hieu qua xii ly nitrat bdi vkt lieu Fe° nano la tdi uu nhit, sau 40 phut Fe“
nano cd the xii ly dupe 98,9% mau nude cd nong dp nitrat ban dau la 30 mg N-NO37L. Vdi ndng dp 6 nhilm nitrat ban d iu < 60 mg N- N03‘/L thi ndng dp nitrat edn lai sau x u ly dat tieu chuin QCVN 08:2008/BTNMT (cot B2);
Vdi ndng dp 6 nhilm nitrat ban dau < 40 mg N- N03'/L thi ndng dp nitrat c6n l^i sau xu 1^ dat lidu chuin QCVN 08:2008/BTNMT (cot A2).
Ldi cam im
Cdng trinh dupe hokn thknh dudi su hd trp kinh phi cua dd tki TN-13-31. Cac tac gia xin trkn trong cam on.
N.X. Huaii, N.N Quynh /Tap chi KJioa hoc DHQGHN, Khoa hpc Tu nhen va Cong nghe. Tap 29, So 4 (2013) 16-23 23
TM lieu tham khao
[1] Trin Vin San, Nghien cuu xii ly nitrat trong mrdc lir nhien btag v$t lieu Bentonite bien u'nh La, Al/La, Luan vSn 'Oiac sp Khoa h9C, ngwh Khoa hoc m6i truang, Tnidng dai hpc khoa hoc V nhiSn, DHQGHN, 2010
[2] Le van Cat, Xii Vj nude thai gi^u hgp chit Nito va Nitrat, Nxb }6ioa Hoc Tu Nhien Cong Ngha. HI Noi, 2007.
[3] LS Due. Nguyen Xuan Huan, L4 Thj ThCiy An, Pham Thi ThCiy Duong, Trin Thi Thiiy, Nghien cuu che tao vat li^u Fe'^ nano bing phuemg phap dung bohidrua (NaBHi) khti mu6i sit II (FeSOj-THjO), Tap chi Khoa hoc DHQGHN, Khoa hoc Tu nhien vi Cong nghe 27, S6 5S (2011)23-29.
[4] Yuan-Pang Sun, Xiao-qin Li, Jiasheng Cao, Wei-xian Zhang, H. Paul Wang, A method for
the preparauon of stable dispersion of zero- valent iron nanopartides, Colloids and surfaces A; Physicochem. Eng. Aspects 308 (2007) 60- 66.
Yu-Hoon Hwang, Do-Gun Kim, Hang-Sik Shin (2011). “Mechanism study of nitrate reduction hy nano zero valent iron". Journal of Hazardous Materials 185,1513-1521
Yun Zhang, Yiinin Li, Jianfa Li, Liujiang Hu, Xuming Zheng (2011), “Enhanced removal of nitrate by a novel composite; Nanoscale zero valent iron supported on pillared clay"
Chemical Engineenng Journal 171 526- 531.
Cheng I F. “Reduction of nitrate to ammonia by zero-valent iron”, Chemosphere, 1997, 35.
Huang Y H, Zhang T C. Effects of low pH on nitrate reduction by iron powder. Water Res, 2004, 38(H)’ 2631-2642
Research and Application o f Nano Zero Valent Iron (nZVI) Materials for the Removal of Aqueous Nitrate
Nguyen XuSn Huan', Nguyin Nhu Quynih^
^Faculty o f Environmental Sciences, VNU University o f Science, 334 Nguyin Trai, Thanh Xuan, Hanoi, Vietnam
^University o f Science and Technology o f Hanoi, 18 Hoang Quoc Viit, C m Gidy, Hanoi, Vietnam A bstract: Application nZVI materials for environmental remediation is a new direction of many scientists over all the world. In this paper, the objectives were: synthesis of nZVI material using liquit- phase reduction method by borohydride (NaBIi,); its appheation to remove nitrate contaminant and the various fators affect nitrate removal efficiency as pH, time and initial P concentration.
CharactenzatiODS o f B-nZVI were determined by X-ray diffraction method (XRD); Brunauer Emmett Teller method (BET); scanning electron microscopy method (SEM). Concentration of nitrate in solutions were measured by spectrophotometer scanning method (A. = 430nm). XPD results showed that nZVI material is relatively homogeneous, with a peak of Fe” (29 = 44.7). The specific surface area of nZVI was 60m’/g, its diameter was 10 - 18.6 nm. The nZVI was efficient in removing nitrate from aqueous solution containing 30 mg/L of nitrate, where 98.9% nitrate was removed within 40 minutes at pH 2 and the ratio of 1 g/L (m:v).
Keywords: Fe^nano, material, removal, nitrate, water.
