w w m y wz Vol. 13, No. 1, pp. 60~66, 2008 œ û m w m HCl EDTA w ½z Á * Ÿ w y œw Effects of HCl and EDTA on Soil Washing to Remediate Lead-contaminated Soil in a Firing Range Hyo-Sik KimÁSang-Il Choi* Department of Environmental Engineering, Kwangwoon University ABSTRACT Laboratory soil washing experiments with HCl or EDTA were conducted to remediate lead-contaminated soil in a firing range. After lead bullets were removed by standard sieve #18 (1.0 mm), Pb concentrations were measured by EPA Method 3050B (9,443 mg/kg) and Korea Standard Test (4,803.5 mg/kg). The results of the batch test showed that the removal efficiency curve was logarithmic and approximately 90% of lead in soil was removed, when HCl was used. In case of EDTA, the removal efficiency increased proportionally to the concentration of EDTA, up to 98% lead removal with 0.1 M EDTA. High mixing strength resulted in increase of removal efficiency and kinetics showed that the most lead was extracted in 10 min. Key words : Firing range, Soil washing, Lead, HCl, EDTA, Sequential extraction û k m w m» w» w lab-scale x ww. m œ x EPA Method 3050B ƒƒ 4,803.5 mg/kg, 9,443 mg/kg ùkû. z m x HCl w ƒ (logarithmic) w ùkü š 0.1 M 90%, EDTA w ƒw 0.1 M 98%. z w, HCl EDTA w ƒ w m ü ƒw ù 200 rpm 300 rpm w ùkû,» 10 ü š 60 z ƒƒ y. :, m, û, EDTA, HCl, 1. 2003 m y t w 9 e, û, w ƒ m» w ùkû. w» *Corresponding author : sichoi@kw.ac.kr š : 2007. 11. 14 : 2007. 12. 12 m :2008.4.30¾ 60 y w m z e ù x y» s ü û,, e w m š š, p k kv w û ƒw ùkû. w k m e e û k w w w.
û m w m HCl EDTA w 61 m û, y, e,» y w. û m t w eyw, w û m m e w (Campanella et al., 1989).» w š phƒ 6~8 û w» û yw x wš» w m ph w yû, k û, û e x w» (, 2003). m w š» w, ù w w k mw w» w w w v ƒ. m ƒ w y» yw (Chemical treatment), (Solvent extraction), m (Soil washing / flushing),» (Electrokinetic method), y (Phytoremediation) (Mulligan et al., 2001). ph y y w ƒ ƒ š» m w ƒ y w m l Á w. w, y,»,»,», y w w m w w y g m l w m» m y w w» š.» p m» w k ü û m w p wš, HCl EDTA w p m» sƒwš w. 2. x 2.1.» p w I ew m w. ü 5 tm(0~20 cm) w š û k x w» w t #18(1.0 mm) m w m ³ w yww. x ww» Áyw» p» w. ph m œ x (y, 2002) m 1 : 5(w/w)ƒ yww 1 k k z ph d w,» w zy (direct ashing method) w š CEC 1N e d w. ü û m œ x 100 ml ƒv j m 10 g 0.1 N HCl 50 ml w s k» 1 kwš 5B w z ICP-OES(Perkin Elmer Optima 2000 DV, USA) w w š, m ü w EPA Method 3050B w w. 2.2. w û p ü û p wxk w» w Tessier et al.(1979) w w š(ruiqiang Liu et al., 2007), Table 1 ùkü. w 15 ml Teflon centrifuge tube m 0.5 g Table 1 ƒ yww. k z yw 3,000 rpm 10 w 0.45 µm membrane filter w û w. 2.3. z m x m m» w» w m Áyw p q wì, m yw, w. ù k p (chelating agent) w, ƒ š HCl citric acid, tartaric acid» w û z EDTA w z m x ww m û EPA Method 3050B w w. 2.3.1 w y z» w 0.01, 0.05, 0.1, 0.2, 0.5 M HCl 0.01, 0.05, 0.1, 0.2 M EDTA ƒƒ w. k m z š w 1 : 3 [soil(g) : solution(ml)] š w š, 300 rpm 1 k g.
62 ½z Á Table 1. Scheme of sequential extraction procedure for extractable lead fractions Step Method Designated Pb species 1 Soil 0.5 g + 12.5 ml, 1 M NH 4 NO 3, ph 7.0, 0.5 h shaking Exchangable (EX) 2 12.5 ml, 1 M Na-acetate, ph 5.0, 6 h shaking Carbonate-bound (CB) 3 12.5 ml, 0.04 M hydroxylamine hydrochloride in 25% acetic acid,, 6 h at 95 o C water bath Fe/Mn Oxides-bound (OX) 1.5 ml of 0.01 M HNO 3 and 2.5 ml of 30% H 2 O 2 5 h at 85 o C in water bath, followed by an 4 additional 1 ml of H 2 O 2, 1h at 85 o C in water bath, then 7.5 ml of 1 M NH 4 NO 3, 10 min shaking at Organic matter-bound (OM) room temperature 5 12.5 ml, 4 M HNO 3, 16 h at 80 o C in water bath Residual (RS) 2.3.2 w û p» w 2.3.1 x mw w 100, 200, 300 rpm 1, 3, 5, 10, 20, 30, 60, 120, 180 û w š, 60 m w w z m ü û xk y w. w 0.1 M EDTA 300 rpm w m w m œ x EPA Method 3050B mw p w. 3. x š 3.1. m Áyw p û p Áyw p» Table 2, 3 ùkü. (Table 2), silt, clay #200 w(0.075 mm w) fine fraction 17.5% m œ w p sƒƒ w q. m Áyw p x (Table 3), ph 5.5 š, w 14.3% m w (10~18%) s.» w 7.1% m» w (0.5~5%) š, y 6.6 meq/100 g ù kû. m» w (Tapan and Singh, 2003),» y m» y f w». w» carboxyl»ù phenol» w» w» ww w» y (organic matter- metal complex) x w w e (Sparks, 1995). m œ x w» (Table 3) m Table 2. Particle size distribution of lead contaminated soils Sieves Mass fractions No. Opening size [mm] [%] 18~20 0.85~1.0 3.73 20~40 0.425~0.85 21.2 40~60 0.25~0.425 19.7 60~100 0.15~0.25 20.9 100~140 0.106~0.15 7.8 140~200 0.075~0.106 9.2 200~ 0.075~ 17.5 y m» ƒ 48 w 4803.5 mg/kg ùkû. ü w û k Áyw ty w w m z m» k w ù û k (phase) w» q. w» ü û xk s Carbonatebound fraction(cb), 56% > Fe/Mn Oxides-bound fraction (OX), 26% > Organic matter-bound fraction(om), 10% > Residual fraction(rs), 5% > Exchangable fraction(ex), 1% ùkû. CB fraction w û q, k (Mobility) ƒ (Phytoavailability) û OM, RS fraction û û m Ÿ w w. 3.2. w HCl EDTA z w (Fig. 1), HCl w Moutsatsou et al.(2006) w ƒ ƒw û z (logarithmic) ùkû, 0.1 M w 90%
û m w m HCl EDTA w 63 Table 3. Physicochemical properties and concentration of lead contaminated soils ph Water Content [%] Organic Content [%] Bulk Density [g/cm 3 ] CEC a [meq/100 g] KST b Total Con. c a 5.49 14.3 7.1 1.7 6.6 4803.5 9443.5 Cation Exchange Capacity, b Korea Standard Test, c EPA Method 3050B m EDTA w EDTAü H +ƒ ù š ù» ww xk. coordination numberƒ 6 û 6 (ligand) œw EDTA ww yw yw x w» (½, 1999; Kim, 2003), x ƒ ƒw ƒƒ HCl w w ùkû p HCl û w z. Fig. 1. Total lead concentration in washed soils as function of washing agent concentration. ùkþ. m» w H + ƒ ƒw m ƒ w k w (, 2004), Cl w m y x w w 2+ƒ wš, Pb Cl w w ƒ û PbCl 2 e x w» (Moutsatsou et al., 2006; Wei et al., 2005). EDTA w x EDTA yw (coordination compound) x w 3.3. w x k z ƒ 0.1 M HCl 0.1 M EDTA w p» w x Elovich model w ùkü (Fig. 2). ³ w y d w Elovich model kinetic ƒ (Coefficient of determination) û t ƒ š (Min jang., et al), Elovich equation 1 x tx. q=a+b ln(t) Eq. 1 q p t (mg/kg), t, A B ƒƒ r»» ùkü. HCl EDTA w Fig. 2. Kinetics of lead extraction for HCl and EDTA with the different mixing strength along with curves obtained from Elovich model.
64 ½z Á Fig. 3. Fractionation-specific percentages of lead in soils as a function of mixing strength after washing for 60 min. Table 4. Lead distributions of washed soils as function of mixing strength Reagent Mixing strength [rpm] EX CB OX OM RS Total conc. Initial 72.5 2404.1 1102.3 460.6 240.6 4280.1 0.1 M HCl 0.1 M EDTA 100 311.2 391.1 182.8 85.2 79.4 1050 200 194.7 152.1 94 36.3 43.5 520.7 300 232.9 182.8 122.8 36.1 38.7 613.1 100 21.6 199.1 103.8 38.9 36.2 399.7 200 33.9 34.9 70.5 46.1 33.9 219.5 300 32.5 27.6 77.6 27.0 26.1 190.9 ƒ w m ü ƒw ù 200 rpm 300 rpm w ùkû,» 10 ü š 60 z ƒƒ y. HCl 100 rpm» 10 75%ƒ 200 rpm 300 rpm ƒƒ 89, 90% û 180 90~95%. EDTA 100 rpm 10 90%ƒ 200 rpm 300 rpm ƒƒ 95, 97% û 180 98~99%ƒ (Fig. 2). w yƒ m z 60 w m w sxk y w» w ww. x (Fig. 3, Table 4), HCl EDTA w x 2, 3, 4 CB, OX, OM fraction w CB 83~93%, OX 83~91%, OM 81~94%ƒ š, p CB fraction j s w. wì HCl EX fraction Fig. 4. Comparisons of lead concentration in washed soils by KST and EPA Method 3050B. ƒw y w, CB, OX, OM fraction m w» xk w m w» (½, 2002). EDTA EX faraction ƒw û EDTA complexation j e» xk w» q.
û m w m HCl EDTA w 65 w ƒ z ƒ 0.1 M EDTA, 300 rpm m ü û m œ x EPA Method 3050B w (Fig. 4), x ww» EPA Method 3050B m œ x 2 ù ú wì w 30 z l w ùkü. 4. œ m xkƒ w y w k m k. w m w ƒ jš w (speciation) swwš w y. û k m w m» w» w lab-scale x ww. (1) ûk w» ƒ 4803.5 mg/kg (m œ x ) Áyw ty w m» k w ù û k (phase) w» q. CB(56%) > OX(26%) > OM(10%) > RS(5%) > EX(1%) ùkù û w. (2) HCl EDTA z HCl ƒ ƒw (logarithmic) ùkû, 0.1 M w 90% ùkþ. EDTA w ƒw š, ƒ HCl w w ùkû HCl. (3) z w, HCl EDTA w ƒ w m ü ƒw ù 200 rpm 300 rpm w ùkû,» 10 ü š 60 z ƒƒ y 180 HCl 90~95%, EDTA 98~99%ƒ. (4) x, HCl EDTA CB, OX, OM fraction w CB 83~93%, OX 83~91%, OM 81~94%ƒ. HCl EX fraction ƒw š, EDTA û complexation g e ƒw ù w. y m w y» x 2007 Ÿ w ü w w,. š x ½ y, 2005, m y w field ³ m œ z sƒ, w w wz w y wz 2005œ w tz, p. 160. ½, 2002, Soil washing w sÿ Ÿ m, w w w. ½, 1999. EDTA w û m z û, w m y wz, 4(1) 3-11., ½, «y, œ y,, y, x, 2004, EDTA yw w m w (I): û, w w m y wz, 9(4), 1-7. y, y, x,, 2007. s» l, w s» wz, 24(2), 116-124. w, z, 2004, šxs» ƒ û,, e j yw sƒ, w s» wz, 21(8), 791-801., 2003, m Áyw p y wsƒ, w sƒ.,,, w», x, 2000,» w û m w, w y wz, 9(3), 437-441. w, ½, ½, 2004, m( m)» y p, wy œwz, 26(4), 467-474. y,, ûª, 2005, m» w m p, wy œwz, 27(8), 1072-1080. y,, ûª, 2004, m» w m w w, wy œwz, 26(11), 1181-1190. y, 2005, m w e», Ÿ w w.
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