The characteristics and mechanisms f or dual2cation organobentonites to sorb organic compounds from water

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1 ACTA SCIEN TIAE CIRCUMSTAN TIAE Vol. 19,No. 6 Nove., (, )., Langmuir Freundlich, (partition) (adsorption). ;,, ;,. ; ; ; ;. The characteristics and mechanisms f or dual2cation organobentonites to sorb organic compounds from water ZHU Lizhong, CHEN Baoliang, L I Mingxia, ZHAN G Sunwei (Department of Environmental Science,Zhejiang Univesity,Hangzhou ) Abstract A series of dual2cation organobentonites are synthesized by replacing the metal ions in bentonite with both long2chain alkyl or aryl quaternary ammonium cations, such as dodecyltrimethylammonium ( D TMA ), tetradecyltrimethylammonium ( TPA ), cetyltrimethylammonium ( CTMA ), octade2 cyltrimethylammonium ( O TMA),and short2chain alkyl or aryl quaternary ammonium cations,such as te2 tramethylammonium ( TMA). The optimal conditions and the properties for dual2cation organobentonites to sorb p2nitrophenol,phenol and aniline from water are investigated. The mechanisms and characteristics of the interactions between organic pollutants and the organic phase of the bentonite in water system are also discussed. The interlayer spacings, organic carbon contents and sorption properties of dual2cation organobentonites are related to the ratio of long2 to short2chain quaternary ammonium cations, and the length of alkyl2chain of large quaternary ammonium cations exchanging on bentonite. The sorption of or2 ganic compounds to dual2cation organobentonites is also related to the properties of organic compounds. Sorption isotherms of p2nitrophenol,phenol and aniline are typically nonlinear,and the isotherms fit closely to Freundlich or Langmuir equation. Both adsorption and partition occur to the sorption of organic com2 pounds to dual2cation organobentonites. The separate contributions of adsorption and partition to the total sorption of organic compounds to dual2cation organobentonites are analyzed mathematically ;the relative ef2 fect is a function of the equilibrium concentration of the organic compounds. Keywords organobentonite,quaternary ammonium cation,organic pollutant,adsorption,partition. [1, 5 ],. [1 3 ], 3 ( )

2 ;. (sorption) (par2 [5 tition) (adsorption) 6 ].,,.,. ; (sorption) ;, , (CEC) 60 meq/ 100 g ; (CTMAB) ( TMAB) ; (D TMAB,95 %) ( TPAC,90 %) (O TMAB, 80 %),. THB282A,, 2,L ECO CS2344,X PertMPD X , ; 011 g/ ml 0112 g/ ml 0105 g/ ml. 113 ( TMAB) (D TMAB TPAC CTMAB O TMAB). : g 400 ml, h,, 400 ml 2,, 80 90, h,, 100,., CEC., 40D TMAB 40 % CEC TMAB 40 % CEC D TMAB ml 015 g ( ),25 ml,, r/ min 1 h, 10 min,, ( ), X %,,

3 6 : Table 1 The interlayer spacing and organic carbon contents of original bentonite and dual cation organobentonites 40 TMAB 40DTMAB 20DTMAB 40DTMAB,nm , % DTMAB 20 TPAC 20CTMAB 20OTMAB,nm , % : ;, 60D TMAB > 40D TMAB > 20D TMAB > 40 TMB, 20O TMAB > 20CTMAB > 20 TPAC > 20D TMAB. 212 p H., : 25 p H g/ 25 ml 1 h TMAB 20D TMAB 40D TMAB 60D TMAB 40D TMAB 1 2., Langmuir Freundlich, TMAB ;21 20DTMAB ; 31 40DTMAB ;41 60 TMAB Fig. 1 Isothermal sorption curves for p2ni2 trophenol 2 40TMAB/ 40DTMAB 11 ;21 ;31 Fig. 2 Isothermal sorption curves for phenol aniline (1) aniline ; (2) p2nitrophenol ; (3) on 40 DTMAB2organobentonite

4 Table 2 Regression data for sorption isotherms of organic compounds on dual2cation organobentonites ( Q :mg/ g, C e : g/ ml) Q = ln C e TMAB Q = ln C e DTMAB Q = ln C e DTMAB Q = ln C e DTMAB Q = ln C e DTMAB Q = ln C e TPAC Q = ln C e CTMAB Q = ln C e - 68, OTMAB Q = ln C e Q = ln C e TMAB Q = ln C e DTMAB Q = ln C e DTMAB Q = ln C e DTMAB Q = ln C e DTMAB Q = ln C e TPAC Q = ln C e CTMAB Q = ln C e OTMAB Q = ln C e Q = ln C e TMAB Q = ln C e DTMAB Q = ln C e DTMAB Q = ln C e DTMAB Q = ln C e DTMAB Q = ln C e TPAC Q = ln C e CTMAB Q = ln C e OTMAB Q = ln C e : (1),,. (2), 60D TMAB > 40D TMAB > 20D TMAB > 40 TMAB ( 1). (3),, 20O TMAB > 20CTMAB > 20 TPAC > 20D TMAB., 2 ( K ow ) ( S ) ( K oc ) ( 3). K oc. 40D TMAB 40 TMAB 40D TMAB : (1) (40 TMAB) 3 : > >,,

5 6 : ( K ow ), ( S) ( K oc ) Table 3 Octanol2water partition coefficient ( K ow ),aqueous solubility ( S) and partition coefficient ( K oc ) of organic compounds 2 ( K ow ) , g/ ml ( K oc ) ,,. (2) 3 : > >,,,,. (3) 40D TMAB, ; : > > ( 2). 214,.,., : : : Q T = Q P + Q A (1) Q T = aln C e + b (2) K d = Q P / C e (3) K d = K oc f oc (4), Q T, Q P, Q A, C e, K d, K oc, f oc, a b. 4, : Q P = K oc f oc C e (5) Q A = aln C e + b - K oc f oc C e (6) ( 1) a b ( 2) K oc ( 3) (4) (5), ( 4). 4 ( Q A ),, Langmuir, 4. Q p Q A, 60D TMAB, ( 3) ;, Q p Q A C e, d Q p / d C e d Q A / d C e, 4. 4 C 1 d Q p / d C e =

6 d Q A / d C e. 4 Q A Langmuir Table 4 Functions of adsorption amount ( Q A ) and partition sorption amount ( Q P ) with concentrations of organic compounds on dual cation organobentonites and analogue equation of Q A ( Q P ) ( Q A ), g/ g Q A langmuir, g/ g Q P = C e Q A = ln C e C e 1/ Q A = / C e TMAB Q P = C e Q A = 11363ln C e C e 1/ Q A = / C e DTMAB Q P = C e Q A = 33946ln C e C e 1/ Q A = / C e DTMAB Q P = C e Q A = 11428ln C e C e 1/ Q A = / C e DTMAB Q P = C e Q A = 23914ln C e C e 1/ Q A = / C e DTMAB Q P = C e Q A = 34438ln C e C e 1/ Q A = / C e TPAC Q P = C e Q A = 13709ln C e C e 1/ Q A = / C e CTMAB Q P = C e Q A = 16638ln C e C e 1/ Q A = / C e O TMAB Q P = C e Q A = 16250ln C e C e 1/ Q A = / C e Q P = C e Q A = ln C e C e 1/ Q A = / C e TMAB Q P = C e Q A = 13222ln C e C e 1/ Q A = / C e DTMAB Q P = C e Q A = 28763ln C e C e 1/ Q A = / C e DTMAB Q P = C e Q A = 17950ln C e C e 1/ Q A = / C e DTMAB Q P = C e Q A = 22721ln C e C e 1/ Q A = / C e DTMAB Q P / C e Q A = 26292ln C e C e 1/ Q A = / C e TPAC Q P = C e Q A = 16134ln C e C e 1/ Q A = / C e CTMAB Q P = C e Q A = 18172ln C e C e 1/ Q A = / C e O TMAB Q P = C e Q A = 20786ln C e C e 1/ Q A = / C e Q P = C e Q A = ln C e C e 1/ Q A = / C e TMAB Q P = C e Q A = 13799ln C e C e 1/ Q A = / C e DTMAB Q P = C e Q A = 40317ln C e C e 1/ Q A = / C e DTMAB Q P = C e Q A = 19856ln C e C e 1/ Q A = / C e DTMAB Q P = C e Q A = 35121ln C e C e 1/ Q A = / C e DTMAB Q P = C e Q A = 40121ln C e C e 1/ Q A = / C e CTMAB Q P = C e Q A = 27566ln C e C e 1/ Q A = / C e O TMAB Q P = C e Q A = 30838ln C e C e 1/ Q A = / C e O TMAB Q P = C e Q A = 22692ln C e C e 1/ Q A = / C e ( Q A ) ( Q P ) 40TMAB/ 60DTMAB Fig. 3 p2nitrophenol sorption amount ( Q A, Q P, Q T ) on 60DTMAB2organoben2 tonite 4 40TMAB/ 60DTMAB Q A, Q P Fig. 4 Changing rate of p2nitrophenol sorption amount ( Q A and Q P ) with concentration

7 6 : : (1) ;, Langmuir. (2) Q p Q A,,. (3),,,,. 4 : (1) d Q p / d C e ; d Q A / d C e,. ( 2) dq P / d C e d Q A / d C e, Q P Q A. (3) C e < C 1,d Q A / d C e > d Q p / d C e > 0, Q A Q p, ; C e > C 1,0 < d Q A / d C e < d Q p / d C e, Q p Q A. 3 (1) ;,. (2), : > >. (3) (sorption) (partition) (adsorption). (4), ( Q A ) ( Q p ) ;,,,,. 1 Boyd S A,Mortland M M,Chiou C T. Sorption characteristics of organic compounds on hexadecyltrimethylammonium2smentite. Soil Sci Soc Am J,1988,52 : Smith J A,Jaffe P R,Chiou C T. Effect of ten quaternary ammonium cations on tetrachloromethane sorption to clay from water. Environ Sci Technol,1990,24 : Zhu L,Li Y, Zhang J. Sorption of organobentonites to some organic pollutants in water. Environ Sci Technol,1997,31 (5) : Zhu L, Ren X, Yu S. Use of Cetyltrimethylammonium Bromide2bentonite to Remove Organic Contaminants of Varying Polar Character from Water. Environ Sci Technol,1998,32 (21) : Smith J A. Galan A. Sorption of nonionic organic contaminants to single and dual cation bentonites from water. Environ Sci Technol,1995,29 (3) : ,,..,1999,19 (4) :

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