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American Journal of Environmental Protection2013; 2(6): 161-169Published online November 10, 2013 (http://!s"ien"epublishin##roup!"om/$/%$ep)doi: 10!116&'/$!%$ep!20130206!1

Modified activated carbon and bentonite used to adsorb

petroleum hydrocarbons emulsified in aqueous solutionEman Abdelwahab Emam

ep%rtment o* Petroleum +e*inin# n#! %nd Petro"hemi"%ls, %"ult. o* Petroleum %nd inin# n#!, ue niversit., ue, #.pt

Email address:em%mt%h.%hoo!"om

To cite this article:m%n 4bdel%h%b m%m! odi*ied 4"tiv%ted 5%rbon %nd entonite sed to 4dsorb Petroleum 7.dro"%rbons mulsi*ied in 48ueous

olution! American Journal of Environmental Protection! ol! 2, No! 6, 2013, pp! 161-169! doi: 10!116&'/$!%$ep!20130206!1

Abstract: 4dsorption is one "ommonl. used te"hni8ue *or tre%tment o* petroleum "ont%min%ted %ter! his stud. %imsto modi*. the %dsorption sur*%"e o* bentonite "l%. %nd %"tiv%ted "%rbon %s or#%no"l%. %nd %"id modi*ied %"tiv%ted "%rbon,respe"tivel.! he modi*ied %nd unmodi*ied %dsorbents ere "h%r%"teried b. %n%l.sis o* spe"i*i" sur*%"e %re%, "%tione"h%n#e "%p%"it. %nd point o* ero "h%r#e (p7 p")! urthermore, %dsorbents e**i"ien"ies ere ev%lu%ted in the %dsorptiono* petroleum h.dro"%rbon *rom oil-%ter emulsion! he s.ntheti" %ste%ter s%mples ere #ener%ted b. emulsi*.in#diesel oil in distilled %ter to investi#%te the e**e"ts o*: (i) "ont%"t time, (ii) initi%l h.dro"%rbon "on"entr%tion, (iii) p7, %nd(iv) %dsorption isotherm! he modi*i"%tion o* bentonite %nd %"tiv%ted "%rbon produ"ed hi#her %dsorption "%p%"it. th%n theunmodi*ied %dsorbents! <n %ddition, the results shoed th%t the %dsorption o* h.dro"%rbon depend stron#l. on p7 %ndin"re%sed ith in"re%sin# "ont%"t time %nd the e8uilibrium %s re%"hed %*ter 3 %nd & hr ith "l%.s %nd %"tiv%ted "%rbons,respe"tivel.! he h.dro"%rbon remov%l e**i"ien". %"hieved in the *olloin# order: or#%ni" bentonite = %"id modi*ied%"tiv%ted "%rbon = bentonite = %"tiv%ted "%rbon! he modi*ied bentonite is %n e"ellent %ltern%tive in the %dsorption o*h.dro"%rbon *rom oil-%ter emulsion remov%l ith the hi#hest %dsorption "%p%"it. (&' m#/# %t 2 #/>)! reundli"h isotherm

%s best to des"ribe the %dsorption isotherm o* h.dro"%rbons *rom oil-%ter emulsion b. the %ll %dsorbents!

Keywords: Petroleum 7.dro"%rbon, ?il-@%ter mulsion, 4dsorption, entonite, 4"id odi*ied 4"tiv%ted 5%rbon,?r#%no"l%.

1. Introduction

Petroleum industr. is %mon# m%$or users o* %ter, %nd produ"es % l%r#e volume o* %ste%ter, v%r.in# in"omposition %nd pollut%nt "on"entr%tion, in"ludin#h.dro"%rbon "ont%inin# %ste%ter! 7.dro"%rbons me%n

oil, #re%se, "rude petroleum, t%rs, ve#et%ble %nd miner%loils, %nim%l *%ts, li#ht %nd he%v. *uel, %s ell %s theirmitures, hi"h %re insoluble or poorl. soluble in %ter!7.dro"%rbon-"ont%inin# %ter h%s to distin"t "omponents,% #r%vit. sep%r%ble ph%se %nd %n emulsi*ied ph%se!7.dro"%rbons %re present %s A*ree oilB (h.dro"%rbons th%tsep%r%te *rom %ste%ter %nd *lo%t to the li8uid sur*%"e)%nd %s Aemulsi*ied oilB (h.dro"%rbons th%t rem%inin# st%blesuspension %nd do not sep%r%te *rom the %ste%ter)! heemulsi*ied %ste%ter under#oes in"omplete mi"robi%lde#r%d%tion C1D hen dis"h%r#ed ithout tre%tment, %nd notonl. de#r%des %ter 8u%lit. but is %lso toi" to hum%n %nd

m%rine li*e %nd environment C2D! here*ore the remov%l o*h.dro"%rbon *rom oil-%ter emulsion h%s % #re%t

import%n"e *or the environment C3,&D!%n. te"hni8ues %re %v%il%ble *or the remov%l o*

h.dro"%rbon *rom oil-%ter emulsion! hese te"hni8uesin"lude the use o* % v%riet. o* *ilters CED, "hemi"%l dosin#C6D, #r%vit. sep%r%tion CD, biolo#i"%l pro"esses C',9D %nd%ir *lot%tion C10D! 7oever, these te"hni8ues %re ine**e"tive

in removin# sm%ller oil droplets o* emulsions, p%rti"ul%rl.in st%ble emulsions %nd hen h.dro"%rbon "on"entr%tion islo! oreover, membr%nes %re the most e**e"tive *or oilemulsion sep%r%tion *rom %ter C1D, hoever, *oulin# o*these membr%nes is *re8uent C11D! 4dsorption onto lo-"ostm%teri%ls is one te"hni8ue used l%r#el. *or removin#or#%ni"s dissolved in %ter!

1.1. Adsorption

4dsorption is % sep%r%tion pro"ess in hi"h #%s or li8uidmole"ules %re %dsorbed on the sur*%"e o* %n %dsorptionsolid! here is % v%riet. o* %dsorbents! he most "ommon

%re %"tiv%ted "%rbon (45), "l%., sili"%, %lumin% %nd eolite!45 is %n e**e"tive %dsorbent, h%s % hi#h sur*%"e %re%, %n



162 m%n 4bdel%h%b m%: odi*ied 4"tiv%ted 5%rbon %nd entonite sed to 4dsorb Petroleum 7.dro"%rbonsmulsi*ied in 48ueous olution

etensivel. developed pore stru"ture, % hi#h "r.st%lline*orm %nd me"h%ni"%l stren#th C12D! <n %ddition, 45 possesses #ood porous teture %lloin# the hi#h %dsorption"%p%"it. in the remov%l o* % ide v%riet. o* or#%ni""ompounds in"ludin# oil *rom %ter %nd h%s proven to bete"hni"%ll. *e%sible C12-1&D! +emov%l o* petroleumh.dro"%rbon polluted #round-%ter usin# o* 45 %sinvesti#%ted, %nd it %s re"ommended th%t poder%"tiv%ted "%rbon is more e**e"tive in the tre%tment o*#round %ter th%n #r%nul%r %"tiv%ted "%rbon C13D!

he sur*%"e "hemistr. o* "%rbon m%teri%ls is b%si"%ll.determined b. the %"idi" %nd b%si" "h%r%"ter o* theirsur*%"e, %nd "%n be "h%n#ed b. modi*.in# them ithoidiin# %#ents either in the #%s ph%se or in solution C1ED!%n. methods o* modi*.in# the 45 sur*%"e h%ve beenintrodu"ed usin# "hemi"%l/ph.si"%l tre%tment C16D,impre#n%tion C1D %nd sur*%"e modi*i"%tion ith sur*%"t%ntC1ED! <t h%s %lso been shon th%t "hemi"%l modi*i"%tions

"%n improve the %dsorption "%p%bilities o* %"tiv%ted"%rbons *or v%rious mole"ules C1E-1D! odi*i"%tion o* thesur*%"e "hemistr. o* %"tiv%ted "%rbons m%. be % possible%ttr%"tive route to%rd novel %ppli"%tions o* these m%teri%ls%s %n %dsorbent *or "ont%min%nts remov%l!

5l%.s %re ver. import%nt miner%ls %s % result o* theirsur*%"e properties %nd the *%"t th%t the. %re re%"tive hen"em%Fin# them ver. import%nt in m%n. industri%l%ppli"%tions %nd environment%l "ontrol C1&D! he. %rem%inl. "omposed o* l%.ers (sheet-liFe stru"tures) %nd %rethere*ore re*erred to %s ph.llosili"%te miner%ls! ?r#%ni"%ll.modi*ied "l%.s %re proposed %s % #ood option *or remov%l

o* oil *rom produ"ed %ter C2-&,1'D! ome studies h%veshoed th%t repl%"in# the inor#%ni" e"h%n#e "%tions o*"l%. miner%ls ith or#%ni" "%tions "%n result in #re%tl.enh%n"ed "%p%"it. o* the m%teri%ls to remove or#%ni""ont%min%nts C2,1'D!

he %dsorption *or some or#%ni" pollut%nts usin# bentonite or#%no"l%. h%s been studied C1&,1'D! <t %sreported th%t bentonite or#%no"l%. is e**e"tive in theremov%l o* h.dro"%rbon *rom oil. %ters! <n *iltr%tion("olumn) s.stems, % miture o* or#%no"l%. %nd %nthr%"ite"%n remove %s mu"h %s E0 G o* its ei#ht in oil hi"h is%bout E - times the remov%l r%te o* %"tiv%ted "%rbon C1&D!4nother stud. h%d %lso shon th%t bentoniteor#%no"l%./%nthr%"ite ere 8uite e**e"tive in removin# oil*rom % number o* oil-%ter emulsions C19D!

1.2. Adsorption Isotherm

he %dsorption isotherm indi"%tes hether mole"ules"%n be removed b. %dsorption %nd des"ribe the distributiono* mole"ules to be %dsorbed beteen the %dsorbent %nd thesolution! he. %lso #ive %pproim%te v%lues o* %dsorption"%p%"ities %t re%listi" oper%tin# "onditions! urthermore,the. "%n be used to %ssess the %pproim%te "onsumption o*%dsorbent %s ell %s the "ost o* the inst%ll%tion! >%n#muir%nd reundli"h isotherms %re used *or *ittin# the

eperiment%l d%t% in %dsorption studies to underst%nd theetent %nd de#ree o* *%vour%bilit. o* %dsorption! he

reundli"h isotherm is de*ined %s %n empiri"%l modelrepresentin# the e8uilibrium beteen %dsorb%te %nd%dsorbent! he >%n#muir isotherm is % m%them%ti"%l modelderived *rom theoreti"%l "onsider%tions! hese isothermsh%ve "onst%nts in their #ener%l *orm #iven b. e8u%tions 1%nd 2, respe"tivel. C20D!

( ) ( )eee bC abC q += 1/ (1)

n

ee C k q/1

= (2)

hese models %re re%rr%n#ed to the line%r *orm %s *ollos:

ee abC aq

111+= (3)

( ) ( ) ( )ee C n

k q lo#1

lo#lo#

+= (&)

here qe is the %mount o* %dsorbed %dsorb%te per unitei#ht o* %dsorbent (m#/#), C e is the "on"entr%tion o*%dsorb%te in the li8uid (m#/>), k, n %re the "onst%ntsspe"i*i" to test "onditions %nd the "%rbon t.pe (reundli"h"onst%nts) %nd a, b %re the "%p%"it. %nd ener#. o*%dsorption (>%n#muir "onst%nts)!

he "onst%nts a %nd k indi"%te the %**inities *or%dsorption! he slope (1 /n) indi"%tes the e**e"ts o*"on"entr%tion on %dsorption "%p%"it. %nd *or most or#%ni"s(1/n) H 1! 4 l%r#er v%lue o* F indi"%tes % hi#her r%te o*%dsorb%te remov%l C1&D! <t should be noted th%t the isotherm

"onst%nts %re import%nt in underst%ndin# the %dsorptionme"h%nism %nd their subse8uent %ppli"%tion *or predi"tin#some import%nt desi#n p%r%meters!

he essenti%l "h%r%"teristi"s o* the >%n#muir isotherm"ould be e%mined b. %n %dsorption dimensionless "onst%nt,sep%r%tion *%"tor or e8uilibrium p%r%meter r th%t %s"%l"ul%ted b. *olloin# e8u%tion C21D:

01

1

bC r

+

= (E)

here b is the >%n#muir "onst%nt rel%ted to the ener#. o*%dsorption (>/m#) %nd C 0 is the initi%l %dsorb%te

"on"entr%tion (m#/>) %nd these v%lues ere derived *rom>%n#muir isotherm! he "h%r%"ter o* the %dsorptionisotherm %s rel%ted to the v%lue o* r ! he %dsorption isun*%vor%ble (r = 1), line%r (r I 1), *%vor%ble (0 Hr H 1), orirreversible (r I 0)!

he m%in ob$e"tive o* this stud. is to investi#%te thee**i"ien"ies o* the modi*i"%tion sur*%"es o* bentonite %nd%"tiv%ted "%rbon *or the remov%l o* petroleum h.dro"%rbon*rom oil emulsi*ied %ter! he or#%ni" bentonite %nd %"id%"tiv%ted "%rbon ere s.nthesied b. usin# "et.ltrimeth.l%mmonium "hloride (545) %nd nitri" %"id on the bentonite %nd %"tiv%ted "%rbon, respe"tivel.! he

unmodi*ied %nd modi*ied %dsorbents ere "h%r%"teried b.the determin%tion o* spe"i*i" sur*%"e %re%, "%tion e"h%n#e



4meri"%n Journ%l o* nvironment%l Prote"tion 2013; 2(6): 161-169 163

"%p%"it. %nd point o* ero "h%r#e! 4dsorption "%p%"ities o*the %ll %dsorbents ere investi#%ted ith v%rious oper%tin# p%r%meters su"h %s "ont%"t time, initi%l h.dro"%rbon"on"entr%tion, p7 v%lue h%s been investi#%ted! >%n#muir%nd reundli"h isotherm e8u%tions ere emplo.ed to8u%nti*. the %dsorption e8uilibrium!

2. Experimental

2.1. Hydrocarbon-Water Emulsion

he dispersed petroleum h.dro"%rbon ph%se used %sdiesel oil supplied b. ue 5omp%n., hi"h h%s %n%pproim%ted spe"i*i" #r%vit. o* 0!'& %t 2E K5! istilled%ter %nd "ommer"i%l sur*%"t%nt riton LM-100 (supplied b. >ob%"hemie, <ndi%) ere used! he h.dro"%rbon-emulsion in %ter %s prep%red b. miin# riton LM-100ith %ter *irst *or 10 minutes then dispersed the

h.dro"%rbon ph%se into the %ter to #ive the desired"on"entr%tion o* h.dro"%rbon! he solution %s then mied%t 2EK5 in % be%Fer %t hi#h stirrin# r%te *or one hour toensure uni*orm droplet sie!

2.2. Activated Carbon

4 "ommer"i%l %"tiv%ted "%rbon *rom N?+< Nederl%nd!! t.pe N+ 54+?N 4 0!E-1!E %s used %nd is%bbrevi%ted %s N+! he "h%r%"teris%tions o* the N+ %re3E0 F#/m3 %pp%rent densit., 13 t G %sh "ontent, 10 t Gmoisture "ontent (%s p%"Fed) %nd min! 'E0 iodine number!4ll %n%l.ses %re b%sed on N?+< t%nd%rd est ethods

(N)! he N+ %s used ith %nd ithout modi*i"%tion!5hemi"%l modi*i"%tion ith nitri" %"id %s used toenh%n"e the %dsorption "%p%"it. o* the N+! o this purpose % "ert%in %mount o* N+ %s %shed sever%l timesith distilled %ter! N+ %s dried in %n oven %t 10E

o5

overni#ht %nd then so%Fed in 1 nitri" %"id solution *or 2&hr ith "onst%nt sh%Fin# in %n orbit%l sh%Fer %t % "onst%nttemper%ture o* 2E

o5! urin# this time the r%tio o* solution

to N+ %s *ied to 1 > per E #! ubse8uentl. the %"idsolution %s removed %nd the N+ %s %shed sever%ltimes ith distilled %ter, de"%nted %nd dried overni#ht %t10E

o5%nd then stored in % v%"uum desi""%tor! he %"idi"

modi*ied N+ is %bbrevi%ted %s N4-N+!

2.3. Bentonite Clay

entonite "l%. %s supplied *rom the phin illin#t%tion 5omp%n. (4le%ndri% *ree one, #.pt)! N%tur%l bentonite h%s lo %lumin% "ontent %nd "ont%ins hi#h sili"%"ontents %nd its "hemi"%l "omposition (G): i?2 I EE!12,4l2?3 I 16!1&, e2?3 I '!2E, 5%? I 1!1, #? I 2!'6, N%2? I 1!&1, 2? I 1!0E %nd i?2 I 1!1'!he %n%l.sis %sm%de in 5entr%l et%llur#i"%l +ese%r"h <nstitute in4le%ndri%! o produ"e or#%ni" bentonite "l%. (or#- bentonite), the sur*%"t%nt used %s "et.ltrimeth.l%mmonium "hloride (545), pur"h%sed *rom i#m%-

4ldri"h! <niti%ll., % dispersion o* bentonite (& t G) indistilled %ter %s prep%red under %#it%tion *or 3 hr! 4 pre-

dissolved e8uiv%lent %mount o* sur*%"t%nt (%""ordin# to the"%tion e"h%n#e "%p%"it. o* bentonite) %s slol. %dded tothe bentonite suspension %nd the miture %s stirred *or %*urther 2& hr! 4 produ"t or#%no"l%. (or#-bentonite) %s%shed sever%l times ith distilled %ter to remove e"esssur*%"t%nts, *iltered %nd dried in %n oven %t E0 - 60 K5 *or&' hours, "rushed %nd sieved, %nd then stored in % v%"uumdesi""%tor!

2.. Characteri!ations o" the Adsorbents

he spe"i*i" sur*%"e %re% %nd "%tion e"h%n#e "%p%"it.(55) o* the unmodi*ied %nd modi*ied %dsorbents eredetermined usin# e%rsO method C22D, %nd the %mmonium%"et%te method C23D, respe"tivel.! 4 potentiometri" titr%tionmethod C2&D %s used to determine the p7 o* point o* ero"h%r#e (p7 p")!

2.#. Adsorption $rocedure

4ll eperiments ere "%rried out %t %mbient temper%turein b%t"h mode! Prior to e%"h eperiment % predetermined%mount o* %dsorbent %s %dded to % "oni"%l *l%sF %nd *illedith % 200 ml o* h.dro"%rbon-%ter emulsion h%vin# thedesired p7 %nd stirred ith "onst%nt %#it%tion (200 rpm)usin# %n orbit%l sh%Fer! he desired initi%l p7 %s %d$usted%ddin# % N%?7 or 72?& solution! he *l%sF "ont%inin# thes%mple %s ithdr%n *rom the sh%Fer %t % set timeinterv%l! he s%mples ere *iltered throu#h *ilter p%pers(@h%tm%n No! 3)! he eperiments ere "%rried out underdi**erent eperiment%l "onditions su"h %s "ont%"t time, p7,initi%l "on"entr%tion o* h.dro"%rbon %nd %dsorptionisotherm! he %mount o* h.dro"%rbon removed %sdetermined!

2.%. Hydrocarbon Analysis

he tot%l h.dro"%rbon "ontent %s me%sured %""ordin#to the st%nd%rd method 4- 3921! he s%mples ere%"idi*ied to % p7 H 2 b. %ddin# "on"entr%ted 72?&!7.dro"%rbons ere etr%"ted *or 1 min b. vi#oroussh%Fin# ith the s%me volume o* 1,1,2-tri"hlorotri*luoroeth%ne! here%*ter, the h.dro"%rbon-"ont%inin# solvent l%.er %s sep%r%ted, eluted throu#h %"olumn "ont%inin# 4l2?3 %nd deh.dr%ted ith N%2?&! heetr%"ted h.dro"%rbons ere me%sured b. in*r%redspe"tros"op. (?54-220 7?+<4)!

3. Results and iscussion

4dsorption h%s been idel. studied %s %n e**e"tivete"hni8ue *or removin# or#%ni" "ont%min%ted %ter! heremov%l e**i"ien". is in*luen"ed b. v%rious *%"tors su"h %s%dsorbent t.pes, %dsorbent modi*i"%tions, initi%l or#%ni""on"entr%tion %nd p7 v%lue! %t"h mode %dsorptioneperiments %re des"ribed %imed %t obt%inin# the optimum"onditions *or remov%l o* the petroleum h.dro"%rbon *rom

oil-%ter emulsion! he "h%r%"teristi"s o* the unmodi*ied%nd modi*ied %dsorbents su"h %s spe"i*i" sur*%"e %re%,



16& m%n 4bdel%h%b m%: odi*ied 4"tiv%ted 5%rbon %nd entonite sed to 4dsorb Petroleum 7.dro"%rbonsmulsi*ied in 48ueous olution

"%tion e"h%n#e "%p%"it. %nd point o* ero "h%r#e eredetermined!

3.1. Characteristics o" Adsorbents

he "h%r%"teristi"s o* N+, N4-N+, bentonite %nd or#-

bentonite di**ered (%ble 1)! he spe"i*i" sur*%"e %re% o* N4-N+ %s %bout 13! G loer th%n th%t o* N+, hi"hindi"%tes th%t 7N?3 modi*i"%tion de"re%se the spe"i*i"sur*%"e %re% o* the %"tiv%ted "%rbon! his "ould %rise *rom pore blo"F%#e b. %dsorbed nitri" %"id mole"ules! e"%useo* its sm%ll mole"ul%r sie, nitri" %"id "%n e%sil. %""ess the pore stru"ture o* the %"tiv%ted "%rbon! he 55 v%lue o* N4-N+ (1!&2 me8/#) %s 2 times hi#her th%n th%t o* N+!he di**eren"e indi"%tes th%t the nitri" %"id mi#ht introdu"e%"idi" sur*%"e oides on the "%rbon sur*%"e hi"h "%used*orm%tion o* % l%r#e number o* o.#en-"ont%inin#*un"tion%l #roups! <t %s %lso reported th%t modi*i"%tion o*%"tiv%ted "%rbon ith 7N?3 in"re%sed the 8u%ntit. o*%"idi" *un"tion%l #roups on %"tiv%ted "%rbon sur*%"e %so.#en #roups %nd stru"tures "ont%inin# N? bonds th%t"h%n#e the sur*%"e "hemistr. %nd "%n %lter the sur*%"e %re%%nd porosit. o* the ori#in%l %"tiv%ted "%rbon C1ED! henumber o* %"idi" *un"tion%l #roups is "losel. rel%ted to the"%p%"it. o* %"tiv%ted "%rbon to %dsorb h.dro"%rbon"ompounds; thus N4-N+ should h%ve % #re%ter %**init.*or h.dro"%rbon "ompounds th%n N+!

&able 1. Characteristics of unmodified and modified adsorbents

!arameter "R#"A$

"R#bentonite

or%$

bentonite

pe"i*i" sur*%"e%re%, m2/#

' E6!' 2!1 '!

55, me8/# 0!6' 1!&2 0!E3 0!&1

p7 p" !'E 6!& !3 6!6

he 55 o* or#-bentonite %s 0!&1 me8/# loer th%nth%t o* bentonite (0!E3 me8/#)! his result %s epe"ted %s% result o* %n ion e"h%n#e ith the 8u%tern%r. %mmonium#roup (545) o* the modi*ied bentonite! he 545modi*i"%tion h%s %lso de"re%sed the spe"i*i" sur*%"e %re% o*the or#-bentonite (%ble 1)! 7oever, this result %sunepe"ted sin"e modi*i"%tion o* the "l%. should ide%ll.

in"re%se the b%s%l sp%"in# o* the "l%. interl%.er hi"himplies more %dsorption sites %re %""essible! ?ne possiblere%son *or the observed redu"tion in the sur*%"e %re% o* or#- bentonite m%. rel%te to introdu"e the l%r#e sur*%"t%ntmole"ules in the "l%. interl%.er! ependin# on the t.pe o*the sur*%"t%nts, the intern%l pore sp%"es m%. be predomin%ntl. o""upied b. lon#-"h%ined sur*%"t%nts! hism%. le%d to % de"re%se in the spe"i*i" sur*%"e %re% o* or#- bentonite "omp%red ith the "l%. st%rtin# m%teri%l(bentonite)! his su##ests th%t %dsorption is m%inl.o""urrin# on the etern%l sur*%"e o* the or#-bentonite,hen"e the "orrespondin# lo sur*%"e %re% obt%ined!

ur*%"e "h%r#e in the %8ueous s.stems depends on%"tivities o* potenti%l-determinin# ions (7Q %nd ?7R) %nd

ele"trol.te "on"entr%tions! ependin# on suspension p7,the %dsorbent sur*%"es "%n be%r net ne#%tive, or positive, orno "h%r#e! he p7 here the net tot%l p%rti"le "h%r#e isero is "%lled the point o* ero "h%r#e (p7 p"), hi"h is oneo* the most import%nt p%r%meters used to des"ribe v%ri%ble"h%r#e sur*%"es! <* the p7 o* % suspension is %bove its p7

p"

the suspension sur*%"e ill h%ve % net ne#%tive "h%r#e %nd predomin%ntl. ehibit %n %bilit. to e"h%n#e "%tions (one positive ion b. %nother), hile the suspension ill m%inl.ret%in %nions (ele"trost%ti"%ll.) i* its p7 is belo its p7 p" (one ne#%tive ion *or %nother)! <n suspension, rese%r"hersh%ve #ener%ll. relied on potentiometri" titr%tion, hi"h%ssesses "h%n#es in sur*%"e potenti%l ith "h%n#es in the%"tivities o* 7Q %nd ?7R, to determine the point o* ero(p7 p")!

he e**e"t o* the modi*i"%tion %s investi#%ted b. potentiometri" titr%tion o* the %"tiv%ted "%rbon %nd bentonite be*ore %nd %*ter modi*i"%tion! he potentiometri"

titr%tion d%t% ere used in the determin%tion o* the point o*ero "h%r#e (p7 p")! 4""ordin# to modi*. the sur*%"e potenti%l ith "h%n#es in the %"tivities o* 7Q %nd ?7R, the p7 p" v%lues o* N+ %nd N4-N+ %re !'E %nd 6!&,respe"tivel. (%ble 1)! 4t p7 more or less p7 p", thesur*%"e "h%r#e o* %"tiv%ted "%rbon is ne#%tive or positive,respe"tivel.!

imil%r beh%vior %s *ound %t p7 p" v%lue *rom !3 to6!6 *or bentonite %nd or#-bentonite, respe"tivel.! he p7 p" %s %**e"ted b. ori#in%l bentonite, but most %**e"ted b. 545 modi*i"%tion! he prob%ble re%son *or thisdi**eren"e %s %ttributed to the introdu"ed 8u%tern%r.

%mmonium #roup o* the modi*ied bentonite ith ne#%tivesur*%"e "h%r#e!

3.2. E""ect o" Contact &ime

<n order to est%blish the e8uilibrium time *or m%imum%dsorption o* h.dro"%rbon *rom oil-%ter emulsion, the petroleum h.dro"%rbon %dsorbed on the %dsorbents(bentonite, or#-bentonite, N+, N4-N+) ere studied %s% *un"tion o* "ont%"t time, hi"h v%ried *rom 0!E to 10 hr!he stud. %s "%rried out ith 2 # %dsorbent/> usin# initi%lh.dro"%rbon "on"entr%tion o* 100 m#/> %t %n initi%l p7 I !he rel%tionship beteen the %mounts o* h.dro"%rbon

%dsorbed per #r%m o* %dsorbent qe %s % *un"tion o* the"ont%"t time %s reported in %ble 2! 4lso, i#! 1 shos theresults o* the h.dro"%rbon remov%l %s % *un"tion o* "ont%"ttime! <t %s observed th%t the %dsorption o* h.dro"%rbonin"re%sed ith in"re%sin# "ont%"t time! 7oever, theremov%l o* h.dro"%rbons b. %dsorption pro"ess on "l%.s%nd %"tiv%ted "%rbons re%"hed e8uilibrium in the *irst period o* the pro"ess %*ter 3 hr %nd & hr, respe"tivel.! he%dsorption pro"ess is r%pid %t the be#innin# o* the pro"essdue to the %dsorption o* h.dro"%rbon onto the sur*%"e siteso* %dsorbents! @ith in"re%sin# "ont%"t time no dr%m%ti"%ll.enh%n"ement %s observed! <t is obvious th%t in the *ield o*e"onomi"%l "onsider%tion this prolon#ed time is not

pr%"ti"%l or suit%ble!he %dsorption "%p%"it. o* the or#-bentonite is hi#her



4meri"%n Journ%l o* nvironment%l Prote"tion 2013; 2(6): 161-169 16E

th%n the 4N-N+! 4lso, the s%me trend is beteen bentonite %nd N+! <t m%. be %ttributed to th%th.dro"%rbon droplets %re usu%ll. l%r#er th%n the pores o*%"tiv%ted "%rbon, the "%rbon is 8ui"Fl. blinded b. oildroplets resultin# in plu# or *ill the pores! 7.dro"%rbon%dsorption "%p%"ities o* %bout &', 3'!E, &2 %nd 30 m#/#ere observed durin# the *irst & hr ith or#-bentonite, bentonite, N4-N+ %nd N+, respe"tivel. (%ble 2)!

&able 2. Effect of contact time and initial pH on the hydrocarbon adsorbed

per unit ei!ht of adsorbent

&ontact

time' hr

'e ( m%(%

"R# "A$"R# bentoniteor%$

bentonite

0 0 0 0 0

0!2E 12!E 21!E 1' 20

0!E 16!E 2!E 2E 31!E

1 21!E 32!2 30 3'!E

1!E 2&!E 3E 32 &2

2 2 3!E 3E &E

3 2'!E &0!E 3'!3 &!'E

& 30 &2 3'!E &'

6 29!E &2!E 39!E &'!2

' 30!'E &3!2E 39!2E &'!9

10 31 &3!E 39!E &9

p)

2!E 30!E 2E 20 3E

E 29!E 32!E 2!E &0!E

30 &2 3'!E &'

9 29!E &0!E 39!E &9!9

11 30!E 3'!E &0!E &'!E

)i*ure 1. Effect of the contact time on the adsorption of hydrocarbon fromoil"ater emulsion

4s shon in i#! 1, the h.dro"%rbon %dsorption "%p%"it. usin# N4-N+ is hi#her th%n N+ ith %ll di**erent"ont%"t time! his di**eren"e o* %dsorption "%p%"it. indi"%tes th%t the 7N?3 modi*i"%tion "%used *orm%tion o* %l%r#e number o* o.#en- %nd nitro#en-"ont%inin#*un"tion%l #roups %nd h%vin# l%r#e %mounts o* the sur*%"e%"idi" #roups hi"h "%n e"h%n#e their %"tive sites ith theh.dro"%rbon "ompounds present in %8ueous solution! henumber o* %"idi" *un"tion%l #roups is "losel. rel%ted to the"%p%"it. o* %"tiv%ted "%rbon to %dsorb h.dro"%rbon"ompounds; %s % result N4-N+ %""essible hi#her%dsorption "%p%"it. *or h.dro"%rbons th%n N+!

he hi#hest %dsorption "%p%"it. o* or#-bentonitemodi*ied b. 545 (&' m#/#) m%. be %ttributed to the"h%n#e o* the sur*%"e properties *rom h.drophili" toh.drophobi" "h%r%"ter! his is %n indi"%tion o* theinter"%l%tion o* the %mmonium 8u%tern%r. "%tion o* thesur*%"t%nt in the "l%.s! imil%r results ere obt%ined b.

?liveir% et %l! C3D *or the "l%. tre%ted ith 545! <t "%n be"on"luded th%t or#-bentonite is more %ppropri%te m%teri%ls*or the remov%l o* h.dro"%rbon *rom oil-%ter emulsions!

3.3. E""ect o" pH

p7 is one o* the most import%nt p%r%meters hile%ssessin# the %dsorption "%p%"it. *rom %8ueous solution!he p7 o* the s.stem "ontrols the %dsorption "%p%"it. dueto its in*luen"e on the sur*%"e properties o* the %dsorbent!here*ore, %dsorption *rom solution "%n be hi#hl. p7dependent! he in*luen"e o* p7 in the r%n#e o* 2!E - 11 %sstudied Feepin# %ll other p%r%meters "onst%nt (h.dro"%rbon

"on"entr%tion I 100 m#/l; "ont%"t time I & hr, %dsorbentdos%#e I 2 #/>)! he p7 dependen"e o* %mounts o*h.dro"%rbon %dsorbed per #r%m o* %dsorbent 8e onto theunmodi*ied %nd modi*ied %dsorbents%re reported in %ble 2!he eperiments "%rried out usin# N+ sho th%t there%s no si#ni*i"%nt "h%n#e in the remov%l o* h.dro"%rbonover the entire p7 r%n#e (i#ure 2)!

)i*ure 2. Effect of pH on the adsorption of hydrocarbon from oil"ater

emulsion

0

20

40

60

80

100

0 2 4 6 8 10

R e m o v a l , %

Contact Time, hr

NRS

NA-NRS

bentonite

org-bentonite0

20

40

60

80

100

2 4 6 8 10 12

R e m o v a l ,

%

Initial !

NRS NA-NRS

bentonite org-bentonite



166 m%n 4bdel%h%b m%: odi*ied 4"tiv%ted 5%rbon %nd entonite sed to 4dsorb Petroleum 7.dro"%rbonsmulsi*ied in 48ueous olution

his result indi"%tes th%t neither 7Q nor ?7 ions "ouldin*luen"e the %dsorption "%p%"it. o* the h.dro"%rbon"ompounds usin# N+! <n other ords, the %dsorption o*h.dro"%rbon "ompounds on N+ does not involve %n ion-e"h%n#e me"h%nism! 7oever, it stron#l. %**e"ted itsremov%l hen the modi*ied "%rbon (N4-N+) %s %pplied!he h.dro"%rbon remov%l in"re%sed ith in"re%sin# p7usin# N4-N+! he hi#hest %dsorption "%p%"it. %s%"hieved %t p7 I b. N4-N+ (&2 m#/#) %nd it sli#htl.de"e%sed ith in"re%sin# the p7 up to 11! he in"re%se o*the h.dro"%rbon %dsorption "%p%"it. ith in"re%sin# p7 isdue to the *%"t th%t the sur*%"e *un"tion%l #roups o* theoidied "%rbons (4N-N+) ionie le%din# to #re%terretentive poer to%rds the h.dro"%rbon "ompounds!

oth bentonite %nd or#-bentonite shoed simil%r beh%viour %t lo p7 (loer th%n p7 ), %lthou#hh.dro"%rbon remov%l ith or#-bentonite is "onsider%bl.hi#her th%n unmodi*ied bentonite! he h.dro"%rbon

remov%l ith or#-bentonite in"re%sed ith in"re%sin# p7%nd re%"hed % pl%te%u o* m%imum v%lue (99!' G) henthe initi%l p7 %s '! 7oever, the %dsorption o*h.dro"%rbon in"re%sed *or bentonite ith in"re%sin# p7*rom 2!E to p7 (&0 G to G, respe"tivel.) %*terthou#htsli#htl. in"re%sed ith in"re%sin# p7 to 11 ('0!E G)! <t "%n be seen th%t the sur*%"e "h%r#e o* bentonite is % stron#*un"tion o* the p7! he better %dsorption %bilit. o* or#- bentonite m%. be rel%ted to th%t the 8u%tern%r. %mmonium%s %tt%"hed to the "l%. sur*%"e %nd p%rti%ll. neutr%liedthe ne#%tive "h%r#e o* the bentonite! he or#-bentonite %sless ne#%tive "h%r#ed %nd be"omes h.drophobi" in

"h%r%"ter due to the sur*%"t%nt e"h%n#e th%n bentonite!he less ne#%tive "h%r#ed sur*%"e redu"ed the repulsion beteen or#-bentonite %nd h.dro"%rbon "ompounds hi"h%re bene*i"i%l to the h.dro"%rbon %dsorption on the or#- bentonite sur*%"e throu#h h.drophobi" bondin# beteenh.dro"%rbon mole"ules in oil-emulsion %ter %nd %lF.l"h%in o* 545! <t is be"%use the lon# "h%in %lF.lC573(572)1E N(5l)(573)3D o* the 8u%tern%r. %mmoniumm%. provide % more h.dro"%rbon "ompounds %dsorptionsur*%"e to improve the per*orm%n"e o* the or#-bentonite! <nthis "%se, h.dro"%rbon "ompounds "%n be inter"epted b.lon# liner %lF.l "h%in mu"h more e%sil., hi"h is bene*i"i%lto m%Fe %dsorption o""ur smoothl.!

3.. E""ect o" Initial Hydrocarbon Concentration

i#ure 3 summ%rises the e**e"t o* the initi%l h.dro"%rbon"on"entr%tion in the r%n#e o* 2E - &00 m#/> onh.dro"%rbon %dsorption *rom oil-%ter emulsion b.unmodi*ied %nd modi*ied %dsorbents %t % %dsorbent dos%#eo* 2 #/>, p7 I %nd % "ont%"t time o* & hr! he resultsshoed th%t the s%me trend o* %ll %dsorbents th%t, the%dsorption o* h.dro"%rbon de"re%se ith in"re%sin# the"on"entr%tion o* %dsorb%te! he h.dro"%rbon remov%l r%teo* %ll %dsorbents %re v%ri%ble *or %bout E - E1 G, 'E - 6EG,90 - 6 G %nd 99!3 - &!E G b. N+, bentonite, 4N-N+

%nd or#-bentonite, respe"tivel.!

)i*ure 3. Effect of initial hydrocarbon concentration on the adsorption of

hydrocarbon from oil"ater emulsion

hese results ere epe"ted %nd the epl%n%tion o* theseresults is th%t the %dsorption o* di**erent "on"entr%tion o*h.dro"%rbon onto the "onst%nt %dsorption sites o* %dsorbent%nd %t % "onst%nt time o* %dsorption! 7oever, %t lo"on"entr%tion o* h.dro"%rbon, the r%tio beteen theh.dro"%rbon "ompounds %nd the %dsorption sites is ne%rl.simil%r! 4t % hi#h "on"entr%tion o* h.dro"%rbon the r%tio beteen h.dro"%rbon "ompounds %nd the %dsorption sitestend to in"re%se! 4""ordin#l., the number o* *ree%dsorption sites tends to de"e%se, under this "ondition theremoved %mount o* h.dro"%rbon tends to de"e%se!urthermore, one "%n re%lie *rom the d%t% in i#ure 3 th%t

or#-bentonite is more potent th%n other %dsorbents *orremov%l o* h.dro"%rbon *rom oil-%ter emulsion! heepl%n%tion o* these results is th%t 545 modi*ied bentonite "ont%ins % lon# "h%in %lF.l hi"h m%. enh%n"ethe inter%"tion beteen h.dro"%rbon "ompounds %nd or#- bentonite mole"ules!

3.#. Adsorption Isotherm

4dsorption isotherms ere determined *or %dsorbentdos%#es in the r%n#e o* 0!E - 1E #/> *or the unmodi*ied %ndmodi*ied %dsorbents! he initi%l h.dro"%rbon "on"entr%tion%s 100 m#/> %t p7 %nd the s%mples ere %#it%ted *or &

hr! 4s shon in i#! &, the remov%l o* h.dro"%rbonin"re%sed #r%du%ll. *rom 26, &, 3', 62 G up to '&, 99, 93,100 G usin# N+, N4-N+4, bentonite %nd or#-bentonite,respe"tivel.! 7oever, these results ere epe"ted sin"e %sthe dose o* %dsorbent in"re%ses, the number o* %dsorbentsites in"re%ses! hese %mounts %tt%"h more ions to theirsur*%"es! imil%r results ere reported here m%n. t.pes o*m%teri%ls ere used %s %dsorbents C2ED! 7oever, in p%rti"ul%r *or or#-bentonite here onl. % "on"entr%tion o* '#/> is re8uired, to redu"e the h.dro"%rbon *rom %n initi%l"on"entr%tion o* 100 m#/> to non-dete"t%ble levels! <n%ddition, the in"re%sin# in the %dsorbent dos%#es more th%n

' #/> ith other %dsorbents le%ds to no si#ni*i"%nth.dro"%rbon remov%l! he epl%n%tion o* these results is

0

20

40

60

80

100

0 100 200 "00 400

R e m o v a

l , %

Initial h#$rocarbon concentration, mg%&

NRS NA-NRS

bentonite org-bentonite




th%t %t lo dos%#e o* %dsorbent the %dsorption sites %rediluted in the solution %nd %v%il%ble *or inter%"tion ithh.dro"%rbon *rom %ter here%s %t hi#h "on"entr%tion o*%dsorbent no si#ni*i"%nt remov%l due to possible%##re#%tion o* %dsorbent in the %ter! 4""ordin#l., the%v%il%bilit. o* *ree %dsorption sites is limited *or remov%l o*h.dro"%rbon! 5onse8uentl., the "on"entr%tion o* the%dsorption site in %ter should be optimied!

)i*ure . Effect of adsorbent dosa!e on the adsorption of hydrocarbon

from oil"ater emulsion

4dsorption isotherms *or the *our %dsorbents ereepressed usin# >%n#muir isotherm b. plottin# 1/qe %#%inst1/C e (%s shon in i#! E) %nd reundli"h isotherm b. plottin# lo# qe %#%inst lo# C e (%s shon in i#! 6)! heresults in i#ures E %nd 6 %re "orrel%ted b. the >%n#muir

%nd the reundli"h e8u%tions (see e8u%tions 1, 2 %nd E)ith the resultin# p%r%meters listed in %ble 3! heisotherms .ield "onst%nts hose v%lues epress the %**init.o* %dsorb%te *or the sur*%"e o* %dsorbent! or pr%"ti"%lre%sons the %dsorption "%p%"it. o* %n %dsorbent should be%s hi#h %s possible! 4pplin# the >%n#muir isotherm model,it %s observed th%t the (a) v%lue *rom the >%n#muirisotherm %s 2 times l%r#er *or N4-N+ %nd or#-bentoniteth%n *or N+ %nd bentonite, respe"tivel. (%ble 3)!urthermore, the v%lues o* r "%l"ul%ted b. the 8! (E) %re beteen 0 %nd 1 indi"%tin# % so-"%lled *%vour%ble%dsorption C21D! he hi#her v%lues o* k (%ppl.in# the

reundli"h model) indi"%tin# more sorption, so the resultssho th%t or#-bentonite o**ered % m%imum %dsorption"%p%"it. "omp%red ith other %dsorbents! 4lso, the%dsorption "%p%"it. o* N4-N+ is hi#her th%n th%t o* N+%nd bentonite! <n %ddition, 1/n v%lue *or or#-bentonite is0!&'! he sm%ller v%lues o* 1/n, the hi#her the %**init. beteen %dsorb%te %nd %dsorbent! or bentonite %nd N+(%ble 3) the (1/n) v%lues %re l%r#er th%n 1, indi"%tin# th%tthe %dsorption "%p%"it. o* bentonite %nd N+ ill be hi#h%t hi#h %dsorbent dos%#es but ill r%pidl. diminish %t loerdos%#es o* %dsorbent! <t "%n be "on"luded th%t, the %"idtre%tment usin# 7N?3 is % #ood method to enh%n"e the"%p%"it. o* %"tiv%ted "%rbon to %dsorb h.dro"%rbon, but themodi*i"%tion o* bentonite ith 545 ehibited % hi#hest"%p%"it. to %dsorb h.dro"%rbon *rom oil-%ter emulsion!

)i*ure #. #an!muir isotherm adsorption of hydrocarbon from oil"ater

emulsion

he %dsorption d%t% obt%ined b. >%n#muir isothermsmodel ith loer "orrel%tion "oe**i"ient (+2 I 0!'9&9)usin# N+ hile %ll the %dsorption d%t% %n%l.ed b. thereundli"h isotherms model "on*orm best to *olloin#reundli"h e8u%tion ith #ood "orrel%tion "oe**i"ients (+2I 0!931& - 0!99EE)! 7en"e, the >%n#muir e8u%tion does not*it the eperiment%l results ver. ell! ?n the "ontr%r.,reundli"h isotherm is best to des"ribe the %dsorption o*h.dro"%rbons *rom oil-%ter emulsion b. the %ll %dsorbents!

)i*ure %. $reundlich isotherm adsorption of hydrocarbon from oil"ater

emulsion

*. &onclusions

he results sho th%t the studied %dsorbents "%ne**i"ientl. %dsorbed the petroleum h.dro"%rbon *rom oil-%ter emulsion in %ter! he results o* this stud. "le%rl.demonstr%te the import%n"e o* "hoosin# the optimum%dsorption p%r%meters to obt%in hi#h %dsorption r%tes o* theh.dro"%rbon, hi"h is essenti%l *or %n. pr%"ti"%l%ppli"%tion o* %dsorption pro"ess! he sur*%"e modi*i"%tion

o* bentonite %nd %"tiv%ted "%rbon redu"ed the spe"i*i"sur*%"e %re%, 55 %nd p7 p"! he %dsorption "%p%"it. o* the

0

20

40

60

80

100

0 " 6 ' 12 1(

R e m o v a l , %

A$)orbent $o)age, g%&

NRS

NA-NRS

bentonit

org-bentonit

0

0*04

0*08

0*12

0*16

0*2

0 0*( 1 1*(

1 + e

1%Ce

NRS

NA-NRS

bentonit

org-bentonit

0

0*(

1

1*(

2

2*(

0 0*( 1 1*( 2

& o g + e

-

&og Ce

NRS NA-NRS

bentonit org-bentonit



16' m%n 4bdel%h%b m%: odi*ied 4"tiv%ted 5%rbon %nd entonite sed to 4dsorb Petroleum 7.dro"%rbonsmulsi*ied in 48ueous olution

*our %dsorbents %s %"hieved in the *olloin# order: or#- bentonite = N4-N+ = bentonite = N+! he h.dro"%rbon%dsorption "ondition depends stron#l. on p7 %nd the initi%loil "on"entr%tion! he time to %tt%in e8uilibrium is be.ond3 %nd & hr usin# "l%.s %nd %"tiv%ted "%rbons, respe"tivel.,here the h.dro"%rbon %s removed to % non-dete"t%blelevel (n!d!) ith ' #/> o* or#-bentonite! he %dsorption

isotherms d%t% ere ell *itted ith the reundli"h model!<t "%n be "on"luded th%t, the nitri" %"id modi*i"%tion is %#ood method to enh%n"e the "%p%"it. o* %"tiv%ted "%rbon to%dsorb h.dro"%rbon, but the modi*i"%tion o* bentonite ith545 ehibited % hi#hest %dsorption "%p%"it. %nd "%n be"onsidered %s % promisin# %dsorbent *or the remov%l o*h.dro"%rbon *rom oil-%ter emulsion!

&able 3. Adsorption isotherms constants for hydrocarbon removal from oil"ater emulsion after % hr contact time

Adsorbent+an%muir ,reundlich

a

m%(%

b

+(m%r R 2

+

m%(%1(n R 2

N+ 31!2E 0!011 0!&39 0!'9&9 0!19' 1!29' 0!931&

N4-N+ 6E!9 0!10& 0!0'' 0!9'9 6!2&6 0!69' 0!99EE

entonite 63!291 0!13 0!06'1 0!96E6 0!'01 1!13' 0!96E3

or#-bentonite 123!&6 0!16E 0!0E1 0!99E 21!'63 0!&'1 0!9'E

Re-erences

C1D spino%-STme, 7! %nd >in, ! @!: ?il %ter sep%r%tion,usin# % h.drophili" pol.sul*onepol.vin.lp.rrolidoneultr%*iltr%tion membr%ne! +ev! <nt! 5ont%m! 4mbient!, 200&,20 (2), '2!

C2D 5%v%l"%nti, J! ! ! >!; 4breu, 5! 4! !; 5%rv%lho, ! N!;obrinho, ! 4! !; en%"hour, ! %nd %r%Un%, ?! !:+emov%l o* e**luent *rom petro"hemi"%l %ste%ter b.%dsorption usin# or#%no"l%.! Petro"hemi"%ls, riveF P%tel

(d!), <N 9'-9E3-E1-0&11-, 2012, 229&!C3D ?liveir%, S! 5!; ot%, ! !; ilv%, ! !; +odri#ues, ! S!

! %nd >%borde, 7! !: Per*orm%n"e o* n%tur%l sodium "l%.tre%ted ith %mmonium s%lt in the sep%r%tion o* emulsionoil in %ter! r%ili%n Journ%l o* Petroleum %nd S%s, 2012, 6(&), 111'3!

C&D

ol%, !; %rimi, S! %nd %lehi, !: odelin# o*%dsorption bre%Fthrou#h beh%viors o* oil *rom s%lt. %tersin % *ied bed o* "ommer"i%l or#%no"l%./s%nd miture!5hemi"%l n#ineerin# Journ%l, 2013, 21', 116 12E!

CED

%ns%l !; von 4rnim !; te#m%ier ! %nd Pl%n"F 7!: **e"to* *ibrous *ilter properties on the oil-in-%ter-emulsionsep%r%tion %nd *iltr%tion per*orm%n"e! 7%%rdous %teri%ls,

2011, 190 (1-3), &E-E0!

C6D u, V! %nd 5hun#, ! ! >!: 5o%#ul%tion o* oil in %terusin# s%dust, bentonite %nd "%l"ium h.droide to *orm*lo%tin# sheets! 4ppl! 5l%. "i!, 2011, E3, 63&6&1!

CD

erm%n, V! %nd %mir, 4!: ineti"s o* dropletsOsediment%tion in % "ontinuous #r%vit. settler! 5hem! n#!"i!, 2003, E', 20'9-2102!

C'D re#n%rd, ! P!-4!; 7Whener, P!; 7Xner, 4! %nd Ye.er, J!:e#r%d%tion o* e%thered diesel *uel b. mi"roor#%nisms*rom % "ont%min%ted %8ui*er in %erobi" %nd %n%erobi"mi"ro"osms! nviron! oi"ol! 5hem!, 1996, 1E, 299-30!

C9D omeni"o, ! !; Siudi"e, 4! >!; i"h%ud, >!; %itt%, !%nd runi, !: iesel oil %nd P5-de#r%din# ps."hrotrophi" b%"teri% isol%ted *rom 4nt%r"ti" se%%ters (err% Nov% %.,

+oss e%)! Pol%r +ese%r"h, 200&, 23 (2), 1&11&6!

C10D @%t"h%r%sin#, !; 4n#F%thun.%Ful, P! %nd 5h%v%de$, !:iesel oil remov%l *rom %ter b. *roth *lot%tion under lointer*%"i%l tension %nd "olloid%l #%s %phron "onditions!ep%r%tion %nd Puri*i"%tion e"hnolo#., 200', 62, 11'12!

C11D @%n#, !; 5hu, >!; 5hen, @!: oulin#-resist%nt "ompositemembr%nes *or sep%r%tion o* oil-in-%ter mi"roemulsions!5hinese J! 5hem! n#!, 2006, 1& (1), 3&E!

C12D

4demilu.i, ! !; 4m%di, ! 4! %nd 4m%F%m%, N! J!:4dsorption %nd tre%tment o* or#%ni" "ont%min%nts usin#%"tiv%ted "%rbon *rom %ste Ni#eri%n %mboo! J! 4ppl! "i!

nviron! %n%#e!, 2009, 13 (3), 39 - &!C13D 4.ot%muno, ! J!; o#b%r%, +! !; ?#%$i, ! ?! ! %nd

Probert, ! !: Petroleum "ont%min%ted #round-%ter:+emedi%tion usin# %"tiv%ted "%rbon! 4pplied ner#., 2006,'3 (11), 12E'126&!

C1&D ?Fiel, !; l-%.ed, ! %nd l-%d., ! V!: re%tment o*oil-%ter emulsions b. %dsorption onto %"tiv%ted "%rbon, bentonite %nd deposited "%rbon! #.pti%n Journ%l o*Petroleum, 2011, 20, 91E!

C1ED 4hn, 5! !; im, V! !; @oo, ! 7! %nd P%rF, J! !:+emov%l o* "%dmium usin# %"id-tre%ted %"tiv%ted "%rbon inthe presen"e o* nonioni" %nd/or %nioni" sur*%"t%nts!7.dromet%llur#., 2009, 99, 209213!

C16D 5hen, J! P! %nd @u, !: 4"id/b%se-tre%ted %"tiv%ted "%rbons:"h%r%"teri%tion o* *un"tion%l #roups %nd met%l %dsorptive properties! >%n#muir, 200&, 20, 223322&2!

C1D 4mud%, ?! !; Si%, 4! 4! %nd ello, <! 4!: +emov%l o*he%v. met%l *rom industri%l %ste%ter usin# modi*ied%"tiv%ted "o"onut shell "%rbon! io"hem! n#! J!, 200, 36,1&1'1!

C1'D %sooleh, ! !; %#ir, !; %mii*%r, ! %nd Nem%ti, 4!:4dsorption o* petroleum h.dro"%rbons on or#%no"l%.! Journ%lo* 4pplied 5hemi"%l +ese%r"hes, 2010, & (1&), 1923!

C19D o%ed, 7! %nd ir%r%#h%v%n, !: Pr%"ti"e periodi"%l o*h%%rdous! oi" %nd +%dio%"tive @%ste %n%#ement! 200E,9 (2), 13013&!




C20D ren, !; 5ubuF, ?!; 5i*t"i, 7!; ren, ! %nd 5%#l%r, !:4dsorption o* b%si" d.e *rom %8ueous solutions b. modi*iedsepiolite: 8uilibrium, Fineti"s %nd thermod.n%mi"s stud.!es%lin%tion, 2010, 2E2 (1-3), ''96!

C21D

ulut, !; ?%"%r, ! %nd en#il, <! 4!: 4dsorption o*m%l%"hite #reen onto bentonite: 8uilibrium %nd Fineti"

studies %nd pro"ess desi#n! i"roporous %nd esoporous%teri%ls, 200', 11E (3), 23&2&6!

C22D e%rs, S!: etermin%tion o* spe"i*i" sur*%"e %re% o* "olloid%lsili"% b. titr%tion ith sodium h.droide! 4n%l! 5hem!,19E6, 2', 19'119'3!

C23D Pri.%nth%, N!; enevir%thn%, 5!; Sun%thil%Fe, P! %nd@eer%soori.%, +!: 4dsorption beh%vior o* *luoride %t norm%l bri"F (N) %ter inter*%"e! <nt J nviron Prote" "i!, 2009,3, 1&01&6!

C2&D

4shoF, 4!; %n%s, ! %nd 4n$%li, P!: +emov%l o* 5r.st%liolet d.e *rom %ste%ter b. sur*%"t%nt modi*ied %lumin%!

ep%r%tion %nd Puri*i"%tion e"hnolo#., 200E, &&, 1391&&!

C2ED ul%.mon, 4! 7! %nd sh%sh, J! !: +emov%l o* oil *rom%ste%ter b. or#%no"l%. prep%red *rom <r%8i bentonite!Journ%l o* n#ineerin#, 16 (&), E'-E9', 2010!

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