AMMONIUM ADSORPTION ON NATURAL ZEOLITE (CLINOPTILOLITE): ADSORPTION ISOTHERMS AND KINETICS MODELING

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1 ISSN UDC =111 Rcivd: Accpd: Original scinific papr AMMONIUM ADSORPTION ON NATURAL ZEOLITE (CLINOPTILOLITE): ADSORPTION ISOTHERMS AND KINETICS MODELING DAJANA KUČIĆ, MARINKO MARKIĆ, FELICITA BRIŠKI Faculy of Chmical Enginring and Tchnology, Univrsiy of Zagrb, Croaia -mail: A bach sorpion procss for rmoval of ammonium ions from auous soluion using naural zoli was sudid. Tr diffrn paricl sizs of zoli (1-2 mm, 2-4 mm and 4-10 mm) wr usd in h xprimns. Sorpion of ammonium ions on naural zoli wr carrid ou a 298 K wih h iniial concnraions of ammonium in h rang of mg NH 4 + -N/dm 3. Euilibrium daa wr fid by Frundlich and Langmuir isohrm and sorpion kinic daa by psudo-firs and scond ordr. Th paramrs wr simad by linar and non-linar mhod. Rsuls show ha non-linar mhod may b suprior way o compu h paramrs. Th Langmuir isohrm modl fid br h xprimnal daa wih a maximum monolayr adsorpion capaciy of mg NH 4 + -N/g (1-2 mm), mg NH 4 + -N/g (2-4 mm) and mg NH 4 + -N/g (4-10 mm), rspcivly. Also, h psudo-scond-ordr kinic modl was h bs applicabl modl o dscrib h sorpion kinics. Th obaind rsuls suggs ha h naural zoli is a good adsorbn for rmoval of ammonium ions from auous soluion and ha ion xchang incrasd wih dcrasing of paricl sizs of naural zoli. Ky words: ammonium ions, naural zoli, sorpion isohrms, linar and non-linar rgrssion. Adsorpcija amonijvih iona na prirodni zoli (clinopiloli): Adsorpcijsk izorm i kiničko modliranj. U ovom radu ispiivano j uklanjanj amonijvih iona iz vodn oopin adsorpcijom na prirodni zoli. Korišn su ri različi vličin čsica zolia (1-2 mm, 2-4 mm i 4-10 mm). Sorpcija amonijvih iona na zoli provdna j pri 298 K s počnim koncnracijama amonijvih iona od mg NH 4 + -N/dm 3. Eksprimnalni rzulai su prikazani adsorpcijskim modlima, Langmuir-ovom i Frundlich-ovom izormom i kiničkim modlima, psudoprvi i psudo-drugi rd. Paramri su procijnjni linarnom i nlinarnom rgrsijom. Nlinarna rgrsija bolj procjnjuj paramr. Langmuir-ova adsorpcijska izorma daj bolj slaganj s ksprimnalnim rzulaima kapaci zolia iznosi mg NH 4 + -N/g (1-2 mm), mg NH 4 + -N/g (2-4 mm), odnosno, mg NH 4 + -N/g (4-10 mm). Takođr, psudo-drugi rd bolj opisuj kiniku sorpcij. Iz dobivnih rzulaa, vidljivo j da j zoli dobar adsorbns za uklanjanj amonijvih iona iz vodn oopin i da ionska izmjna ras sa smanjnjm vličin čsica zolia. Ključn rijči: amonijvi ioni, prirodni zoli, sorpcijsk izorm, linarna i nlinarna rgrsija. INTRODUCTION Nowadays, h prsnc of nirogn xcss in h nvironmn has causd urophicaion of laks and rivrs all ovr h world [1]. Nurin compounds such as ammoniacal nirogn (NH 4 -N) which is a colorlss, oxic, odorous and corrosiv gas [2], ar ofn prsn in communal and som indusrial waswars [1], lachas and condnsas ha may volv during composing procss [3,4]. Highr Th Holisic Approach o Environmn 2(2012)4, Pag 145

2 concnraion of ammonium may caus a sharp dcras of dissolvd oxygn in naural wars and oxiciy o auaic organisms [5]. Hnc, rmoving ammonium from waswar is of gra imporanc in nirogn polluion conrol. Th radiional mhods for ammonium rmoval from was srams ar basd on physicochmical and biological ramns. Nowadays, ion xchang and adsorpion ar mor inrsing as possibl ramn mhods [6]. Th rmoval of h ammonium ions from auous soluions hrough adsorpion on naural zolis (clinopiloli) is found o b vry promising [7]. Naural zolis ar aluminum silica minrals wih high caion xchang capaciis (CECs) and high slciv propris [6]. Insid h framwork srucur of zoli, alkali or alkalin-arh caions ar rvrsibly fixd in h caviis and can asily b xchangd by surrounding posiiv ions lik Na +, K +, Ca 2+, Mg 2+ [5,8]. In conras o h aluminium and silicon srucur aoms, which ar muually bound by chmical (covaln) bonds ovr common oxygn aoms, caions ar bound wih h alumosilica srucur mainly by wakr lcrosaic bonds, which caus hir mobiliy and capabiliy of bing xchangd wih soluion caions [9]. Ion xchang capaciy, slciviy, paricl siz of zoli, ph valu and mpraur of auous soluion ar imporan facors for adsorpion of ammonium ions on zoli [6]. Th aim of his sudy was o invsiga h adsorpion ponial of diffrn paricl sizs of zoli for h rmoval of ammonium ions from auous soluion. Adsorpion isohrms and kinics wr invsigad and diffrn adsorpion isohrm modls wr usd o valua h xprimnal daa by linar and non-linar mhod. MATERIALS AND METHODS Marials Th sandard soluion usd in his sudy was ammonium sulfa p.a. (Kmika, Croaia). Th zoli (clinopiloli) usd in h xprimns was from h Krapina rgion, Croaia. I was crushd in laboraory jaws crushr (Mas, A092 TE, Ialy) and sivd o paricl siz fracions bwn 1 and 10 mm (SIEVE-SHAKER, Modl RA- 86-1, WS Tylr, SAD). Zoli was washd wih dminralizd war o rmov h paricls adhrd o surfac, and drid a 378 K for 2 hours. Adsorpion xprimns wr carrid ou using diffrn sizs of h zoli, 1-2 mm, 2-4 mm and 4-10 mm. Adsorpion sudis Adsorpion xprimns wr carrid ou by adding 0.5 g of zoli of diffrn paricl sizs ino 100 cm 3 Erlnmyr flasks conaining 50 cm 3 of diffrn iniial concnraions ( mg NH + 4 -N/dm 3 ) of ammonium soluion. All flasks wr shakn a 200 rpm for 24 hours a 298 K. Afr filraion (mmbran por siz 0.45 µm, Sarorius, Grmany) h concnraions of ammonium ions in auous soluion wr drmind spcrophoomricaly (Spcrophoomr DR/2400, Hach a USA) a = 680 nm [10]. Masurd concnraions ar xprssd as mg NH 4 + -N/dm 3. Th adsorpion capaciy a uilibrium (mg Th Holisic Approach o Environmn 2(2012)4, Pag 146

3 NH 4 + -N/g) was drmind by using following uaion: ( o m ) V (1) whr γ o and γ rprsn h iniial and uilibrium concnraion of ammonium ion in auous soluion (mg NH 4 + -N/dm 3 ); V is h volum of h ammonium soluion (dm 3 ) and m is h amoun of adsorbn (g). Th rmoval fficincy (%) of zoli can b calculad as follows [11]: o Rmoval prcnag = 100 (2) o Bach kinics sudis Kinic xprimns wr idnical o hos of uilibrium ss. Th auous sampls wr wihdrawn a prs im inrvals and h concnraions of ammonium ions wr drmind spcrophoomricaly [10]. Th amoun of sorpion a im, (mg NH 4 + -N/g), was calculad by xprssion: ( o m ) V (3) whr γ (mg NH + 4 -N/dm 3 ) is h liuid phas concnraion of ammonium ions a diffrn im. RESULTS AND DISCUSSION Adsorpion isohrm Adsorpion isohrms ar basic ruirmns for h dsign of sorpion sysm [12]. Ths daa provid informaion abou h capaciy of h adsorbn or h amoun ruird for rmoving a uni mass of polluan undr h sysm condiions. Diffrn sizs of zoli wr usd as adsorbn o drmin h adsorpion capaciy of ammonium ions, Fig.1. From Figs.1 and 2 i can b sn ha adsorpion capaciy and rmoval fficincy riss wih dcras in paricl siz of zoli. This is bcaus h smallr h paricl siz h grar h spcific surfac ara, which promos xrnal surfac adsorpion, and implis ha h caions in zoli of smallr paricl siz ar xchangd much mor asily wih hos in auous soluion [5,11]. Also, Fig.1 shows ha h ammonium adsorpion capaciy of zoli incrasd wih h incras of iniial ammonium concnraion in auous soluions, indicaing ha plny of radily accssibl sis ar availabl a h sar of adsorpion. Afr uilibraion, whn h adsorbn bcoms saurad, a plaau is rachd indicaing ha no mor sis ar availabl for furhr adsorpion. Th Holisic Approach o Environmn 2(2012)4, Pag 147

4 Figur 1. Adsorpion isohrms of ammonium adsorpion on diffrn paricl sizs of zoli (1-2 mm, 2-4 mm and 4-10 mm) Slika 1. Adsorpcijsk izorm adsorpcij amonijvih iona na različi vličin čsica zolia (1-2 mm, 2-4 mm and 4-10 mm) Figur 2. Effc of paricl sizs on h rmoval of NH 4 + ion a diffrn iniial concnraions Slika 2. Ujcaj vličin čsica zolia na uklanjanj NH 4 + iona pri različiim počnim koncnracijama Th ion-xchang isohrms characriz h uilibrium rlaionships bwn h amouns of xchangd ion by zoli and is uilibrium concnraion in soluion [11,13]. To characriz h + xchang uilibrium of NH 4 ions by zoli, h Frundlich and Langmuir modls in h concnraion rang of 1000 o 7000 mg NH 4 + -N/dm 3 wr usd. Th Frundlich isohrm is an mpirical uaion usd o dscrib mulilayr adsorpion wih inracion bwn adsorbd ions [14]. Th Frundlich uaion is xprssd as [13, 15]: Th Holisic Approach o Environmn 2(2012)4, Pag 148

5 K F 1 n (4) whr K F (an indicaor of adsorpion capaciy) and 1/n (is h adsorpion innsiy) ar Frundlich consans. Th dimnsion 1/n givs an indicaion of h favorabiliy of adsorpion and valus n > 1 rprsn favorabl adsorpion condiions [11]. Euaion (4) may also b wrin in h logarihmic form as 1 ln ln K F ln (5) n whr valus of K F and n ar calculad from h inrcp and slop of h plo. Th Langmuir isohrm hory assums monolayr covrag of adsorba ovr a homognous adsorbn surfac. A basic assumpion is ha all adsorpion sis ar uivaln and adsorpion on aciv sis is indpndn of whhr h adjacn is occupid [12]. Th Langmuir adsorpion modl can b xprssd as [13,16]: and linarizd uaion: b o (6) 1 bk L ( 1 b ) 1 b (7) whr is h amoun of polluan adsorbd on h sorbn a uilibrium (mg NH N/g), K L is h Langmuir adsorpion consan rlad o h nrgy of adsorpion (dm 3 /mg) and b is h mono-layr adsorpion capaciy of adsorbn (mg NH 4 + -N/g). Thrfor, a plo of γ / vrsus γ givs a sraigh lin of slop 1/b and inrcp 1/(b K L ). Adsorpion of NH + 4 by zoli can also b valuad o s whhr i is favorabl by using a dimnsionlss paramr or sparaion facor R L ha is givn by [13,14]: L (1 1 K R (8) whr γ o (mg NH + 4 -N/dm 3 ), is h highs iniial concnraion of adsorba and K L is Langmuir consan. Th R L paramr is considrd as mor rliabl indicaor of xchang. Thr ar four probabiliis for h R L valu: (i) for favorabl xchang, 0<R L <1, (ii) for unfavorabl xchang, R L >1, (iii) for linar xchang, R L = 1, and (iv) for irrvrsibl xchang, R L = 0 [13]. Th valus of R L in his sudy hav bn found o b 0.093, and , rspcivly, indicaing ha adsorpion of ammonium ions on diffrn sizs of zoli is favorabl. Th valus of K F, K L, n, b and R 2 for diffrn paricl sizs of zoli, ar givn in Tabl 1. Fig. 3 (a) (c), shows h xprimnal uilibrium daa for ammonia concnraions from 1000 o 7000 mg NH N/dm 3 and h prdicd horical Frundlich and Langmuir isohrm. Th isohrm paramrs wr simad by linar and non-linar rgrssion analysis using Las Suar mhod implmnd in Scinis sofwar (Fig. 4 and Tabl 1). I can b sn ha paramrs wr br simad by non-linar rgrssion mhod. Also, vry high rgrssion corrlaion cofficin, R 2, was obaind by Langmuir modl. Th obaind rsuls suggs ha Langmuir modl was suiabl for dscribing h sorpion uilibrium of ammonia ions by zoli. Th Langmuir paramr b shows + ha maximum NH 4 xchang incrass wih dcrasing paricl siz. L o ) Th Holisic Approach o Environmn 2(2012)4, Pag 149

6 Tabl 1. Langmuir and Frundlich isohrm consans and corrlaion cofficins for ammonium adsorpion on diffrn paricl sizs of zoli Tablica 1. Paramri Langmuirov i Frundlichov izorm dobivni adsorpcijom amonijvih iona na različi vličin čsica zolia Linar rgrssion Non-linar rgrssion Adsorbn Paricl siz, mm Isohrm Paramrs Valu Valu Zoli 1-2 Langmuir K L (dm 3 /mg) b (mg NH 4 -N/g) R Frundlich K F (mg NH 4 -N/g) n R Langmuir K L (dm 3 /mg) b (mg NH 4 -N/g) R Frundlich K F (mg NH 4 -N/g) n R Langmuir K L (dm 3 /mg) b (mg NH 4 -N/g) R Frundlich K F (mg NH 4 -N/g) n R Th Holisic Approach o Environmn 2(2012)4, Pag 150

7 Figur 3. Isohrm plos for ammonia adsorpion on diffrn paricl sizs of zoli: (a) 1-2 mm, (b) 2-4 mm and (c) 4-10 mm Slika 3. Langmuir-ova i Frundlich-ova adsorpcijska izorma dobivna adsorpcijom amonijvih iona na različi vličin čsica zolia: (a) 1-2 mm, (b) 2-4 mm and (c) 4-10 mm Th Holisic Approach o Environmn 2(2012)4, Pag 151

8 Figur 4. Esimad valus by linar and non-linar mhod Slika 4. Linarna i nlinrna procjna paramra Sorpion kinics daa Th adsorpion kinics was invsigad for br undrsanding of h dynamics of adsorpion of ammonium ions ono zoli. Fig.5 shows h ffc of h conac im on h rmoval of ammonium ions wih diffrn paricl sizs of zoli a h lows and h highs concnraion, 1000 and 7000 mg NH 4 + -N/dm 3. Th adsorpion upak was found o b fas and i incrasd wih an incras of conac im. Th fasr iniial adsorpion ra may b du o h availabiliy of h uncovrd sorpion sis of h adsorbn a h sar of xprimn. Afr 5 hours h adsorpion procss rachd uilibrium (Fig.5) and h rmaining vacan surfac sis wr difficul o b occupid du o h formaion of rpulsion among ammonia ions on h surfac and in h bulk phas [16]. Ths phnomnon lad o a dcras of adsorpion ra, wha was wll xhibid by plaau lin afr 7 h of sorpion occurrd (Fig.5) and i confirms ha h procss has rachd h sady-sa condiion [16]. In ordr o prdic h mchanism involvd during h prsn sorpion procss and h ponial ra conrolling such as chmical racion procsss, wo kinic modls wr usd o fi h xprimnal daa, psudo-firs ordr and psudo-scond ordr. Th paramrs wr valuad according linar and non-linar mhod. Th kinic paramrs ar hlpful for h prdicion of adsorpion ra, which givs imporan informaion for dsigning and modling h procsss [17]. Rsuls of prsn sudy suggs ha non-linar mhod is br han linar mhod in drmining kinic paramrs of a paricular kinic modl (Fig.4, Tabl 2 and 4). This is mainly bcaus ransforming a non-linar kinic modl o a linarizd form nds o alr h rror disribuion, and hus disor h paramrs. Non-linar analysis conducd on h sam abscissa and ordina rsuls in h sam rror disribuion and is hrfor a br way o obain h kinic paramrs han linar mhod [18]. Also, i has bn rpord ha i is no suiabl o us h corrlaion cofficin of a linar rgrssion analysis for comparing h bs appropria modl [17,18]. Th Holisic Approach o Environmn 2(2012)4, Pag 152

9 Figur 5. Effc of conac im on adsorpion of ammonium on diffrn paricl sizs of zoli Slika 5. Ujcaj konaknog vrmna na adsorpciju amonijvih iona na različi vličin čsica zolia Th psudo-firs-ordr kinic modl known as h Lagrgrn uaion, has bn widly usd o prdic adsorpion kinics. A kinic modl of psudo-firs ordr is givn in h form [17,18]: d d k f ( ) (9) Ingraing E. (9) for h boundary condiions = 0 o = and = 0 o =, E. (9) may b rarrangd for linarizd daa ploing as shown by E. (10): k f log( ) log (10) whr and (mg NH 4 + -N/g) ar h amoun of ammonium adsorbd a uilibrium and a im and k f is h psudo-firs-ordr ra consan (1/min). Th slop and inrcp of plos of log ( - ) vrsus wr usd o drmin h firsordr consan k f and uilibrium adsorpion capaciy by linar rgrssion (Tabl 2 and 3). Th Holisic Approach o Environmn 2(2012)4, Pag 153

10 Tabl 2. Characrisic paramrs of h diffrn kinic modls (psudo-firs and scond ordr) simad by linar rgrssion for ammonia sorpion on diffrn paricl sizs of zoli Tablica 2. Procjna paramra linarnom rgrsijom za različi kiničk modl (psudo-prvi i drugi rd) pri sorpciji amonijvih iona na različi vličin čsica zolia Zoli γ o, mg NH N/dm 3 d p, m m, xp mg NH N/g Psudo-firs ordr k 1, 1/min Psudo-scond ordr, calc mg NH k 2, N/g R 2 g/mg min, calc mg NH N/g R Th Holisic Approach o Environmn 2(2012)4, Pag 154

11 Tabl 3. Characrisic paramrs of h diffrn kinic modls (psudo-firs and scond ordr) simad by non-linar rgrssion for ammonia sorpion on diffrn paricl sizs of zoli Tablica 3. Procjna paramra nlinarnom rgrsijom za različi kiničk modl (psudo-prvi i drugi rd) pri sorpciji amonijvih iona na različi vličin čsica zolia Zoli γ o, mg NH d p, N/dm 3 mm, xp mg NH N/g Psudo-firs ordr k 1, 1/min Psudo-scond ordr, calc mg NH k 2, N/g R 2 g/mg min, calc mg NH N/g R Th Holisic Approach o Environmn 2(2012)4, Pag 155

12 Th psudo-scond-ordr modl is basd on h assumpion ha h ralimiing sp may b a chmical sorpion involving forcs rough h sharing or xchang of lcrons bwn adsorbn and adsorba [14]. Th psudo-scondordr kinic modl is givn as [17]: d d k s ( 2 ) (11) For h boundary condiions = 0 o = and = 0 o =, h ingrad form of uaion (11) bcoms: k S 1 2 which has a linar form: (12) 1 1 (13) 2 k s whr and (mg NH 4 + -N/g) ar h amoun of ammonium adsorbd a uilibrium and a im and k s is h psudo-scond-ordr ra consan (g/mg min). Fig.6 shows h plos of agains for h psudo-scond ordr modl for sorpion of ammonium ono naural zoli. Figur 6. Psudo-scond-ordr kinic modl plos of ammonium adsorpion on zoli (1-2 mm) Slika 6. Kinički modl psudo-drugog rda adsorpcij amonijvih iona na zoli (1-2 mm) Th bs-fi modl was slcd basd on boh rgrssion corrlaion cofficin (R 2 ) and h calculad valus. Low R 2 valus and noabl variancs bwn h xprimnal and horical upaks shown in Tabl 2 and 3 rval clarly h poor fiing of psudo-firs-ordr modl. Thus, h adsorpion of ammonium ions on naural zoli is no a firs-ordr racion. Fiing kinics paramrs of adsorpion of ammonium ions ono zoli according o psudo-scond-ordr modl (E.13) ar abulad in Tabls 2 and 3. Th rsuls show ha psudo-scond-ordr modl fis h xprimnal daa ui wll, h R 2 valus rach h uniy and h xprimnal and horical upaks ar in good agrmn (Fig.4). Th Holisic Approach o Environmn 2(2012)4, Pag 156

13 This indicas ha his modl can b applid for h nir concnraion rang of adsorpion procss, suggsing ha chmisorpion migh b h ra-limiing sp ha conrolld h adsorpion procss of ammonium on h zoli [5]. Also, from Tabl 2 and 3 i can b sn ha h psudoscond-ordr ra consan (k s ) dcrasd wih incrasd iniial concnraion. CONCLUSION Th prsn work showd ha naural zoli, clinopiloli, from Croaia can b usd as an adsorbn for rmoval of ammonia ions from auous soluions. Th ammonium ions adsorpion was found o dcras wih incrasing paricl siz in rang of 1-10 mm. Th Langmuir modl fid wll h xprimnal daa wih a maximum adsorpion capaciy of mg NH 4 + -N/g, mg NH 4 + -N/g and mg NH 4 + -N/g for paricl sizs bwn 1-2 mm, 2-4 mm and 4-10 mm, rspcivly. Kinic sudis suggs ha ammonium adsorpion on zoli could b dscribd mor favorably by h psudoscond ordr kinic modl han by psudofirs ordr and h paramrs ar br simad by non-linar mhod. Acknowldgmn This work was suppord by h Minisry of Scinc, Educaion and Spors of h Rpublic of Croaia undr Rsarch Projc REFERENCES [1] M. A. Wahab, S. Jllali, N. Jdidi, Effc of mpraur and ph on h biosorpion of ammonium ono Posidonia ocanica fibrs: Euilibrium, and kinic modlling sudis, Biorsourc Tchnol 101 (2010), [2] T. Kaosol, N. Pongpa, Ammonia Gas rmoval from Gas Sram by Biofilraion using Agriculural Rsidu Biofilr Mdias in Laboraory-scal Biofilr, Proc. Wrld. Acad. Sci. E. 77 (2011) [3] F. Briški, Z. Gomzi, N. Horgas, M. Vuković, Arobic composing of obacco solid was, Aca. Chim. Slov. 50 (2003) [4] D. Kučić, N. Kopčić, I. Ćosić, M. Vuković, F. Briški, Drminaion of ammonia and carbon dioxid in xhaus gass during composing of obacco was in closd racor, Proc., 3 rd Inrnaional Symposium in Enviromnal Managmn -Towards Susainabl Tchnologis, Faculy of Chmical Enginring and Tcnology, Zagrb, Croaia (2011) [5] D. Wn, Y.-S. Ho, X. Tang, Comparaiv sorpion kinic sudis of ammonium ono zoli, J. Hazard. Mar. 133 (2006) Th Holisic Approach o Environmn 2(2012)4, Pag 157

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