Selec i e pho oca aly ic emo al o p ocaine – compa ison o
molecula ly imp in ed and non-imp in ed TiO2 ma e ial
K. Tolić Čop*, D. Mu a džić Pa lo ić*, L. Čakić*, I. Gabelica**
*Depa men o Analy ical Chemis y, Facul y o Chemical Enginee ing and Technology, Uni e si y o
Zag eb, T g Ma ka Ma ulića 19, 10000 Zag eb, C oa ia
(E-mail: k olic@ ki .unizg.h ; d[email p o ec ed]izg.h )
**Depa men o ma e ials, Facul y o mechanical enginee ing and na al a chi ec u e, I ana Lučića 5, 10000
Zag eb, C oa ia
Abs ac
Pha maceu icals a e ubiqui ois in ou daily li es and a e he e o e easily en e he en i onmen . Such
in isible small o ganic molecules pollu e e e y pa o en i onmen ; and cons i u e a majo p oblem
o he en i e ecosys em. Con en ional wa e ea men echniques a e unsui able o his ype o
pollu an s, so ad anced oxida ion me hods such as pho oca alysis a e being in es iga ed. Due o he
mo e economical and simple pho oca aly ic pe o mance, a ca alys was p epa ed in his wo k by
deposi ing a TiO2 ilm on an Al2O3 ce amic oam subs a e. The pho oca aly ic ac i i y o p ocaine
unde UV-A ligh was in es iga ed h ough expe imen s o op imiza ion o eac ion condi ions by
changing he pH and ini ial d ug concen a ion. The ob ained esul s indica ed he p ocaine is deg aded
mos apidly in an alkaline medium (pH 10) and a a concen a ion o 10 mg/L. Conside ing ha
deg ada ion is gene ally e y slow a di e en concen a ions and pH alues ( emo al hal -li es
be ween 110 and 690 min), a di e en ype o ca alys was used o imp o e he pho oca aly ic e iciency
o p ocaine. Indeed, he pho oca alys was p epa ed in he same way as he p e ious one, only wi h he
addi ion o a pollu an molecule o he eac ion mix u e. The acid-ca alyzed sol-gel eac ion led o he
o ma ion o imp in ed p ocaine molecules on a TiO2-Al2O3 ce amic. The pho oca aly ic expe imen s
we e epea ed unde he same eac ion condi ions, and he esul s highligh ed he impo ance o
de eloping new ca alys s such as molecula ly imp in ed ma e ials, as hese inc eased he selec i i y o
emo al o non-deg adable molecules such as p ocaine.
Keywo ds: molecula ly imp in ed ma e ial; pho oca alysis; p ocaine; so p ion; wa e
INTRODUCTION
Since con en ional me hods o e icien was ewa e ea men a e no su icien o he
emo al o small o ganic molecules, such as pha maceu icals, ad anced oxida ion p ocesses
ha e been de eloping o many yea s. He e ogeneous pho oca alysis is one o he p omising
echnologies based on he pho oac i a ion o semiconduc o s ha ac as an ac i e ca aly ic
su ace wi h he aim o deg ada ion and e en ually mine alizing pe sis en o ganic pollu an s
(Pa el e al., 2019; Mansou i e al., 2021; Kuma i e al., 2023). To simpli y he p ocess and
inc ease p oduc i i y, a ious composi es a e syn hesized based on TiO2 immobiliza ion. Solid
subs a es can be di e en ; ibe s, polyme s, magne ic pa icles o , as in his wo k, ce amics
such as Al2O3 (An onopoulou e al., 2021). To o e come he p oblems o complex
en i onmen al ma ices and o imp o e he selec i i y and ac i i y o TiO2 o he emo al o
o ganic mic opollu an s, molecula imp in ing echniques a e used o p oduce ma e ials
con aining ecogni ion si es o he a ge molecule. Va ious app oaches a e ha e been
de eloped o he syn hesis o hese ma e ials, anging om polyme iza ions o nume ous
me hods in which a empla e molecule is imp in ed on an ino ganic subs a e, o example by
sol-gel echnique (de Escoba e al., 2018; Wang e al., 2016; Wang e al., 2024; Lulu e al.,
2020). In his s udy, he a ge subs ance chosen was p ocaine, one o he oldes es e - ype local
anes he ics in use, cha ac e ized by high s abili y unde en i onmen al condi ions and esis an
o emo al by con en ional me hods in was ewa e ea men plan s (de ec ed in mic og am
quan i ies in indus ial pha maceu ical was ewa e ) (Badea e al., 2002; Munzhelele e al.,
2024; Quei oz e al., 2019). The e o e, he main objec i e o his wo k was o compa e he
capabili ies o wo TiO2-based ma e ials (wi h and wi hou imp in ing empla e) o p ocaine
emo al om wa e .
MATERIALS AND METHODS
The pho oca alys used in his wo k was p epa ed by c ea ing a highly po ous ce amic Al2O3
oam using a simple and cheap eplica ion me hod based on polyu e hane imp egna ion. The
nanos uc u ed TiO2 ilm was deposi ed on he Al2O3 oam subs a e, which was ailo ed o he
dimensions o he eac o , by sol-gel assis ed dip-coa ing. A de ailed p ocedu e o he
syn hesis o he basic pho oca alys (NIP – non-imp in ed pho oca alys ) is p e iously
published (Š agelj e al., 2020). The molecula ly imp in ed pho oca alys (MIP) was p epa ed
in he same way, only wi h he addi ion o he a ge molecule in he TiO2 sol. A MIP was eady
o use a e insing he empla e wi h a mix u e o ace ic acid and me hanol (1:9) un il he
p ocaine peak was no longe isible in he ch oma og am. The eac ion sys em consis ed o
wo UV lamps moun ed abo e an open ec angula eac o , illed wi h 100 mL o p ocaine
solu ion. Con inuous mixing o he aqueous phase was ensu ed by a pe is al ic pump wi h a
low a e o 30 mL/min. Fi s , p elimina y expe imen s we e ca ied ou o de e mine he
hyd oli ic (da k) and pho oly ic s abili y (UV only) o p ocaine. Subsequen ly, so p ion
expe imen s we e pe o med o es ima e he u iliza ion o he ac i e si es o bo h pho oca alys s
(TiO2 wi hou UV). P io o i adia ion, he pho oca alys s we e exposed o p ocaine in he da k
o 30 min o es ablish a so p ion/deso p ion equilib ium. Pho oca aly ic expe imen s we e
pe o med o es ima e he mu ual in luence o he eac ion condi ions on he emo al a e by
changing he pH (4 – 10) and he ini ial concen a ion o he pollu an (5 – 15 mg/L). To u he
es ima e he eusabili y o he pho oca aly ic ac i i y o he pho oca alys , h ee expe imen s on
he cyclic deg ada ion o p ocaine we e pe o med. The expe imen s las ed 6 hou s, du ing
which samples (500 μL) we e aken a speci ic ime in e als and s o ed a − 4 °C in he da k.
The samples we e moni o ed using he Agilen 1100 HPLC-DAD sys em.
RESULTS AND DISCUSSION
P elimina y expe imen s showed ha he p ocaine molecule is a hyd oly ically and
pho oly ically s able molecule (Figu e 1), which emphasizes he need o use a pho oca alys
and a ligh sou ce o inc ease he emo al o pollu an s om an aqueous medium.
Figu e 1. P elimina y expe imen s
The so p ion expe imen s show a la ge di e ence in he selec i i y o he pho oca alys s used
compa ed o p ocaine.. App oxima ely 86 % o he p ocaine so bed on o MIP du ing he 240-
min so p ion ime, indica ing an inc eased selec i i y o his ype o ma e ial o he emo al
0
0,2
0,4
0,6
0,8
1
060 120 180 240 300 360
c/c0
, min
Hyd olysis Pho olysis So p ion - NI So p ion - MI
o p ocaine. The NIP composi e showed a low so p ion capaci y o p ocaine binding (~ 3 %
o so p ion), so he main ole o p ocaine emo al by pho oca alysis is expec ed a e ac i a ion
o he deposi ed TiO2 wi h UV ligh .
Figu e 2. Syne gis ic e ec o so p ion and pho oca alysis on p ocaine emo al wi h a) NIP
and b) MIP
The Figu e 2 show he pho oca aly ic ac i i y upon emo al o p ocaine wi h a NIP and MIP
pho oca alys , which ca ied ou he eac ion o 6 hou s. P io o i adia ion, he pho oca alys s
we e in con ac wi h he pollu an o 30 min o allow he p ocaine molecules o each
so p ion/deso p ion equilib ium p io o pho oca alysis. Bo h igu es show ha , p ocaine is
emo ed by mo e han 90 %, while in he case o MIP, he syne gis ic e ec o , so p ion and
pho oca alysis con ibu es o p ocaine emo al. The so p ion a ini y o p ocaine is low (mos ly
less han 10 %) o NIP compa ed o MIP ma e ial p oduced wi h i s imp in .
Figu e 3. Kine ic cu es o p ocaine pho oca alysis
Figu e 3 show he as es deg ada ion o p ocaine a pH 10 and 10 mg/L o bo h pho oca alys s.
I can also be seen ha pH plays an impo an ole as i a ec s he su ace cha ge o he ca alys
and he dissocia ion o he pha maceu ical. The nega i e su ace cha ge o NIP a alkaline
solu ion esul ed in an inc eased kine ic a e o p ocaine emo al, p obably by some s onge
elec os a ic mechanisms, as p ocaine has a pKa close o 8.9. P ocaine inc eased he kine ic a e
wi h highe pH, indica ing s ong elec os a ic o ces be ween he neu al molecule and he
possibly nega i ely cha ged pho oca alys (Mokhbi e al., 2014). An inc eased numbe o moles
o p ocaine in ol ed in deg ada ion slowed down he emo al due o a limi ed numbe o ac i e
si es on he ca alys s. A signi ican accele a ion o p ocaine deg ada ion om wa e is e iden
when using he imp in ed ma e ial; he hal -li es o deg ada ion wi h MIP anged om 63.59
o 106.64 min.
Acknowledgemen
This s udy was suppo ed by he C oa ian Science Founda ion unde he p ojec numbe HRZZ-IP-
2022-10-4400 en i led De elopmen o molecula ly imp in ed polyme s o use in analysis o
pha maceu icals and du ing ad anced wa e ea men p ocesses (MIPdePha ma).
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