Modifikacija i primena višeslojnih ugljeničnih nanocevi za izdvajanje arsena iz vode
Modification and application of multiwalled carbon nanobutes for the separation of arsenic from water
Author
Veličković, Zlate S.Mentor
Ristić, MirjanaCommittee members
Uskoković, Petar
Perić-Grujić, Aleksandra

Marinković, Aleksandar
Vuruna, Mladen

Metadata
Show full item recordAbstract
Predmet istraživanja u okviru izrade ove doktorske disertacije bio
je razvoj novih, efikasnijih adsorbenata za uklanjanje arsena iz vode.
Ispitivanja su uključivala razne vrste modifikacija višeslojnih ugljeničnih
nanocevi.
U prvom delu ispitivanja je izvršena priprema dva adsorbenta na
bazi višeslojnih ugljeničnih nanocevi (MWCNTs), koje su najpre modifikovane
oksidacijom (o-MWCNTs), a zatim su aminofunkcionalizovane
(e-MWCNTs) i ispitivane kao potencijalni adsorbenti za uklanjanje
As(V) iz vode. Takođe, o-MWCNTs i e-MWCNTs su dalje modifikovane
u cilju poboljšanja njihovih adsorpcionih karakteristika.
Na e-MWCNTs je naneseno gvožđe(III)-oksid u formi goetita na
dva načina, vezivanjem Fe3+ jona, kao i vezivanjem Fe2+ jona, koji su
zatim oksidovani pomoću KMnO4; na ovaj način dobijeni su e-
MWCNTs/Fe 3+ i e-MWCNTs/Fe2+ adsorbenti.
o-MWCNTs su naknadno funkcionalizovane sa SOCl2 i aminovane
amino-polietilenglikolom (PEG); na taj način je dobijen još jedan
novi adsorbent, MWCNTs-PEG.
Svi... adsorbenti, dobijeni modifikacijom MWCNTs, su detaljno
okarakterisani, primenom brojnih instrumentalnih tehnika: FTIR, XRD,
BET, SEM, TEM, EDS i ispitivanjem elementarnog sastava, pre i posle
adsorpcije, čime su dobijeni podaci značajni za opisivanje mehanizma
adsorpcije.
U drugom delu istraživanja su ispitivane adsorpcione karakteristike
sirovih i modifikovanih MWCNTs, za izdvajanje As(V) i As(III) iz
vode, eksperimentima u šaržnom sistemu. Ispitivan je uticaj pH vrednos6
ti rastvora, vremena kontakta, početnih koncentracija arsena i temperature.
U okviru ispitivanja adsorpcionih karakteristika sirovih i modifikovanih
MWCNTs, kao adsorbenta za As(V) iz vodenog rastvora, eksperimentalno
dobijene vrednosti su upoređivani sa šest ravnotežnih i četiri
kinetička teorijska modela. Maksimalni adsorpcioni kapaciteti ispitivanih
adsorbenata, određeni prema modelu Langmuirove adsorpcione izoterme,
su bili u opsegu od 3,55 mg g-1 za MWCNTs bez modifikacije do
23,47 mg g-1 za e-MWCNTs/Fe2+.
Na osnovu dobijenih rezultata ispitivanja zaključeno je da je najefikasniji
adsorbent e-MWCNTs/Fe2+, koji se može uspešno koristiti za
uklanjanje anjonskih vrsta As(V) iz vodenih rastvora, kako pri niskim,
tako i pri visokim koncentracijama. Kod ovog adsorbenta su dobijena
dobra slaganja između eksperimentalnih rezultata i vrednosti dobijenih
modelom, pomoću nekomercijalnog računarskog programa MINTEQ,
što omogućava modelovanje sistema i predviđanje rezultata adsorpcije.
The research goal of this Ph.D thesis is development of new,
more efficient adsorbents for arsenic removal from water. The research
was conducted on two modified multiwall carbon nanotubes
(MWCNTs).
In the first part, two adsorbents based on multiwalled carbon
nanotubes (MWCNTs) were synthesized. These adsorbents were prepared
by oxidation (o-MWCNTs) following by amination (e-
MWCNTs), and examined as potential adsorbents for arsenic removal
from water. Moreover, o-MWCNTs and e-MWCNTs were further
modified in order to improve their adsorption capacities. Iron(III)
oxide, in the form of goethite, was incorporated in the e-MWCNTs surface
in two different ways. The first approach was addition of Fe3+
ions, while the second was oxidation of incorporated Fe2+ ions using
KMnO4, hence giving both e-MWCNTs/Fe 3+ and e-MWCNTs/Fe2+ adsorbents,
respectively.
Also, o-MWCNTs were functionalized with SOCl2 and aminated
with amino-polyethylene glycol (PEG), making thus one new adsorbent,
MWCNTs-PEG. ...All adsorbents were characterized in detail
using numerous instrumental techniques: FTIR, XRD, BET, SEM,
TEM, EDS. Elementary composition was determined before and after
adsorption. These results gave useful information for characterization
of adsorbent before and after adsorption, as well as for the description
of adsorption mechanism.
In the second part, the adsorption characteristics of raw and
modified MWCNTs were determined using the batch system adsorp8
tion experiments. The influence of pH, contact time, initial concentrations
and temperature was examined. The kinetic and equilibrium data
for the arsenate ion adsorption on synthesized adsorbents were determined
by using six equilibrium and four kinetic theoretical models, applying
linear and nonlinear fitting methods, in order to evaluate the adsorption
mechanism. The maximum adsorption capacities of investigated
adsorbents for the removal of arsenate species, determined from
the Langmuir adsorption isotherm, were in the range from 3.55 mg g-1
for raw-MWCNTs to 23.47 mg g-1 for e-MWCNTs/Fe2+.
Based on presented results, the study showed that the e-
MWCNTs/Fe2+ is the most promising adsorbent for the successful removal
of As(V) species from aqueous solutions at low and high concentrations.
Good agreement of experimental and calculated data was
obtained for e-MWCNTs/Fe2+, using non-commercial software
MINTEQ. This method enables accurate, swift and efficient modeling
system and prediction of adsorption results.