Fındık ve ceviz kabuğundan üretilen aktif karbon ile diklofenak sodyum, siprofloksasin ve sülfametoksazol adsorpsiyonunun incelenmesi
Investigation of the adsorption of diclofenac sodium, ciprofloxacin and sulfahmetoxazole by activated carbon produced from hazelnut and walnut shell
Yazar: SEDA TÜNAY
Danışman: DR. ÖĞR. ÜYESİ RABİA KÖKLÜ ; PROF. DR. MUSTAFA İMAMOĞLU
Sakarya Üniversitesi / Fen Bilimleri Enstitüsü / Çevre Mühendisliği Ana Bilim Dalı
Derece: Doktora, 2023
Konu: Çevre Mühendisliği = Environmental Engineering

Özet:
Ülkemiz fındık ve ceviz üretiminde önemli bir paya sahip olmakta ve buna bağlı
olarak yüksek miktarda fındık ve ceviz kabuğu ortaya çıkmaktadır. Fındık ve ceviz
kabukları düşük maliyete sahip olmaları, yerel olarak büyük miktarlarda mevcut
olmaları ve her yıl yenilenebilir olmaları gibi avantajlara sahiptir. Dolayısıyla aktif
karbon üretiminde hammadde olarak kullanılmaları ve bu şekilde ekonomiye
kazandırılmaları önem arz etmektedir. Bu çalışmanın amacı, fosforik asitle aktive
edilmiş fındık (HSAC) ve ceviz (WSAC) kabuğu karbonunun sulu çözeltilerden ve
atık sulardan diklofenak (DC), siprofloksasin (CIP) ve sülfametoksazol (SMX)
giderimindeki etkinliğini belirlemektir.
HSAC ve WSAC'nin karakterizasyon çalışmaları yüzey alanı, gözenek boyutu
dağılımı, elementel, FT-IR, SEM ve termogravimetrik analizler gibi çeşitli analitik
işlemlerle yapılmıştır. HSAC ve WSAC'nin adsorpsiyon özelliklerinin belirlenmesi
amacıyla, DC, CIP ve SMX'i sulu çözeltilerden ve atık sulardan uzaklaştırma
yetenekleri başlangıç konsantrasyonu, temas süresi, pH, adsorban dozu ve sıcaklık
gibi çeşitli parametrelerle test edilmiştir.
SEM çalışmaları, HSAC ve WSAC yüzeyinin çeşitli boyut ve şekillerde çok sayıda
düzensiz çukur içerdiğini göstermiştir. HSAC ve WSAC'nin BET yüzey alanları
sırasıyla 1173 m 2 g -1 ve 1428 m 2 g -1 olarak bulunmuş, WSAC'nin daha büyük bir
yüzey alana sahip olduğu belirlenmiştir. DC, CIP ve SMX'in adsorpsiyon dengesini
modellemek için Langmuir, Freundlich, Temkin ve Dubinin-Radushkevich
izotermleri kullanılmıştır. HSAC ile elde edilen maksimum adsorpsiyon kapasiteleri
DC, CIP ve SMX için sırasıyla 125, 95.2 ve 285.7 mg g -1 ; WSAC ile elde edilen
maksimum adsorpsiyon kapasiteleri DC, CIP ve SMX için sırasıyla 135.1, 185.2 ve
476.2 mg g -1 olarak hesaplanmıştır. Yapılan incelemeler ile DC, CIP ve SMX
adsorpsiyonunun Langmuir izoterm modeli ile uyumlu olduğu sonucuna varılmıştır
ve bu durum monomoleküler yani tek tabakalı adsorpsiyonun baskın olduğunu
göstermiştir. Adsorpsiyon mekanizmasının kinetik davranışının değerlendirilmesi
sonucunda, yalancı ikinci dereceden modelin DC, CIP ve SMX adsorpsiyonu için en
uygun kinetik model olduğu belirlenmiştir. Termodinamik çalışmalar, DC, CIP ve
SMX'in HSAC ve WSAC ile adsorpsiyonunun kendiliğinden ve endotermik
olduğunu ortaya koymuştur.
Kentsel atık su arıtma tesisi çıkış atık suyundan alınan numunelerde HSAC ile
yapılan adsorpsiyon çalışmaları sonucunda elde edilen giderim verimleri DC, CIP ve
SMX için sırasıyla %61.9, %54.2 ve %63.1; WSAC ile yapılan adsorpsiyon
çalışmaları sonucunda elde edilen giderim verimleri DC, CIP ve SMX için sırasıyla
%74.2, %77.4 ve %60.2 olarak olarak bulunmuştur.
Sonuç olarak, HSAC ve WSAC'nin atık sulardan DC, CIP ve SMX giderimi için
kolay bulunabilir, çevre dostu ve etkili birer adsorban olduğu ifade edilebilir.

Abstract:
Since hazelnuts and walnuts are produced in significant quantities in Turkey, large
quantities of hazelnut and walnut shells occur every year. Cheap, locally accessible
agricultural byproducts are favored for the synthesis of activated carbon (AC) to
reduce commercial AC production costs. Hazelnut shell (HS) and walnut shell (WS)
might be considered as acceptable precursors for AC manufacturing due to their low
cost, local availability in large quantities, and renewability year after year. Other
advantages of HS and WS include low economic value compared to various
precursors used in AC manufacturing, no labor required for harvesting as they are
field ready material, and long-term storage without deterioration. As a result, it is
critical to convert discarded hazelnut and walnut shells into value-added materials
and investigate their adsorption capacities for the removal of various contaminants
from wastewater.
The purpose of this study is to test effectiveness of phosphoric acid-activated
hazelnut (HSAC) and walnut (WSAC) shell carbon for the adsorption of diclofenac
(DC), ciprofloxacin (CIP), and sulfamethoxazole (SMX) from aqueous solutions and
wastewater.
Characterization of HSAC and WSAC was carried out using several techniques
including proximate analysis, elemental analysis, Brunauer-Emmett-Teller (BET)
surface area measurement, scanning electron microscopy (SEM) images, and
Fourier-transform infrared spectroscopy (FT-IR). The impact of pH, contact time,
dosage, initial concentration, and temperature on batch adsorption of DC, CIP, and
SMX by HSAC and WSAC was investigated. The adsorption kinetics of DC, CIP,
and SMX were studied using pseudo-first-order, pseudo-second-order, and
intraparticle diffusion kinetic models. The adsorption equilibrium of DC, CIP, and
SMX onto HSAC and WSAC was studied using Langmuir, Freundlich, Temkin, and
Dubinin-Radushkevich isotherm models. The adsorption thermodynamics of DC,
CIP, and SMX onto HSAC and WSAC were also calculated to assess the changes in
free energy (ΔG), enthalpy (ΔH) and entropy (ΔS).
For the production of HSAC and WSAC, the hazelnut and walnut shells were
cleaned with deionized water, dried overnight at 105°C, then crushed to a size of 1-
1.5 mm using a steel blender. Then, equal parts of H 3 PO 4 and HS or WS (150 g) were
added to 150 mL deionized water. The suspensions were kept in in a water bath at
80°C and then, dried at 105°C overnight. The impegrenated materials were then
pyrolyzed at 600°C under N 2 gas flow (100 mL min –1 ) in the tube furnace. The
pyrolized samples in the furnace were cooled down to ambient temperature under N 2
gas flow (100 mL min –1 ). Then, the samples were cleaned with hot deionized water.
To remove any remaining acid in the products, they were submerged in a 1%
NaHCO 3 solution overnight. Then, the products were washed with hot deionized
water until the pH of the washing water reached 7.0. The produced AC's were dried
at 105°C for 24 h, sieved to a particle size of 250-500 µm, and then stored in brown
glass vials for use in the following studies.
A variety of analytical techniques, including BET surface area measurement, pore
size distribution, C, H, N elemental analysis, FT-IR, SEM, and thermogravimetric
analysis were used to carry out the characterization studies of HSAC and WSAC.
Proximate analyses of HSAC and WSAC were performed according to the
requirements of the American Society for Testing and Materials (ASTM). FTIR
measurements between 450 and 4,000 cm -1 were used to identify the functional
groups on the surface of the HSAC and WSAC. N 2 adsorption-desorption isotherms
at 77 K were used to compute the multipoint surface area of the HSAC using the
BET method. The surface morphology of HSAC and WSAC was examined using
SEM images. The pH pzc values of HSAC and WSAC were experimentally
determined. Lactonic, phenolic, and carboxylic groups in the HSAC and WSAC
were calculated after Boehm titration.
Batch experiments were used to assess the adsorption dynamics of DC, CIP, and
SMX with HSAC and WSAC. The effects of variables including contact time, initial
concentration of DC, CIP and SMX, HSAC and WSAC dosage, pH of the aqueous
phase and temperature were performed. Individual aqueous solutions of DC, CIP and
SMX (50 mL) were used in the batch adsorption experiments. An exact quantity of
HSAC/WSAC was poured into the DC, CIP, and SMX solution at a certain
concentration, and the suspensions were then shaken for a predefined period of time
at 25°C (except of temperature effect experiments). A known amount of
HSAC/WSAC was added to the DC, CIP and SMX solution at definite concentration
and then the suspensions were shaken for predetermined time at 25°C (except of
studies on the temperature effect). Following that, centrifugation was used to
separate the suspensions. To determine equilibrium concentrations of DC, CIP and
SMX in the supernatant phase, a UV-vis spectrophotometer was employed for DC
and CIP at 276 nm, and SMX at 265 nm.
The characterization results showed that HSAC and WSAC had ash contents of
13.5% and 11.9, respectively. High concentrations of activating agents and the
inorganic content of hazelnut and walnut shells may be the cause of the high ash
content. HSAC and WSAC were found to have 6.4% and 10.4% moisture,
respectively. The amounts of volatile matter in HSAC and WSAC were calculated to
be 10.9% and 17.8%, respectively. HSAC includes 81.1% C, 1.6% H, and 1.1% N,
while WSAC has 71.6% C, 1.6% H, and 1.1% N, according to the results of the
elemental analysis. The pH pzc of HSAC and WSAC were calculated to be 4.24 and
4.26, respectively.
In the N 2 adsorption/desorption isotherm results of HSAC and WSAC, the obtained
isotherms demonstrated hysteresis in I(b) and H4 according to IUPAC classification.
Type I(b) isotherms have been identified for materials having a broader pore-size
distribution, such as bigger micropores and possibly narrow mesopores (2.5 nm). In
micro mesoporous carbons, H4-type hysteresis has been commonly documented.
According to the pore-size distribution plots, HSAC and WSAC exhibit small pore-
size distributions. HSAC and WSAC BET surface areas were calculated to be 1173
m 2 g -1 and 1428 m 2 g -1 , respectively.
Batch adsorption studies on the DC, CIP and SMX using HSAC and WSAC showed
that the adsorptions reached to equilibrium at 1440 min. Adsorbed amounts of DC,

30

CIP and SMX per gram HSAC and WSAC incresed by increasing of initial
concentrations of DC, CIP and SMX. The removal of DC, CIP and SMX from real
wastewater collected from the effluent of the urban wastewater treatment plant in
Sakarya, Turkey was found to be 61.9%, 54.2% and 63.1% using HSAC, and 74.2%,
77.4% and 60.2% by WSAC, respectively.
The adsorption equilibrium of DC, CIP and SMX onto HSAC and WSAC was
modeled using Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms
equations. The maximum adsorption capacities obtained with HSAC were 125.0,
95.2 and 285.7 mg g -1 for DC, CIP and SMX, respectively; the maximum adsorption
capacities obtained with WSAC were calculated as 135.1, 185.2 and 476.2 mg g -1 for
DC, CIP and SMX, respectively. It was also concluded that DC, CIP and SMX
adsorption onto HSAC and WSAC were compatible with the Langmuir isotherm
model and monolayer adsorption was dominant. As a result of the evaluation of the
kinetic behavior of the adsorption mechanism, it was determined that the pseudo-
second order model was the most suitable kinetic model for DC, CIP and SMX
adsorption on the HSAC and WSAC. Thermodynamic studies showed that DC, CIP
and SMX adsorptions onto HSAC and WSAC were spontaneous and endothermic.
The obtained results in this study showed that HSAC and WSAC could be accepted
as low-cost, efficient, easily accessible and environmentally friendly adsorbents for
the treatment of wastewater containing DC, CIP and SMX.