الملخص الإنجليزي
This study explores the feasibility of amoxicillin removal, via adsorption, from synthetic
wastewater resembling pharmaceutical waste. Carbon nanotubes on powdered activated
carbon substrate, that include potassium hydroxide, were synthesized using chemical
vapor deposition method. The synthesized nanoparticles were then functionalized using
nitric and sulfuric acid mixture to enable dispersion and better interaction with the targeted
contaminant which was later used as adsorbent to remove amoxicillin from the aqueous
solution. Characterization for the synthesized nanoparticles was conducted using Fourier
transform infrared spectrum, x-ray diffraction, scanning electron microscopy and
thermogravimetric analysis. The characterization results showed that carbon nanotubes
were successfully fabricated. The results also exhibited that carbon nanotubes retained
their structure after acidic treatment. In addition, surface characterization using FTIR
results confirm the addition of oxygen containing group to the surface of the nanoparticles.
Besides that, good crystallinity and thermal stability was achieved.
In this work, pH, temperature, adsorbent dosage, contact time and stirring speed were
investigated. It was found that the adsorption capacity has a proportional relationship with
temperature highlighting the endothermic nature of the adsorption process. On the
contrary, adsorption capacity was found to be inversely proportional to pH. Adsorption
capacity decreased with the increase of adsorbent dosage but at the same time increase in
adsorbent dosage leads to an increase in removal efficiency, so proper dosage selection
requires considering both adsorption capacity and removal percent. However, stirring
speed showed insignificant effect on the adsorption capacity with a slight improvement at
high temperature. The results showed that functionalized nanoparticles pose high removal
efficiency of amoxicillin in the aqueous solution with a maximum adsorption capacity of
357.14 mg/g once a model solution of 500 ppm amoxicillin concentration was used. The
optimum conditions for kinetic, pH and temperature were found to be 6 hours, pH of 2
and temperature of 40 ˚C, respectively. While maximum adsorption capacity of 250 mg/g
in 5 hours, at pH of 2 and temperature of 50 ˚C were obtained when a model solution of
100 ppm amoxicillin concentration was tested.
Kinetic, isothermal, and thermodynamic models were also investigated during this study.
The models revealed an endothermic nature of the adsorption process and formation of a
monolayer of amoxicillin molecules in the adsorbent surface. The models suggests that
chemisorption is the main adsorption mechanism. Further investigation on adsorbent
regeneration and reusability showed that adsorbent was best regenerated using sodium
hydroxide, the adsorbent maintained good adsorption capacity after two consecutive
adsorption desorption experiment.
