FABRICATION OF NANO AND POROUS MATERIALS & THEIR UTILIZATION IN THE PURIFICATION OF WATER CONTAMINATED WITH ARSENIC, COPPER, AND LEAD
ZÜLEYHA ÖZLEM KOCABAŞ ATAKLI
Materials Science and Engineering, PhD Dissertation, 2013
Prof. Dr. Yuda Yürüm (Thesis Supervisor), Prof. Dr. Ferhat Yardım, Assoc. Prof. Selmiye Alkan Gürsel, Asst. Prof. Alpay Taralp, Asst. Prof. Fevzi Çakmak Cebeci
Date &Time: July 19th, 2013 - 10:00
Place: FENS G032
Keywords: Nanomaterials, Porous materials, Heavy metal, Arsenic, Adsorption.
Water pollution mainly caused by arsenic and heavy metal ions is a growing threat to environment and public health. Adsorption is one of the most efficient methods for the removal of the contaminants due to its high efficiency, easy operation and low cost. This thesis aims to develop nano and porous materials, and then implement these into adsorptions of arsenic, lead, and copper in order to investigate an effective water purification system for communities. In this study, specific functional nanomaterials comprising ferric ion loaded red mud, iron oxide/activated carbon, titanium dioxide nanoparticles, and titanium dioxide/activated carbon nanocomposites have been successfully fabricated. The obtained nanomaterials are characterized by using X-ray diffraction, Raman spectroscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectrometer.
The arsenic removal efficiency of ferric ion loaded red mud considering effect of pH, initial arsenic concentration, and contact time is evaluated and the higher adsorption capacities found 11.640 mg/g for As(V) at pH 7.0 and 5.254 mg/g for As(III) at pH 2.0. The presence of ferric ion in the system increased the uptakes of arsenic species from water; therefore, the following study is focused on utilization of iron oxide nanoparticles deposited uniformly on activated carbon support with high loadings by microwave hydrothermal treatment. Maximum adsorption capacity is 27.78 mg/g for As(V) and for a loading of 0.75 g/L, 99.90% uptake is reached within 5 minutes. On the other hand, the beneficial adsorptive eliminations of Pb(II), Cu(II), and As(III) from water are also demonstrated using anatase nanoadsorbent produced by sol-gel method. The maximum experimental adsorption uptakes were 31.25 mg/g for Pb(II), 23.74 mg/g for Cu(II), and 16.98 mg/g for As(III), respectively. XPS analyses revealed that the surface oxygen-containing functional groups including hydroxyl groups were involved in the adsorption process. In order to prevent release of the nanoparticles to the environment, activated carbon was used as a support material for TiO2 nanoparticles. It was observed that As(III) uptake capacity of the nanocomposite was improved approximately 2.7 times as compare to the bare TiO2 nanoparticles. Finally, the effectiveness of titanium dioxide nanoparticles in removing arsenic species from water was enhanced by the photocatalytic oxidation experiments converting As(III) to As(V). The maximum adsorption capacities were found 12.13 mg/g for As(III) in the absence of UV-A illumination, 41.38 mg/g for As(V), and 36.55 mg/g for As(III) in the presence of UV-A illumination.
Overall, anatase nanoadsorbent are able to reduce Pb(II) and Cu(II) concentrations below the MCL requirements for drinking water. The enhanced As(III) removal are observed under UV-A illumination by using TiO2 nanoparticles and they are able to reduce As(III) concentrations below the MCL requirements for drinking water up to moderate initial concentrations. Additionally, 10-AC/TiO2 nanocomposite, having a considerable As(III) uptake capacity, can be also potentially used in arsenic removal.