Hussien A. Motaweh

Functionalized carbon nanotubes based filters for chromium removal from aqueous solutions

This investigation examines the filtration efficiency of chromium from aqueous solution using two types of commercial multiwalled carbon nanotubes (MWCNTs) (Taunit-M (TM) and Taunit-MD (TMD)). These MWCNTs were modified using two complementary treatments, purification (using a mixture of hydrochloric acid and hydrogen peroxide) and functionalization (using nitric acid). The effect of these treatments on the morphology of MWCNT Taunit filters was characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy to estimate the outer diameter distribution and element content deposited on filters. Effects of different parameters, i.e., carbon nanotube filter mass, concentration of chromium in aqueous solution, and pH of aqueous solution, on removal of this heavy metal were determined. From these investigations, the removal efficiency of chromium could reach 97% for modified TM and 70% for modified TMD at concentration of 10 ppm, suggesting that modified TM is an excellent adsorbent for chromium removal from aqueous solutions and more efficient than modified TMD. A significant increase in chromium removal by modified TM at pH = 2 has been observed compared with higher pH values. It was found that modified TM filters can be reused through many cycles of regeneration with high performance. Modified TM filters may be a promising candidate for heavy metal ion removal from industrial wastewater.

Morphological and structural modifications of multiwalled carbon nanotubes by electron beam irradiation

Effects of electron beam irradiation on a morphology and structure of multiwalled carbon nanotubes sample in a normal imaging regime of a scanning electron microscope (SEM) were investigated. Direct SEM observations give evidence that irradiation by electron beam in SEM eliminates morphological unevenness, in the form of round spots of white contrast, on the surface of carbon nanotubes (CNTs) and makes the tubes thinner. Electron dispersive analysis and Raman spectroscopy are used to explore the origin and nature of these spots. From this analysis we found that e-beam irradiation improves the CNTs graphitization. The synergy of thermal heating and ionization produced by the irradiation are discussed as possible mechanisms of the observed effects.

High efficiency of multiwalled carbon nanotubes filters for benzene removal from aqueous solutions: quantitative analysis using Raman spectroscopy

High Efficiency of Multiwalled Carbon Nanotubes Filters for Benzene Removal from Aqueous Solutions: Quantitative Analysis using Raman Spectroscopy The environmental application of multiwalled carbon nanotubes (MWCNTs) as a new type of filters to remove benzene from aqueous solutions was investigated. The surface functionalization of MWCNTs enhances their performance for this application. Arrays of MWCNTs were synthesized via chemical vapor deposition (CVD) by spray-pyrolysis method. An aliquot of these MWCNTs array was oxidized by concentrated nitric acid. The Fourier transform infrared analysis showed that the peaks corresponded to the hydroxyl and carboxylic acid groups in oxidized MWCNTs (O-MWCNTs) are more intense than that in raw MWCNTs (R-MWCNTs). The images of scanning electron microscopy indicated that the O-MWCNTs have a lower degree of entanglement and decreased nanotubes diameters. Energy dispersive X-ray spectroscopy showed high oxygen content for O-MWCNTs compared to R-MWCNTs. In order to estimate the removal efficiency of MWCNTs filters, Raman spectroscopy as a quantitative technique to make concentration measurements of benzene in water solutions was conducted and used to estimate the purification efficiency. The removal efficiency of benzene by O-MWCNTs was found to reach 99% for concentration of 500 ppm, indicating the existence of specific π-π electronic interactions between benzene molecules and the surface of O-MWCNTs. Functionalized MWCNTs possess good potential applications to water and wastewater treatment, maintaining a high qualityof water, and could be used for cleaning up environmental pollution.

Silica Nanoparticles Preparation Using Alkali Etching Process

Silica (SiO2) nanoparticles have found applications in many advanced areas. This research work is concerned with the preparation of silica nanoparticles by wet alkali chemical etching technique of commercial silicon powder using (KOH, n-propanol and water). The synthesized nanoparticles were systematically characterized by XRD, FTIR and PL spectroscopy. The XRD results revealed the amorphous nature of silica nanoparticles. FTIR spectroscopy confirmed the presence of Si-O in all the samples. PL spectra have shown emission band at around 516 nm. Then, nanosilica is promise material for the realization of light-emitting silica-based optoelectronic devices.

Porous silicon powder as an adsorbent of heavy metal (nickel)

New and inexpensive nanoporous silicon (NPS) powder was prepared by alkali chemical etching using sonication technique and was subsequently investigated as an adsorbent in batch systems for the adsorption Ni(II) ions in an aqueous solution. The optimum conditions for the Ni(II) ion adsorption capacity of the NPS powder were studied in detail by varying parameters such as the initial Ni(II) concentration, the solution pH value, the adsorption temperature and contact time. The results indicated that the maximum adsorption capacity and the maximum removal percent of Ni(II) reached 2665.33 mg/g and 82.6%, respectively, at an initial Ni(II) concentration of 100 mg/L, adsorption time of 30 min and no effect of the solution pH and adsorption temperature.