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.
Designing efficient and stable water
splitting photocatalysts is
an intriguing challenge for energy conversion systems. We report on
the optimal fabrication of perfectly aligned nanotubes on trimetallic
Ti–Mo–Fe alloy with different compositions prepared
via the combination of metallurgical control and facile electrochemical
anodization in organic media. The X-ray diffraction (XRD) patterns
revealed the presence of composite oxides of anatase TiO2 and magnetite Fe3O4 with better stability
and crystallinity. With the optimal alloy composition Ti–(5.0
atom %) Mo–(5.0 atom %) Fe anodized for 16 h, enhanced conductivity,
improved photocatalytic performance, and remarkable stability were
achieved in comparison with Ti–(3.0 atom %) Mo–(1.0
atom %) Fe samples. Such optimized nanotube films attained an enhanced
photocatalytic activity of ∼0.272 mA/cm2 at 0.9
VSCE, which is approximately 4 times compared to the bare
TiO2 nanotubes fabricated under the same conditions (∼0.041
mA/cm2 at 0.9 VSCE). That was mainly correlated
with the emergence of Mo and Fe impurities within the lattice, providing
excess charge carriers. Meanwhile, the nanotubes showed outstanding
stability with a longer electron lifetime. Moreover, carrier density
variations, lower charge transfer resistance, and charge carriers
dynamics features were demonstrated via the Mott–Schottky and
electrochemical impedance analyses.
Carbon nanotubes (CNTs) have become the focus of attention of many scientists and companies worldwide. CNT-based filters have a prospective advantage in comparison to the commercial filters already in operation because they are light weight and do not require electricity to operate. This investigation handles the filtration efficiency of manganese and iron from aqueous solution using commercial multiwalled carbon nanotubes (MWCNTs) (Taunit). The effects of different parameters such as CNT filter mass, concentration of manganese and iron in aqueous solution and pH of aqueous solution on removal of these heavy metals are determined. From these investigations, the removal efficiency of manganese and iron could reach 71.5% and 52% respectively for concentration 50 ppm, suggesting that Taunit is an excellent adsorbent for manganese and iron removal from water. There was a significant increase in removal efficiency at pH = 3 for manganese and pH = 8 for iron. The effect of oxidation on the structural of MWCNTs was characterized by scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) techniques to investigate the functionalization with oxygen-containing and outer diameter distribution. It was found that functionalized CNT-based filters are more efficient at removing manganese and iron from aqueous solutions. Oxidized MWCNTs may be a promising candidate for heavy metal ion removal from industrial wastewater.
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