Abstract
Ceramic-based nanocomposite membranes are gaining great attention in various applications, such as water treatment; gas separation; oil and gas, amid their superior fouling resistance and remarkable chemical/thermal stability. Here, we report for the first time the use of spark plasma sintering (SPS) process to fabricate a porous alumina–carbon nanotubes (Al2O3–CNT) nanocomposite membrane for water treatment. The challenge is this work is to achieve a balance between the amount of porosity, desired for a high water flux, and the membrane strength level, required to resist the applied pressure during a water flow experiment. The effect of SPS process parameters (pressure, temperature, heating rate, and holding time) on the microstructure and properties of the developed membrane was investigated and correlated. A powder mixture composed of Al2O3 and 5 wt % CNT was prepared with the addition of starch as a pore former and gum Arabic and sodium dodecyl sulfate as dispersants. The powder mixture was then sintered using SPS to produce a solid but porous nanocomposite membrane. The structure and microstructure of the developed membrane were characterized using X-ray diffraction and field emission scanning electron microscopy. The performance of the membrane was assessed in terms of porosity, permeability, and mechanical properties. Moreover, the adsorption capability of the membrane was performed by evaluating its removal efficacy for cadmium (II) from water. The microstructural analysis revealed that CNT were distributed within the alumina matrix and located mainly along the grain boundaries. The permeability and strength were highly influenced by the sintering pressure and temperature, respectively. The results indicated that the membrane sintered at a pressure of 10 MPa, temperature of 1100 °C, holding time of 5 min, and heating rate of 200 °C/min exhibited the best combination of permeability and strength. This developed membrane showed a significant removal efficiency of 97% for cadmium (II) in an aqueous solution.
Highlights
Water treatment has become an essential necessity due to water shortages, and sometimes water crises, in many regions around the world
We report the use of spark plasma sintering (SPS) to synthesize porous alumina–carbon nanotubes (CNT) nanocomposite membrane and the influence of SPS process parameters on the membrane’s properties, namely porosity, permeability, and mechanical strength
The structure and phase analysis of both as-received raw materials and SPS samples were characterized by X-ray diffraction (XRD) equipment (AXSD8, Bruker, Karlsruhe, Germany) with Cu-Kα radiation at a scanning speed of 1 degree/min
Summary
Water treatment has become an essential necessity due to water shortages, and sometimes water crises, in many regions around the world. Incorporating nanomaterials into the membrane, improves its permeability, thermal stability, fouling resistance, and mechanical properties, as well as providing new functions like self-cleaning and contaminant degradation [2] One example of such a nanomaterial additive is carbon nanotubes (CNT), which have been found to be attractive for heavy metal ions removal [13,14,15,16,17,18,19] and water purification applications [20,21,22,23,24,25,26,27,28,29,30,31,32,33,34] due to their unique properties, including enhanced permeability, contaminant rejection, disinfection, and antifouling behavior. We report the use of SPS to synthesize porous alumina–CNT nanocomposite membrane and the influence of SPS process parameters on the membrane’s properties, namely porosity, permeability, and mechanical strength. The membrane’s potential to remove cadmium ions (Cd (II) or Cd2+) from water was evaluated
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