Properties and the application of polyacrylonitrile membranes with the addition of nanotubes for heavy metals removal

The paper presents results of research on the production, properties and application of polyacrylonitrile (PAN) based membranes with the addition of multiwallet carbon nanotubes (MWCNT) for the removal of heavy metals such as lead, zinc, cobalt and nickel. The research has shown that the introduction of nanotubes into a PAN matrix results in increased mass per unit area, thickness, water sorption, porosity, pore size of the membranes and hydrophobic properties of their surfaces. Moreover, the modifier improved the transport and separation properties of MWCNT/PAN composite membranes. The use of 0.1% MWCNT addition in the PAN matrix increased the distilled water flux through the membrane 9, 11 and 12 times at transmembrane pressure amounting to 0.1, 0.15 and 0.2 MPa, respectively. The degree of heavy metals removal for all the obtained membranes was determined by atomic absorption spectrometry and for subsequent ions was: 100% (Co2+), 72 ÷ 100% (Zn2+), 70 ÷100% (Ni2+) and 65 ÷ 100% (Pb2+). The instrumental methods used, including: scanning electron microscopy, Fourier transform infrared spectroscopy, wide-angle X-ray scattering, differential scanning calorimetry and thermogravimetric analysis, demonstrated the impact of MWCNT addition on structural composition of produced composite membranes and confirmed the high degree of the modifier dispersion in the polymer matrix.