Multiwall carbon nanotubes (MWCNTs) were chemically modified to form nanocomposite with thorium oxide. The MWCNTs/ThO₂ nanocomposite was characterized using different modern techniques including Fourier transform infrared spectroscopy, X-ray powdered diffraction, scanning electron microscope, and transmission electron microscope. The average size of MWCNTs/ThO₂ nanocomposite was in the range from 5 to 10 nm. The nanocomposite material was investigated for its adsorption behavior for Pb(II) ions removal from its aqueous system. For the adsorption of Pb(II) by MWCNTs/ThO₂, the equilibrium was achieved within 50 min. The temperature and pH have also found to play important role in the adsorption process and maximum adsorption was found at 45°C and pH 5.5.

In the current study, new biomasses were prepared from fungi isolates including, Penicillium chrysogenum and Aspergillus ustus and utilized for the removal of heavy metals. During the study, the influences of various experimental factors including solution pH, temperature, and contact time on biosorption process were investigated. The synthesized fungi biosorbents were successfully applied for the removal of heavy metals from various waste effluents. The experimental results were indicated the excellent uptake property of the materials for target heavy metals. The average concentrations of Cd (II), Cu (II), and Pb (II) in different wastewater samples collected from Western, Eastern, and Northern region of Saudi Arabia were found to be in the range of 2.6–234 µg/L. The concentrations of Cu(II) in all the analyzed contaminated water samples were fairly exceeded the maximum concentration level for drinking water stipulated by World Health Organization. The applied biosorption technique for heavy metal removal is new, low cost and was adopted in eco-friendly way.