Synthesis and Study of the Properties of a Composite Material Based on Sulfohumic Acid and Multi-Walled Carbon Nanotubes

A composite sorption material based on sulfohumic acid (SHA) and multi-walled carbon nanotubes (MWCNTs) was synthesized. The composite was obtained via ultrasonic-enhanced coprecipitation, which ensures the efficient incorporation of nanotubes into the sulfohumic matrix. The structural and physicochemical properties of the initial SHA and the SHA:MWCNTs composite were studied using elemental analysis, conductometric titration, infrared spectroscopy, thermogravimetric analysis, and electron microscopy. The introduction of MWCNTs was shown to alter the surface morphology, increase roughness, and form a more developed porous structure. Thermogravimetric analysis indicates increased thermal stability of the composite material. The sorption properties of the synthesized composite with respect to Cu2+ ions from aqueous solutions were also studied. It was established that the SHA:MWCNTs composite possesses higher sorption capacity compared to the original SHA. Analysis of sorption isotherms revealed that the process is predominantly described by the Langmuir model, while satisfactory agreement with the Freundlich model indicates the energetic heterogeneity of the sorbent surface. These results demonstrate the potential of the SHA:MWCNTs composite as an effective sorption material for removing heavy metal ions from aqueous solutions.