Synthesis, characterization and investigation of adsorption properties of silica based polymer modified composite adsorbent

The adsorption method is widely used in the removal of dyes, which constitute an important part of the pollutants in industrial wastewater, with its advantages such as ease of application and high efficiency. In this thesis, firstly, pyrogenic silica (PS) was modified with polymerizable 3-methacryloxypropyltrimethoxysilane (MPS) then MPS on the surface of the obtained modified structure (SM) was copolymerized with N Vinylimidazole (VIm) to obtain SMV coated with polymer. In the last step, SMV was partially quaternized with 1-bromobutane (BB) over the VIm fractions and thus SMVQ was obtained. The silicas obtained at each step were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), BET surface analysis, wettability analysis and thermogravimetric analysis (TGA) methods. The adsorption properties of the adsorbents from aqueous solutions of the model dyestuff Acid Orange 8 (AT8) were investigated depending on the pH, and it was found that the optimum pH for the adsorption was 2. The adsorption of AT8 on PS and SMVQ was investigated depending on the contact time, initial AT8 concentration and temperature, and the obtained data were applied to Lagergren-first-order, pseudo-second-order, intraparticle diffusion kinetic models and Langmuir and Freundlich isotherm models. The contact time experiments were carried out at 25, 35 and 50°C and kinetic and thermodynamic parameters were calculated. The highest adsorption amounts were found as 433 mg g‒1 for PS and 933 mg g‒1 for SMVQ at 50°C and pH 2 conditions. It has been concluded that the prepared silica-based polymer modified composite adsorbents can be effective adsorbents for anionic dyes and similar organic/inorganic pollutants from wastewater.