Study of Tetracarboxyphenylporphyrin Covalently Bound to Silica in the Removal of Crystal Violet from Aqueous Solution

In this work, the Tetracarboxyphenylporphyrin Covalently Bound to Silica was used as adsorbent to remove Crystal Violet (CV) from aqueous solution. Silica gel immobilizing Tetracarboxyphenylporphyrin (TCPP) chromophore was prepared by the reactions of 3-aminopropyl silica gel (SiO₂-NH₂) with the TCPP. The 3-aminopropyl silica gel (SiO₂-NH₂) was selected as the carrier because of its ability to immobilize the functional groups through a covalent bond. Micrometer-sized SiO₂-NH₂ beads were prepared by reacting silica gel with 3-aminopropyl(triethoxy)silane (H₂N(CH₂)₃Si(OEt)₃). The immobilization of TCPP chromophores on SiO₂-NH₂ was performed by the sol-gel method. The bond formation was confirmed by the appearance of an amide bond at 1650 and 1539 cm⁻¹ in the FT-IR spectra. The SiO₂-NH₂-TCPP was used as adsorbent for removing Crystal Violet from aqueous solutions. The dye adsorption experiments were carried out by using bath procedure. UV-visible absorption spectroscopy was used to record the adsorption behavior. The pH effects, the contact time and the initial dye concentration were changed to obtain the best experimental conditions. The dye adsorption equilibrium was rapidly attained after 25 min of contact time. The experimental data were best fitted to isotherm models.