Green and simple synthesis of poly (catechol-tetraethylenepentamine)@aminopropyl-modified silica composite for removing toxic Cr(VI)

Herein, we propose an excellent absorbent, poly (catechol-tetraethylenepentamine) coating onto SiO 2 NH 2 microsphere, which is fabricated via a simple synthesis route. The effect of different molar ratio of catechol on the adsorption properties of silica modified composite was studied. The poly (catechol-tetraethylenepentamine)@SiO 2 NH 2 (PCTA@AS) exhibits outstanding adsorption to Cr(VI) compared to SiO 2 NH 2 . The structural characterizations and adsorption performance of the product are analyzed by SEM, TEM, FTIR, XPS, etc. Many factors affecting the adsorption behavior of PCTA@AS were systematic explored, including pH, initial Cr(VI) concentration, contact time, adsorbent dosage, and temperature. The experimental data revealed that the adsorption behavior is suitable to be described by pseudo-second-order kinetic model and Langmuir isotherm model. The maximum uptake capacity of PCTA@AS composite up to 400.85 mg/g at 303 K, is much higher than the pure SiO 2 NH 2 , and the removal rate close to 100% when the initial concentration of the solution is below 180 mg/L. Accordingly, the removal process of the material is spontaneous and endothermic and attributed to the partial reduction of Cr(VI) to Cr(III). Based on these, it is considered that the PCTA@AS with good regeneration ability and is expected to be an ideal material on the removal of Cr(VI) from sewage.