Efficient and Rapid Photocatalytic Reduction of Hexavalent Chromium Achieved by a Phloroglucinol-Derived Microporous Polymeric Organic Framework Solid

A microporous polymeric organic framework (POF) based on phloroglucinol (phlo-POF) was for the first time evaluated on photoreduction and removal processes of hexavalent chromium (Cr6+) from aqueous solutions. The phlo-POF synthesis was based on reaction of phloroglucinol and terephthalaldehyde under hydrothermal conditions. Structural and chemical characterization was performed using UV–vis–NIR diffuse reflectance spectroscopy (DRS), FT-infrared spectroscopy, and thermogravimetric methods, while surface area analysis was employed to determine other physical and surface properties. Batch experiments were conducted on contaminated water to determine the rate and extent of Cr6+ removal and its immobilization by the phlo-POF material. The kinetic studies showed a rapid removal of Cr6+ ions from the water in the presence of the phlo-POF, best described by the zero-order kinetic model. The efficiency of the material with UV–C irradiation on Cr6+ reduction was compared with a well-studied material, the Degussa P-25 TiO2 catalyst, and found to be ∼200% higher. Cycle experiments verify the successful reuse of the phlo-POF photocatalyst for at least ten times for Cr6+ reduction.