Treatment of Groundwater-Rich Organic Compounds Using Activated Carbon with Additional Germanium Dioxide (GeO(2)): Kinetics and Adsorption Studies of Methylene Blue and Congo Red

[Image: see text] Activated carbon/GeO(2) composites were synthesized using the sol–gel method and then used as catalysts for the photodegradation of organic pollutants methylene blue (MB) and congo red (CR). The composites were characterized using an X-ray diffractometer and Fourier transform infrared spectroscopy to analyze the structure and chemical bonds of the composite materials, respectively. The ultraviolet–visible (UV–vis) absorption wavelength ranges of the composites toward the pollutants were 550–700 nm for MB and 450–550 for CR. The band gap energies of the composites were calculated, with the values found to be <4.5 eV. It was shown that the adsorption ability of the composites increased with the irradiation time of the pollutants. Furthermore, the adsorption kinetics data were found to be a good fit to a pseudo-first-order kinetics model.