Novel diamino-functionalized fibrous silica submicro-spheres with a bimodal-micro-mesoporous network: Ultrasonic-assisted fabrication, characterization, and their application for superior uptake of Congo red

Abstract The practical removal of toxic organic dyes from water is vital for a safe, clean, and healthy environment. A key research challenge in the uptake of hazardous organic dyes is the design, development, and implementation of adsorbents with high affinity to achieve both improved uptake performance and fast adsorption kinetics for dye pollutants. In this work, fibrous silica submicro-spheres (KCC-1) were prepared by a facile ultrasonic-assisted hydrothermal protocol. Then, diamino-functionalized KCC-1 (DA-KCC-1) with micro-mesostructured fibers was prepared via a simple ultrasonic-assisted post-grafting method. As a potential environmentally silica-based material, DA-KCC-1 was used as an adsorbent for dye removal from water for the first time and Congo red was chosen as a model compound. Characterization studies revealed that both KCC-1 and DA-KCC-1 possess fibrous dendrimeric submicro-spheres morphology with a bimodal-micro-mesoporous architecture and high accessible surface area (up to 725 and 540 m2 g−1 for KCC-1 and DA-KCC-1, respectively). Some key experimental parameters affecting the adsorption efficiency (viz. initial pH value, adsorbent dose, initial dye concentration, etc.) were investigated and optimized. The maximum uptake capacity was found to be ~400 mg g−1 according to the Langmuir model. The findings can contribute to a better understanding of the adsorption properties of functionalized-fibrous KCC-1.