Innovative Use of Brazilian Clays in Porous Aerogels and Hydrogels for Water Dye Purification

ABSTRACT This research focused on the synthesis of starch‐based hydrogels and aerogels that were cross‐linked with citric acid and sodium hydroxide, and enhanced with chocolate clays—specifically Ch and chocobofe (Cb) at concentrations of 10% and 15% by weight. The primary goal was to evaluate their effectiveness in removing methylene blue (MB) from solutions. The hydrogels and aerogels were characterized using various techniques, including picnometry, scanning electron microscopy, Fourier‐transform infrared spectroscopy (FTIR), and thermogravimetric analysis. Additionally, the pH at the zero point charge (pHzpc) was assessed. The adsorption performance of these materials was tested under different conditions, such as varying adsorbent dosages, contact times, and initial dye concentrations to determine the most effective material. This research aims to provide an environmentally sustainable solution to water pollution. FTIR analysis indicated interactions that altered the density, morphology, thermal stability, and pHzpc of the developed hydrogels and aerogels. The results showed that aerogel composites exhibited superior adsorption capabilities compared to hydrogel composites. The maximum adsorption capacity of MB reached 90%, with the aerogel composite containing 15% Cb (SA + 15% Cb) achieving a maximum capacity of 75 mg g −1 , according to the isotherm model. The aerogel composites with 15% clay exhibited a better fit to the Langmuir isotherm model, indicating that the removal of the dye is favorable. Therefore, incorporating clays into aerogels can enhance their performance, making them a viable alternative for developing new eco‐friendly materials.