The in–situ growth of molecular sieve from palygorskite leads to composite materials with high hydrophobicity and adsorption of VOCs

Significant advances have been made in the treatment of volatile organic compounds (VOCs), but effective adsorption in humid environments remains a critical challenge. A trade–off typically exists between improving hydrophobicity and maintaining adsorption capacity. In this work, we present an innovative approach to enhance hydrophobicity without compromising adsorption performance. Palygorskite (Pal) was coated with a molecular sieve (type: MCM–41) via an in–situ growth method, and the resulting composite (Pal/M) was further modified with 3–aminopropyl triethoxysilane (APTES) to prepare NH ₂–Pal/M through post–synthesis modification. By increasing the silicon content, reducing hydroxyl groups, and introducing amine groups, the hydrophobicity of the material was significantly enhanced while preserving its adsorption properties. NH ₂–Pal/M exhibited superior adsorption capacity compared to pure Pal and MCM–41, achieving a maximum adsorption capacity of 291 mg·g ⁻¹ for formaldehyde and 322 mg·g ⁻¹ for acetaldehyde in static adsorption tests. In dynamic experiments at 0 % humidity, NH ₂–Pal/M achieved breakthrough times of 67 min (breakthrough adsorption capacity: 3.946 mg·g ⁻¹) for formaldehyde and 49 min (8.420 mg·g ⁻¹) for acetaldehyde. Even at 80 % humidity, it retained breakthrough times of 24 min (1.399 mg·g ⁻¹) for formaldehyde and 18 min (3.122 mg·g ⁻¹) for acetaldehyde, demonstrating its hydrophobic nature and effective performance in humid conditions. This study highlights a cost–effective approach to synthesizing adsorbent materials from natural porous minerals, providing a practical solution for VOCs treatment in water vapor–rich environments such as industrial emissions.