Organo and Magnetic Palygorskite: Inorganic and Functional Characterization

Palygorskite’s fine particle size (≤37 µm) and negative surface charge across the entire pH range hinder its recovery and limit its applications [1,2]. To overcome these limitations, a palygorskite/Fe₂O₃ composite (44/56 wt%, PM 44/56) was synthesized by a combustion method. Fe(NO₃)₃·9H₂O and starch were dissolved in a palygorskite suspension at 180 °C to form a xerogel, followed by heating at 300 °C [3]. The composite was organophilized with CTAB (1:1) at pH 8, yielding PMO 44/56 [2]. XRD, XRF, BET, FTIR, SEM–EDS, zeta potential, and Gouy analyses confirmed preservation of the palygorskite structure and predominant maghemite (γ-Fe₂O₃) formation, enabling magnetic separation in water. CTAB reduced the specific surface area, shifted the isoelectric point from pH 2.1 to 3.8, increased positive surface charge, and enhanced interfacial interactions with intrinsic ≡Fe–OH/≡Fe–OH₂⁺ sites, making the material promising for aqueous environmental remediation.