Sepiolite as an effective natural porous adsorbent for surface oil-spill

The adsorption of oil, spilled on a surface, by a variety of mineral sorbents was investigated. Edible oil adsorption was low (mg oil/m2 clay) on motmorillonite, high on sepiolite and extremely high on talc, suggesting that the magnitude of adsorption correlates with clay hydrophobicity. Despite the high adsorption on talc the efficiency (g oil/g clay) of the clay to remove the oil was low, reaching 60% removal, while complete oil removal was achieved by sepiolite and only 45% by montmorillonite. XRD, SEM and FTIR measurements support the suggestion that high oil loadings on sepiolite indicated adsorption mainly on external surfaces as multilayers accompanied by desorption of water. The adsorption of hydraulic oil spilled on a road pavement by a variety of mineral sorbents was studied. As found in the case of the edible oils, the most efficient (g oil/g clay) sorbent was high quality sepiolite reaching complete adsorption while, oil removal by two organo-clays only reached 50%. On a lower quality sepiolite oil adsorption increased from 84% to 97% upon preheating the clay up to approximately 300 °C, explained in terms of water loss. However, adsorption on the clay treated at 400 °C decreased non-dramatically, strengthening our suggestion that the oil can penetrate into the sepiolite tunnels but most of the adsorption is on the external surfaces in multilayers. Oil adsorption by the high quality sepiolite was nearly complete even at an oil/sorbent ratio of 6 (w/w) indicating the potential of this sorbent for oil removal.

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► Adsorption of oil, spilled on a surface, by mineral sorbents was investigated.
► Oil removal by organo-clays reached 50% but its removal by sepiolite was complete.
► Oil adsorption by sepiolite was complete even at an oil/sorbent ratio of 6 (w/w).
► XRD, SEM and FTIR studies suggest water desorption and multilayer oil adsorption.
► Oil adsorption increased upon preheating sepiolite to 300 °C.