SORBSIL® hydrogels contain a high level of moisture, typically 65%. This moisture provides an ideal environment for the adsorption of polar molecules in the oil. The high surface area and uniform pores within the sponge like-like structure of SORBSIL silica results in the selective adsorption of the undesirable soap, phosphathides and trace metals in their hydrated form. The silica and adsorbed species are filtered out from the oil during normal processing. During manufacture, SORBSIL silicas are milled and classified to minimise fine particles thus ensuring that high filtration rates are maintained within the refening process. SORBSIL silicas have a higher adsorption capacity for phosphatides and trace metals compared to bleaching earths. SORBSIL silicas may be used in conjunction with bleaching earth or in isolation to add value to the refining process.