The conditions of petroleum extraction may allow asphaltenes to precipitate, causing deposition that clogs wells, pipes and equipment, consequently reducing productivity. In this work, the solubility parameters precipitation onset polar fractions heavy crudes from Brazilian fields were estimated using a simplified system n-heptane/toluene mixtures. Asphaltenes extracted by two different methods...

in the present study ethanol and water extracts of 15 seaweeds, dictyota dichotoma var. velutricata, dictyota indica, iyengaria stellata, padina pavonia, sargassum swartzii, sargassum variegatum, stoechospermum marginatum, stokeyia indica, jolyna laminarioides, caulerpa taxifolia, halimeda tuna, ulva fasciata, ulva lactuca, solieria robusta, and melanothamnus afaqhusainii, were evaluated for th...