title: The containment of oil spills in porous media using xanthan/aluminum solutions, gelled by gaseous CO2 or by AlCl3 solutions.
abstract: The gelation in situ of polymers may be a method for temporarily containing organic solvents and other petroleum derived products, which may enter the subsurface. In order to create gels that are neither toxic to humans nor to the ecosystem, we have investigated on the use of the biopolymer xanthan gum with aluminum as a crosslinking agent. Firstly we have considered xanthan/sodium aluminate solutions, which upon preparation are strongly basic and do not gel. The gelation takes place in acid solutions so that Al(III) ions are released, and is instantaneous. Therefore, a special technique must be used for generating the gel structure in situ. The un-gelled solution must be injected and an acid must be added afterwards. We have investigated on the gelling reaction induced by gaseous carbon dioxide, which is an acid gas. The insufflation of CO(2) above the solution generates a layer of gel whose thickness progressively increases as CO(2) diffuses in the polymer solution. Secondly we have investigated on the use of aluminum chloride as the source of Al(III) ions. Also in this case, due to the full availability of Al(III) ions, the gelling reaction would be instantaneous. Therefore, the solution of AlCl(3) must be added on the top of the xanthan solution after its injection. For both gelling systems we have studied both theoretically and experimentally the rate of formation of the gel layer which progressively thickens after the insufflation of CO(2) or after the addition of the AlCl(3) solution.
authors.affiliation: Dipartimento di Ingegneria Chimica, Università di Napoli Federico II, Piazzale Tecchio, 80122 Napoli, Italy. gioia@unina.it
authors.forename: Francesco
authors.initials: F
authors.lastname: Gioia
authors.forename: Pier Paolo
authors.initials: PP
authors.lastname: Ciriello
mesh_terms: D000535:Aluminum / Q000737:chemistry*; D000077410:Aluminum Chloride; D017607:Aluminum Compounds / Q000737:chemistry*; D002245:Carbon Dioxide / Q000737:chemistry*; D002712:Chlorides / Q000737:chemistry*; D003264:Containment of Biohazards / Q000379:methods*; D005782:Gels / Q000737:chemistry*; D008956:Models, Chemical; D011135:Polysaccharides, Bacterial / Q000737:chemistry*; D016062:Porosity; D012996:Solutions; D014867:Water / Q000737:chemistry
chemical_list: D017607:Aluminum Compounds; D002712:Chlorides; D005782:Gels; D011135:Polysaccharides, Bacterial; D012996:Solutions; D014867:Water; D002245:Carbon Dioxide; D000077410:Aluminum Chloride; D000535:Aluminum; C002563:xanthan gum