The Synthesis Of Surfactants Of Modified Alkali Lignin For Enhanced Oil Flooding

Lignin was the third natural organic compound after cellulose and hemicellulose resource. At present, the annual output of China’s pulp continues to increase, and the lignin was either burned or discharged into rivers ultimately, which result in not only waste of resources but also pollution of the environment. Therefore, rational use of alkali lignin becomes important.In this paper, in order to lower environmental pollution and the cost of oil recovery, lignin-based surfactants were tried to be prepared with new structures for enhanced oil recovery (EOR). The chemical structure of the surfactants could be represented by the general formula as follows:The feasible modification route includs the oxidation reaction of alkali lignin firstly, and then followed by high temperature sulfonation with sodium sulfite, amination with organic amines and formaldehyde, and alkylation with halogenated aliphatic hydrocarbons. The effects of temperature, time and dosage of the regents were investigated. After primary optimization, the surface tension of the modified product was about24mN/m determined, which was reduced by20mN/m when compared with the surface tension of the unmodified lignosulfonate reported in literatures. With alkali lignin as feedstock, the lowest oil-water interfacial tension reached to10"2mN/m with ideal stability. The product of the reactions was further characterized by Kjeldahl nitrogen method, infrared spectroscopy, nuclear magnetic resonance analysis, etc. The analysis proved that the hydrophilic and lipophilic groups were chemicaly bound in the surfactants.