Abstract
Deresination effect of mixtures of anionic with nonionic surfactant was evaluated during the hot alkali refining in a conventional five-stage refining process of sulfite pulp obtained from mixed hardwood species.
Binary surfactant mixtures, such as a mixture of sodium dodecylbenzene sulfonate (I) with polyoxyethylene nonylphenyl ether (n=9 or 11) in the ratio of 1:1, or mixtures of sodium secondary alkyl sulfate with polyoxyethylene nonylphenyl ether (n=9) (II) in the ratio ranging from 4:1 to 1:4, have greater deresination effect than either component taken separately, showing synergistic effect for resin removal. The deresination effect of mixtures of other anionic surfactant with polyoxyethylene nonylphenyl ether (n=11) is found to be poorer as compared to nonionic surfactant alone.
Surfactant mixtures described above are slightly inferior for resin removal to (II) under the addition in amounts of below 0.1%, based on pulp, but above 0.1%, they show excellent effectiveness. It may be concluded that these mixtures are the most suitable agents for deresination of hardwood pulp, when high amounts of nonionics are added in the refining of hardwood sulfite pulp.
