OXYGEN DELIGNIFICATION OF WHEAT STRAW SODA PULP WITH ANTHRAQUINONE

A four factors and three levels orthogonal experiment (L-9(3(4))) was conducted to evaluate the effects of alkali charge (Ac), oxygen pressure (P), maximum temperature (T-max) and holding time at maximum temperature (t) on the oxygen delignification with anthraquinone (AQ) of wheat straw soda pulp. The pulp yield, kappa number, intrinsic viscosity and brightness were analyzed to determine significant factors and optimum conditions. The optimal pulp was obtained as Ac was 3% with P of 0.5 MPa at 120 degrees C for 85 min. In contrast to the conventional oxygen delignification, the addition of AQ was positive to produce pulp with higher yield but it did not generate other negative impacts on pulp kappa number, viscosity and brightness. The reaction of AQ in oxygen delignification is different from that in alkali pulping.