Effect of Hornbeam chips fungal pre-treatment on bleachability of its Bio-kraft pulp

Bio-kraft pulp made from Hornbeam chips fungal pre-treated (1, 2 and 3 weeks) was used for investigation of its bleachability by DED sequence. Before and after of each step in mentioned sequence, pulps and bleaching spent liquors characterized and then 60g/m2 standards handsheets made from above pulps and tested in optical properties. Results shown that by increasing in chips pre-treatment time, lignin contents of pulps is more lacked by passing of DED sequence steps. Also, pulp viscosity and DP are lacked by increasing in pre-treatment time simultaneously increasing in hexenuronic acids and this is due to not full selectivity of fungle. Fungal pre-treatment of chips has not significant effect on brightness of unbleached pulps but due to softening in lignin structure, could be improved bleaching process as with increasing in pre-treatment time brightness increased and opacity decreased in final paper. Generally, it seems that Hornbeam chips fungal pre-treatment has good efficiency on its pulp bleachability although chemical consumption in bleaching increased up to 3 weeks pre-treatment.