performance of amylase on properties of recycled occ pulp pre-soaked at different ph(s)

upgrading recycled fiber properties has been a constant concern in pulp and paper industry. in this respect many researches has been applied. the present paper has been considered the effect of amylase enzyme in pulping stage of old corrugated container (occ). also, pre-soaking of occ (first step of pre-soaking for 6 hours in 3% consistency in different ph(s) and second step of pre-soaking at 60˚c for 18 hours with constant ph) in acid, neutral and alkaline ph on physical and mechanical properties (air resistence, tensile index, burst index, tear index and fold) of recycled paper and its effect on amylase performance was investigated. soaking itself improved mechanical properties. alkaline ph pre-soaking had the most efficient effect on the mechanical properties. the results indicated that α-amylase treatment improved the mechanical properties (except tear index) in the non-soaked samples but amylase treatment had no significant effect on the soaked samples in the experimented ph ranges. the results showed that independent effects of soaking and alkaline treatments had superior effect on mechanical properties compared to enzymatic treatment. statistically, none of treatments had significant effects on air resistence.