Effect of sodium ascorbate on weathering performance of NaOH pulping and paper

Abstract

This study aimed to decelerate the weathering of paper from light by utilizing the antioxidant property of sodium ascorbate (SA), which is an ascorbic acid salt. Three different sessions of cooking were carried out by adding 2.5%, 5.0% and 7.5% of SA in proportion to the weight of a completely dried chip in addition to 24% NaOH in order to identify the influence of SA on cooking. It was observed that the pulp yield decreased when SA was added to the cooking. For that reason, it was decided to add SA into the control pulps instead of adding the digester. The same amount of SA was added to the control. The SA-added pulps were held in the agitator initially first for 2 hours and then 12 hours before making paper. So as to determine the influence of the treatment on the process. The paper was treated for 72, 144 and 256 hours and values of ∆L, ∆a, ∆b and ∆E were identified in order to determine the period of the SA’s efficacy against weathering. The total discoloration in all the samples of paper, displayed an increase with an extension of the time period. The lowest discoloration after a 256-hour time period was seen in the sample group where 7.5% of SA was added and soaked in the water. The final results indicated that the most appropriate concentration was 5% and that pulp suspension must be retained for 12 hours to improve mechanical properties.