The Effects of H2O2 Bleaching and DTPA Spraying on the Brightness Stability of Hornbeam CMP Pulp following Accelerated Irradiation Aging

In this research, hornbeam chips were cooked under chemimechanical pulp (CMP) conditions, and the pulps were prepared at a yield level of 85%. The CMP pulps were separately bleached with hydrogen peroxide and sodium dithionite with and without treatment with DTPA. Then 60 gr/m 2 handsheets were made. The goal was to determine whether complementary bleaching with sodium dithionite improves optical behavior of the handsheets. Following DTPA solution spraying on the surface of hand sheets, brightness, opacity, and yellowness were improved, and the K/S ratio and PC number were decreased. Among different samples and following optical aging, it was found that in longterm aging, DTPA spray has considerable effect on improving the stability of brightness and increasing the paper’s durability against optical deterioration.