جستجوی مقالات مرتبط با کلیدواژه "دی تیونیت سدیم" در نشریات گروه "جنگلداری"

In this research, beech and hornbeam chips were chosen randomly from the chips pile of Mazandaran Wood and Paper Industries and cooked under CMP conditions and pulps were prepared at the yield of 85%. The CMP pulps were separately bleached with hydrogen peroxide and sodium dithionite and 60 gr/m2 hand sheet were made. Then, a solution of 0.5 percent of DTPA was sprayed over a number of hand sheets. Then, their optical characteristics were measured and compared using TAPPI Standard test methods. The results of this study explored that following H2O2 bleaching brightness and greenness increased and opacity, absorption coefficient, K/S ratio and a* factor decreased. After complementally bleaching with sodium dithionite, the most part of optical properties improved. Following DTPA solution spraying on the surface of hand sheets, brightness, opacity and greenness improved and absorption coefficient, K/S ratio and a* factor decreased.  Among the different treatments, DTPA spray has a great effect in stability of brightness and increasing it durability against optical deterioration. Also, the complementally bleaching pattern in improving the optical properties of the paper obtained from hornbeam CMP pulp was more noticeable than that of beech.

Efficient use of waste papers and improve their quality has always been one of the targets in the pulp and paper industries. This study aimed to compare two stages bleaching of deinked pulp of newspaper and Magazine recycled pulp mixture using Sodium Dithionite (Y) and hydrogen peroxide (P).
Firstly, the pulp was bleached using 1% hydrogen peroxide and in the next stage bleaching was performed using 0.5 and 0.75 percent dithionite and of hydrogen peroxide Respectively for 60, 90 and 120 minute.
The results showed that with increase dosage of hydrogen peroxide in the second stage of PP sequence, decrease in bulk, opacity and increase in strength properties wasnt significant but increase in brightness and effluent COD showed significant changes. Prolongation of bleaching time in the second stage of PP sequence cause significant reduction in bulk, opacity and increase of effluent COD, brightness and strength properties. with increase the time of bleaching reactions in second stage of PY sequence, bulk and opacity reduction and increase in strength properties and brightness wasn’t significant, but with chemical dosage increasing, just brightness increasing was significant. Also, according to the results, with increase of chemical dosage in second stage of PY sequence, increase in the amount of Effluent COD load wasn’t significant, but with increasing of time of bleaching reactions in second stage of this sequence, increase in the amount COD load was significant.
Regarding to the results, effluent’s COD, brightness level and strength properties of PP sequence was higher than PY while bulk and opacity of that was lower than PY ones.