بررسي امكان تهيه آلفاسلولز از ضايعات چوبي كارخانه هاي خميرسازي با روشهاي سازگار با محيط زيست

Alphacellulose preparation from pulp mills wastewood with environmental compatible

Research on utilization of wastewood in our country is urgently required due to low per capita forest area. Pulp mills generally produce a large volume of wastewood. In this investigation, wastewood from underscreen preparation line of the Iran Wood and Paper Industries (CHOOKA) was used. The investigation was conducted using environmentally friendly processes, both in cooking and in bleaching. Hence, instead of prehydrolyzed Kraft pulping, prehydrolyzed Soda/AQ process was used.After several preliminary cooks, three final cooking conditions were chosen, labeled as A I (Active Alkality: AA 26%, L/W 9), A2 (AA 28%, L/W 10) and A3 (AA 26%, L/W 10). The fixed variables were prehydrolysis and cooking temperature and times (170 °C, 90 and 150 min. respectively), L/W for prehydrolysis 7.5 and Anthroquinone (AQ) concentration 0.1%. Prepared pulps were defibrated and washed with warm water. These treatments were replicated at least three times and their effects on total yield, screened yield and Kappa No. were statistically analyzed. As a result, A3 was chosen as the optimum treatment.To separate uncooked barkchips, pulps screened with 16 mesh screen, were screened again with 50 mesh screen. In order to the process to be more environmentally friendly, bleaching was performed in 2 sequences with delignification agent, Oxone (X), followed by alkali extraction (E) and finally by an F{202 sequence (P). The Oxone concentration was 4% and that of 1{202 was 6.5% (based on pulp O.D. weight). Oxone and H2O2 sequence temperature was 70°C; and for extracting, it was 60°C . This is the first time that an Oxone sequence has been used in Iran. The resulting XEXEP-bleached pulp contained 74.6% alphacellulose and 0.64% ash. This alphacellulose can be mixed with high purity alphacellulose to achieve both price reduction and quality improvement.