| Due to the more added chemicals, high deinking wastewater pollution load, and “alkaline blackening†phenomenon of fiber with higher lignin content, conventional alkaline deinking is no longer meet the needs of efficient recycling of waste paper. Therefore, it is urgent to develop deinking technology that has stronger ability to adapt waste paper, can improve the performance of waste paper and is more friendly to the environment. In this paper, the weak alkaline deinking technology of waste newsprint paper and its optimization conditions were studied. The potential and the problems of popularization and application of the technology were discussed.The whiteness of alkaline deinking pulp is better than that of neutral deinking, and its residual ink concentration is much lower than the neutral deinking pulp. However, the anionic trash amount and the COD of the wastewater for the alkaline deinking process are much higher than the neutral deinking. The weak alkaline deinking is the most ideal process for the waste newsprint paper.The moderate adding of sodium hydroxide and hydrogen peroxide in deinking process can increase the carboxyl content and the retention of fillers of deinked pulp, improving fiber’s ability to run up and weakening the influence of fiber hornification. The adding of sodium hydroxide and hydrogen peroxide has little influence on fiber length, width, and fines content. Subsequent alkaline H2O2bleaching can further increase the carboxyl content of recycled pulp fiber, improve the run up ability of fiber and weaken the negative impact of the fiber hornification.The weak alkaline deinking process was pilot plant tested successfully in10#deinking pulp production line of Huatai group. The residual ink of weak alkaline deinking pulp is low, and the whiteness is same to the alkaline deinking pulp. The weak alkaline deinking process saves a large amount of chemicals, so the COD of waste water decreased significantly and the production cost of deinking pulp is very low. |
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