Evaluation and Optimization of Old Magzines Deinking Process of a Modified Lignin Sulfonates Deinking Agent

keywords:deinking agent  optimization  secondary fiber  waste paper  old magzines

Abstract:Deinking is an important process in waste paper recycling process, and this study mainly focuses on the properties of the deinking agent and process optimization. DIA-30 prepared in our laboratory, and FS and LD, were the three representative deinking agents studied herein. Brightness, effective residual ink concentration (ERIC), dirt, macro-stickies, fiber loss during repulping, flotation, and washing processes were measured to evaluate the performance of the deinking agents and optimize process conditions. Each of the deinking agents exhibited different advantages: DIA-30 was optimal for deinking efficiency, brightness enhancement, as well as dirt and macro-stickies removal, whereas LD was optimal for ink removal during flotation process but performed poorly in terms of brightness enhancement. FS showed a relatively balanced performance compared to those of DIA-30 and LD in the deinking process, but DIA-30 is the best option for deinking due to its outstanding comprehensive properties. The optimal repulping conditions for the deinking of 100% old magzines (OMG) using DIA-30 are as follows: repulping temperature, 60℃; pulp consistency, 13 wt%; repulping time, 20 min; H2O2 dosage, 0.5 wt% (oven-dried pulp); NaOH dosage, 1.2 wt% (oven-dried pulp); Na2SiO3 dosage, 0.3 wt% (oven-dried pulp); and optimum DIA-30 dosage, 0.1 wt%.