Using chitosan as a chelating agent in deinking of recycled old newsprint pulp

The application of chelating agents to increase the efficiency of hydrogen peroxide is important in various related processes. Synthetic chemicals such as ethylenediaminetetraacetic acid (EDTA) are commonly used in these processes. The feasibility of using natural and environmentally friendly products instead of synthetic materials is an important and interesting subject. In this study, the performance of hydrogen peroxide in the deinking process was considered and the use of chitosan as a natural chelating agent in the deinking process of waste newspapers was investigated. The results showed that hydrogen peroxide bleaching along with the deinking process had a positive impact on the optical properties and reduced the burst and tear indices with no effect on the tensile and fold strengths. Chitosan, similar to the EDTA chelating agent, improved brightness, whiteness, dirt removal, and metal ion absorption in comparison with the treatment without a chelating agent. EDTA performs better than chitosan in removing ink from the pulp. Furthermore, in comparison to the treatment without a chelating agent, both chelating agents improved tear and burst indices, but had no effect on the fold and tensile strengths. The current research can be a small but promising step in using natural materials, such as chitosan biopolymers, instead of synthetic chelating agents, such as EDTA.