Investigation on the Appearance Properties of Waste Newspaper Deinked by Cellulase Compared

In this research، deinking of waste newspaper was investigated by chemical and enzymatic methods. Chemical deinking of waste newspaper was accomplished under the following conditions: treatment time of 10،20 and 30 minutes، chemicals usage as hydrogen peroxide 1%، sodium hydroxide 1%، DTPA 0. 3% and surface active agent 0. 15% (based on oven-dried waste paper)، consistency of 10% by washing، flotation and combined washing and flotation processes، separately. Enzymatic deinking was carried out using cellulase enzyme at different concentrations of 0. 025، 0. 05، 0. 1 and 0. 2 percent (based on oven-dried waste paper)، treatment time of 10،15 and 20 minutes، consistency of 10% at a pH range of 5-5. 5 by washing process. The results obtained showed that increase of cellulase concentration from 0. 025 to 0. 1% along with improving the deinking efficiency decreased dirt count and dirt area at both wire and felt sides. Deinking efficiency was decreased as cellulase concentration increased to 0. 2%. In general، the results from comparison of the appearance properties of the waste newspaper deinked by chemical and enzymatic methods showed that papers with the same appearance properties as chemical method can be produced using cellulase. However، chemical deinking of waste newspaper resulted in papers with lower dirt count، lower dirt area and improved deinking efficiency. In all chemical and enzymatic treatments performed، wire side had higher dirt count and the lower dirt area compared to felt side.