Thesis (M.Sc.) - Asian Institute of Technology, 2002

A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science, School of Environment, Resources and Development

Enzymatic deinking is becoming an interesting technology in paper recycling. The deinking of paper can be achieved using enzyme treatment instead of chemical treatment. Moreover, deinking with enzymes can be carried out under condition that has less impact on occupational health and are more acceptable for environmental sustainability. The goal of this study was to determine the mechanical properties and optical properties of paper prepared with pulp that has been deinked either in conventional way or by the use of enzyme. In this study, basesheets surface sized with chitosan and oxidized starch were printed using ink-jet inks and processed for laboratory scale deinking. During deinking, various enzymes were used. The deinked pulp was used to prepare handsheets. These handsheets \·Vere assessed for the following properties; physical strength, brightness and opacity. The ink content of deinked pulp was also measured by the determination of effective residual ink concentration (ERIC) after the deinking process. The overall result of enzymatic deinking was compared with that of the traditional method. Chitosan deinked handsheet obtained greater tensile index, brightness and ERIC in the enzymatic process as compared with the chemical method. In case of oxidized starch deinked handsheet, chemical deinking exhibited better properties than that of enzymatic deinking. Enzymatic deinking provided superior effect on brightness and residual ink concentration. However, enzymatic deinking did not give better results in strength and optical properties when compared with control.