Photo-induced Yellowing of Mg(OH)2-based Peroxide Bleached Deinked Pulp

Na Yun, Beihai He

Abstract


The effects of ultraviolet (UV) irradiation on the changes in color and chemical structure of the surfaces of unbleached, PNaOH-, and PMg(OH)2- bleached deinked pulp (DIP) were studied by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. The analysis of color changes in pulp surfaces during the photo yellowing was performed by measuring the brightness loss, post color (PC) number, and CIELAB parameters (L*, a*, b*, and ΔE*). The results showed that the pulp brightness loss, PC number, and chromatic aberration had a linear relationship with b*. During the UV irradiation, the pulp brightness loss, PC number, and chromatic aberration (ΔE*) increased quickly, and then the changes slowed down. After being irradiated with UV for 360 min, the band intensity of the pulps at 1729 cm-1 increased distinctively and a new band at 1674 cm-1 appeared. This indicated that p-quinone groups were produced during the irradiation process, thus resulting in paper yellowing. The band intensity at 1674 cm-1 of PMg(OH)2-bleached pulp was lower than that of PNaOH-bleached pulp, which indicated that the brightness stability of PMg(OH)2 pulp was better than that of PNaOH pulp.

Keywords


Deinked pulp; Hydrogen peroxide bleaching; Mg(OH)2; Photo yellowing; FTIR

Full Text: PDF

Welcome to BioResources! This online, peer-reviewed journal is devoted to the science and engineering of biomaterials and chemicals from lignocellulosic sources for new end uses and new capabilities. The editors of BioResources would be very happy to assist you during the process of submitting or reviewing articles. Please note that logging in is required in order to submit or review articles. Martin A. Hubbe, (919) 513-3022, hubbe@ncsu.edu; Lucian A. Lucia, (919) 515-7707, lucian.lucia@gmail.com URLs: bioresourcesjournal.com; http://ncsu.edu/bioresources ISSN: 1930-2126