Laccase treatment of recycled blue dyed paper: physical properties and fiber charge

Abstract

Recycled blue colored paper was treated with laccase under various combinations of physical and chemical parameters including enzyme concentration, temperature, oxygen, and reaction time. Laccase treatment of recycled dyed pulp increased acid group content, tear index, tensile index, and color removal in a dose-dependent manner. Lengthening the treatment time from 2 to 4 h was beneficial to acid group content (12% increase), dye removal, and tensile index but had a detrimental 8% decrease on the tear index. A higher reaction temperature (65 vs. 45 degrees C) had a beneficial effect on acid group content (+31%), and tensile index (+26%) and a slightly negative effect on tear index (-5%), but significantly reduced the ability of laccase to remove color. Comparison of reactions subjected to different levels of oxygen supplementation showed the greatest beneficial effect for laccase treatment with slow oxygen bubbling. The experimental results indicate that laccase treatment increases fiber carboxylic acid content and tensile strength, in addition to reducing the color of the enzyme treated paper.

Enzymatic deinking of secondary fibers: cellulases/hemicellulases versus laccase-mediator system

“…Their activities involved in starch hydrolysis (-11 amylase, E.C. 3.2.1.1; and glucoamylase, E.C.3.2.1.3) were studied on soluble starch 12 (Calbiochem) and p-nitrophenyl glucoside (Sigma) for -amylase and glucoamylase 13 activities, respectively (Wood and Bhat, 1988). The endoglucanase, exoglucanase, 14 endoxylanase and -amylase activities, determined in 50 mM sodium acetate buffer (pH 5) at 15 50 ºC, were followed by the release of reducing sugars estimated as glucose or xylose at 540 16 nm (Nelson 1944).…”

“…4 shows the changes of brightness and residual ink concentration in deinked pulps 9 from newspaper and magazine fibers after a laccase-mediator containing deinking sequence 10 (P−L−D−B), and the corresponding control deinking sequence. Compared to carbohydrate 11 hydrolases, no significant differences were found when the laccase-mediator system, using 12 0.5% w/w of different synthetic (HBT and VIO) and natural (SIN, FER and PCO) mediators, 13 was integrated in the deinking sequence. In fact, deinked pulps with slightly lower brightness 14 and different colour tones were obtained depending of the mediator used.…”

A newly isolated Paecilomyces sp. WSH-L07 for laccase production: isolation, identification, and production enhancement by complex inducement

“…Laccases use molecular oxygen as an electron acceptor to catalyze the oxidation of a wide range of organic and inorganic substrates, including o,pdiphenols, aminophenols, polyphenols, polyamines, lignin, some inorganic ions, aryl diamines, and methoxyphenol acid [25]. Due to their broad substrate spectrum, laccases have attracted increasing attention in industrial and environmental Welds, such as pulp deligniWcation, dye decolorization, environmental pollutant detoxiWcation, biopolymer modiWcation, and biotransformation [8,13,17,20,25].…”

Two Decades of Laccases: Advancing Sustainability in the Chemical Industry

“…In another study, laccases alone were used to treat recycled blue office paper. The results indicate that this enzymatic treatment is able to enhance the physical properties of the resulting paper as witnessed by an increase in tensile strength, fiber carboxylic acid content, and a reduction in color of formed handsheets . In a patent application, LMS HBT treatment was used to degrade and reduce the fluorescent whitening agent (FWA) Tinopal SFP, a type of diaminostilbene FWA commonly used by the paper industry to increase the whiteness of paper products .…”