Cellulose oxidation by Laccase-TEMPO treatments

Abstract

17In this work, laccase-TEMPO (Lac-T) treatments were applied to bleached commercial 18 dissolving pulp in order to introduce carbonyl and carboxyl groups, which were found to 19 improve dry and wet strength-related properties. Also the solubility behavior towards xanthate 20 reactions was assessed. The effect of a refining step (R) before the oxidative treatment, the 21 absence or presence of oxygen pressure, TEMPO dose (2 or 8% oven dried pulp) and reaction 22 time (8 or 20h) were thoroughly examined. Treatments conducted in the presence of oxygen 23 pressure exhibited greater amount of functional groups. Introducing a pre-refining treatment 24 resulted in similar functional groups but higher wet strength was achieved. Specifically, a high 25 W/D strength ratio was observed, indicating that wet strength-related property was satisfactorily 26 developed. Besides the fact that all Lac-T treatments caused severe cellulose degradation, no 27 fiber strength loss was detected. In fact, all oxidized samples presented higher wet zero-span 28 tensile strength, mainly in R+ Lac-T (O 2 ) sample, which suggested the formation of hemiacetal 29 linkages between the new introduced aldehyde groups and available free hydroxyl groups 30 resulting from fibrillation. 31 32

Carboxylated Polysaccharides Decorated with Ultrasmall Magnetic Nanoparticles with Antibacterial and MRI Properties

“…Several other TEMPO‐mediated protocols were also proposed by different research groups, including those using enzymes (lacasse), or even TEMPO‐electromediated oxidation in order to avoid halide‐based activation of the catalyst …”

“…[26] The 6-carboxy pullulan notably exhibits higher water solubility than pullulan. [26,29] Several other TEMPO-mediated protocols were also proposed by different research groups, including those using enzymes (lacasse), [30,31] or even TEMPO-electromediated oxidation in order to avoid halide-based activation of the catalyst. [32,33] The purified carboxylated polysaccharides were subsequently used to obtain nanocomposite particles consisting of Figure 2.…”

Laccase/TEMPO-mediated bacterial cellulose functionalization: production of paper-silver nanoparticles composite with antimicrobial activity

“…It is the highest content of carboxyl groups under the used conditions. The optimization of the laccase/TEMPO oxidation procedure was conducted previously by the research group for vegetal cellulose (Quintana E, Roncero MB, Vidal T, Valls C (2017) Cellulose oxidation by Laccase-TEMPO treatments. Carbohydrate Polymers, 157, 1488Polymers, 157, -1495Polymers, 157, .…”

Enzyme biotechnology in degradation and modification of plant cell wall polymers

“…Remarkable polymerization and consequently improved dispersion and adsorption properties have been achieved with lignosulphonates , Zhou et al 2013, presumably in part due to the high solubility of these lignins (Fiţigȃu et al 2013). On the other hand, Grönqvist et al 2006, Saastamoinen et al 2012, Reynaud et al 2013, Liu et al 2016, Witayakran and Ragauskas 2009, Elegir et al 2008, Fillat et al 2012, Chandra and Ragauskas 2002, Widsten et al 2010 Laccase-mediator LPMO Bleached pulp Aldehydes and carboxyl groups Viikari et al 1999, Aracri et al 2011, Aracri and Vidal 2012, Quintana et al 2011, Cassland et al 2013 Brumer et al 2004, Xu et al 2012 enhanced solubility of kraft lignin has been achieved by laccase catalyzed grafting with guaiacol sulfonate (Lund and Ragauskas 2001). Laccase-aided-grafting of acrylamide with organosolv lignin, aiming at a better compatibility in polymer blends, has been achieved in presence of peroxides in dioxane-water solutions (Mai et al 2000).…”