LAUSR

The aim of this work was to study the feasibility of using orange tree pruning to obtain lignocellulose nanofibers (LCNFs) and their application in paperboard recycling process. The orange tree pruning was treated with an environmentally friendly process (13% NaOH on dry matter, at liquid/solid ratio of 8, 170 °C and 40 min). The cellulosic pulp obtained was used for the isolation of LCNFs by means of two different pretreatments, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated (TO-LCNFs) and mechanical refining (Mec-LCNFs), followed by high-pressure homogenization treatment. The reinforcement effect produced by the LCNF addition on paperboard recycled fiber was compared with other conventional industrial techniques such as chemical addition and mechanical beating. It was shown that TEMPO-mediated oxidation produces a greater delamination in fiber during its nanofibrillation, obtaining smaller width nanofibers with greater specific surface. The LCNF addition, especially TO-LCNFs, presents reinforcement effects comparable to those achieved by mechanical beating for the different mechanical properties, with the advantage of not modifying the fiber physically and increasing the numbers of recycling cycles. The economic analysis of both treatments shows that despite the Mec-LCNF cost is slightly higher, it is presented as an alternative to mechanical beating for use in paperboard recycling process.