ORIGINAL PAPER The effect of pre-treatment on the production of lignocellulosic nanofibers and their application as a reinforcing agent in paper Eduardo Espinosa . Juan Domı ´nguez-Robles . Rafael Sa ´nchez . Quim Tarre ´s . Alejandro Rodrı ´guez Received: 3 October 2016 / Accepted: 28 March 2017 / Published online: 3 April 2017 Ó Springer Science+Business Media Dordrecht 2017 Abstract In this work, three different lignocellu- losic nanofibers (LCNF) were produced from unbleached wheat straw soda pulp by using different pre-treatments: mechanical, enzymatic, and TEMPO [(2,2,6,6-tetramethylpiperidin-1-yl) oxy radical]-me- diated oxidation processes. The different LCNF were characterized and studied by their chemical composi- tion (FTIR), crystal structure (XRD), thermal degra- dation behaviour (TGA), morphological (TEM), and their reinforcement effect on papermaking slurries. The pre-treatment used to obtain LCNF showed significant differences on the nanofibrillation yield (37–95%), carboxyl content (74–362 lmol g -1 ), cationic demand (428–1116 leq g -1 ), and on its dimensions (7–14 nm), thermal stability, and struc- ture. Regarding application as reinforcement on papermaking slurries, LCNF obtained by TEMPO- mediated oxidation produced a greater reinforcing effect than the other LCNF. Nevertheless, the obtained LCNF from mechanical process produce a similar increase in the mechanical properties of the paper- sheets due to its high length, compared with LCNF obtained by TEMPO-mediated oxidation. Keywords Wheat straw Á TEMPO Á Enzymatic Á Mechanical Á Isolation Á Characterization Introduction In the near future, bio-economy should become the engine that drives the advancement of developed and developing countries. To reach this objective, one of the main vectors must be research into effectiveness and efficiency of exploitation of natural resources, with the ultimate objective to maximise their use entirely and, therefore, generate the least possible amount of residue. The lignocellulosic materials constitute a very heterogeneous set of raw materials in origin and composition (all sharing the prevalence of lignin and cellulose as fundamental constituents), subject to be fully exploited. In recent decades, cellulosic fibers from lignocellulosic biomass have been researched for application in multiple industry sectors such as construction industry, paper and cardboard industry, biomedicine, etc. (Lu et al. 2014; Mohammadkazemi et al. 2009). Thus, to supply such growing demand, it is necessary to research non-wood cellulosic raw materials, such as fast-growing annual plants and waste from agricultural activity (Vargas et al. 2012; Feria et al. 2012). E. Espinosa Á J. Domı ´nguez-Robles Á R. Sa ´nchez Á A. Rodrı ´guez (&) Chemical Engineering Department, Faculty of Science, University of Co ´rdoba, Building Marie-Curie, Campus of Rabanales, 14014 Co ´rdoba, Spain e-mail: a.rodriguez@uco.es Q. Tarre ´s Group LEPAMAP, Department of Chemical Engineering, University of Gerona, c/M. Aure `lia Campmany, no. 61, 17071 Gerona, Spain 123 Cellulose (2017) 24:2605–2618 DOI 10.1007/s10570-017-1281-2