Nanocellulose Production: Exploring the Enzymatic Route and Residues of Pulp and Paper Industry

Abstract

Increasing environmental and sustainability concerns, caused by current population growth, has promoted a raising utilization of renewable bio-resources for the production of materials and energy. Recently, nanocellulose (NC) has been receiving great attention due to its many attractive features such as non-toxic nature, biocompatibility, and biodegradability, associated with its mechanical properties and those related to its nanoscale, emerging as a promising material in many sectors, namely packaging, regenerative medicine, and electronics, among others. Nanofibers and nanocrystals, derived from cellulose sources, have been mainly produced by mechanical and chemical treatments; however, the use of cellulases to obtain NC attracted much attention due to their environmentally friendly character. This review presents an overview of general concepts in NC production. Especial emphasis is given to enzymatic hydrolysis processes using cellulases and the utilization of pulp and paper industry residues. Integrated process for the production of NC and other high-value products through enzymatic hydrolysis is also approached. Major challenges found in this context are discussed along with its properties, potential application, and future perspectives of the use of enzymatic hydrolysis as a pretreatment in the scale-up of NC production.

Recent Developments in Nanocellulose-Reinforced Rubber Matrix Composites: A Review

“…Cellulose is the most abundant renewable organic material that could be found on Earth [ 48 , 49 ]. From a chemical standpoint, cellulose is a high molecular weight polysaccharide that is constituted from the repetition of 10,000 to 15,000 β-(1,4)-bound-D-glucopyranosyl units [ 50 , 51 ]. These units are arranged in 4 C 1 -chain configurations where each repeating monomer is rotated 180° to its adjacent unit depending on the source [ 52 , 53 ].…”

“…On the other hand, crystalline domains are generally more resistant to mechanical, chemical, biological, and enzymatic treatments [ 5 ]. Different isolation techniques, inter- and intramolecular forces, as well as molecular configurations, enable cellulose to exhibit allomorphs such as I α , I β , II, III I , III II , IV I and IV II [ 5 , 51 ]. These allomorphs could be transformed from one to another through thermal or chemical reactions [ 54 , 55 ].…”

Production of Nanocellulose by Enzymatic Treatment for Application in Polymer Composites

“…Cellulose, due to the presence of a large amount of hydrogen bonds in it, is a material whose enzymatic modification requires a synergistic correlation of cellulolytic enzymes [ 31 , 32 , 33 , 34 , 35 ]. Scientists in their works have proved that the effectiveness of this complicated process is influenced not only by the conditions of the hydrolysis reaction, such as temperature, pH of the reaction environment [ 36 ] or the type, activity level and concentration of the selected substrate [ 37 , 38 ], but also the type or degree of polymerization of the cellulose used, its crystallinity and porosity [ 39 , 40 ]. Moreover, it was noticed that the efficiency of the modification process of this polysaccharide is influenced by the dispersion–morphological properties and polymorphism of the selected cellulose material [ 41 , 42 , 43 , 44 ].…”

Nanocellulose Production Using Ionic Liquids with Enzymatic Pretreatment

“…An eco-friendly alternative method of nanocellulose production is the application of ionic liquids or enzymes, since these methods do not generate hazardous waste, as is the case with acid hydrolysis. Different classes of enzymes have been applied in nanocellulose preparations, including cellulases, xylanases, and lytic polysaccharide monooxygenases [27]. However, cellulases, which are produced by cellulolytic organisms, including fungal species such as Aspergillus, Trichoderma, or Clostridium, are the most commonly used in preparation of nanocellulose [27,28].…”