Ryota Kose

Aqueous counter collision using paired water jets as a novel means of preparing bio-nanofibers.

This study involved a detailed investigation of a novel approach to reducing naturally occurring cellulose fibers into nanofibers solely by the use of aqueous counter collision (ACC) without any chemical modification. In this process, equivalent aqueous suspensions of cellulose are ejected from dual nozzles and collide at high speed and pressure. Even a few repetitions of the collision process are sufficient to produce nano-sized fibers dispersed in water. This work compared the ACC nano-pulverization of stable Iβ-rich and meta-stable Iα-rich cellulose samples. The ACC method is applicable to various kinds of polymeric materials with hierarchical structures, either natural or synthetic, as a means of preparing aqueous dispersions of nano-sized structures.

Cellulose production by Enterobacter sp. CJF-002 and identification of genes for cellulose biosynthesis

Enterobacter sp. CJF-002, which had been isolated as a cellulose producer with saccharides as a carbon source, was shown to efficiently produce cellulose from beet molasses (B-Mol) and biodiesel fuel by-product (BDF-B), renewable non-edible and inexpensive biomasses. The cellulose production rates of Enterobacter sp. CJF-002 using B-Mol and BDF-B as carbon sources were faster than those of Acetobacter xylinum (A. xylinum) ATCC23769, a representative cellulose producing bacterium. To clarify the biosynthetic machinery of cellulose in the strain, genes responsible for cellulose biosynthesis were cloned. Six open reading frames (ORFs) were suggested to be clustered and their amino acid sequences had high similarities with those of BcsA, BcsB, BcsZ (endoglucanase), BcsC, YhjQ, and YhjK from Escherichia coli, respectively. Of these, the former four genes showed low similarities to corresponding orthologs in a cellulose biosynthetic gene cluster of A. xylinum. A bcsC-knockout mutant produced no cellulose, confirming that the gene is essential for cellulose production of Enterobacter sp. CJF-002. The predicted three-dimensional structure of BcsZEn from Enterobacter sp. CJF-002 had high similarity with that of CMCax (endoglucanase) from A. xylinum ATCC23769 in spite of the low similarity in their amino acid sequences. Taken together, A. xylinum and Enterobacter sp. CJF-002 might produce cellulose via a similar synthetic mechanism.

One-Step Production of Amphiphilic Nanofibrillated Cellulose Using a Cellulose-Producing Bacterium

Nanofibrillated bacterial cellulose (NFBC) is produced by culturing a cellulose-producing bacterium (Gluconacetobacter intermedius NEDO-01) with rotation or agitation in medium supplemented with carboxymethylcellulose (CMC). Despite a high yield and dispersibility in water, the product immediately aggregates in organic solvents. To broaden its applicability, we prepared amphiphilic NFBC by culturing strain NEDO-01 in medium supplemented with hydroxyethylcellulose or hydroxypropylcellulose instead of CMC. Transmission electron microscopy analysis revealed that the resultant materials (HE-NFBC and HP-NFBC, respectively) comprised relatively uniform fibers with diameters of 33 ± 7 and 42 ± 8 nm, respectively. HP-NFBC was dispersible in polar organic solvents such as methanol, acetone, isopropyl alcohol, acetonitrile, tetrahydrofuran (THF), and dimethylformamide, and was also dispersible in poly(methyl methacrylate) (PMMA) by solvent mixing using THF. HP-NFBC/PMMA composite films were highly transparent and had a higher tensile strength than neat PMMA film. Thus, HP-NFBC has a broad range of applications, including as a filler material.

Preparation of fine fiber sheets from recycled pulp fibers using aqueous counter collision

The utilization of waste paper is very important for saving wood resources and reducing waste generation. Various techniques for preparing cellulose nanofibers, which is a material recently proposed for potential applications in the paper industry, have been investigated. In the present study, fine fibers were prepared using recycled pulp and a nanoengineering aqueous counter collision treatment, and sheets composed of these fine fibers were prepared by filtration under reduced pressure conditions. Measurement of specific surface area and optical microscopic observation of fine fibers showed the recycled pulp was not readily miniaturized by the treatment compared with virgin pulp. The tensile strength of sheets produced from recycled pulp by 5 times of the treatment was higher than of those prepared from recycled pulp by 60 times and from virgin pulp regardless of the number of the treatment. Furthermore, the density of the sheet produced from recycled pulp by 5 times was lower than other sheets.

Preparation and characterization of two types of separate collagen nanofibers with different widths using aqueous counter collision as a gentle top-down process

Two types of single collagen nanofibers with different widths were successfully prepared from native collagen fibrils using aqueous counter collision (ACC) as a top-down process. A mild collision of an aqueous suspension at a 100 MPa ejection pressure yielded nanofibers, termed CNF100, which have an inherent axial periodicity and are ~100 nm in width and ~10 μm in length. In contrast, ACC treatment at 200 MPa provided a non-periodic, shorter and thinner nanofiber, termed CNF10, that was ~10 nm in width and ~5 μm in length. Both nanofibers exhibited the inherent triple helix conformation of native collagen supramolecules. Even a medial collision that exceeded the above ACC pressures provided solely a mixture of the two nanofiber products. The two nanofiber types were well characterized, and their tensile strengths were estimated based on their sonication-induced fragmentation behaviors that related to their individual fiber morphologies. As a result, CNF10, which was found to be a critical minimum nanofibril unit, and CNF10 exhibited totally different features in sizes, morphology, tensile strength and viscoelastic properties. In particular, as the mechanical strength of the molecular scaffold affects cell differentiation, the two collagen nanofibers prepared here by ACC have the potential for controlling cell differentiation in possibly different ways, as they have different mechanical properties. This encourages the consideration of the application of CNF100 and CNF10 in the fabrication of new functional materials with unique properties such as a scaffold for tissue engineering.

Green Extraction Process for Oil Recovery Using Bioethanol

In this chapter, a novel green extraction process known as solvent extraction–crystallisation–evaporation (SECE) is introduced. The SECE is meant to be a sustainable approach for oil recovery from palm oil milling and refining processes. It utilises bioethanol as the extraction solvent instead of hexane. SECE is demonstrated for the extraction of residual oil from spent bleaching clay (SBC, i.e. waste from the palm oil refining processes), as well as from various waste products in the milling process, e.g. mesocarp fibres, decanter cake, etc.

Concentration of Cellulose Nanofiber Dispersion by Osmosis

Cellulose nanofiber (CNF) has recently emerged as a promising new bio-nanomaterial. Typically, a dispersion of CNFs with a high water content is prepared by chemical and/or mechanical treatment. A rapid water removing method of the CNF dispersion should be developed for its use. In this study, a new method to concentrate the CNF dispersion was investigated by using osmosis with a sucrose solution. This method achieved a concentration of 1 wt% dispersion of CNF into 19 wt%. The sucrose was also present in the concentrated CNF dispersion after osmosis. The concentration rate at 50 ̊C was higher than that at 23 ̊C. The concentration depended on the cutoff size of the molecular weight for the porous membrane. The porous membrane with a low-molecular-weight cutoff suppressed the amount of sucrose in the concentrated CNF dispersion, and increased the maximum CNF concentration of the CNF dispersion after osmosis. (Received 26 September, 2017; Accepted 14 November, 2017) # corresponding author: Ryota Kose (E-mail: kose@cc.tuat.ac.jp) 浸透圧を利用したセルロースナノファイバー分散水の濃縮

Residual oil recovery using bio-ethanol from spent bleaching clay and its characterization

Residual oil from oil palm refining waste, spent bleaching clay (SBC) was recovered through a pilot plant scale up solvent extraction process. To develop a green extraction and sustainable approach for recovery of oil, bio-ethanol was used as a solvent instead of hexane. The SBC was extracted in a round-bottomed jacketed vessel subjected to heat and two different pressures. Two consecutive separation processes was applied in this study, fractional crystallization followed by evaporation. The yields of residual oils extracted slightly under vacuum pressure were higher by 64% than those from the extraction at atmospheric pressure. The residual oil recovered by evaporation exhibited inferior qualities in term of free fatty acid (FFA). In contrast, the oil recovered by fractional crystallization shows superior FFA content to that of crude palm oil (CPO) which was suitable for food applications.