Publications by authors named "Gu Joong Kwon"

This study reports dicarboxylate cellulose nanofibrils (DCNF) as a novel reducing and supporting agent for producing silver nanoparticles (AgNPs) with high efficiency (63.82 % reduction) and loading (6.88 %) using UV light.

View Article and Find Full Text PDF

In this study, lignin nanoparticles (LN) and octadecylamine-modified LN (LN-ODA) were utilized as coating materials to enhance the hydrophobic, antioxidant, and ultraviolet radiation-shielding (UV-shielding) properties of a TEMPO-oxidized nanocellulose film (TOCNF). The water contact angle (WCA) of the TOCNF was approximately 53° and remained stable for 1 min, while the modified LN-ODA-coated TOCNF reached over 130° and maintained approximately 85° for an hour. Pure TOCNF exhibited low antioxidant properties (4.

View Article and Find Full Text PDF

Rapid, efficient and green method of Pd nanoparticles (PdNPs) synthesis on TEMPO-oxidized cellulose nanofibril (TCNF) is demonstrated here. The nanohybrid (PdNPs/TCNF) exhibited peroxidase and oxidase-like activities evident by the oxidation of three chromogenic substrates. Enzyme kinetic studies using 3,3',5,5'-Tetramethylbenzidine (TMB) oxidation uncovered the excellent kinetic parameters (low K and high V) and good specific activities of 215 U/g and 107 U/g for peroxidase and oxidase-like activities, respectively.

View Article and Find Full Text PDF

Nanozyme-based dye degradation methods are promising for the remediation of water pollution. Though Pd nanoparticles (PdNPs) are known to act as nanozymes, their dye degradation capability has not been investigated. Low nanozyme activities, easy aggregation, difficulties in recovery and reuse are the major challenges in achieving this.

View Article and Find Full Text PDF

This study reports the preparation of a polybutylene succinate (PBS) film reinforced with pure cellulose nanofibril (PCNF) and lignocellulose nanofibril (LCNF) by a two-step process that consists of solvent dispersion and twin-screw extrusion. Compared to the conventional one-step process, this method offered improved mechanical properties. The addition of 5% CNF increased the tensile properties up to 18.

View Article and Find Full Text PDF
Article Synopsis
  • A cellulose acetate (CA)/cellulose nanofibril (CNF) film was created using a solvent casting method, where CNF serves as a reinforcement to enhance the film's tensile strength.
  • The study tested different ratios of CNF (3, 5, and 10 parts per hundred) and experimented with eco-friendly plasticizers (triacetin and triethyl citrate) along with two solvents (acetone and NMP).
  • Results indicated that using NMP for dispersion improved the film's mechanical properties significantly, with up to a 38% increase in tensile strength and a 65% increase in elastic modulus compared to pure CA, especially with a maximum effective CNF loading of 5 phr.
View Article and Find Full Text PDF

Lignocellulose nanofibrils (LCNFs) with different lignin contents were prepared using choline chloride (ChCl)/lactic acid (LA), deep eutectic solvent (DES) pretreatment, and subsequent mechanical defibrillation. The LCNFs had a diameter of 15.3-18.

View Article and Find Full Text PDF

In this study, the effect of lignin esterification with fatty acid chloride on the properties of lignin and lignin/poly(lactic acid) (PLA) composites was investigated. Lignocellulose ( S. et Z.

View Article and Find Full Text PDF

We aimed to improve the mechanical properties of alginate fibers by reinforcing with various cellulose nanofibrils (CNFs). Pure cellulose nanofibril (PCNF), lignocellulose nanofibril (LCNF) obtained via deep eutectic solvent (DES) pretreatment, and TEMPO-oxidized lignocellulose nanofibril (TOLCNF) were employed. Sodium alginate (AL) was mixed with PCNF, LCNF, and TOLCNF with a CNF content of 5-30%.

View Article and Find Full Text PDF

A novel microwave-assisted green method that synchronously synthesizes silver nanoparticles (AgNPs) and AgNPs decorated holocellulose nanofibrils (AgNPs/HCNF) within a minute and without using a reducing agent is reported. As obtained nanomaterials were well characterized using various analytical techniques. AgNPs applied as a colorimetric probe for the selective recognition of Hg(II) (linear range 10-200 μg L, detection limit 1.

View Article and Find Full Text PDF
Article Synopsis
  • The study focused on creating wet-spun filaments using different types of nanofibrils: lignocellulose nanofibril (LCNF), holocellulose nanofibril (HCNF), and nearly purified-cellulose nanofibril (NP-CNF).
  • It was found that the diameter of the filaments increased in this order: NP-CNF ≤ HCNF < LCNF, and removing lignin enhanced defibrillation efficiency and overall filament properties.
  • Orientation of the cellulose nanofibrils (CNFs) improved the tensile strength and elastic modulus of the filaments, with tensile strength ranking from highest to lowest as HCNF > NP-CNF > LCNF.
View Article and Find Full Text PDF

The adsorption characteristics of silver nanoparticles (AgNPs) on cellulose nanofibrils (CNFs) were investigated herein with different chemical compositions. Pure cellulose nanofibers (PCNFs), lignocellulose nanofibers (LCNFs) with different lignin contents (LCNF-20% and LCNF-31%), and holocellulose nanofibers (HCNFs) with hemicellulose were used in this study. Furthermore, CNFs and silver nitrate were mixed and reacted at different temperatures, and NaBH was used as the reducing agent.

View Article and Find Full Text PDF

Kraft lignin (KL) or plasticized KL (PKL)/poly(lactic acid) (PLA) composites, containing different lignin contents and with and without the coupling agent, were prepared in this study using twin-screw extrusion at 180 °C. Furthermore, ε-caprolactone and polymeric diphenylmethane diisocyanate (pMDI) were used as a plasticizer of KL and a coupling agent to improve interfacial adhesion, respectively. It was found that lignin plasticization improved lignin dispersibility in the PLA matrix and increased the melt flow index due to decrease in melt viscosity.

View Article and Find Full Text PDF
Article Synopsis
  • Poly(butylene succinate) (PBS) composites mixed with wood flour (WF) were created through twin-screw extrusion, showing varying effects on tensile strength based on the inclusion of polymeric diphenylmethane diisocyanate (pMDI).
  • As the WF content increased, tensile strength decreased for composites without pMDI, but increased for those with pMDI, while kraft lignin (KL) negatively impacted tensile properties in both cases.
  • The melt flow index (MFI) dropped with higher WF content but rose with more KL; pMDI increased melt viscosity, leading to lower MFI, and the composites exhibited reduced thermal stability compared to neat PBS, with changes in crystallization rates
View Article and Find Full Text PDF

Cellulose and chitosan solutions were prepared in 60% LiBr and mixed with a different weight ratio. The washing and drying of the prepared cellulose⁻chitosan composite films were performed under identical conditions. The color of the liquefied mixtures and films was initially transparent but changed from colorless to brownish yellow depending on the ratio of chitosan in the solution.

View Article and Find Full Text PDF

TEMPO oxidation was conducted as a pretreatment to achieve efficient nanofibrillation of long paper mulberry bast fibers (PMBFs). The pH dependency of nanofibrillation efficiency and the characteristics of the resulting cellulose nanofibrils (CNFs) were investigated. As the pH increased, the negative value of the zeta potential of TEMPO-oxidized fibers increased.

View Article and Find Full Text PDF

We prepared highly crystalline samples of a cellulose I-ethylenediamine (EDA) complex by immersing oriented films of algal (Cladophora) cellulose microcrystals in EDA at room temperature for a few days. The unit-cell parameters were determined to be a = 0.455, b = 1.

View Article and Find Full Text PDF

This study investigated in vitro antioxidant activity of Sonchus oleraceus L. by extraction solvent, which were examined by reducing power, hydroxyl radical-scavenging activity(HRSA) and 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assays. 70% MeOH extract had the greatest reducing power while EtOH extract had the greatest HRSA.

View Article and Find Full Text PDF