THE INFLUENCE OF NANOCELLULOSE AND SILICON DIOXIDE ON THE MECHANICAL PROPERTIES OF THE CELL WALL WITH RELATION TO THE BOND INTERFACE BETWEEN WOOD AND UREA-FORMALDEHYDE RESIN

Urea-formaldehyde (UF) resin is used as an adhesive in the most wood-based composite plants in China. The quality of such composites is strongly affected by the mechanical properties of the cell wall in relation to the interface between UF resin and wood. This research investigates the mechanical properties of the cell wall in the bond interface of wood and UF resin with nanocellulose and silicon dioxide, and compares the mechanical properties of wood-adhesive interface cell walls to their gluing strength. The hardness and reduced modulus of the cell wall were investigated by means of nanoindentation. The test results show that there was a close relationship between the mechanical properties of the cell walls at the wood-adhesive interface and the percentage of nanocellulose or SiO2 in the UF. The shear strength of UF resin with nanofibrillated cellulose (NFC) or nano-SiO2 in bonded wood also gradually increased when the content of these two kinds of nanomaterials was increased from 0% to 2%

The Antibacterial Properties and Safety of a Nanoparticle-Coated Parquet Floor

Floor antibacterial technology prevents the human body from cross-infection with bacterial diseases. The most commonly used approach to endow daily-used floors with antibacterial properties is to apply a thin film of antibacterial agents on the parquet floor surface. In the present study, five commercial antibacterial nanoparticles were first dispersed in melamine resin solution, and then applied on a floor. Afterwards, the antibacterial properties of the nanoparticle-coated floor were investigated, in which Escherichia coli was used as the target bacteria. The impact of the nanoparticle dispersing agents on the ultimate antibacterial properties of the floor were also investigated. The results showed that silver nanoparticle-loaded hydroxyl zirconium sodium phosphate (Ag-HZDP) was most suitable as the antibacterial agent of a melamine coating for parquet flooring. With the help of sodium hexametaphosphate, the antibacterial agent was able to disperse well in the melamine resin solution and was also able to disperse well on the floor surface. When the loading amount of Ag-HZDP was 1 wt % or higher, the prepared antibacterial floor was able kill almost all the bacteria cultivated on its surface. Moreover, the prepared antibacterial floor had a lower toxicity compared with a pristine cedar substrate. The present study provides an effective way to provide daily-used parquet floors with excellent antibacterial properties

Cobalt ferrite/cellulose membrane inserted catalytic syringe filter for facile in-situ filtration/degradation of emerging organic pollutants in water via activating peroxymonosulfate

In this study, a novel membrane was prepared from CoFe2O4 deposited commercial cellulose filter paper, and employed in the design of a catalytic syringe filter. The filter was used for the removal of various synthetic organic chemicals (SOCs) including rhodamine B, dimethyl phthalate, bisphenol A, ibuprofen, norfloxacin, 4-chlorophenol and diclofenac in water through in-situ activating peroxymonosulfate, which simulated an actual syringe-driven filtration process. The impact of SOC concentration, injection speed, series-connected filter number on the in-situ filtration/degradation performance of the filter were systematically investigated. The results demonstrated that the prepared filter had excellent catalytic capability towards all mentioned SOCs. Specifically, three series-connected filters could completely degraded SOCs even when the concentration of each SOC was higher than 0.1 mM. ESR and quenching tests indicated that the ·OH and SO4−· were main radical species dominating the SOC degradations. Meanwhile, high-valent metal-oxo species were also generated which participated in the SOC degradations. Furthermore, the filter had promising longtime use stability which maintained its effectiveness for 2 h of uninterrupted water flow. This study provides a facile and practical means to introduce advanced oxidation techniques for organic pollutant removals in actual wastewater through syringe-driven in-situ membrane filtration/degradation process

Enhancement of mechanical strength of particleboard using environmentally friendly pine (Pinus pinaster L.) tannin adhesives with cellulose nanofibers

International audienceContext Condensed tannins have been successfully used as substitutes for phenol in the production of resins for wood products. However, the enhancement of the properties of tannin-based resins with nontoxic and cost effective additives is of great interest.• Methods In the present work, the performance enhancement of tannin-based particleboards with cellulose nanofibers was investigated.• Results In presence of 2 % of cellulose nanofibers, the viscosity of tannin-based adhesives and the internal bonding strength (IB) of the corresponding particleboards were increased from 350 to 5,462 mPa·s and from 0.85 to 0.98 MPa respectively. The modulus of elastic (MOE) and modulus of rupture (MOR) of the resins were also notably increased while thickness swelling (TS) of the panels was not affected.• Conclusion The addition of cellulose nanofibers to tannin adhesives is an effective method for the production of high performance particleboards. Tannin-based adhesive containing 2 % of cellulose nanofibers exhibits the best mechanical strength.Key messageThe addition of cellulose nanofibers into tannin-based adhesives notably enhanced the mechanical properties of the wood particleboards produced. The formulation containing 2 % (w/w) of cellulose nanofibers exhibited the best mechanical strength

Coating Two-Dimensional Nanomaterials with Metal–Organic Frameworks

We demonstrate the coating of various 2D nanomaterials including MoS2 nanosheets, graphene oxide (GO), and reduced graphene oxide (rGO) with zeolitic imidazolate frameworks (i.e., ZIF-8) via a facile procedure. Additionally, ternary core–shell structures like Pt-MoS2@ZIF-8, Pt-GO@ZIF-8, and Pt-rGO@ZIF-8 have also been prepared. As a proof-of-concept application, a memory device based on MoS2@ZIF-8 hybrid was fabricated and it exhibited write-once-read-many-times (WORM) memory effect with high ON/OFF ratio and long operating lifetime. It is expected that MOF coated 2D nanomaterials may find wide applications in energy storage and conversion, catalysis, sensing, and information storage devices