Volume 15 Issue 1

Mesoporous heteropolyacid (HPA) nanorods having a composition of [C16H33N(CH3)3]xH3-xPW12O40 ((CTA)xH3-xPW, x = 1, 2, and 3) were synthesized by surfactant encapsulation and were evaluated for their catalytic activity in cellulose hydrolysis. The (CTA)H2PW nanorods were found to be most active with 57.2% yield of 5-hydroxymethylfurfural (5-HMF) at ~100% conversion in water/methyl isobutyl ketone (MIBK) biphase, which was higher than (CTA)H2PW nanosphere at 140 °C for 11 h. The yields of 5-HMF and glucose were obtained as 4.5% and 54.3% at 160 °C for 8 h in water system, respectively. (CTA)H2PW nanorods showed higher tolerance to such feedstocks as lignocellulose, i.e. corn straw with 19.8% and 8.3% yields for glucose and xylose at 35.4% conversion in water. Moreover, (CTA)H2PW nanorods showed higher stability and long duration with ten times reuse. (CTA)H2PW nanorods presented higher efficiency and reusability in conversion of cellulosic biomass.

Diatomite is extensively used as a natural environmental material because of its biogenic origin and stable structure. The zeolitic imidazolate framework (ZIF-8) is a prototypical metal-organic frame (MOF) that is well known for its high surface areas and chemical stability. Herein, a facile method for the generation of diatomite in situ loaded by ZIF-8 (D/Z) was reported. The results of powder x-ray diffraction (PXRD) analysis confirmed the successful loading of ZIF-8 on the diatomite. The ZIF-8 were distributed uniformly on the surface of the diatomite from the scanning electron microscope (SEM) images. The specific surface of the D/Z increased due to the loading of the ZIF-8. Methylene orange (MO-) in an aqueous form was efficiently separated and removed through a simple mixture and filtration process where the D/Z was employed as an absorbent, and the removal rate of the MO- increased in the case of the sample with more ZIF-8 loaded on the diatomite. In addition, the D/Z was reused after several regenerations by washing out the adsorbed dye.

Old books suffer from aging and deterioration spurred by acidification, oxidation, and other factors. To preserve these important historical documents, it is important to implement deacidification and reinforcement methods to extend their durability. In this study, microdroplets of 75 g/L sodium hydroxide solution were atomized before being utilized to neutralize acidity in the paper. As well, styrene acrylic latex was diluted to 10 times for atomization to function as a reinforcing agent. In addition to studying these methods individually, the effects of simultaneous deacidification and reinforcement were also studied.

Scoured jute fiber was modified with silica hydrosol and then mixed with polylactic acid to form bio-based fiber-reinforced composites. The effects of modification methods on the morphology and hydrophobicity of the fibers, as well as the tensile strength and fracture structure of the composites were studied. Also, the influence of sodium hydroxide concentration, MTMOS concentration, and numbers of dipping steps on the tensile strength of the composites were examined. The results indicated that silica hydrosol condensation could be used to prepare a smooth hydrophobic surface on modified fibers, while a rough hydrophobic surface could be prepared when alkaline treatment was carried out onto the surface of incompletely condensed silica hydrosol film. Rough hydrophilic fibers revealed poor interfacial compatibility and adhesion strength. Smooth hydrophobic surfaces improved interfacial compatibility and dispersibility of the fibers in hydrophobic matrix, whereas a rough hydrophobic structure further improved the adhesion strength through mechanical interlock. The data illustrated that morphology of the silica hydrosol modified fiber surface depended on the alkaline treatment conditions and amounts of adsorbed silica hydrosol, while the effect of MTMOS precursor concentration was negligible.

Old books suffer from aging and deterioration spurred by acidification, oxidation, and other factors. To preserve the important historical documents, a de-acidification and reinforcement method was studied using ultrasonic atomization via deacidification by Na2CO3 solution and styrene acrylic latex composite as reinforcing agent. These agents were atomized into micron-sized droplets and were absorbed by paper. In this study, the physical properties, internal structure, and surface morphology of the paper before and after aging were comprehensively studied for explaining the treatment mechanism. The paper pH, strength properties, brightness, color difference, and apparent morphology typically have been determined in detail as the important factors for evaluating the treatment effect of the preservation method for old paper. The analysis results showed that the pH of the paper after deacidification was successfully increased. Thus, even after aging, the pH of the deacidified paper was still higher than 7. The change of color difference of paper after treatment was not noticeable, meeting the requirement for the basic principle of an old book. Furthermore, the deacidification treatment had no clear influence on the breaking length and tear index of the paper. This study revealed a new perspective on the conservation of old books.

Methods suitable for the determination and classification of green timber mix (western hemlock and amabilis fir), with respect to species and moisture content, were developed and tested using near infrared spectroscopy and chemometrics. One thousand two hundred samples were distributed into a calibration set (720 samples) and a prediction set (480 samples). Partial least squares (PLS) and least squares-support vector machines (LS-SVM) for both regression (PLSR and LS-SVR) and classification (PLS-DA and LS-SVC) with different spectral preprocessing methods were implemented. LS-SVM outperformed PLS models for both regression and classification. The coefficient of determination (R2p) and root mean square error (RMSEP) of prediction for the best LS-SVR model with spectra pretreated by smooth and first derivative were 0.9824 and 8.7%, respectively, for wood moisture content prediction in the range of 30% to 253%. The best classification model was LS-SVC with spectra pretreated by smooth and second derivative, with overall accuracies of 99.8% in the prediction set, when the samples were divided into four classes. NIRS combined with LS-SVM can be used as a rapid alternative method for qualitative and quantitative analysis of green hem-fir mix before kiln drying. The results could be helpful for sorting green hem-fir mixes with an on-line application.

The effects of montmorillonite nanoclay and poly(ethylene-alt-maleic anhydride) via vacuum impregnation technique in relation to the physicochemical, mechanical, and thermal properties of bamboo-reinforced nanocomposites were investigated. The functional groups in the raw bamboo and nanocomposites were identified using Fourier transform infrared spectroscopy. X-ray diffraction plots showed the prominent peak intensity at a diffraction angle of 73° due to the transformation of the amorphous structure to a crystalline structure in the prepared nanocomposite. The morphologies of the raw bamboo and the nanocomposites were compared using scanning electron microscopy analysis. There was an increase in the modulus of elasticity from 7.82 to 19.0 GPa (143%) and a corresponding increase in the modulus of rupture from 68.7 to 121.5 MPa (77%) of the raw bamboo to the nanocomposites, respectively. This increase implied a high increase in the mechanical properties of the developed nanocomposite. Both results from the differential scanning calorimetry and thermogravimetric analysis showed appreciable improvements in the thermal properties of the developed nanocomposite.

Commercial American old corrugated container pulp (AOCC) boards were used as the starting material for repulping and low consistency (LC) refining to investigate the effects of LC refining plate geometry on the fibre and strength properties of the generated pulp. Specific refining energy that ranged from 0 to 120 kWh/air-dried ton (ADT) of pulp was explored for the two bar edge lengths (BEL) of refining plate patterns, wide 0.99 km/rev BEL and interim 2.01 km/rev BEL. The results showed that fibre length, curl index, kink index, and pulp freeness decreased while fines content increased with increasing refining energy input for both of the two refining plates during LC refining. LC refining with 2.01 BEL plate at low intensity of 0.24 J/m showed less fibre length reduction and more tensile strength development than that obtained with 0.99 BEL plate at high intensity of 0.48 J/m when compared at the same specific energy. Moreover, to achieve the desired tensile strength of the AOCC pulp, lower energy was needed for the interim 2.01 BEL plate than the wide 0.99 BEL plate. Thus, the interim 2.01 km/rev BEL refining plate provided potential for saving refining energy to reach a desired tensile strength of AOCC pulp.

The influence of natural protrusion, also known as silica bodies, was studied in relationship to sliding resistance reinforcement in an oil palm fibre-polyethylene composites. Experimental work on oil palm fibres-LLDPE composites (using fibres with and without protrusions) was conducted, which included x-ray microtomography (µ-CT scan), scanning electron microscopy, and degree of grafting analyses. A finite element micromechanical model was then developed using information from the experimental results to simulate fibre pull-out from the matrix. Microscopic observation after mechanical tests of the composites showed crater marks due to silica bodies in contact with the matrix, whereas fibres were uniformly distributed inside the matrix from the µ-CT scan. Likewise, the degree of grafting analysis showed a positive influence of silica bodies as an additional reinforcement to the composites. These were further supported by the modelling results of fibre pull-out, which showed a clear difference between models with and without silica bodies.

Electrochemical properties of a carbon paste electrode (graphite) modified with hazelnut and walnut shells were investigated. The adsorption of 4-chlorophenol (4-CP) on the studied materials was determined, and the hazelnut shells were found to provide a higher adsorption capacity. The hazelnut and walnut shells were used to modify the carbon paste electrode to detect 4-CP by cyclic voltammetry. Compared to an unmodified electrode, all of the new paste electrodes showed much higher sensitivity in the 4-CP detection.