Volume 11 Issue 4

Cellulose nanofibril (CNF) is a type of nano-sized cellulosic material with a high aspect ratio and a large specific surface area, which makes it a promising additive to flocculate particles such as fillers. In this study, CNFs were prepared by wet disk-milling with three different degrees of fibrillation. The effect of the CNF on the flocculation of precipitated calcium carbonate (PCC) was elucidated. A photometric dispersion analyzer (PDA) investigated the flocculation phenomena resulting from the interactions between the PCC and the CNF, or polymers, in real-time. The results clearly showed that CNF could be used to control the flocculation behavior of the PCC particles. Scanning electron microscopy (SEM) images showed that the CNFs functioned as bridges between the two PCC particles. A significant reflocculation capability was observed in one- and two-component systems that consisted of CNFs. The addition of cationic starch (C-starch) could induce more efficient flocculation within a two-component system.

Effects of metal salt catalysts and gasification temperature on the gasification characteristics of combustible solid waste were studied, based on the source-classified waste in a fluidized bed gasifier, to provide guidance for utilizing the source-classified waste effectively. The results showed that the gasification characteristics of combustible solid waste, such as paper and sawdust, improved noticeably after adding NaCl, K2CO3, or sodium dodecyl benzene sulfonate (LAS). Adding NaCl to sawdust increased the yield of CO and CH4, while the gasification was inhibited gradually with increasing addition. Adding NaCl promoted the generation of H2 in paper gasification. NaCl played a catalytic role only when it exceeded a certain value. Adding K2CO3 increased the yield of H2 noticeably in sawdust and paper gasification. The catalytic effect of K2CO3 on sawdust was better than that on paper. Similar results were obtained for LAS in producing H2 in gasification. The carbon conversion efficiency and the gasification efficiency were increased with additional LAS. Moreover, the catalytic effect of K2CO3 was superior to that of LAS by comparison. As the temperature rises, the activity of the metal salt catalyst is enhanced, but it is inhibited if the temperature is too high.

Bamboo is one of the most important non-wood raw materials for the pulp and paper industry in Asia and particularly in China. However, its high silicon content can cause challenges in the pulping and alkali recovery systems. Further understanding of the distribution, morphology, and composition of silicon in bamboo culm will be beneficial in solving these challenges. In this study, modern analytical tools such as scanning electron microscopy (SEM) and scanning electron microscopy equipped with an energy dispersive X-ray (SEM-EDX) were used to characterize the distribution, morphology, and composition of silicon in the bamboo culm. The results showed that silicon is mainly distributed in the outer skin and inner skin. The silicon deposits exist in a number of shapes, and sinuate is the most common one. Their sizes range from about 0.15 μm to 0.9 μm in the cell wall and between 0.3 μm to 1.5 μm in the cell lumen. Localized silicon deposits are present in the forms of its oxide, silica, monatomic silicon, and/or organosilicon. Based on the above results, two potential techniques are recommended for pulp mills to minimize silicon-related challenges.

Senior managers in the forestry and wood-processing sectors in the Slovak Republic were asked to complete questionnaires. The aim of the research was to identify the importance of certain factors that affect the process of their motivation. A total of 493 senior managers were surveyed. The respondents used a five-point rating scale to rate the significance of each motivation factor, where 5 was very important and 1 was unimportant. The importance of 36 motivation factors was studied for senior managers through the use of statistical methods. Based on the study, it was concluded that the base salary is the most important factor of motivation, followed by job security as the second most important motivation factor, and the third most important factor was the fair appraisal system.

The physical and mechanical performance of wood from the rose gum (Eucalyptus grandis) and the Gympie messmate (Eucalyptus cloeziana) species were investigated. The wood samples were treated with a two-stage freeze-heat thermal process. Fast-growing trees were used for preparing test samples, which were subjected to thermal treatments. The freezing stage had the treatment temperature fixed at -22 °C for 72 h, while the temperature of the heat stage ranged from 180 to 200 °C for 3.5 h. The measurements of mass loss, density, and equilibrium moisture content were determined to better understand the mechanical properties. Static bending, compression parallel to grain, Janka hardness, and impact tests were applied to reveal changes in the mechanical behavior of the treated wood. In general, the freezing stage decreased the mass loss and increased the moisture content of wood (when combined with the heating stage), which showed the opposite trend for the heating stage. Modulus of elasticity and compression strength were increased only after the heating stage, while decrements were found for modulus of rupture, impact strength, and Janka hardness. The two-stage treatments did not prevent a decrease in the mechanical properties; however, they were helpful in preventing higher mechanical resistance losses in hardness (the Gympie messmate) and impact resistance (the rose gum).

Spent cooking liquor from kraft pulping, known as black liquor, was applied to linerboard (corrugated medium) by surface sizing in order to increase strength properties. The influence of alum in black liquor on linerboard properties was also investigated. The surface application of black liquor improved the dry strength of linerboard. A slight addition of alum into black liquor (2.5% on black liquor solids) significantly improved strength properties such as tensile strength, TEA, compressive strength, and bursting strength. The results implied that black liquor with alum can be used for industrial grade papers that require high strength properties. The air permeability of corrugated medium increased after 5 g/m2 of dry pick-up. Black liquor appeared to penetrate the paper pores, and aggregates of lignin and carbohydrates in the black liquor increased bonds between fibers, which improved strength. The surface sizing of black liquor and alum addition also affected the hydrophobicity of linerboard.

The paper recycling sector has undergone major changes in recent years, particularly regarding the quantity and quality of various materials processed. Material originating from board grades will increasingly dominate the recycling market as the use of printing papers decreases and the amount of non-fiber elements increases. Users of recycled fiber material have to overcome three main challenges: price, quality, and availability. This paper focuses on the quality dilemma in terms of measurement needs and possibilities from the user viewpoint. It includes a discussion of the factors causing deterioration in the quality of paper used for recycling. Today, the average fiber age is low compared to what the fibers can tolerate. Therefore, the characteristic phenomena in the paper recycling loop are not caused by the degradation of individual fibers, but by a blending process in which different fiber grades and non-fiber components are blended in a non-optimal way. A novel method is introduced in this article for evaluating the quality of recycled fiber material using a new parameter, the fiber integrity value. Part 2 of this paper will focus on the application of this new parameter and demonstrates its correlation with paper properties.

Paper sludge generated from the paper industry is classified as solid waste, comprising primarily wood fiber with excellent toughness and CaCO3 with low thermal conductivity. The purpose of this work was to investigate the adaptability of paper sludge with wood fiber into cement-based insulation mortar. The addition of paper sludge with wood fiber was found to be beneficial for optimizing the performance of cement-expanded polystyrene (EPS)/paper sludge (CEP) mortar. In detail, the addition of paper sludge with low fiber content in the range of 2.5% to 7.5% improved the toughness and softening coefficient of CEP mortar. In comparison, an increase of wood fiber content notably improved the properties of CEP mortar when its addition level reached 15%. Additionally, paper sludge with different fiber contents decreased the thermal conductivity of CEP mortar, ranging from 0.0897 to 0.0885 W/(m·K). In conclusion, paper sludge with wood fiber exhibited good adaptability in CEP mortar.

Activated carbon was prepared from pyrolyzed pinewood char using KOH, H3PO4, H2O2, and heat-only treatments. Activated carbon prepared by the heat-only treatment had a total surface area of 233.2 m2/g, a total pore volume of 0.138 cm3/g, a microporous surface area of 129.9 m2/g, and a microporous volume of 0.07 cm3/g. The most significant improvement of pore properties for the chemically treated pinewood char was obtained by the KOH treatment, which produced a total surface area of 1124.4 m2/g, a total pore volume of 0.723 cm3/g, a microporous surface area of 923.6 m2/g, and a microporous volume of 0.485 cm3/g. After the H3PO4 treatment, pinewood char had a total surface area of 455.5 m2/g, a total pore volume of 0.251 cm3/g, a microporous surface area of 393.3 m2/g, and a microporous volume of 0.211 cm3/g. The least significant improvement was obtained from the H2O2 treatment, which produced a total surface area of 363.0 m2/g, a total pore volume of 0.202 cm3/g, a microporous surface area of 271.5 m2/g, and a microporous volume of 0.141 cm3/g. Transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR) were performed to compare separate treatment stabilities and functional group properties.