Effects of residual phenolic compounds on xylanase-assisted ClO2 bleaching of hardwood kraft pulp

In both pulping and bleaching processes, lignin in the pulp fiber is degraded into smaller molecules that need to be rinsed away. However, despite the installation of automatic washing equipment, the small phenolic compounds among other lignin degradation products can hardly be completely removed from the brownstock. Among the myriad of small phenolic compounds degrading from lignin, some are water-soluble and highly reactive with bleaching reagents. To understand the impact of residual phenolic compounds from black liquor on pulp bleaching, six monomeric phenolic model compounds were tested in this study. Catechol and vanillin showed inhibitory effects on xylanase activity, while catechol, vanillin, and guaiacol interfered with the delignification reaction in the chlorine dioxide (D) and alkaline extraction (E) stages of the bleaching sequence, thereby preserving the integrity of cellulose in the pulp. Because the efficiency of xylanase and bleaching reagents is hindered by the presence of these phenolic compounds, higher operational cost and more bleaching reagents are needed, which are incompatible with modern environmental policies in the world. Nonetheless, the presence of remaining soluble phenolic compounds in the brownstock can improve the bleaching selectivity important for the production of high-quality pulp with less-degraded cellulose chains.

Kenaf plant pest and disease detection using faster regional based convolutional neural network

<span>Kenaf plant is a fibre plant whose stem bark is taken to be used as raw material for making geo-textile, particleboard, pulp, fiber drain, fiber board, and paper. The presence of plant pests and diseases that attack causes crop production to decrease. The detection of pests and diseases by farmers may be a challenging task. The detection can be done using artificial intelligence-based method. Convolutional neural networks (CNNs) are one of the most popular neural network architectures and have been successfully implemented for image classification. However, the CNN method is still considered a long time in the process, so this method was developed into namely faster regional based convolution neural network (RCNN). As the selection of the input features largely determines the accuracy of the results, a pre-processing procedure is developed to transform the kenaf plant image into input features of faster RCNN. A computational experiment proves that the faster RCNN has a very short computation time by completing 10000 iterations in 3 hours compared to convolutional neural network (CNN) completing 100 iterations at the same time. Furthermore, Faster RCNN gets 77.50% detection accuracy and bounding box accuracy 96.74% while CNN gets 72.96% detection accuracy at 400 epochs. The results also prove that the selection of input features and its pre-processing procedure could produce a high accuracy of detection. </span>

Fiber Separation From Wood Pulp Using Slider Crank Mechanism

The Fiber separating machine is used to separate the fibers from their raw material (wood pulp). The machine is based on slider crank mechanism in this an iron disk is mounted to the electrical motor. A slider with a rough tooth is present in its bottom. By using the connecting rod, the disk and slider are connected together. The connecting rod converts the rotary motion into the linear motion. By using the forward and backward motion the fibers are de - fiberized from the raw material (wood pulp). This machine is used for small scale industries where bulk machines are not required. The main application of this wood pulp fiber is the making of napkins.

Morphology and color change of pulp fiber sheet in seawater and soil

Paper, or a pulp fiber sheet, is biodegradable and it can be a promising alternative to plastics, thus avoiding a serious form of marine pollution. However, its degradability in marine environments has not been well studied. This study investigated how a network of pulp fibers disintegrates in seawater compared with soil. Samples of pulp fiber sheets were exposed to seawater and soil for 4 months under stationary conditions at 25 °C. Digital photo images and scanning electron microscopy (SEM) images were used for morphological and color change investigations, while Fourier transform infrared (FT-IR) analysis was used to compare the chemical components of the samples before and after degradation. The area of the sample decreased by 22.3% in the seawater. The degradation rate in seawater was much lower than in the soil. The degradation mechanism in seawater was different from that in the soil because of the different microorganisms in each environment.

Optimization of Technological Parameters of Straw Fiber-Based Plant Fiber Seedling Pot Raw Materials

Straw fiber seedling pots are a promising substitute for plastic seedling pots. The mixing mode of straw fiber affects the mechanical properties of the raw material membrane of the seedling pot. To explore the processing technology of making the raw material membrane of the seedling pot with two kinds of plant fibers in a layered manner, the optimal combination of the process parameters of the raw material membrane of the seedling pot without additives in the production process was studied experimentally. Response surface methodology (RSM) was used to analyze the parameters (beating degree of unbleached softwood kraft pulp fiber, beating degree of wheat straw fiber, wheat straw fiber quality percentage content, and film grammage) with regard to the dry tensile index and Z-direction tensile index of the seedling pot body. The optimal process parameter combination with a certain dry tensile index and Z-direction tensile index of seedling pot raw material was obtained by using four factors and five levels of a quadratic regression orthogonal rotation center combination design parameter optimization experiment. The optimal technical parameters were optimized as wheat straw fiber quality percentage content 70%, film grammage 70 g/m2, unbleached softwood kraft pulp fiber beating degree 47–48 °SR, and wheat straw fiber beating degree 65–75 °SR. With the optimal conditions, the dry tensile index of the seedling bowl raw material film was between 21 and 22 N·(m·g−1), and the Z-direction tensile index was greater than 2.1 N·(m·g−1). Using wheat straw fibers and unbleached sulfite wood pulp fibers as raw materials for seedling pots, the raw material membrane of the seedling pots was made in a layered manner. The experimental study proved this feasibility. With this mixing process of raw materials, the straw fiber-based plant fiber seedling pot would meet the demands of a crop nursery after adding chemical additives. The research results provide a theoretical basis and technical support for the manufacture of the raw material membrane of the seedling pot body.

Physical properties of handsheets derived from Coi (Streblus asper Lour.) pulp fiber as papermaking material traced from ancient times

There have been recent attempts to revive the traditional production of handmade paper from the bark of the Coi (Streblus asper Lour.) tree in Thailand. A sheet sample of Coi handmade paper, made from the traditional production, was collected and examined microscopically for the first time. Film-like material and cubic calcium particles were found on the sheet sample surface, which is consistent with the results of the authors’ previous research. Meanwhile, handsheets derived from Coi pulp fiber, freshly made in the laboratory, demonstrated a low air permeance and brightness with high opacity due to the film-like material and cubic calcium particles. With a high felting power of Coi pulp fiber coupled with a possible strengthening role of the film-like material, both the beaten and unbeaten fibers were used to form handsheets with high strength. Some potential aspects of Coi pulp fiber suitable for creating a unique Thai banknote paper have been demonstrated, for which further studies are suggested.

Rheological behavior of magnetic pulp fiber suspensions

This paper is focused on the rheology of magnetic pulp suspensions in absence and presence of an external magnetic field. Magnetic fibers were prepared by the lumen loading method using bleached eucalyptus fibers and cobalt ferrite (CoFe2O4) nanoparticles. The effect of mass consistency, temperature, concentration of magnetic fibers, and magnetic field strength on yield stress and apparent viscosity of the suspensions were investigated. In the absence of an applied field, a dependence of yield stress with consistency, as well as with the percentage of magnetic fibers present in the suspension, was found. In flow tests, all the suspensions exhibited shear-thinning behavior, showing that the viscosity is only affected by the consistency of the suspension. On the other hand, magnetorheological measurements show a negative effect of the applied magnetic field on the viscosity of the suspension.