Volume 34, Issue 1

In this investigation, a nondestructive technique has been developed for determining chemical composition of jute fiber by chemometric modeling with pretreated FT-NIR spectroscopic data. The chemical composition of jute fibers in wet chemical method were, 58 to 61.80 % α-cellulose, 13.0 to 21.90 % lignin, 9.89 to 16.8 % pentosan and 79.02 to 88.33 % holocellulose. FT-NIR spectral data from range 9000–4000 cm −1 of all jute samples were collected from the instrument. Spectral data of jute samples were pretreated with second order derivatives (SOD), standard normal variate (SNV) techniques and both together were used before calibration. Two chemometric calibration techniques: partial least square regression (PLSR) and artificial neural network (ANN) were assessed for predicting chemical compositions of Jute fibers. Result shows that prediction efficiency ( R 2 {\text{R}^{2}}) of ANN varies from 72–99 % for calibration, validation and test datasets. However, by PLSR, R 2 {\text{R}^{2}} are much higher and consistent than those by earlier one. For α-cellulose, lignin, pentosan and holocellulose R 2 {\text{R}^{2}} values hover around 95–99 %. Thereby, a non-destructive, simple and cost effective novel method is being proposed to determine chemical compositions of jute with pretreated FT-NIR spectral data and chemometric calibration techniques.

Microfibrillated cellulose (MFC) with and without added CMC was exposed to short-term dynamic thermal treatment using a steam jet cooker. The effects of the elevated temperature (130 °C, ∼3 bar) and shear forces on the rheology, crystallinity index, UV/VIS adsorption and water retention were measured. Jet cooking increased the viscosity and gel strength of the MFC and MFC/CMC mixture but with CMC alone a slight decrease in viscosity was observed. The water retention capacity and crystalline indices of the MFC were not greatly affected by the short-term thermal treatment and shear forces, although a slight increase in the UV/VIS absorbance was observed.

Chlorine dioxide is commonly used as a bleaching agent in kraft pulp mills. Scrubbers are required to remove any remaining ClO 2 from the plant tail gases. To control the air emissions of chlorine compounds, chlorine dioxide and chlorine contents must be monitored to ensure that the strict regulatory standards are met. However, the currently used analytical method is not suitable for detection of low concentrations of chlorine and chlorine dioxide. A new method for measuring chlorine dioxide and chlorine emissions was developed, which ensures compliance with the stringent requirements imposed by the authorities. The two species could be measured separately with a limit of quantification of 3 ppm. The method was robust and easy to use in the pulp mill environment and it was validated both in the laboratory and the field. The specificity of the method was demonstrated, Cl 2 analysis was not sensitive to the presence of ClO 2 and vice versa. The uncertainty (±2×RSD) of the analytical method in the field was estimated from duplicate measurements performed in the range of 3–500 ppm for ClO 2 and 3–300 ppm for Cl 2 , and was found to be ±20 % and ±10 %, respectively. Possible interferences in the analytical method are also discussed.

Impregnation with high initial concentration is fast and efficient, leading to a homogeneous delignification in the subsequent cook, resulting in improved screened pulp yield. To obtain high initial alkali concentration, the white liquor flow needs to be significantly increased. The moisture content of the wood chips and the alkali concentration of the white liquor limit the initial alkali concentration of the impregnation liquor that can be reached. It is therefore of interest to evaluate the possibility to implement high alkali impregnation (HAI) industrially and the consequences this would have on the mill system. The effect of HAI on mass and energy balances in a kraft pulp mill has been studied using mill model simulations. The sensitivity to disturbances in important parameters for process control has been compared to impregnation scenarios used industrially. It was shown that high initial alkali concentration can be achieved on industrial scale by increased white liquor flow. HAI has a positive effect on recovery flows and reduces the need for make-up chemicals. The HAI concept is less sensitive to variations in process parameters, such as chip moisture and white liquor concentration, thus diminishing the risk of alkali depletion in chip cores.

Distance between stationary and rotating refining plates, gap, has a direct and significant impact on refining power. Gap is almost universally used to control power in low consistency refining operations. The relationship between power and gap are affected by refiner size, pulp type, plate pattern and refining conditions. In this study, a correlation was developed to describe the power–gap relationships at a wide range of refining conditions and furnish. The correlation was developed using pilot-scale refining data of mechanical pulps. Results showed that a properly defined dimensionless power number is suitable to describe refining power as well as to compare different refiners under the same grounds. The developed correlation was also used to predict mill-scale refining data showing good agreement with between predicted and measured values. Finally, experimental data from force sensor measurements supports the correlation’s theoretical assumptions.

LC refining of mechanical pulps has proven to save energy in the production of TMP pulps. However, the specific role of LC refining as part of a TMP system has not been thoroughly studied since it is difficult to conceive any particular system at industrial-scales and impractical at pilot-scales. In this study, pressure screening and LC refining models that describe fibre length distributions, together with correlations to predict refining power were used to model three basic refining systems. From the simulation results, the impact of important variables such as reject ratio, refiner gap and refining net-power was studied. Performance curves of length-weighed average fibre length were generated from simulation results and were used to assess each system behaviour and also to make comparisons between systems. Data from an industrial scale TMP mill sub-system was gathered and compared to simulation results showing relative errors between 0–18 % on the predicted variables.

Chromogenic sources such as carbon particles and magnetic particles are the key factors restricting the brightness of fly ash. This study explored the feasibility of calcination-carbonation two-step method to improve the brightness of fly ash and apply it to paper filling. The results show that Under the condition of high temperature, the unburned carbon particles in fly ash are removed, and the brightness of fly ash is increased from 30 %ISO to 49 %ISO with the increase of burning loss. The dense calcium carbonate coating can be formed on the surface of fly ash particles modified by the carbonation reaction process after high temperature calcination, and the brightness of fly ash can be further raised to about 66 %ISO. The composite filler prepared by two-step method can be used to paper filling, the brightness of the paper can reach 76 % ISO, and it has good opacity at 20 % filling. Therefore, it is feasible to prepare fly ash-based composite filler by calcining-carbonization method.

The purpose of this work was to study the influence of pulp fiber suspensions refining operating variables on energy efficiency coefficient. Three chemical pulps with different average morphological characteristics were used, obtained from bleached kraft Pinus sylvestris , Eucalyptus globulus and Betula verrucosa . The final objective was to establish the chemical pulps refining efficiency parameters. Refining hydromechanics and energy consumption profiles were analyzed. Average normal and tangential forces on pulp suspension in the gap clearance, resulting rotor-stator distance and no-load and refining conditions power consumption were obtained. The refining trials took place in a laboratory Valley beater, and the manipulated variables were charge on the roll and rotor rotation speed. Global relationships for tangential stress and energy efficiencies in terms of rotation speed and rotor-stator gap were obtained. A relationship between energy efficiency and shear stress was obtained. The results have shown that in a Valley beater increased rotor-stator gaps reduce energy efficiency, concomitantly increasing apparent viscosity and reducing shear stress. No-load power was seen to increase with crowding factor, and thus with flocculation. Inversely, crowding factor and ultimately flocculation had an adverse effect on energy efficiency.

Strength, softness, and absorbency have been identified as the key attributes for disposable consumer products such as tissue, towel and diapers. These attributes are generally evaluated subjectively by users. Although subjective evaluation may be necessary for developing such consumer products, it is time-consuming and expensive. More importantly, it seldom provides guidance or direction regarding process control or product development. The main reason is because subjective evaluation is performed after the fact ( ex post facto ), not before the event (not ex ante ). Accordingly, it has been desirable to develop physical test methods to predict in-use performance of a consumer product. In developing physical test methods to link with subjective evaluation, reliable and relevant subjective data is necessary. Developing physical test methods for softness of hygiene paper has been extremely challenging. The objective of this paper is to demonstrate a feasibility of developing physical test methods which can be highly related to subjective evaluation. To this end, it is hypothesized that tissue softness mainly consists of bulk softness and surface softness. It is assumed that the bulk softness should be determined from bulk stiffness which is defined as the slope between the two specified points in a load-elongation curve from tensile testing. It is also assumed that the surface softness should be determined from the surface properties (roughness and friction) from a surface tester (e. g., Model: KES-SESRU. Kato Tech, Japan). It is suggested that the principles used here for developing physical test methods for tissue softness should be also applicable to other physical properties such as strength and absorbency.

The wet strength of cellulose-cellulose joints, reinforced with PAE-loaded microgels, was decreased by nearly a factor of two when the labile disulfide crosslinks on the supporting microgels were exposed to a reducing agent. The supporting microgels were temperature and pH sensitive poly( N -isopropylmethacrylamide-co-acrylic acid) microgels, prepared with a disulfide crosslinker. The level of PAE loading increased with the microgel carboxyl content. This work illustrates a new approach to increasing the recyclability and compostability of wet-strength papers made with PAE wet-strength resin.

Sustainable thermal insulating materials produced from cellulosic fibers provide a viable alternative to plastic insulation foams. Industrially available, abundant, and inexpensive mechanical pulp fiber and recycled textile fiber provide potential raw materials to produce thermal insulating materials. To improve the fire retardancy of low-density thermal insulating materials produced from recycled cotton denim and mechanical pulp fibers, bio-based fire retardants, such as sulfonated kraft lignin, kraft lignin, and nanoclays, were coated onto sustainable insulating material surfaces to enhance their fire retardancy. Microfibrillated cellulose was used as a bio-based binder in the coating formula to disperse and bond the fire-retardant particles to the underlying thermal insulating materials. The flammability of the coated thermal insulating materials was tested using a single-flame source test and cone calorimetry. The results showed that sulfonated kraft lignin-coated cellulosic thermal insulating materials had a better fire retardancy compared with that for kraft lignin with a coating weight of 0.8 kg/m 2 . Nanoclay-coated samples had the best fire retardancy and did not ignite under a heat flux of 25 kW/m 2 , as shown by cone calorimetry and single-flame source tests, respectively. These cost-efficient and bio-based fire retardants have broad applications for improving fire retardancy of sustainable thermal insulating materials.

The influence of wetting and drying during high-speed inkjet (HSI) printing on the time-dependent mechanical behavior of commercial HSI papers was investigated using a custom-built C-Impact tensile tester. In HSI printing the water based ink solvent penetrates into the paper while the colorants adhere onto the surface. We found that water strongly affected paper stiffness and strength already 0.1 s after wetting. Creep compliance and paper strain at a typical HSI printing input tension of 180 N/m are varying strongly during the different process steps of HSI printing. In order to achieve a good color registration and print quality, we thus recommend that the web tension should be dynamically controlled in each process step to prevent straining after wetting or shrinkage during drying.

This paper presents a proposed mathematical model, describing the calculations involved in deducting the critical compression force for rectangular, parallelepiped paperboard packaging, and permitting the minimisation of the thickness of the package sidewall. A comparison is given between the obtained calculations regarding critical force and the experimentally-determined results. This has shown a sufficient level of accuracy both for the theoretical and the experimental results. This means that the proposed mathematical engineering calculations model can be applied to the design of rectangular, parallelepiped paperboard packaging.

Nowadays in many countries legislation places stringent limits on the dumping of untreated sludge as land fill. One option for handling sludge is incineration. However, log-soaking bottom sludge contains a remarkable amount of sand, which hinders its use as fuel. This gives rise to the need for an appropriate means for separating sand from sludge. A pilot apparatus for the separation of sand from log-soaking bottom sludge was designed. The pilot apparatus consisted of a drum washer and gravity settling. The water consumption of the process was very low. The separation of sand was remarkable and the resulting sludge could be used in grate firing boilers after drying.

Three dominant bacteria including Virgibacillus pantothenticus , Bacillus cereus , and Bacillus subtilis were screened from an activated sludge domesticated via white water in the laboratory. The treatment effects of chemical oxygen demand (COD), electrical conductivity and cationic demand (CD) of the white water by three dominant bacteria were studied in different temperatures. The results showed that the optimum metabolic temperature of the three dominant bacteria was 30 °C with the tested range of 20 °C to 60 °C. The best treatment effect was tended to be stable at a hydraulic retention time of 14 h, COD removal rate was 67.69 %, 77 % and 75.38 %, the electrical conductivity decreased by 0.86 mS/cm, 0.86 mS/cm and 0.62 mS/cm and the CD decreased by 45.61 %, 73.68 % and 50 % for V. pantothenticus, B. cereus, and B. subtilis, respectively.

The microaerobic granular sludge for pentachlorophenol (PCP) degradation was obtained in our laboratory which had excellent effect and physical-chemical properties at PCP loading of 3.0×10 −2  kg·m −3 ·d −1 . In this paper, the effects of PCP loading shock on the operation of microaerobic granular sludge system, dechlorination intermediate product, fermentation climax community and flocculation performance of sludge were studied with the PCP loading of 5.0×10 −2  kg·m −3 ·d −1 and 8.0×10 −2  kg·m −3 ·d −1 . The results showed that the activity of microaerobic granular sludge decreased due to the shock of PCP loading, leading to the reduction of COD and PCP removal efficiency, the accumulation of dechlorination intermediate and short chain fatty acids, and the decrease of sludge flocculation performance. Acidogenic fermentation climax community changed from acetic acid type to acid fermentation and the activity of microaerobic granular sludge could be recovered just for 2 days under the PCP loading of 5.0×10 −2  kg·m −3 ·d −1 , whereas the climax community converted to mixed fermentation of propionic acid and butyric acid and the activity of microaerobic granular sludge struggled to recover the previous level after 8 days under the PCP loading of 8.0×10 −2  kg·m −3 ·d −1 .

Lignin, a renewable product with high potential for various applications, can be recovered from kraft black liquor by precipitation in acid medium. The objective of this study was to evaluate the effect of the addition of kraft lignin to wood biomass on the properties of briquettes. Hymenolobium petraeum , Eucalyptus , and Pinus biomasses received the addition of 0, 3, 6, 9, and 12 % (w/w) of kraft lignin, and briquettes were manufactured. Wood biomasses and briquettes were characterized chemically and physically. Addition of kraft lignin positively influenced the apparent density, energy density, and mechanical resistance of briquettes. Furthermore, kraft lignin increased the calorific value of briquettes. Addition of 6 % (w/w) of kraft lignin was sufficient to improve the quality properties of briquettes, which demonstrates the great potential of kraft lignin as an additive in briquette production.

Thermoplastic elastomer (TPE), made from ethylene propylene diene monomer (EPDM) and polypropylene (PP) base on reactive blending, has an excellent processing performance and characteristics and a wide range of applications. In this paper, EPDM, PP and ammonium lignosulfonate (AL) were selected as raw materials, wood flour (WF) of poplar tree was used as filler, naphthenic oil was used as plasticizer, DCP vulcanization system with dynamic vulcanization was carried, to make a new kind of composite material. This research studied the influences of wood flour and naphthenic oil content on the microstructure, mechanical properties and rheological properties of the composite material. The result showed: the content of wood flour and naphthenic oil has big impact on composite material. With the increase of the wood flour content, the mechanical properties are increased firstly and then decreased. The viscosity and modulus of the composite is improved with the increase of wood flour. With of the increase of the amount of naphthenic oil, the mechanical properties, viscosity and modulus of the composites decreased. When the content of wood flour is between 30–60 parts and the content of naphthenic oil is less than 20, the EPDM/PP/AL composite is suitable for using as the core layer elastic material of composite floor.