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Electrochemical paper-based analytical devices (ePADs) are receiving increasing attention in recent years, overcoming the publication number of colorimetric paper-based analytical devices in the literature. This chapter covers recent advances in the manufacturing of ePADs for chemical analysis. Initially, an introduction about its beginning in the literature and mainly practical theoretical principles are discussed. The following sections present how the devices are being fabricated and used in the literature, exploring their advantages and limitations and describing electrochemical sensing detection and future outlooks.

Fluorescent paper-based analytical devices (FL PADs) are receiving increasing attention in recent years, owing to the development of new technologies for the fabrication of brighter fluorophores and phosphors, especially nanomaterials. This chapter covers recent advances in the construction of FL PADs for qualitative and quantitative assays. It commences by introducing the most often used fluorescent probes, including organic dyes, quantum dots, carbon dots, upconversion nanoparticles, and their use as reporters. The second part presents the fluorescence response produced by the PADs, which can be either brightness-based (“turn-on” and “turn-off”) or color-based (ratiometric fluorescence). We approach the different signal responses by presenting recent examples of developed FL PADs, exploring their advantages and limitations, and describing their fabrication technologies and sensing mechanisms.

In this paper, we report the performance of paper pulp as an innovative viscosity modifying admixture (VMA) for cement composites. Two different levels of fineness were obtained by mechanical milling of the same source of paper pulp. Their effects on viscosity modification, hydration kinetics, autogenous shrinkage, and compressive strength of cement grouts were measured, and their structural integrity at high pH was assessed. A new parameter was proposed to quantify nonlinearity induced by VMAs. Results showed that the hierarchical structure of paper pulp makes it possible to activate bridging flocculation and swelling mechanisms of hydrophile paper pulp fibers at different levels to produce versatile VMAs. The coarser milled paper pulp fibers mainly influences the plastic viscosity. By contrast, the milled paper pulp consisting of ultra-fine fibers significantly modifies both plastic viscosity and dynamic yield stress, induces more nonlinearity in the mixtures, and increases compressive strength of mortars at low dosages.

Miniaturization of the devices and simplification of the procedures have become main trends in (bio)chemical analysis. The continuous development of low-cost portable analytical platforms is a consequence. In this context, the material employed for the development of analytical devices plays an essential role, being paper one of the main substrates. In this chapter, a very simple electrochemical platform, which allows performing decentralized analysis, is described for enzymatic determination of glucose. It employs a very simple three-electrode cell consisting of a single-use paper-based electrode, acting as working electrode (WE), combined with two metallic wires (from a commercial standard connector) acting as reference and counter electrodes. To prepare the WE, a drop of carbon ink is deposited in a hydrophilic area delimited by wax, which was previously printed and heated. This chapter includes the step-by-step procedure for constructing the platform and developing the biosensor, as well as important issues that should be considered when running the experiment and reporting the results.

Paper has been considered a versatile material for the fabrication of environmentally friendly electrochemical (bio)sensor devices, mainly due to its abundance, low cost, easy disposal (by incineration, for example) and biological compatibility. Paper-based electrochemical devices can be fabricated by inexpensive technology, and used in simple and portable diagnostic systems, providing high sensitivity and precision. This chapter presents an overview of electrochemical systems constructed from paper, summarizing the main advantages and disadvantages of paper types and fabrication techniques and the different exploited electrochemical detection techniques such as amperometry, voltammetry, electrochemical impedance spectroscopy and potentiometry.

In this chapter the capsaicin derivative grafting onto cellulose ispresented as an alternative to obtain bioactive papers. First, grafting of nonivamide (capsaicin derivative) onto cellulose fibers using polycarboxylicacid as linking agent is discussed. The effect of different reaction variables(namely, time, temperature, and catalyst amount), on reaction occurrenceand efficacy is analyzed. From this data, the optimal reaction conditionsare selected and then grafting reaction is applied to commercial paper sheets. Final properties like antioxidant, insect repellent, and antimicrobialactivity, as well as mechanical properties of the modified paper are presentedand discussed. Fil: Muratore, Florencia. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; Argentina Fil: Goñi, Maria Laura. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; Argentina Fil: Serrano, Luis. Universidad de Córdoba; España Fil: Labidi, Jalel. Universidad del País Vasco; España Fil: Barbosa, Silvia Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentina Fil: Martini, Raquel Evangelina. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; Argentina

Cellulose nanopaper (CNP) is a fascinating free-standing thin film material, prepared from renewable nanocellulose and displaying special properties such as transparency, haze, thermal stability, mechanical strength, and flexibility. The nanostructured nature of CNP enables gas barrier films and high specific surface areas for interface functionalization. Re-engineering CNP by physical and chemical design allows to tailor its properties, enabling hydrophobic and transparent paper, smart sensors, substrates for optoelectronic devices, and conductive or luminescent papers. This chapter rationally describes the chemical and physical manipulations that can be performed on CNP to modulate its properties, classifying them as: covalent chemical modification on nanocellulose before processing them into nanopaper thin films; covalent chemical modification on CNP surface; and noncovalent modification of CNP by coating or blending nanocellulose with other materials.

Sustainability is essential in future technologies to harmonize with our environment. Cellulose is one of the nature's most abundant natural polymers, the main chemical components of wood and plants. Owing to its own unique material properties, compared with the conventional usage, nanocellulose with a crystalline structure can be considered for various industrial applications. This chapter reviews the fabrication and performance of nanocellulose-based electroactive paper (EAPap) actuators in terms of its three subareas: piezoelectric, ionic, and hybrid EAPap along with their applications. Cellulose is known to have piezoelectric and ion migration effects, and these two effects can be maximized, which result in piezoelectric EAPap and ionic EAPap. To further improve functionality of cellulose, hybrid composites of inorganic functional materials are introduced by incorporating carbon nanotubes, graphene, titanium dioxide, and tin oxide with cellulose. Since cellulose is biocompatible, sustainable, biodegradable, capable of broad chemical modification, and hydrophilic and has high mechanical strength and stiffness, various cellulose-based devices are possible.

This chapter discusses general aspects of paper spray ionization that is used in mass spectrometry (MS). The methodology and theory are associated with a number of different related applications. The first part of this chapter discusses the fundamentals of paper spray and some modifications, such as tissue spray, are also included. The second part focuses on recent applications, including the analysis of biologically important molecules. These studies show that paper spray MS has great potential for use as a rapid sampling ionization method and for the direct analysis of biological and chemical samples at ambient conditions.

Flexible and wearable electronics have recently attracted increasing attention, because they can open up new possibilities for next-generation portable devices. Cellulose paper serves various purposes in daily life, including in writing, printing, wrapping, and packaging applications. Since paper materials are sustainable, mass produced, inexpensive, biocompatible, recyclable, lightweight, and flexible, the use of paper has recently been extended to flexible electronic applications. In this chapter, we describe cellulose-based flexible paper electronics. Wood-derived cellulose pulp or nanocellulose is composited with conductive nanomaterials such as silver nanowires, carbon nanotubes, and graphene. The as-prepared paper composites are successfully applied as transparent conductive paper, paper antenna, paper sensor, and paper supercapacitor. These paper devices demonstrated both high device performance and flexibility compared with the state-of-the-art polymer-based flexible devices. Our findings provide a promising route to realize green and flexible paper electronics.

The modification of electrodes with nanomaterials is a widespread practice in Electroanalysis because it does not require the use of instrumental components for signal amplification or additional detection techniques, decreasing the cost and facilitating the decentralization of analyses. Different nanostructures, mainly carbon nanotubes, graphene, or metallic nanoparticles, have been used as modifiers on paper-based electrochemical devices. Among others, gold nanoparticles (AuNPs) favor the preconcentration of heavy metals in stripping analysis because of the easy adsorption of the metal in the elementary state on AuNPs. In this experiment, a nanostructured paper-based platform is applied to the electroanalysis of inorganic arsenic in wines by chronoamperometric stripping of the electrodeposited As(0). The electrochemical cell consists of a paper-based carbon working electrode coupled to a screen-printed carbon card. Electrodeposition of AuNPs is performed in a tetrachloroauric(III) acid plating solution.

Paper is recycled at a relatively high rate in the U.S. Rates are particularly high for corrugated boxes, which are predominantly recovered from businesses rather than from households. Packaging is a major source of recycled paper, as well as a major market for the recycled fiber. Paper coated with plastic or wax is difficult to recycle. The paper-recycling process involves re-suspending the fibers in the slurry, and separating contaminants. Recycled fibers tend to be shorter and weaker than virgin fibers. Contaminants in the recycled paper can cause problems with operation of the process as well as with paper performance. With proper design, recycled paper can perform very similarly to paper made from virgin fiber.

While paper and paperboard are being used in many applications, their largest application is as materials for packaging applications. Paper and paperboard could be made into a wide range of packaging, either with or without additional treatments, alone or combined with other materials. They are made from renewable resources and recovered paper; and are recyclable. This article provides an overview of paper and paperboard making process, including a brief history; and characterizations of paper and paperboard and properties.

Wood is the dominant raw material for paper and paperboard production. More than 50% of the average global paper furnish is from virgin wood-based pulp. The other sources are recycled fiber (RCF) from recovered paper (RCP), nonwood fiber, and mineral pigments. This article presents the types and characteristics of pulpwood resources, occurrence, availability, and productivity of wood resources. The trends in wood usage in the pulp and paper industry were discussed. A critical concern for the global pulp and paper industry there will be reasonable access to the vast softwood resources in Siberia.

Electroanalysis comprises many different techniques. One of the simplest is chronoamperometry, a potential step technique, where the potential moves forward from an initial to a final value (single step technique), but that can also move back (to the initial or other potential value) in the double potential step technique. Then, the intensity of the current (“amperometry”) is recorded with time (“chrono”), with an i-t curve being the response signal (chronoamperogram). The analytical signal is an instantaneous current measured at a fixed time. As the current contains two components, faradaic and nonfaradaic, and the latter one decays faster, the current is usually measured some seconds after the potential step. In this experiment, a single-step chronoamperometry is employed for the determination of ascorbic acid in fruit juices. A cyclic voltammogram is first recorded to select the values of the initial and final potentials. A low-cost paper-based electrochemical cell is employed to fit with the simplicity of the technique.

Food packaging materials are critical contributors to the safety and quality of food. Packaging can be classified into primary and secondary packages. This article describes the following paper product packages: paperboard folding carton, corrugated paperboard case, fiber drums, beverage packaging, and carded packaging. It was found that paper products form the wide range of food packages. This is due to the paper flexibility, biodegradability, low cost, recyclability, and ease of printing. The perceived environmental and associated waste management advantages of paper-based packaging will see this form of food packaging continue to be developed.

During the last few decades, recovered paper and board has become the principal raw material of the paper industry, and 57% of all paper produced worldwide today is based on recovered paper. In addition to the fibrous raw material, recovered paper also contains other substances that are introduced by the paper product itself (printing inks, stickies, mineral particles) or during its use and subsequent collection (scraps and leftovers, sand, glass, etc.). Hence, when producing new paper from recovered paper, the pulp has to be cleaned intensely. In the stock preparation systems of paper mills, different processes like pulping, screening or flotation are used for cleaning.

The objective of this research was to develop lightweight cement mortars with good thermal-insulation properties by incorporating expanded polystyrene (EPS) and paper sludge ash (PSA), both of which are problematic waste materials. The mortars formed had low thermal conductivity and low bulk density compared to control samples. Ground EPS produced lower thermal conductivity samples than powdered EPS. Resource efficient mortars containing up to 20% PSA, and 60% of EPS are considered suitable for use in rendering and plastering applications. The authors wish to thank the Spanish Ministry of Science and Innovation and European Union (FEDER) for project funding (BIA2007-61170), and the FPI scholarship (BES-2009-012166) award to Verónica Ferrándiz Mas which allowed her to develop her doctoral thesis. This research was carried out in the Civil and Environmental Engineering Department at Imperial College London, with funding from the Spanish Ministry of Economy and Competitiveness (EEBB-I-12-0574) to support Verónica Ferrándiz Mas.

This paper presents for the first time the influence of mixing different thermally activated paper sludges (APS) and fly ash (FA) on the pozzolanic reaction kinetics in APS–FA–Ca(OH)2 systems as a previous step to manufacture the future commercial ternary blended cements. In this study, two paper sludge wastes from different origins and activation conditions (laboratory (LS) and industrial (IS) scale) have been investigated, once mixed with fly ash at a ratio of 1:1 by weight. The results indicated that binary blends of pozzolans exhibited a high pozzolanic activity, showing that the hydrated phases produced during the pozzolanic reaction depend on the origin and activation conditions of clay wastes. At all times of reaction, the predominant phase turn out to be the LDH structures when LS pozzolan was used; meanwhile for the IS pozzolan the C4ACH12 along with the LDH were the main phases during the first 28 days.

Food spoilage and poisoning are two main problems in food industry area that are caused by contamination of bacteria. The process of contamination of food by bacteria usually occurs in food processing, packaging, and distribution handling. In spite of food preservation techniques such as drying, freezing, heating, fermentation, and salting that can extend the shelf life, recontamination still may occur in the food products. Process packaging as the final process in food production system is key process to protect food product from bacteria contamination and prolong their shelf life. In the past few years, many researchers investigated and developed antibacterial system to preserve food, fruit, vegetable, and beverage. This chapter highlights the development of antibacterial coating as a new method of food preservation system. It also provides the release mechanism of bioactive compound to food system in antibacterial coating. In addition, this review also shows the release effect of bioactive compound to the bacterial activity.

[EN] This work deals with the frost resistance of blended cements containing calcined paper sludge (source for metakaolin) as partial Portland cement replacements. Freeze–thaw tests were performed on blended cement mortars containing 0%, 10% and 20% waste paper sludge calcined at 650 °C for 2 h. Cement mortar specimens were exposed to freezing and thawing cycles until the relative dynamic modulus of elasticity fell below 60%. The performance of the cement mortars was assessed from measurements of weight, ultrasonic pulse velocity, compressive strength, mercury intrusion porosimetry and SEM. Failure of the control cement mortar occurred before 40 freeze/thaw cycles, while cement mortar containing 20% calcined paper sludge failed after 100 cycles. After 28 and 62 freezing and thawing cycles, cement blended with 10% and 20% calcined paper sludge exhibited a smaller reduction in compressive strength than the control cement.

Publisher Summary The papermaking process consists of several major steps: stock preparation, sheet forming, pressing, drying, and surface finishing. Starch is an important component of many paper grades. Starch consumption by weight in papermaking and paper conversion processes ranks third after cellulose fiber and mineral pigments. Starch is used as a flocculant and retention aid, as a bonding agent, as a surface size, as a binder for coatings, and as an adhesive in corrugated board, laminated grades, and other products. The major starch sources are corn, potato, waxy maize, wheat, and tapioca. Refined starches are supplied in powder form or as slightly aggregated pearl starch. Unmodified (native) starch is rarely used in the paper industry, except as a binder for laminates and in the corrugating process. Most starches for use in papermaking are specialty products that have been modified by controlled hydrolysis, oxidation, or derivatization. This chapter also covers various topics such as: application requirements for starch, dispersion of starch, environmental aspects of starch, starch analysis in paper, and use of starch in papermaking furnish, for surface sizing of paper, as a coating binder, as adhesive in paper conversion, and in newer specialty papers.

The structure and basic starch chemistry are explained as well as the swelling and retrogradation processes during/after cooking (gelatinization) and cooling. The markets of the global starchy products are analyzed showing the regional differences of the weight of different product lines and raw materials used between Europe and North America. An overview is given on all starch modifications done by starch producers (derivatization and thinning), and in situ at the customer (thinning). The impact of different starch modifications and the cooking process on the application properties is discussed.

This chapter discusses several methods employed for the treatment of waste from paper and pulp industries. The paper and pulp process uses plenty of water, and the waste generated from this industry contains solvents, chlorinated compounds, resins, and most importantly lignin, which is highly resistant to degradation. Chlorinated compounds are also toxic to many microorganisms.. Conventional biological methods such as activated sludge and aerated lagoons help in reducing the chemical oxygen demand (COD) load and toxicity, but these methods cannot effectively remove the color from bleach plant effluents; in addition they consume energy for aeration. White rot fungus appears to be efficient in color removal. Anaerobic degradation is affected by the presence of sulfate. Destruction of adsorbable organic halogen is another aspect that needs to be addressed. Carrying out biodegradation at thermophilic conditions would be advantageous since the waste stream from the paper mill is generally around 50 o C but finding efficient microorganisms is still a research challenge.

[EN]This paper considers calcined paper sludge as an alternative source of metakaolin, an established supplementary cementitious material. Calcination of the sludge generated in the recycling of newsprint paper at 700 °C yields a product with pozzolanic properties. The effects of this recycled metakaolin on the rheology and conduction calorimetry of cement pastes have been studied and compared to the effects of commercial metakaolin. The effects are similar and the results show that calcined paper sludge has the potential to be used as a supplementary cementitious material. This offers a route for utilising this waste material, as an alternative to the increased environmental burden associated with the production of metakaolin from natural kaolinite resources.

End-use applications of paper require a wide range of properties with respect to interactions with liquids. At one extreme are tissue papers and toweling. They are designed to imbibe water quickly. At the other extreme are cupstock and greaseproof papers that are designed to inhibit the passage of liquids. It is remarkable the degree to which variations in the processes and chemical additives used in the manufacture of paper can achieve such diverse products. On a microscopic scale paper is porous, directional, and rough. Papermakers and specialists have used two different approaches to define and measure wettability and penetration by liquids. The specialists have carried out tests involving smooth, flat surfaces, or filaments composed of pure materials such as cellulose films or other components of paper. On the other hand, the paper industry has developed a wide range of practical, empirical tests that predict aspects of product performance.

Nondestructive evaluation of paper refers to the analysis and measurement of paper properties using noninvasive means. Most of these properties can be measured or derive online in the paper mills. The important technique used for the evaluation of these properties include: β-rays, γ-rays, x-ray techniques, infrared and visible light, microwave and radio-frequency techniques, magnetic reluctance, ultrasonics, pneumatic and aerodynamic apparatus, and various advanced optical devices. The present study describe the measurements of basis weight, moisture, filler and coat weight, caliper, formation, fiber orientation, smoothness and surface properties, gloss and optical properties, and some strength properties of the paper.

This work presents a first approach towards the development of a cost-effective enzymatic paper-based glucose/O2 microfluidic fuel cell in which fluid transport is based on capillary action. A first fuel cell configuration consists of a Y-shaped paper device with the fuel and the oxidant flowing in parallel over carbon paper electrodes modified with bioelectrocatalytic enzymes. The anode consists of a ferrocenium-based polyethyleneimine polymer linked to glucose oxidase (GOx/Fc-C6-LPEI), while the cathode contains a mixture of laccase, anthracene-modified multiwall carbon nanotubes, and tetrabutylammonium bromide-modified Nafion (MWCNTs/laccase/TBAB-Nafion). Subsequently, the Y-shaped configuration is improved to use a single solution containing both, the anolyte and the catholyte. Thus, the electrolytes pHs of the fuel and the oxidant solutions are adapted to an intermediate pH of 5.5. Finally, the fuel cell is run with this single solution obtaining a maximum open circuit of 0.55 ± 0.04 V and a maximum current and power density of 225 ± 17 μA cm−2 and 24 ± 5 μW cm−2, respectively. Hence, a power source closer to a commercial application (similar to conventional lateral flow test strips) is developed and successfully operated. This system can be used to supply the energy required to power microelectronics demanding low power consumption., F. Javier del Campo acknowledges funding from the Spanish Ministry of Economy through the DADDi2 project (TEC2013-48506-C3). Juan Pablo Esquivel would like to thank the support from Marie Curie International Outgoing Fellowship (APPOCS-328144) within the 7th European Community Framework Programme. Shelley D. Minteer and Fabien Giroud would like to thank the National Science Foundation (CHE-1057597) for funding. Neus Sabaté acknowledges funding from the European H2020 Framework Programme (Grant Agreement 648518 - SUPERCELL - ERC 2014 CoG).

The enzymatic modification of cellulose, the major carbohydrate in different pulp fibres, offers unique opportunities for new applications, due to the different modes of action of individual cellulases. Although they all act on the same glycosidic β-1,4-linkage, different structural and functional modifications can be obtained depending on the type of fiber, enzyme and process phase used. Thus, cellulase based applications have been developed aiming at energy saving in refining, improvement of beatability, drainage and runnability of the paper machine, or enhancing de-inking processes. In these applications, the enzymatic treatment has been carried out on coarse or refined mechanical pulps, chemical pulps or recycled fibers at different phases of the processing. When applying cellulases, it is important to minimize the detrimental effects of these enzymes on the yield and strength properties of fibers. In this paper, the mode of action and effects of different types of cellulases; cellobiohydrolases and endoglucanases, are reviewed in the light of present applications.

Beating improves mechanical properties in papers made of kraft pulp. The effect is often assumed to arise from increased “bonding” in the dry paper, perhaps also from the removal of curl and other similar defects in the fibers. In contrast, it is argued here that bonding in dry paper does not explain the effect of beating when considering the elastic modulus of paper. Instead beating primarily influences the elastic modulus of fibers through the drying stresses and bonding in the wet web. The elastic modulus of paper made of a beaten kraft pulp is essentially equal to the average modulus of the fibers in the sheet. Because of the strong coupling with drying stresses, paper is dissimilar to ordinary fiber composite materials. The hypothesis put forward in this paper explains the results of a variety of experiments where beating, grammage, wet pressing, filler content or drying shrinkage were varied.

The effects of retained wood resin and polysaccharides on paper strength, optical properties and fiction were studied. Wood resin, glucomannans and pectic acids were extracted from thermomechanical pulp (TMP). The wood resin was added in colloidal form to the fibre suspension and aggregated by the addition of cationic polymers or electrolytes. In part of the tests, polysaccharides were also added. Hand sheets were made and tested. The amounts of resin and polysaccharides in the sheets were determined by gas chromatography. The strength properties of the hand sheets deteriorated when the amount of wood resin was increased up to 2 mg/g. When the amount of wood resin was increased from 2 mg/g to 10 mg/g, only a slight decrease in strength properties was obtained. The static friction was lowered when the amount of wood resin was increased in the sheets. However, the optical properties were not significantly affected, even at high wood resin levels. When polysaccharides were added to fibre suspensions, together with wood resin, the strength properties were higher compared, at the same resin content, to sheets without added polysaccharides. Deacetylated glucomannans and pectic acids especially diminished the negative effect on paper strength caused by high wood resin content. Some of the polysaccharides were probably adsorbed onto the surface of the TMP fibres or wood resin droplets, which will increase the hydrophilicity of the surfaces, thereby promoting hydrogen bonds in the sheet. Aggregates of polymer and polysaccharides could also be retained in the fibre network.

Quality targets of supercalendered uncoated magazine papers, supercalendered papers have been increased year by year. Very high gloss and smoothness levels have been reached, but simultaneously darkening or blackening of the paper surface has become a severe obstacle for many paper producers. However, on given gloss or smoothness level some papers tend to blacken more easily than other apparently similar papers. This suggests that in raw materials and/or paper structure there must be significant differences. The results obtained in pilot scale studies indicate that the impact of paper structure parameters, mainly formation, on calender blackening is important. In calendering the thickest areas in paper sheet are heavily pressed. In these areas, the light scattering coefficient decreases to such an extent that the thickest places become almost transparent. This gives paper an uneven and blackened appearance. In connection with calender blackening of paper the light absorption coefficient of fibres and paper changes only marginally. Formation of paper does clearly depend on fibre composition. Consequently chemical fibres, because these increase more fibre flocculation and additionally are more compressible than mechanical fibres, tend to increase more blackening of the paper surface in calendering. Late wood fibres tend to blacken more easily than early wood fibres. This applies as well to chemical pulps as to mechanical pulps.

Water and water quality are an essential part of the production of pulp, cardboard, and paper. In this chapter some possibilities for using membranes to purify effluents and recirculate waste and process waters are reviewed. Driving forces to use membranes and barriers as well as challenges are discussed in the introduction. Furthermore, a discussion on process water and effluent quality leads readers to understand the demands that pulp and paper industry process waters and effluents set on membranes and filters. In this chapter mostly industrial applications are reviewed, focusing on membrane processes and their performances in specific applications. The applications are divided into the following main topics, depending on the aim of the applied membrane process: purification of wastewaters, membrane processes to circulate process waters, the simultaneous purification of water and recovery of valuable materials, and the purification of raw water.

In this chapter, the inorganic and organic precipitation/dissolution phenomena, solid/liquid and solid/gas equilibria and solubility equations, crystallization kinetics, and their effect on the size of the suspended particles and porosity variation are discussed and formulated.

A review of the primary considerations and formulations of the various single-phase fluid models for formation damage by fines migration and clay swelling effects is presented. The applicability and parameters of these models are discussed.

Publisher Summary Paper consists of a web of pulp fibers, usually formed from an aqueous slurry on a wire or screen, and held together by hydrogen bonding. The same basic steps are involved for either hand- or machine-made paper. The steps are: forming (applying the pulp slurry to a screen), draining (allowing water to drain by means of a force such as gravity or a pressure difference developed by a water column), pressing (further dewatering by squeezing water from the sheet), and drying (air drying or drying of the sheet over a hot surface). The paper machine is a device for continuously forming, dewatering, pressing, and drying a web of paper fibers. The most common type of wet end machine was the fourdrinier, where a dilute suspension of fibers is applied to an endless wire screen or plastic fabric. Water is removed by gravity, or the ΔP developed by table rolls, foils or suction equipment, and the drilled couch. The web at this point is 18-23% consistency. More water is squeezed out in the press section to a consistency of 35-55%. Finally the sheet is with steam heating in the dryer section. Modem paper machines can be quite expensive, costing up to several hundred million dollars each.

This chapter provides background information on the use of nonwood fiber in pulp and paper. Nonwood fiber is increasingly being used worldwide as a fiber source for papermaking. Annual plants have been used since the early 1800s, except for cotton. Straw has traditionally been pulped by boiling solutions of lime for board grades of paper; this led to a bright yellow pulp. Sodium hydroxide was used to make bleachable grades of pulp as well as board grades. The soda anthraquinone (AQ) method is replacing the soda method and the results of the soda/AQ for straw are said to be similar to those for kraft pulping of straw. Other methods of pulping include neutral sulfite and chlorine systems. Ash and silica both interfere with the pulping of many nonwood fibers. The cellulose, hemicellulose, lignin, and extractive contents are fundamental to pulping.

Paper is a pliable material used for writing, packaging, and a variety of specialized purposes. Paper consists of a web of pulp fibers, usually formed from an aqueous slurry on a wire or screen, and held together by hydrogen bonding. Paper materials are classified as paper such as newsprint, stationary, tissue, bags, towels, and napkins, or paperboard such as linerboard, corrugating media, tubes, drums, milk cartons, recycled board used in shoe and cereal boxes, roofing felt, and fiberboard. Paper may be characterized by moisture content, physical characteristics, strength properties, optical properties, and other criteria depending on its end use. It is very important to obtain a sufficient number of representative samples by using a sampling procedure. When measuring strength properties MD refers to the test force applied in the machine direction CD is force applied in the cross machine direction. Paper properties depend on the orientation of the paper since the MD and CD properties are not identical. The MD of paper is parallel to the direction of travel during the manufacture of the paper; CD is perpendicular to MD. Paper properties such as tensile, fold, and compression vary significantly between these directions. This is often attributed to fiber orientation, but often of even more importance is the fact that in the machine direction paper is dried under much higher restraint than in the cross machine direction.

Waste papers are recycled by deinking. All over the world, the flotation method is the mainstream as the deinking method because of the advantages such as higher pulp yield, less use of water, less area for installation and less total reagent cost. The flotation method is mainly consisted of pulping and flotation processes, the former for ink separation from cellulose, the latter for ink rejecting out from the system. Function to assist the mechanical separation of printing ink from cellulose is required for the deinking agent in the pulping process. In the flotation process, there are three particles, namely, ink, cellulose and bubble, and main four interaction between them in the flotation cell. The following relationship must be held to reject out the ink particles effectively. Vr0

There are several definitions regarding wood and properties of wood that are useful to understand. One of the most fundamental of these is the moisture content of wood. The moisture content of wood is a measure of the water content relative to either the total wet weight of material or to the weight of oven-dried wood material. The oven-dry weight is determined by drying the wood to constant weight at 103-105°C (217-221 °F). The pulp and paper industry almost invariably reports the moisture content of wood and other materials in terms of the total weight of material. The moisture content of wood is typically 50 %, but varies from 30 to 60 %. This corresponds to 0.43 to 1.5 kg water per kg dry wood. It is the responsibility of the woodyard operations to obtain a steady supply of suitable wood. Wood sources are: roundwood, chips, slabs, edgings, and sawdust and planar shavings. Measurements of wood can be based on weight, by solid wood volume, by gross, stacked volume, or as volume of chips.

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