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The blend (wax M) of crude by-product polyolefin wax (wax K) and a fractionated commercial paraffin wax (wax J) was suggested to replace the wax J as a coating agent for wax-coated papers. The rheological properties of waxes J, K, and M were examined and compared. The correlation between viscosity and shear rate applied on these waxes maintained at 90 oC and 130 oC was identified. In particular, this paper, for the first time, presented non-Newtonian shear thinning behavior of not only wax K but also its blend of wax M in terms of their viscosity affected by shear rate at an operating temperature below their melting temperature of higher-melting-temperature DSC endothermic peaks (HMTEPs). They showed non-Newtonian behavior, so-called shear thinning behavior, at 90 oC in the light of characteristics of both suspension systems and polymer systems. In addition, the profiles of viscosity at 130 oC of all the waxes versus the shear rate exhibited Newtonian fluid behavior. Wax J also showed the behavior of a dilatant fluid. Then, the physical properties including water vapor transmission rates (WVTR), surface roughness, and coated weights, of thin papers coated with waxes J (WJP), K (WKP), and M (WMP) were evaluated, characterized, and compared. As a result, WMP had an equivalent value to that of WJP or the lowest value among wax-coated papers in terms of WVTR. The surface roughness and the barrier property of WVTR were minimized and enhanced, respectively, by blending waxes J and K. The additional physical properties, including dynamic contact angles, surface tension, wet and dry tensile strength, optical examination of the wax-coated fiber structure, and antimicrobial properties of the wax-coated papers, were evaluated. The excellent antimicrobial properties of clinoptilolite added to wax J or wax M appeared.

A simple electrochemical approach has been strategically developed for in situ generations of ZnO nanoparticles using Zn rods as electrodes and hydrogen peroxide as the oxidant without the formation of any by-product. These ZnO nanoparticles were extended for remediation of pollutants present in paper mill effluents, and separation efficiency was found to be above 90% for hydrocarbons, 92% for lignin, 99% for phenol, and 93% of chemical oxygen demand (COD), as confirmed by gas chromatography-mass spectrometry and COD analysis. It was also observed that the experimental setup could successfully remove 99% of the color from the sample. These ZnO nanoparticles have been proven in the past to be antibacterial and were explored for its ability to inhibit the growth of both Gram-positive and Gram-negative bacteria in the effluent samples after the removal of toxic pollutants. Therefore, we proposed an electrochemical reaction for the in situ synthesis of ZnO nanoparticles for remediation of paper mill effluent as well as inhibit the bacterial growth in the treated effluent sample.

In this research, simultaneous quantification of cysteine (Cys) and histidine (His) using a paper-based sensor was investigated for the first time. A microfluidic paper-based sensor is a promising amino acid determination tool due to its low cost, low sample consumption, and fast analysis and is easy to make. We used SBA-15 as porous materials that are crystalline compounds formed with surfactants and TEOS as a silica source. The SBA-15 sample was characterized by X-ray diffraction, Fourier transform infrared, and scanning electron microscope techniques. The microfluidic paper-based sensors were fabricated using a wax pen, and the mesoporous SBA-15 modified filter paper. The fabricated sensors for Cys and His determination are operated based on an indicator-displacement assay. A comparative determination study of Cys and His on the sensors was carried out. The results illustrated that the addition of silica nanoporous material led to an immediate and uniform color change. The sensors were successfully exploited in the simultaneous determination of urinary Cys and His levels, thus providing the potential opportunity for clinical diagnosis. The linear range of 1.0 to 90.0 μM and 1.0 to 100 μM for His and Cys was obtained from the calibration data. The detection limits were also calculated (S/N = 3) for His and Cys of 0.5 μM and 1.5 μM, respectively. The proposed method showed a good agreement with the results achieved by a standard method.

The problem of utilizing and processing cellulose and mineral fibrous waste contained in sludge obtained following mechanical treatment of wastewater from the production of paper and cardboard from recyclable materials is analyzed. A technology for producing a cellulose-mineral sorbent from this type of waste to mitigate emergency spills of oil and oil products is described. It is shown that an affordable, fast-acting and convenient sorbent can be produced from these wastes, having sufficient sorption capacity and the ability to retain oil products. The contaminated material can be safely and economically reclaimed or destroyed following use. Mechanisms for activating sorption properties, along with the composition, properties, and options for practical application of the sorbent, are considered.

Materials containing silver nanoparticles (AgNPs) are of great interest for household uses, including drinking water disinfection. Although various Ag-containing materials are available, the development of low-cost, reusable, and durable systems is a challenge in water disinfection. Herein, we developed a low-cost, reusable, and durable cellulose filter paper (CFP) containing AgNPs decorated with a tannic acid (TA) and chitosan (CS) matrix (CFP-CSTAAg). The formation of CFP-CSTAAg composite was confirmed by FTIR, and XRD techniques. The formation of CSTAAg composite on CFP greatly improved the mechanical performance. CFP-CSTAAg is driven by gravity of 100 ml of a water sample containing Staphylococcus aureus for 30 min. The composite showed 99 % killing efficiency of bacteria as the bacteria cells did not pass through composite. The low-cost CFP-CSTAAg composite was reusable, providing a 98 % bacteria-killing capacity after five treatment cycles. The product’s properties make reusable CFP-CSTAAg composite a promising filter for durable water disinfection as it is a low-cost material and eco-friendly.

A series of new coloring materials in nanoscale based on 5-(2-aminothiazol-5-yl) thiazol-2-amine and 5-(4-aminophenyl) thiazol-2-amine were synthesized. The nanoscale pigments were prepared using a grinding high˗energy ball-milling technique. X-ray diffraction and transmission electron microscopy were employed to determine the particle size of the nanoscale pigments (40–80 nm). The synthesized pigments in normal and nanoscale were applied in the printing of polyester fabrics. The fastness and colorimetric properties of the printed samples were carefully studied. Additionally, the synthesized pigments were applied as water-based flexographic ink for paper and carton. The hue of the color pigments L*, a*, b*, glossiness, and fastness to light were measured. The comparison of the new heterocyclic benzidine analogs in normal and nanoscale with commercial benzidine pigments demonstrated better results, particularly for the nanoscale pigments.

The present study illustrates the electrocoagulation remediation of paper mill wastewater for multiple response optimization. Multiple response optimization can be combined into one desirability function. All variables and responses varied for a unique global solution. The effect of basic electrocoagulation process variables pH (3–10), conductivity (3.15–10 mS/cm), electrode distance (1–2.5 cm) and current density (5–20 mA/cm2) on four response parameters such as chemical oxygen demand, color, total dissolved solids and total organic carbon has been analyzed experimentally and statistically. The global solution for these variables and responses obtained by software over a hundred design points. For unit desirability function variables conditions were pH 7.49, Conductivity 8.34 mS/cm, electrode distance 2.06 cm and current density 9.32 mA/cm2. In these global variable conditions, responses were observed to be COD 70.19%, Color 75.03%, TDS 70.69% and TOC 71.93%, respectively.

Due to the important role of oil source in our life, the separation of water-in-oil emulsion is urgent and necessary. Membrane seperation technology has been an efficient and widely used method in separating oil-water separation. Herein, we report a versatile approach to fabricate surface carbonized membranes with self-standing property from biomass-derived precursor by synergistic charring of phytic acid, arginine and filter paper. The obtained membrane exhibited superhydrophobicity in oil, excellent fouling resistance, and self-supporting ability. The membrane can be cycle-used at least 12 times with high permeation flux (up to 1380 L·m−2·h−1) and separation efficiency (up to 99.4%).

Information on industrial paper obtained from special purpose heat-resistant and fire-resistant fibers by the method of fiber swelling is presented. Results of a study of the effect of fiber cutting length on the mechanical properties the paper are presented. Corresponding dependencies are established.

The gas flow through sheet-like porous materials such as paper can show marked lateral variations due to a heterogeneous, locally varying microstructure. Hence, reliable predictions of such lateral flux variations require an appropriate consideration of local variations in the microstructure. The flow through such sheet-like materials is commonly described with Darcy’s law in which permeances are formulated in terms of microstructure properties, such as porosities, tortuosities, or hydraulic radii. This work proposes an extension of existing permeance models that directly considers the variation and the cross-dependence between local microstructure properties. The extended model is applied to local air fluxes through a paper sheet to exemplarily reveal the joint impact of local porosities and local tortuosities on the air flux. The key extension is to consider a joint distribution of porosity and tortuosity. The latter is constructed from the univariate property distributions using a copula approach and yields local tortuosities including their variation for any encountered local porosity. These values jointly enter any permeance model that qualitatively captures the dependence of the air flux on the porosity. To assess the merit of the model, variations in the air flux and in the pore space properties are independently determined from the same measured microstructure of paper. Air flux variations are provided by computational fluid dynamics simulations on multiple, nonoverlapping segments taken from the microstructure. A statistical analysis of the entire microstructure provides the distribution of local porosity, tortuosity, and thicknesses. Our model quantitatively explains that porosity-dependent variations in the tortuosity, in particular the ones associated with high-volume pathways, decisively determine air flux variations.

Sulfite is a common food additive that prevents oxidation from damaging food nutrients, and it has long been used in the food industry as a bleaching agent. It can harm the human body if taken wrongly or excessively. In this study, three dyes (cresol red, chlorophenol red, and bromocresol green) were explored to analyze the presence of sodium sulfite (SS) in an inexpensive, disposable paper sensor with a lower visible detection limit of 0.05 M. This visual paper sensor detects sodium sulfite with high selectivity and sensitivity at room temperature. An IoT-based sensor was also developed to practically apply the developed method, which is rapid and low-cost and can replace heavy-duty instruments. Both these sensors can substantially impact scenarios such as food quality monitoring and detecting sodium sulfite in medicinal items. Graphical Abstract

While past studies have been carried out to form eco-friendly disposable tableware using non-wood biomass, there is no present groundwork so far where fruit peels waste composited with Mauritian hemp (Furcraea foetida) has been used for such purpose, which is novel to this research work. This study therefore assesses whether the production of 100% biodegradable disposable paper cups with acceptable strength properties using pineapple (Ananas comosus) peels, orange (Citrus sinensis) peels and Mauritian hemp as feedstock is feasible. Soda pulping followed by vacuum molding was done to produce hemp:pineapple peels and hemp:orange peels composite paper cups in different ratios. The cups were tested using relevant standards in terms of appearance and structure, burst strength, tensile strength, weight load, water leakage and biodegradability to find the optimum cup composition by comparing with a suitable control. All cups were visually conformant in terms of color and base stability. The 40:60 hemp–pineapple peels composite cup had characteristics closest to the control, with no cracks and variation rate of weight load, average thickness of 1.42 mm and burst and tensile indexes of 0.25 kPa m2/g and 3.30 Nm/g, respectively. Beeswax coating thickness of 0.70 mm on the optimum cup was adequate to retain cold water for 30 min (minimum) without any leakage. The cup also biodegraded completely in both active soil and damp sand environments within 5 and 6 weeks, respectively. Results therefore reveal that fiber extraction from fruit peel wastes and hemp leaves to produce eco-friendly, biodegradable disposable paper cups is viable.

Although Al-ion battery is attracting researchers’ attention worldwide, its volumetric energy density was not so promising due to low density of graphite-based positive electrodes in the current published literatures. Thus, defect-free yet densely packed graphene electrodes with high electronic conductivity and fast ionic diffusion are crucial to the realization of compacted Al-ion batteries with high volumetric energy density. In the present work, a self-supported and defect-free graphene-positive electrode (RHG-P-2850) was successfully produced by a hydriodic acid reduction of the graphene oxide (GO) method, followed by an ultrahigh temperature (2850 °C) annealing treatment. The density of the RHG-P-2850 (0.32 g cm−3) is currently the highest positive electrode material in the preparation of graphene-positive electrodes from GO. RHG-P-2850 positive electrode enables to deliver considerably high specific capacity 27.1 mAh cm−3 (85 mAh g−1) at the current density 2 A g−1. More importantly, a remarkably stable performance was achieved with 20% fading over 8000 cycles. The results enlighten and promote the design and preparation of densely packed graphene-positive electrode to develop high-performance Al/graphene battery.

Glucose is a typical diagnostic marker of diabetes mellitus but it may be also helpful during diagnosis of some types of poisoning, immunological disorder or long-term stress at hospitalized patients. Diagnosis of diabetes mellitus in time is indispensable for prevention of life-threatening complication and so, accurate and easy device for non-invasive and accurate self-diagnosis is necessary. Simple assay based on filter paper with chitosan layer and with immobilized enzymes glucose oxidase and peroxidase and phone camera detection has been proposed for home-care glucose detection in urine. Data were processed in RGB (red–green–blue) color model when blue color channel showed the best sensitivity to changing glucose concentrations. Assay exerted linear regression from 0 to 4 mmol/l and limit of detection was set to be 166 µmol/l. Assay was not influenced by any interfering substances including maltose, sucrose, sorbitol or fructose or by urine matrix substance such as bovine serum albumin, ascorbic acid, uric acid or urea. Measurement of glucose from spiked urine samples reveals also no influence of the matrix on the assay. Long-term stability was measured and filter papers coated by enzymes showed excellent stability for at least 9 weeks without any special treatment or package. In comparison with differently modified filter paper, filter paper with both chitosan and enzymes showed the best sensitivity to changing glucose concentration. In a conclusion, simple (phone camera detection) and fast (3-min reaction) assay for quantitative detection of glucose from urine was optimized.

Currently the pulp and paper industry is one of the fastest growing sectors of the economy in Russia and other countries. An important aspect of the further development of this industry is associated with an increase in the efficiency of paper production and the quality of finished products with an economical and rational use of raw materials, fuel and energy and other material resources. This is facilitated by the use of modern means of automation and process control. It was experimentally established that there is an extreme dependence between the ratio of the speeds of the paper pulp and the paper machine and the standard deviation of the linear density of the paper web, which determines the degree of non-uniformity of the paper gap. The use of a noise-resistant algorithm for extreme control of an inertial object based on the combination of synchronous accumulation and synchronous detection methods with subsequent search for the maximum amplitude of the second harmonic of the filtered signal, aimed at reducing the root-mean-square deviation of the mass of a square meter of paper web, is considered. It is proposed to simultaneously stabilize the mass flow rate of paper pulp and the coordinate of the fall of the paper pulp jet onto the conveyor mesh, which made it possible to increase the efficiency of paper production.

Photothermal water evaporation using natural solar energy has been attracted more attentions due to wide applications such as water purification, sterilization, power generation and energy conservation. This article reports a low-cost and stable material for efficient generation of water vapor as well as saline and pollution water treatment. The hierarchically porous material consisting of nanoporous carbon and microporous paper is prepared by simply depositing and chemically cross-linking colloidal ink onto a filter paper. A stably homogeneous nanocarbon deposition is formed over microfibers in the paper. The nanocarbon particles greatly increase the surface area of pristine paper (from negligible to 12 m2 g−1) and light absorption. The carbon modified paper allows high water evaporation rate of 1.34 kg h−1 m−2 from a nanoporous carbon film, continuous capillary water transport in the micropores of paper, as well as minimal convective loss to bulk water due to 1D low contact area with water. The pore sizes of filter papers on the water evaporation together with the controlling of surface temperature and evaporating rate are also performed. Finally, this water solar evaporation system is applied for desalination and wastewater purifying (including heavy metal ion and organic pollutions). A safe freshwater is obtained after treatment. This study demonstrates the potential application of chemical modification of inked filter paper to achieve high evaporation rate and efficiency by rational design. A low-cost and stable material for efficient generation of water vapor and wastewater treatment was brought out, which is prepared by simply depositing and cross-linking colloidal ink onto a filter paper. The carbon modified paper allows efficient light absorption, high water evaporation rate from a nanoporous carbon film, continuous capillary water transport in the micropores of paper, as well as minimal energy loss.

We present the study of the preparation of pulp and nanocellulose from Miscanthus × giganteus to improve the quality of the paper for bags. The organosolv miscanthus pulp (OMP) was prepared by the environmentally friendly organosolv method—cooking in a solution of peracetic acid at the first stage and the alkaline treatment at the second stage. Nanocellulose was obtained by hydrolysis of never-dried OMP and subsequent ultrasonic treatment. Structural changes and crystallinity index of OMP and nanocellulose were studied by SEM and FTIR methods. X-ray diffraction analysis confirmed an increase in the crystallinity of OMP and nanocellulose as a result of thermochemical treatment. The nanocellulose had a density of up to 1.6 g/cm3, transparency up to 82%, a crystallinity index of 76.5%, and tensile strength up to 195 MPa. The AFM showed that the particles of nanocellulose have a diameter in the range from 10 to 20 nm. A TGA analysis confirmed that nanocellulose films have a denser structure and lower mass loss in the temperature range 320–440 °C compared to OMP. We established the positive effect of nanocellulose application on the physical and mechanical properties of paper for bags. The application of nanocellulose allows replacing synthetic reinforcing materials and more expensive sulfate unbleached pulp with waste paper in the production of paper and cardboard.

In this work, a novel holey graphene oxide bonded with sulfonic acid groups (S-HGO) was developed using a facile and eco-friendly strategy: erosion and oxidation of graphene oxide (GO) by H2O2 and sulfonation by 4-benzenediazoniumsulfonate. The freestanding paper fabricated by S-HGO shows a high proton conductivity of 4.97 × 10−2 S cm−1 at 60 °C and 100% relative humidity (RH), which is comparable to Nafion 115 (7.67 × 10−2 S cm−1) at the same condition. The holes on S-HGO provide shortcut channels for proton transfer across the GO nanosheet. The chemical-linked sulfonic acid groups afford additional hop sites for proton conduction and endow itself an enhanced thermostability. Under 100% RH and ambient pressure, the freestanding S-HGO deliver a peak power density of 103 mW cm−2 at a load current density of 273 mA cm−2, which is about three times more than that of GO at 35 °C. The results demonstrate that this S-HGO paper is a promising nanoscale inorganic material for proton exchange membranes.

Coated paper is an example of a multi-layer porous medium, involving a coating layer along the two surfaces of the paper and a fibrous layer in the interior of the paper. The interface between these two media needs to be characterized in order to develop relevant modeling tools. After careful cutting of the paper, a cross section was imaged using focused ion beam scanning electron microscopy. The resulting image was analyzed to characterize the coating layer and its transition to the fibrous layer. Such image analysis showed that the coating layer thickness is highly variable, with a significant fraction of it being thinner than a minimum thickness required to keep ink from invading into the fibrous layer. The overall structure of the coating and fibrous layers observed in this analysis provide insights into how the system should be modeled, with the resulting conclusion pointing to a specific kind of multi-scale modeling approach.

Given the effects of metal ions on environment and human’s health, it is very important to identify them in aqueous solutions. Core–shell structures can be used to identify metal ions through preparation of paper sensors. In the present research, ZnO@ZnS nanoparticles with core–shell structure were prepared through two-step low temperature green synthesis process using aloe vera and lettuce extracts. The synthesized nanoparticles were characterized by Fourier transform infrared, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy analyses. The results of FTIR and XRD analyses confirmed successful formation of ZnO@ZnS core–shell structures. Micrographs of the synthesized particles also showed flaky shapes with sharp edges and random orientations. Size range of core–shell nanoparticles varied between 20 and 70 nm. Then, the solution containing green synthesized ZnO@ZnS nanoparticles was distributed onto the papers and after drying at room temperature was used as paper sensors to identify Pb2+ and Fe2+ ions. The color intensity of the sensors changed due to contact with solutions containing different concentrations of Pb2+ and Fe2+ ions (75–1500 μM). In addition, increasing concentration of ions increased color intensity of sensors and the relationship between color intensity and ion concentration was expressed by related equations. Therefore, it was possible to determine the concentration of lead and iron ions according to the color intensity. Comparison between the performance of the sensors exposed to the solutions prepared from deionized water and ZayandehRud River water showed an acceptable error of up to 5%. The results of XRD analysis on paper sensors after contacting with Pb2+ and Fe2+ ions confirmed the formation of PbS and FeS.

The X-ray diffraction internal standard method can quantitatively determine the ash content of paper, but the requirements for the experimental environment are high, the determination is not convenient and the cost is high, and it is difficult to be widely used in the papermaking enterprises. In order to determine the total ash and its components of the single filler paper samples, and meet the ash determination requirements of papermaking enterprises, the continuous X-ray method is proposed. In this paper, an X-ray tube is used as the radiation source and an ionization chamber is used as the detector. Through polynomial fitting of the total ash and voltage logarithm ratio of the single filler paper samples, the mathematical model of total ash is established; the total ash and its components content of paper are calculated according to the mathematical model of total ash and the Beer–Lambert law deformation formula; the total ash and its components content of paper are verified by the burning method. The research results show that the total ash error of the single filler paper samples is less than 4%, and the ash component error is less than 5%.

The C/N ratio and organic loading rates (OLRs) are the main constraint factors of anaerobic digestion (AD) which symbols in digestion mortifications due to the rapid accumulation of volatile fatty acids (VFAs) and total ammonia nitrogen (TAN). In this study, the addition of high C-content wastes; paper waste (PW), cardboard waste (CW), and tissue waste (TW) into food waste (FW) feedstock is individually taken into consideration. At first, batch anaerobic digestion is conducted at a balanced C/N ratio of waste materials and then CSTR anaerobic digestion is carried out at different OLRs to investigate the potential of biogas production and process stability, under mesophilic conditions. In batch anaerobic digestion, co-substrate (PW + FW) feedstock is outperformed the other co-substrate feedstocks in terms of biogas production and process stability due to slow formation of VFAs and stable microbial conversion of VFAs into biogas fuel. The highest specific biogas yield (SBY) of 651 mL/gVS and specific methane yield (SMY) of 350 mL/gVS with a 57% rate of biodegradability are obtained from (PW + FW) feedstock at OLR of 15 gVS/L d. Furthermore, (PW + FW) feedstock with superb performance is then subjected to investigate the optimum OLR in CSTR digester for 30 days. The SBY of 22 L/gVS and SMY of 13 L/gVS is obtained with the utmost rate of VS reduction of 96%. The pH, alkalinity, COD, TS reduction, VS reduction, VFAs, and TAN concentration are all in the optimal range at the C/N ratio of 25 and OLR of 2 gVS/L d. This study provides new information regarding the C/N ratio and OLR for AD own great potential in improving the methane yield and productivity of PW and FW.

The properties of crystal violet lactone (CVL), currently the most commonly used color developer in carbonless papers, were studied. The hypothesis that CVL exhibits different properties in the carbonless and in the office papers was verified, as well as the CVL´s ability to luminesce in the IR region. Furthermore, the impact of thermal and light aging on some physical and chemical properties of the copies was observed. The changes were monitored by observing the IR luminescence at several wavelength ranges. Visual, colorimetric and structure differences between the copies made on the carbonless and the office paper were analyzed. The surface structure of the carbonless paper was analyzed using SEM–EDS.

Due to the hydrophilic nature of paper mulch, it is easy to absorb water during use, which will reduce its mechanical properties and durability, thus affecting its performance. Therefore, the development of paper mulch is hindered. In this paper, in order to improve the hydrophobic performance of paper mulch, we successfully prepared superhydrophobic silicon dioxide/paper mulch by simple, efficient and environmentally friendly solution immersion method without the introduction of adhesive. The contact Angle and rolling Angle between the prepared super hydrophobic paper mulch and water are 156.4° and 1.8°, respectively. The water drop is easy to roll on its surface, and has excellent water drop bouncing performance, which can play an excellent water-repellent function. Studies have shown that the superhydrophobicity of silicon dioxide/paper mulch is less affected by its surface roughness, mainly because the surface covered by a layer of silicon dioxide reduces the surface energy of the paper mulch, and the silicon dioxide on the surface of the paper mulch is enough to reduce the damage of aging on the paper mulch. In addition, the decrease in the contact angle of the SiO2/paper mulch and the increase in the rolling angle after aging are due to the decrease in the amount of SiO2 adhesion on the surface of the paper mulch and the increase in the degree of exposure of fiber bundles. Studies have found that the superhydrophobic paper mulch can reduce the influence of its own aging on its rolling angle after being subjected to friction.

The growing trend in biodegradable and renewable materials has generated a demand for new food packaging applications. This study aimed to produce active cellulose-based papers incorporated with two different essential oil isolated active compounds, eugenol, and linalool, to promote the inhibition of pathogenic bacteria's growth. Cellulose was extracted from eucalyptus sawdust by receiving chemical and mechanical treatment and incorporating the active compounds by microwave. FTIR, SEM, TGA, DSC, and antibacterial activity against E. coli, Salmonella, S. aureus, and L. monocytogenes characterized active papers prepared by casting. Cellulose–eugenol papers showed chemical interactions by hydrogen bonding, in concern to linalool paper bands, identified by FTIR results. Highlighting that after the active compound's addition, the hydrogen energy bond values decreased from 22.5 to 22.3 kJ mol−1, confirming the cellulose fibers' swelling with the oils, which slightly amorphized the papers. The active compounds changed the paper's morphology, increasing porosity and roughness, as seen in the SEM images. Besides, TGA indicated that the active compounds increased the papers' thermal resistance. The active papers exhibited excellent antimicrobial activity against all the microorganisms; the cellulose–eugenol papers demonstrated a more significant antibacterial effect (24 mm), with a larger inhibition zone than linalool paper (12 mm). These results revealed that cellulose-based papers containing eugenol or linalool have good potential to prepare antimicrobial edible papers or coatings for various types of food packaging applications.

To improve the accuracy of color reproduction for camouflage printing, a new color matching method, named monitor-paper-fabric, was proposed by importing color management into textiles, which matched the printing pastes according to the color of the paper card printed by the ink-jet printer after color management. Not like the traditional color matching method, it matched the printing pastes according to the color from computer monitor after color correction. Two color matching methods were analyzed by comparing the color difference. It was found that the “monitor-paper-fabric” color matching method could be considered as a convenient and feasible color matching method. Most color differences between the monitor and the fabric in the camouflage pattern were reduced to lower than 4, except for color blocks 5 and 6. In addition, the color differences of six color blocks between the paper and the fabric were all less than 3.5, and were lower than those between the monitor and the fabric. The color consistency between the paper and the fabric was better than that between the monitor and the fabric.

In this work, the commercial carbon paper was firstly peeled in K2CO3 solution and then was further treated in a KNO3 solution to form functional exfoliation graphene (FEG) on the commercial carbon paper. The FEG/carbon paper was characterized by Raman spectra and scanning electron microscopy, confirming that some typical layered fold graphenes were successfully peeled off and stood on the carbon paper matrix. Then, Fe3O4 nanoparticles (NPs) were grown on the surface of FEG/carbon paper and the as-prepared Fe3O4 NPs/FEG/carbon paper was directly used as supercapacitor electrode. The specific capacitance of Fe3O4 NPs/FEG/carbon paper was about 316.07 F g−1 at a current density of 1 A g−1. Furthermore, the FEG/carbon papers were also functionalized by benzene carboxylic acid to form FFEG/carbon papers, and then the Fe3O4 NPs were grown on the surface of FFEG/carbon paper. The specific capacitance of Fe3O4 NPs/FFEG/carbon paper was 470 F g−1 at a current density of 1 A g−1, superior to some previous reported results. This work might provide a new strategy to prepare various nanostructures on FFEG/carbon papers for future applications.

Carbon fiber paper reinforced thermoplastics (CPT) have broad application prospects because of its simple production process and good mechanical properties. Currently, polyamide 6 (PA6) is a promising matrix for CPT and is widely used for mass-production. However, the performance of CPT materials in marine and harsh environments must be evaluated because of its environmental sensitivity. In this study, the seawater absorption of CPT was analyzed using Fick’s diffusion law. The flexural properties of CPT in harsh and marine environments were studied by three-point bending. Based on the results, it was concluded that seawater and high temperatures have negative effects on the flexural properties of CPT. Microscopy results showed the mechanisms of failure under the action of seawater and high temperatures. Droplet test was employed to analyze the interfacial shear properties between the fiber and resin. The results showed that after seawater immersion, the interfacial shear strength had a discernable decrease.

Calibration curve plays an important role in filter paper method because it affects accuracy in soil suction values. Osmotic coefficient and relative humidity govern the osmotic suction required to develop calibration curve and equation. Most of the researchers used the readily available total (osmotic) suction values from various studies to develop the calibration curve. Very few researchers used the osmotic coefficient in calibration and studied its effect on calibration and measuring suction. In this paper, the effect of the osmotic suction proposed by various researchers on calibration of Whatman 42 Filter paper was studied. Logarithmic and exponential calibration equations were developed and compared. The NaCl solution used in the present study provides limited total suction range of 0–30,000 kPa. The total suction of clayey soil was measured to validate the calibration curves proposed in this study. The feasibility of proposed osmotic coefficients is verified by measuring total suction of soil. The total suction estimated from calibration curve using osmotic coefficients was found to be more accurate.

Carbon paper is commonly used to fabricate electrodes for batteries, and its morphology is crucial to the internal mass transport. In this work, geometric models of carbon paper are obtained by experimental and numerical reconstruction methods. The micromorphology of the carbon paper is obtained with a scanning electron microscope and an X-ray computed tomography scanner, and the binary slicing method is used in the experimental reconstruction method. Three different methods are used for numerical reconstruction, namely the layered 2D fibre, 3D fibre stacking and layered 3D fibre stacking methods. The structure and characteristic parameters of the carbon paper, such as pore size distribution, dimensionless specific surface area, effective diffusion coefficient and anisotropic coefficient, are statistically analysed for comparison. The dimensionless effective diffusion coefficients of Li+ in different directions in the electrolyte-filled carbon paper are obtained using lattice Boltzmann method. Results show that the internal structural features directly affect mass transport. The curves of the calculated effective diffusivity versus porosity are well fitted using a power function similar to Bruggeman equation within the porosity range of 0.66–0.86. The anisotropic coefficient is obtained from the effective diffusion coefficient in different directions.

Paper-based material is receiving more and more attention as an alternative of plastics in flexible electronics. However, conventional paper made of cellulose fibers is opaque owing to its micron-sized void space among fibers. Herein, cellulose fiber paper was changed into transparent paper by sequentially coating cationic cellulose nanofibers (CNFs) and polyvinylpyrrolidone (PVP). The morphology, transparency, thermal and mechanical properties were analyzed. The results show that the coating of CNFs reduces the micron-sized void space in the cellulose fiber paper, favoring the further improvement on the transparency of paper by coating PVP. By optimizing the coating amount of CNFs and PVP, a transparent paper with a transmittance of 88.5 % at 550 nm is obtained. The as-prepared transparent paper also shows improved thermal stability, slightly increased tensile strength and significantly enhanced deformation resistance. It was a potential candidate of flexible electronic substrates.

In this paper, using a low-cost paper fiber (PF) as a substrate, eigenstate polyaniline–coated PFs with graphene (GO/PANI/PF) ternary materials were synthesized by using the chemical oxidative polymerization method. Electrochemical measurements showed that the GO/PANI/PF electrode exhibited an excellent electrochemical performance compared with the PANI electrode. By adjusting the ratio of PANI and PF, the as-prepared GO/PANI/PF–2.5% electrode exhibited the highest specific capacitance 937 F g−1 at current density 1 A g−1 in a 0.5 M H2SO4 aqueous solution, and 74.5% retention of initial capacitance after 2000 charge–discharge cycles at 5 A g−1. The symmetric capacitor on the basis of GO/PANI/PF nanocomposite delivers a superior energy density of 10.12 Wh kg−1 at 456 W kg−1 at a current density of 1 A g−1.

A study was performed to utilize Pencil Lead Drawn Paper Sensor (PLDPS) as a strain and damage sensor by drawing multiply Pencil Sensors on two paper types. To evaluate the optimal paper as a PLDPS substrate of two type papers, i.e., plain and Han papers were used. The stability and uniformity of the mechanical properties, were compared for the paper types. Variability of electrical resistivity (ER) was also determined using four different types of pencil lead to make the PLDPS. In the evaluation of the properties of the PLDPS, for the different pencil lead types, the pencil lead weight was determined by drawing multiple lines and the ER of neat pencil leads and PLDPS compared. Interfacial properties of the PLDPS with different pencil lead types were measured by a spreading test, which provides information on wetting and permeability properties, using double distilled water. The sensitivity and uniformity of the pencil lead paper sensors made of four different pencil leads were compared in tensile loading. Plain paper was more suitable than Han Paper for use as the substrate of PLDPS. In addition, compared to other pencil leads, 6B, which exhibited low sensitivity but high uniformity, was determined to be the most suitable pencil lead.

This paper describes a new type of sensor that can monitor electrical signals for external stress or damage and heat transfer. It is composed of conductive pencil lead graphite, which is sensitive, affordable and easy-to-handle. This work was to detect mechanical damages in composites using Pencil Lead Drawn Paper Sensor (PLDPS). To measure electrical resistance (ER) via bending, by narrowing the distance between glass plates attached with PLDPD, ER increased stepwise while ER decreased with widening the distance reversely. The PLDPS can easily change the shape in a rectangular vortex. ER change responded well in tensile and flexural tests, while it showed leveling off under cyclic compression. Two-dimensional ER mapping was used during impact, drilling and heat transfer tests for detecting damage and thermal transfer. Compared to strain gauges, PLDPS can be applied inexpensively to detect damages successfully under various mechanical tests.

Response surface methodology is a widely used mathematical tool for optimization and recently fast growing toward wastewater treatment process optimization. Paper mill wastewater treatment by electrocoagulation using RSM has been found widespread with use of central composite design. The present research work deals with the comparison of central composite design and hybrid central composite design for treatment of paper mill wastewater by electrocoagulation. The advantages and drawbacks of both designs were described, and detailed statistical evaluation of applied models was performed. The set of experimental runs was determined by using RSM-based central composite design and hybrid central composite design to evaluate the individual and interactive impacts of process parameters on treatment effectiveness. The impact of essential process factors pH (Asghar et al. 2014; Ashrafi et al. 2015; Azadi et al. 2015; Bellebia et al. 2011; Box and Behnken 1960; Box and Wilson 1951; Chen et al. 2000; Chollom et al. 2019), conductivity (3.15–10 mS/cm), electrode distance (1–2.5 cm), and current density (5–20 mA/cm2) on three response parameters of chemical oxygen demand, color, and total dissolved solid was evaluated. Regression coefficient and p value for all response variables are > 0.90 and

The mechanical properties of bag paper before and after processing in a field of a unipolar (negative) corona discharge are investigated. It is shown that the modification of bag paper leads to its strengthening: absolute punching resistance, breaking stress, breaking length, tensile stiffness, tearing resistance in the longitudinal (machine) and transverse directions increase. The strengthening of the material is explained by the increased interfiber interaction due to an increase in the potential of the double electric layer on the surface of the fibers under the action of charge carriers injected into the paper volume during processing in a unipolar corona discharge.

Cellulose-based water filters are an affordable alternative to remove particulate matter; however, bacteria are too small to be removed simply through size exclusion. Cellulose-based water filters prepared by layer-by-layer (LBL) assembly with polypropylene-polyethylene (PP/PE) fabric decorated with silver nanoparticles (AgNPs) were tested to remove bacteria from water samples. The gallic acid reduction method was used to produce potent antibacterial AgNPs; their decoration onto PP/PE woven fabrics and the preparation of five-layered paper filters were further investigated. The use of acidic conditions for loading AgNPs and improving their spatial distribution onto the PP/PE fabrics, as revealed by scanning electron microscopy, was found to be correlated with the fabrics’ antibacterial activity. The PP/PE fabrics decorated with a higher density of AgNPs (at pH 2) showed 96.7 % and 97.9 % reductions in the growth of E. coli and S. aureus, respectively. Similarly, paper filters fabricated by LBL assembly of AgNP@PP/PE fabrics with cellulose filters deactivated growing E. coli and S. aureus bacteria with good efficiency: approximately 99.4 % and 98.7 %, respectively. The results indicate that fabricating water purification filters from the cellulose-based paper is feasible with LBL type assembly. The assembled paper filters could be commercialized for point-of-use water purification in the future to prevent the spread of water-borne diseases.

Screen printed carbon electrodes (SPCEs) are widely used in the field of electrochemical sensors, especially in the areas of food, water, environmental quality, and healthcare applications. In this context, microband SPCEs were fabricated on Whatman paper, overhead projection (OHP) sheet and cotton textile substrates for the development of cost-effective electrochemical biosensors. The fabricated electrodes were subjected to three consecutive processes such as thermal, electrochemical and oxygen plasma treatment. Surface morphologies of SPCEs after each treatment stage were observed using scanning electron microscope for process standardization. Electrochemical performances of the fabricated SPCEs were analyzed using cyclic voltammetry. SPCEs on OHP substrate exhibited a single electron transfer rate at ΔEp of 57 mV and ipa/ipc = 1 (n = 3) with significant repeatability and reproducibility compared to SPCEs on paper and textile substrates. The role of activation of edge plane pyrolytic graphite of SPCEs in achieving the reversible reaction with single electron transfer characteristics has been analysed and reported. The effectiveness of the activated SPCEs on the OHP substrate was tested by detecting 1 mM of uric acid and ascorbic acid with KCl as an electrolyte.