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Selective detection and quantification of biomarkers related to human diseases are essential for preventive healthcare. Surface-enhanced Raman scattering (SERS) spectroscopy is a powerful analytical tool offering high sensitivity. However, the success of this promising analytical tool relies on the ability to effectively fabricate SERS substrate. Herein we have demonstrated a plasmonic paper-based flexible substrate (PPFS) for SERS sensing. In situ growth of silver nanostructures (AgNS) on the paper-based substrate was achieved by using a simple one-step silver mirror reaction (SMR). FESEM and TEM results depicts that the increasing silver ion content influences the morphology (growth of multifacets), as well as size of AgNS. Further, the PPFS substrate was tested with Rhodamine-6G (Rh-6G) dye and an attomole sensitivity with a LOD of 4.54 x 10-18 M was achieved. Further, two biomarkers, lactic acid (LA) and uric acid (UA) were detected on the PPFS substrate, with μM and pM sensitivity, having LOD values of 0.6 x 10-6 and 0.3 x 10-12 M respectively. Above detection levels for UA on PPFS is two orders better than reported values, whereas for LA it is comparable with reported substrates. Finally, UA, LA and their mixtures were tested on PPFS and results compared with commercial substrate. The performance of PPFS were found better in all cases, thus, multifaceted AgNS paper based PPFS offers the potential to be used as a biosensor for detection of various biomarkers from body fluids, responsible for the detection of the critical disease for preventive health care.

Statement of problem Quick response (QR) codes are a fast and efficient technology for linking and accessing identifying information, and their use has been proposed in forensics. The heat resistance and esthetics of denture marking methods (DMMs) have been recommended by the American Dental Association (ADA), but studies on these aspects of printed QR codes are lacking. Purpose The purpose of this study was to determine the optimal printed material with QR codes for implementation as a DMM adjusted to the recommendations of the ADA. Material and methods The behavior of 4 types of paper, bond paper, fiberglass filter paper, ultralong hydroxyapatite nanowire paper, and polyolefin and silica paper with printed QR codes was analyzed. They were exposed to temperatures between 100 °C and 1000 °C in a heat muffle for 1 hour. Each specimen was subjected to both a morphological and a thermogravimetric analysis (TGA) and scanned by using 3 different smartphones. Results The scans were positive for bond paper (33.3%), fiberglass fiber paper (50%), ultralong hydroxyapatite nanowire paper (100%), and polyolefin and silica paper (70.4%). The TGA revealed continuous decomposition curves (average 16.5 minutes at 624 °C). Conclusions Printed QR codes on ultralong hydroxyapatite nanowire paper appear to be suitable as information reservoirs, even surviving incineration, and may be implemented as a DMM conforming to the ADA recommendations.

Paper has been widely employed as cheap material for the development of a great number of sensors such as pregnancy tests, strips to measure blood sugar, and COVID-19 rapid tests. The need for new low-cost analytical devices is growing, and consequently the use of these platforms will be extended to different assays, both for the final consumer and within laboratories. This work describes a paper-based electrochemical sensing platform that uses a paper disc conveniently modified with recognition molecules and a screen-printed carbon electrode (SPCE) to achieve the detection of gluten in a deep eutectic solvent (DES). This is the first method coupling a paper biosensor based on aptamers and antibodies with the DES ethaline. Ethaline proved to be an excellent extraction medium allowing the determination of very low gluten concentrations. The biosensor is appropriate for the determination of gluten with a limit of detection (LOD) of 0.2 mg L−1 of sample; it can detect gluten extracted in DES with a dynamic range between 0.2 and 20 mg L−1 and an intra-assay coefficient of 10.69%. This approach can be of great interest for highly gluten-sensitive people, who suffer from ingestion of gluten quantities well below the legal limit, which is 20 parts per million in foods labeled gluten-free and for which highly sensitive devices are essential. Graphical abstract

In this study, paper ash generated during the incineration process of paper sludge was applied to measure the bulk, strength, and drying energy reduction of paperboard to assess the possibility of using it as an inorganic additive in paperboard mills. Three types of paper ash were fabricated by incineration, crushed, and fractionated with three different screen sizes, and their physical properties were measured. The fabricated paper ashes were added to Korean old corrugated containers (KOCC) stock to make handsheets, and their physical properties and drying energy reduction were determined. In addition, paper ash particles classified into 200 mesh screens were surface-modified with cationic polyacrylamide (C-PAM), and the handsheets were manufactured to analyze the strength improvement effect of paperboard. The bulk and the drying energy reduction improved as the paper ashes were added into the KOCC stock, but the tensile index, compression index, and burst strength decreased. In particular, the higher the average particle size of the paper ash, the higher the bulk and the drying energy reduction, but the lower the strength. The surface modification of the paper ash with C-PAM was effective in improving the strength. Therefore, paper ash made of paper sludge collected from specialty paper mills is effective in improving the bulk and drying energy reduction of paperboard, and surface modification with C-PAM is required to prevent the deterioration of paper strength.

This manuscript aimed to enhance the mechanical, thermal, and ignition properties of bagasse paper when coated with different coatings synthesized from hydroxyethyl cellulose, 1,3-di-p-toluidine-2,2,2,4,4,4-hexachlorocyclodiphosph(V)azane, Talc powder, NaHCO3, cellulose nanocrystal. The effect of these coatings on the mechanical properties was studied by measuring elongation, tensile strength, and burst strength. The stages of degradation and ash residue of the measuring specimens were determined using thermal gravimetric analysis (TGA), behind that, the ignition properties as the flame chamber (UL/94), and limiting oxygen index (LOI) was measured according to standards. These tests proved that 1,3-di-p-toluidine-2,2,2,4,4,4-hexachlorocyclodiphosph(V)azane has a direct effect on improving the mechanical characteristics and enhancing the ignition properties of the coated specimens compared to uncoated. In this study the physical, mechanical, thermal, and ignition properties of the bagasse paper sheets were enhanced by easy and low-cost method via synthesis of new coatings based on commercially available chemicals in a reasonable cost.

Million tons of cellulosic paper have been used for insulating coils in oil-filled electrical power transformers, thereby assuring the electricity supply for our societies. The high working temperatures in transformers constantly degrade paper insulators throughout their service life of up to 40 years. We approached the structural changes in oil-immersed cellulosic paper samples upon thermal stress in a study that compared unbleached softwood Kraft paper used as insulator paper with pure cotton cellulose paper. The model experiments used a thermal treatment in transformer oil at 170 °C for up to 14 days. The samples were characterized by means of 13C CP/MAS NMR spectroscopy, mainly based on deconvolution of the C4 resonance. An automated, fast, and reproducible C4 resonance deconvolution employing the “Peak Analyzer” tool of OriginPro 2020 (OriginLab Corporation, USA) was developed and used to exploit 13C CP/MAS NMR spectroscopy for the characterization of thermally stressed paper samples. Our results show that thermally induced structural changes depend heavily on the composition of paper, that hornification and coalescence of fibrils take place, and that the allomorph composition of cellulose crystallites is altered under the given conditions. Graphical abstract

The pursuit for sustainability in the papermaking industry calls for the elimination or reduction of synthetic additives and the exploration of renewable and biodegradable alternatives. Cellulose nanofibrils (CNFs), due to their inherent morphological and biochemical properties, are an excellent alternative to synthetic additives. These properties enable CNFs to improve the mechanical, functional, and barrier properties of different types of paper. The nanosize diameter, micrometre length, semicrystalline structure, high strength, and modulus of CNFs have a direct influence on the mechanical properties of paper, such as tensile index, burst index, Scott index, breaking length, tear index, Z-strength, E-modulus, strain at break, and tensile stiffness. This review details the role played by CNFs as an additive to improve strength properties of paper and the factors affecting the improvement in paper quality when CNFs are added as additives. The paper also includes techno-economic aspects of the process and identifies areas that need further research.

Graphene paper with good mechanical strength, flexibility, and high conductivity is an emerging functional material for wide applications, but its feasible and scalable preparation remains a challenge. Herein, a high strength, flexible, and conductive graphene/polypropylene (PP) fiber paper was prepared by a traditional papermaking process. In the composite paper, graphene nanosheets were well stabilized on the PP fibers forming a stable three-dimensional conductive interleaved network. Chitosan was found able to build a polar active interface on PP fibers and graphene nanosheets, which can not only promote PP fiber dispersion in water yielding a uniform pulp, but also favor the retention of graphene in the composite paper. As a result, the composite paper presents high strength (15.32 MPa), good conductivity (11,995 S/m), shielding effectiveness (31.1 dB), water resistance, fungi-proof, and thermal conductivity (10.17 W m−1 k−1) properties. This work demonstrates the feasibility of large-scale preparation of graphene composite paper with commercial synthetic fibers through a traditional papermaking process, and expands the potential industrial application of graphene materials. Graphene/chitosan co-aggregates were absorbed on the surface of graphene/chitosan/PP fiber under the electrostatic interaction of CPAM to form graphene/PP fiber.

Cellulosic insulating paper is the essential component of the insulation in power transformers. Under the thermal stress inside the transformer, the cellulosic insulating paper degrades and generates formic acid. Meanwhile, the presence of formic acid further accelerates the aging process of cellulosic insulating paper. This study takes the cellulose molecule composed of D-glucose as the research object. The ReaxFF reactive force field is applied to simulate the high-temperature thermal aging process of cellulosic insulating paper. During pyrolysis process, the number of formic acid molecules presents short-term fluctuations and continuous increases. Though simulation, the main reaction pathways of cellulose pyrolysis to generate formic acid are obtained. In addition, an accelerated thermal aging experiment of oil-paper insulation is designed. The formic acid in the experimental samples is detected by the silanization derivatization method. Through the combination of simulation and experimental results, the feasibility of formic acid as an aging indicator for cellulosic insulating paper is further demonstrated.

An innovative consolidation strategy for degraded paper is presented based on the reversible application of cellulose nanocrystals as sustainable fillers to reinforce mechanical properties and resistance to further degradation. The compatibility and efficacy of the proposed consolidation treatment are assessed first on pure cellulose paper, used as a model, by reliable techniques such as field emission scanning electron microscopy, atomic force microscopy, tensile tests, X-ray powder diffraction, and Fourier transform infrared spectroscopy, evidencing the influence of the surface functionalization of nanocellulose on the consolidation and protection effects. Then, the consolidation technique is applied to real aged paper samples from Breviarium romanum ad usum Fratrum Minorum S.P. (1738), demonstrating the promising potential of the suggested approach. Amperometric measurements, carried out with a smart electrochemical tool developed in our laboratory, demonstrate the reversibility of the proposed treatment by removal of the nanocrystalline cellulose from the paper surface with a suitable cleaning hydrogel. This completely new feature of the consolidation treatment proposed here satisfies a pivotal requisite in cultural heritage conservation because the methodological requirement for the ″reversibility″ of any conservation measure is a fundamental goal for restorers. A paper artifact, in fact, is subject to a number of natural and man-made hazards, inducing continuous degradation. With time, monitoring and consolidation actions need to be often performed to ensure conservation, and this tends to modify the status quo and compromise the artifact integrity. Removable treatments can potentially avoid erosion of the artifact integrity.

Paper manufacturing on a global scale is a highly competitive market which requires to constantly improve the manufacturing process to be competitive. To decrease production cost paper manufactures, add filler material prior to sheet forming to replace costly wood fiber based raw material. This research project investigates the use of in-situ precipitated calcium carbonate produced in the presence of eucalyptus fiber material at a 41.0% filler level prior to beating. The in-situ filler containing eucalyptus fiber suspension was used on a 12’ (304mm) wide Laboratory Fourdrinier Paper Machine together with non-filler containing eucalyptus fiber material, and a commercial precipitated calcium carbonate filler material. The manufactured in-situ fiber suspension resulted in a higher ash retention compared to the addition of the powdered commercial PCC filler material. In addition to commercial filler material retention is improved at higher filler addition above 30%. The increased ash retention is linked to the increased micro fibrillation fiber material of the in-situ filler-fiber suspension forming neckless like particles on the fibers microfibrils. Mechanical paper properties showed an improvement for in-situ precipitated filler material compared to commercial filler material addition. Optical properties could be improved in comparison to the eucalyptus fiber without filler addition for in-situ precipitated filler material and a combination of in-situ and commercial filler material.

We aimed at producing sodium carboxymethylcellulose (CMC) from waste paper cellulose. For this etherification, the raw material was waste paper, the cellulose was initially alkalized with NaOH, the etherifying agent was sodium chloroacetate, and the reaction medium was water or ethanol. The method provided by us, i e, a method for preparing CMC from waste paper, was environment-friendly, could be easily implemented, and could be conveniently applied to make waste paper efficiently used with high profit, and to expand the range of usable raw materials for CMC production. We successfully synthesized CMC and prepared CMC plastic membrane. This practice changes waste into valuables, which is beneficial to our living environment. For preparation of CMC, one of the crucial factors is appropriate pretreatment of the cellulose from waste paper. The pretreatment was done with a self-built hydrolysis method. We experimentally examined the effects of the mass ratios of reactants, reaction temperature, time, and reaction environment of homogeneous or heterogeneous on CMC yield. The innovative points of this research could be stated as follows: the reaction activity of cellulose was improved by pre-hydrolysis; synthesizing CMC with cellulose from waste paper changes waste into valuables is beneficial to our living environment; and a freezing treatment for the cellulose-alkali mixture was innovatively added. The effects were exhibited by a desired final conversion efficiency.

An increase in the environmental and health concerns over fluorochemical‐based, wax‐based, and extrusion‐based paper coatings has led to a growing interest in bio‐based, biodegradable, and repulpable alternatives to obtain water‐ and oil‐repellent coatings. Reported herein is a fluorine‐free, plastic‐free, and cost‐effective water and grease resistant paper coating approach that utilizes blends of corn‐starch (S) and a novel chitosan‐graft‐polydimethylsiloxane (CP) copolymer. The hydrophobic and oleophobic performance of the S/CP‐coated paper was evaluated by varying the ratio of S and CP in the overall blend. The S/CP‐coated papers were observed to have low cobb60 values (water absorptivity) of 13 ± 0.9 g m−2 and an excellent kit rating (oil resistance) of 12/12. The S/CP‐coated paper substrate surface profile was analyzed via scanning electron microscopy (SEM). The repulpability of the coated paper is also demonstrated by washing the coating materials from the paper and recovering the pulp.

Despite previous efforts, the fabrication of superhydrophobic substrate via an environment friendly and easy approach remains a great challenge. In this study, a low cost, simple, and green procedure was developed to prepare a superhydrophobic paper surface that is acceptable for the papermaking industry. First, a wax mixture (beeswax & carnauba wax) was emulsified and coated on the filter paper surface. Then, the coated paper was annealed at different temperatures. The further heat-treatment-rendered wax-coated paper hydrophobic or superhydrophobic because submicrometer or micrometer wax structures were present on the paper surface. The water contact angle of the annealed filter paper sample reached 151.5° at 60 °C, and the sliding angle was under 10°. Further, the relationship between surface composition and the hydrophobic properties of the coated paper samples was discussed. The obtained paper samples showed great potential in water/oil separation, as they had an efficiency over 99%. This work proposed a new simple and mild approach to fabricate superhydrophobic filter papers and explored the hydrophobicity and water/oil separation properties.

Free-standing flexible supercapacitive electrodes have practical application for wearable energy storage devices. In this paper, graphene paper (GP), a flexible electrode substrate, was prepared by one-step reduction of graphene oxide (GO) using HI solution. GP can be used independently as a flexible electrode with specific capacitance of 227 F/g. In order to make up for the shortage of GP specific capacitance storage, polyaniline (PANI) with high specific capacitance and good electrical conductivity was selected to composite with GP by electrochemical polymerization approach. This method to fabricate electrode material by direct electrochemical polymerization avoids the use of conductive binder and organic solvent. Owing to the specific capacitance contribution of PANI and GP, the PANI/GP composites exhibit higher specific capacitance when the polymerization time is 30 s and the polymerization voltage is 0.8 V. At 1 A/g current density, the specific capacitance of composite is up to 759 F/g, which is 3.34 times of neat GP.

Timely and rapid detection of biomarkers is extremely important for the diagnosis and treatment of diseases. However, going to the hospital to test biomarkers is the most common way. People need to spend a lot of money and time on various tests for potential disease detection. To make the detection more convenient and affordable, we propose a paper-based aptasensor platform in this work. This device is based on a cellulose paper, on which a three-electrode system and microfluidic channels are fabricated. Meanwhile, novel nanomaterials consisting of amino redox graphene/thionine/streptavidin-modified gold nanoparticles/chitosan are synthesized and modified on the working electrode of the device. Through the biotin-streptavidin system, the aptamer whose 5'end is modified with biotin can be firmly immobilized on the electrode. The detection principle is that the current generated by the nanomaterials decreases proportionally to the concentration of targets owing to the combination of the biomarker and its aptamer. 17β-Estradiol (17β-E2), as one of the widely used diagnostic biomarkers of various clinical conditions, is adopted for verifying the performance of the platform. The experimental results demonstrated that this device enables the determination of 17β-E2 in a wide linear range of concentrations of 10 pg mL-1 to 100 ng mL-1 and the limit of detection is 10 pg mL-1 (S/N = 3). Moreover, it enables the detection of targets in clinical serum samples, demonstrating its potential to be a disposable and convenient integrated platform for detecting various biomarkers.

Free-standing reduced graphene oxide (rGO) papers were prepared by chemical reduction, thermal reduction and combined chemical-thermal reduction, respectively. Four-point probe and nanoindentation experiments were conducted to investigate the electrical and mechanical properties of rGO papers. The rGO paper prepared by soaking in L-ascorbic acid and thermal annealing in argon at 1000 °C (labeled rGO-AsA-T) showed superior electrical and mechanical properties when compared with rGO papers prepared merely by chemical reduction or thermal reduction. The as-prepared rGO-AsA-T paper exhibited an electrical conductivity of 5.7 × 104 S/m, showing an increase of 90% compared to that in the thermally annealed rGO paper and nearly 40 times that of rGO paper reduced by L-ascorbic acid. It was also found that the rGO-AsA-T paper had the lowest elastic modulus of 288 MPa, showing enhanced flexibility. The nearly free voids in rGO-AsA-T paper proved by scanning electron microscopy (SEM) were due to the capillary action in chemical reduction and were significant in improving the electrical conductivity and flexibility of the paper. The rGO-AsA-T paper with high conductivity and flexibility has a promising application in flexible electronics.

Graphene-based nanomaterials possess broad applications because of their excellent multi-functional properties. In this work, a facile self-assembling method was presented for preparing one kind of graphene oxide-based paper/hollow microspheres hybrid. It was found that most of the hollow microspheres can strongly anchored on the surface of graphene oxide paper (GOP) by an in-situ scanning electron microscope peeling testing combining with molecular dynamics (MD) simulation. In addition, the uniform distribution of hollow microspheres on the surface of GOP cannot only provide a better surface wettability, but also can effectively improve the interfacial stress-transfer capability between such hybrid and polymer matrix. Our work provides a guidance for the structural designs of graphene-based nanomaterials and broaden their applications.

Environmental and health concerns are driving food packaging to reduce the use of poly- or perfluorinated compounds and petroleum-based polymers. Here, we successfully obtained good oil-proof paper by combining cellulose nanofibril (CNF) film with filter paper through film transfer. The process was not only facile but also did not require chemical reagents other than water. To achieve the kit number 12, the basis weight of the CNF film was 2.1 g/m2, which was much less than the amount required for coating. The calendering process further reduced the pores thus improving the oil resistance of the film transfer paper. At a calendering pressure of 20 N/mm, only 1.4 g/m2 of the CNF film was required for kit number 12. This study provides a new way for the application of CNF in the field of oil resistance.

We demonstrated the thermally robust reduced graphene oxide (rGO)/boron nitride nanotube (BNNT) papers and their application in electromagnetic interference shielding. In order to overcome the thermal durability shortcomings of electromagnetic wave shielding paper based on rGO nanomaterial, rGO/BNNT electromagnetic interference (EMI) shielding paper having excellent thermal durability could be manufactured using BNNT nanomaterials having excellent chemical and thermal stability at high temperature. With the addition of a little BNNT, the durability against temperature can be increased by more than two times while there is little reduction in EMI performance.

Superhydrophobic surfaces have high potential in self-cleaning and oil-water separation applications. We developed a three-step method for the preparation of superhydrophobic filter paper. It involved citric acid (CA) pretreatment to activate cellulose fibers, coating with cellulose nanofibrils/functionalized silica (CNFs/m-SiO2) slurry to increase surface roughness, and grafting of hexadecyltrimethoxysilane (HDTMS) to enhance water resistance. The water contact angle (WCA) and siding angle (SA) of the prepared filter paper reached 151.5° and 7.5°, respectively. The results showed that, compared to the coated filter paper without the added CNFs, the coated paper with CNFs had higher retention of m-SiO2, thus roughness required for superhydrophobic surface was achieved. Further test under frequent abrasion and acid or alkali conditions showed that CA pretreatment improved the durability of superhydrophobic filter paper due to chemical crosslinking between the modified substrate and m-SiO2. Besides, the prepared superhydrophobic filter paper had outstanding self-cleaning property and high oil-water separation efficiency for various oil-water mixtures. Therefore, it is expected to be used for the treatment of oily wastewater.

Hydrophobic substrates for surface-enhanced Raman scattering (SERS) of adsorbate species are of great interest in chemical analysis because they can concentrate the analyte molecules in a small area of the surface, thereby improving the SERS sensitivity. Here, we propose a general strategy to fabricate hydrophobic paper-based substrates for SERS applications. The paper substrates have been manufactured by inkjet printing of aqueous emulsions containing Ag and polystyrene (PS) colloidal nanoparticles. In a first stage, the SERS performance of the substrates was optimized by varying the relative amounts of polymer/metal colloidal nanoparticles, the number of printing layers, and the degree of hydrophobicity of the substrates, using crystal violet as a molecular probe, which is well known for its strong SERS activity. In these conditions, the strongest surface Raman enhancement was observed for the highest water contact angle (146°) achieved. The selected Ag/PS-coated paper substrates showed wide applicability for several analytes, but in this study, a detailed analysis is provided for the pesticide thiram as a proof of concept. Several samples spiked with thiram have been analyzed by SERS, giving a detection limit of 0.024 ppm thiram in mineral water and apple juice, while in apple peel, the detection limit achieved for the same pesticide was 600 ng/cm2. We suggest that this one-step fabrication method produces a hydrophobic coating whose nanoscale features improve the SERS performance of the paper substrates. published

The in-situ synthesis of calcium silicate in the fiber can not only meet the requirements for high loading of paper, but also make up and improve the reduction of paper performance caused by filling. In this investigation, the effects of pulp type, beating degree, fiber ratio, reaction time, rotational speed, dosage of lime milk and dispersant on calcium silicate loading and paper properties were investigated. The results showed that when the beating degree was 40 °SR, the ratio of softwood and hardwood pulp was 1:1, the reaction time was 60 min, the rotation speed was 600 r·min−1, the dosage of lime milk was 1.33 times of the theoretical amount, and the dosage of cationic polyacrylamide was 0.3 % (absolutely dry pulp), the ash content of hand-made sheet was 41.2 %, and the loading amount of calcium silicate was 26.3 %. Under this condition, the comprehensive performance of paper was the best.

Usage of cellulosic nanofibers, starch-nanocellulose, and polyacrylamide-nanocellulose hybrid systems were investigated for the replacement of imported long bleached kraft fibers in the production of durable papers. In this study, imported softwood kraft pulp was added to cotton pulp at four levels. Nanofibrillated cellulose (NFC) prepared from chemimechanical pulp was added to cotton pulp at a 5% level with optional 1% cationic starch or 0.1% cationic polyacrylamide. Comparative tests were done without NFC at three levels of either cationic starch or cationic polyacrylamide. For each condition, 80 gm-2 handsheets were made, and the physical, mechanical, and optical properties of the paper were compared. The results showed that increases of NFC yielded higher surface smoothness, tensile strength, resistance to bursting, tearing energy, folding endurance, yellowness, and opacity. It also reduced brightness and porosity whether added singly or in combination with cationic starch or polyacrylamide. Increasing cationic starch also increased surface smoothness, tensile strength, resistance to bursting, and folding endurance, but paper opacity was reduced. The field emission-scanning electron microscopy results showed that increased NFC reduced porosity, the paper surface became smoother, and the pores were relatively filled. Finally, the combined treatment of 5% NFC and 1% cationic starch is introduced as a suitable combination.

For the first time, molecular dynamics simulation was used to analyse the solubility of five kinds of nanoparticles (SiO2, ZnO, Al2O3, Fe2O3, TiO2), cellulose crystalline region and cellulose molec...

In this research work, we present a synthesis of silver and cobalt bimetal nanoparticles stabilized by a carboxymethyl cellulose biopolymer (CMC-AgCo) and its coating on a cellulose filter paper (CFP) to prepare the dip-catalyst. All the prepared samples were subjected to characterization by scanning electron microscopy for surface morphology, EDX, XRD and thermogravimetric analysis. The catalytic properties of the CFP/CMC-AgCo as dip-catalysts were evaluated in the reduction of organic nitroaromatic pollutants of 2,6-dinitrophenol to 2,6-diaminophenol as well as the 4-nitrophenol to 4-aminophenol. It was found that the reduction reaction advanced with the pseudo-first-order kinetics. The CFP/CMC-AgCo catalyzed the 2,6-diaminophenol and 4-nitrophenol with a reaction rate constant of 0.1244 and 0.177 min− 1, respectively. The separation of the CFP/CMC-AgCo was easy as it required a simple pulling of the strip from the reaction medium. Importantly, the catalytic reaction rates and conversion percentages of the two nitroaromatics were well-maintained for multiple times during recycling experiments.

The research aims to evaluate the efficiency of some consolidation materials for tracing paper; hydroxypropyl cellulose (Klucel-E), zinc oxide nanoparticles and nanocellulose. The consolidated materials were used independently, and as hybrid mixtures to improve their properties. The prepared nanomaterials were examined with an Atomic Force Microscope (AFM), and the materials used to consolidate the tracing paper samples after artificial aging were evaluated. Evaluation methods included investigation of the surface morphology by Scanning Electron Microscope (SEM), measurement of mechanical properties (tensile strength and elongation), and detection of chemical changes of the treated samples before and after thermal ageing at 80°C and 65% relative humidity by Fourier transform infrared spectroscopy (FTIR) analysis. Based on the results of the examinations, consolidation by the hybrid mixture consisting of hydroxylpropyl cellulose and nanocellulose proved to be successful; giving the best results when this hybrid mixture was applied on tracing paper samples. This mixture was distinguished by its ability to spread easily inside the paper, giving greater strength to the binding, without forming a film on the surface of the paper and causing stiffness or opacity to treated tracing paper. Therefore, this hybrid mixture was used to consolidate an archaeological tracing map at the Egyptian Geographical Society dating back to (1807 AD).

Lignin/tannin/ZnONP composite coatings were designed for paper-based green packaging. Multiple functions, such as high strength, moisture resistance, low air permeance, heat endurance, UV aging resistance, and antibacterial/mold properties, were successfully integrated into one biobased coating. Prepolymerization improved the physical properties of coatings at high lignin contents. The best ingredient ratio was: 40% lignin, 15% tannin, and 10% ZnONPs (based on tannin weight), and the as-prepared biocoating was labeled LTZn-10. After coated with LTZn-10, the tensile strength and bursting strength of the packaging were efficiently enhanced by more than 3 times and were dramatically increased by 51.6 and 5.6 times at the wet state, respectively, which reveals that the packaging has favorable moisture resistance and it can be used in high humidity environments. Scanning electron microscopy (SEM) proved that most of the pores on the paper were blocked by the coatings, which helped to decrease the air permeance by 10.3 times. Meanwhile, ZnONPs were evenly spread on the coatings, which endowed the packaging with excellent antibacterial/mold performance. No colony or mycelium was found in the test against Gram-negative/positive bacteria and eight common molds. Besides, antibacterial activity is only available while the bacteria come in contact with the coating and no active substances were released into the culture medium, which is a good property that can keep the cargo from contamination of antibacterial agents. In addition, the coated paper presented an improved Tg and thermal degradation temperature, indicating that the coated package has favorable thermostability and can maintain its outstanding physical properties in a wider temperature range. Lignin and tannin promoted the UV stability and service life of the coated paper, as a rare physical decrease was observed after UV aging for 72 h. The function-integrated biobased coating with favorable sustainability is a good candidate to be widely used in paper-based green packaging fields.

A new coating method was developed, based on cellulose regenerated from an N-methylmorpholine N-oxide (NMMO) solution applied to paper. In particular, the purpose of this study was to compare the effectiveness of the “deep coating” method using cellulose regenerated from NMMO solution and the classic pulp refining process as methods to improve paper mechanical properties and overall quality. The “deep coating” name comes from the fact that the coating process is combined with subsequent heating of the coating before its final solidification. As a result of this operation, deep penetration of the cellulosic solution into the paper structure occurs. This increases the contact surface of the solution with the cellulosic fibers, which increases the strength properties of the paper structure. It was found that the cellulosic coating increased the apparent density of the paper, the tensile strength, the elongation, the resistance to bursting, and the double fold number. However, the coating also decreased the air permeability and the tear resistance of the paper samples. Despite some technological difficulties, this method could be an attractive solution in the case of a need for additional functionalization of a paper structure.

Excellent mechanical and electrical properties of graphene-based paper-like materials are essential for applications in flexible conductors, energy-storage devices, etc. The graphene oxide (GO) supernatant separated by centrifugation and ultrasonication has been used to prepare graphene oxide paper and reduced graphene oxide paper (rGOP) with high strength and conductivity. However, this method has cumbersome steps and low supernatant concentration, which greatly increases time and energy consumption, and is not suitable for rapid batch preparation of high-strength and high-thickness rGOP. Herein, a high-speed mechanical shearing method has been used to efficiently exfoliate graphite oxide suspension into high-concentration GO slurry with large lateral size, and rGOP has been further prepared by blade coating and HI acid chemical reduction. Compared with the product prepared by ultrasonic exfoliation method, the average area of GO sheets obtained via the mechanical shear exfoliation method can reach around 16.31 μm2. As a result, the mechanical properties and conductivity of the prepared rGOP have been increased by 30% and 23.5%, respectively, with the tensile strength and electrical conductivity of 478.2 MPa and 208.4 S/cm being obtained. The developed method is of great significance for the large-scale production and emerging applications of lightweight and high-performance rGOP.

Funding Information: The financial support of the Austrian Federal Ministry of Digital and Economic Affairs and the National Foundation for Research, Technology and Development , Austria, is gratefully acknowledged. We also thank the industrial partners Mondi, Canon Production Printing, Kelheim Fibres, and SIG Combibloc for their support. Publisher Copyright: © 2021 Copyright: Copyright 2021 Elsevier B.V., All rights reserved. Hydrophobization of cellulosic materials and particularly paper products is a commonly used procedure to render papers more resistant to water and moisture. Here, we explore the hydrophobization of unsized paper sheets via the gas phase. We employed three different compounds, namely palmitoyl chloride (PCl), trifluoroacetic anhydride/acetic anhydride (TFAA/Ac2O)) and hexamethyldisilazane (HMDS) which were vaporized and allowed to react with the paper sheets via the gas phase. All routes yielded hydrophobic papers with static water contact angles far above 90° and indicated the formation of covalent bonds. The PCl and TFAA approach negatively impacted the mechanical and optical properties of the paper leading to a decrease in tensile strength and yellowing of the sheets. The HMDS modified papers did not exhibit any differences regarding relevant paper technological parameters (mechanical properties, optical properties, porosity) compared to the non-modified sheets. XPS studies revealed that the HMDS modified samples have a rather low silicon content, pointing at the formation of submonolayers of trimethylsilyl groups on the fiber surfaces in the paper network. This was further investigated by penetration dynamic analysis using ultrasonication, which revealed that the whole fiber network has been homogeneously modified with the silyl groups and not only the very outer surface as for the PCl and the TFAA modified papers. This procedure yields a possibility to study the influence of hydrophobicity on paper sheets and their network properties without changing structural and mechanical paper parameters.

Organic dyes are used in many industries, e.g., textile, cosmetics and food. Hence, contamination of organic dyes to water sources is a critical issue. To reduce water pollution by organic dyes, we propose a paper-like adsorbent with a practical and economical production procedure. Subsequently, a flexible adsorbent was produced using a one-step approach by vacuum filtration of graphene oxide (GO) and iron oxide nanoparticles (Fe3O4-NPs) containing dispersion through a membrane and quoted as GO/Fe3O4 paper. For comparison, GO paper was also prepared using the same procedure. Both papers were characterized using UV–VIS absorption spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, electron diffraction X-ray analysis, X-ray photoelectron spectroscopy, and powder X-ray diffraction techniques. At the steady-state conditions, GO/Fe3O4 and GO papers were performed as adsorbent for cationic dyes of methylene blue, neutral red, and anionic dyes of methyl orange and fluorescein. In general, the removal efficiency of GO/Fe3O4 paper was higher than that of GO paper for adsorption of all dyes and this adsorbent revealed satisfactory adsorption properties for cationic dyes when compared to anionic dyes.

A comparative study of the proximate analysis, fire characteristics, and mechanical properties of the papers produced from pretreated and untreated bagasse was carried out. The bagasse collected was washed, dried, depithed and ground to pass through a 5 mm sieve using an electric milling machine. A portion was pulped without pretreatment, while others were pretreated (acetylation) before pulping and washing. After which different mass (0,2,4,6,8 and 10 g) of potassium aluminum sulphate, KAl(SO4)2.12H2O (alum) as flame retardant was added. The proximate analysis, fire characteristics and mechanical properties were determined. Results show that cellulose content increased with an increase in the concentration of potassium aluminum sulphate, while hemicellulose content increased from 24%-34% for flame retarded paper with 0-10 g concentration of alum. Lignin content also increased from 21.3%-63.2% for flame retarded paper with 0-10 g concentration of alum, respectively. Ash content varied with an increase in the concentration of potassium aluminum sulphate. Results from fire characteristics show that flame propagation and flame duration rate decreased with an increase in the concentration of alum, while ignition time and char formation increased in the concentration of alum. The mechanical properties, tensile strength, modulus and elongation at break were enhanced. Conclusively, pretreatment enhanced the properties of bagasse papers produced.

In this elucidation, we synthesized novel molecularly imprinted polymers (MIPOH1-4) that were used as organic fillers on bagasse pulp to form cellulosic paper sheets, the formation of MIPOH1-4 from the reaction of enaminone 3 with methyl methacrylate monomer in the presence of ethylene glycol dimethyl acrylate and 2,2’-azobisisobutyronitrile. The obtained MIPOH1-4 was confirmed via FT-IR and SEM with different pore sizes. And we noticed that the increase of template 3 increases the hydrogen bond between monomer and template and gave sponge surface of MIPOH4. Furthermore, the computational energies of the template with different monomers utilize DFT/B3LYP/6-31G (d) level to know the stability of polymers and hydrogen bonding between them. So that we applied that in paper manufacture through the adsorption of MIPOH4 as an organic filler on bagasse pulp to form novel cellulosic paper sheets with different concentrations and these sheets which characteristic through FT-IR, SEM, sizing test, tensile strength, and elucidation their antimicrobial activity with theoretical and docking studies. The MIPOH4 and cellulosic paper sheets showed the thermal stability and high tendency of sizability of these paper sheets and concluded the interaction between cellulose fibers of pulp with MIPOH polymer with physical hydrogen bonding.

The influence of nanofibrillar cellulose samples on the coating compositions water retention is considered. It was shown that gels of nanofibrillar cellulose and coating compositions based on them are distinguished by a high water-retention capacity during centrifugation (50.8% and 31.0% versus 17.7% with NaCMC). A preliminary assessment of the printing and technical properties of light weight coated paper (LWC) using nanofibrillar cellulose in the coating composition has been carried out. The technical characteristics of nanofibrillar cellulose have been determined, formulations of lightweight paper coatings have been developed for high-speed modern equipment.

In this study, we developed a novel, simple, rapid, and low-cost colloidal gold-based immunochromatography method, with filter paper replacing nitrocellulose membrane as the substrate. To obtain adequately immobilized protein, chitosan was used to functionalize the filter paper. After conditions and parameters were optimized, the novel immunochromatography method was applied for detection of sulfonamide residues in milk. Quantitative detection was accomplished using a smartphone and Photoshop software (Adobe Inc., San Jose, CA), allowing us to screen 13 sulfonamides with a limit of detection ranging from 0.42 to 8.64 μg/L and recovery ranging from 88.2 to 116.9% in milk. The proposed novel method performed similarly to the conventional method that uses a nitrocellulose membrane as the transport medium, and it had lower cost and better usability because of the inexpensive and easily available filter paper.

A new type of polydimethylsiloxane-based paper transparentizing agent was prepared via a combined method. The performance of the transparentizing agent was investigated systematically by adding and dipping, with use of the surface sizing device of a paper machine. Optimum performance was found at 30% concentration of the transparentizing agent and 30 to 45 °C of dipping temperature. Under the optimal conditions, the transparentizing t agent achieved a rapid penetration in the base paper and filled in the pores of the paper, to be further effectively adsorbed and retained on the fiber surface. The transparency of test paper reached as high as 76±0.97 %, which was 37±1.4% higher than that of the control. However, the addition of transparentizing agent reduced the mechanical strength of paper slightly. The as-prepared transparentizing agent was found to exhibit excellent application stability and biodegradability when applied in the paper machine，When used as plastic film, the transparent paper would lose its strength completely after eight weeks. The resulting transparent paper can be used to develop paper-based film and other related plant based transparent/ translucent paper, which has great potential in replacing plastic products and eliminating white pollution.

In the packaging sector of the printing industry, different coating applications are tried and investigated in order to increase the surface appearance and performance characteristics of paper and cardboard. The printability, water and ink absorption capacity, frictional resistance, light sensitivity of the visual graphical design that are going to be printed on the packaging papers are some of them. In this study, different types of cardboards that are used as a packaging material were chosen and coated with nanocrystalline cellulose (NCC)/PVA at different rates (%). In order to determine effective and economical usage conditions, the coating solutions, at three different concentrations as 3 wt.%, 5 wt. %, 7 wt.%, were prepared. The coating was applied on the test papers, which were at the same weights (350 g/m2) and had different surface properties as matte glossy, bright glossy, American Bristol. NCC/PVA existence on the coated paper surface was confirmed with Fourier Transform Infrared Spectroscopy (ATR-FTIR). The impact of the coating, which was prepared at different concentrations, on the packaging materials was studied with respect to thickness, stiffness, water absorbability, contact angle and surface tension.

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.

As sugar is an important intermediate in the early stage in the degradation of cellulose, this paper proposes to use the concentration of total sugar as an indicator of the degree of aging of insulating paper in an oil-paper insulation system. The oil-paper insulation system was simulated at 90, 100 and 110°C, and total sugar concentration in insulating paper and in transformer oil was measured by spectroscopy. The spectrum of sugar reaction was obtained by spectrometer, and TQ Analyst software was used to process the data. Our experiments have shown that the total sugar concentration increases significantly in the early stage of aging, and there is a linear relationship between the logarithm of total sugar concentration and the degree of polymerization. We obtained the relationship between absorbance and total sugar concentration using the partial least square method and the regression goodness of fit is better than 0.91.

All-cellulose paper-based composites with underwater superoleophobicity and high-wet-strength were developed by casting a barrier layer of bacterial cellulose (BC) on a filter paper substrate. To optimize the pore structure of barrier layer, slow gel process of BC dispersion was conducted via acidification and solvent exchange. 1,2,3,4-butanetetracarboxylic acid was used to improve the wet strength and surface hydrophilicity through the crosslinking reaction between fibers. The underwater oil contact angles are higher than 150° in neutral environment, and slightly decrease under acid and alkali conditions. Combined with the micron-sized pore structure of BC barrier layer, the composite papers show good separation performance of oil-in-water emulsion. A denser BC layer can significantly improve the separation efficiency, but also lead to the reduction of flux. During the gelation of BC barrier layer, the increase in the ethanol/water ratio of the dispersion medium is able to increase the flux without obvious negative impact on the separation efficiency. When the ethanol/water ratio is 80%, the separation efficiency and water flux reach 99.2% and 1320 L m−2 h−1·bar−1 for the emulsified soybean oil with the average size of 13 μm, respectively. This type of all-cellulose composite papers provides a new idea for the fabrication of membrane materials for oil–water separation.

A paper-based membrane coated by graphitic carbon nitride (g-C3N4) is prepared via a dip-coating method and used as a separator for sodium metal batteries with merits of low cost and environment-friendliness. Introduction of g-C3N4 effectively improves the ionic conductivity and the structural stability of the separator. Compared with traditional polyethylene separators and Al2O3-coated separators, the g-C3N4-coated separators show better electrolyte wettability, thermal stability, and electrochemical stability. Therefore, Na||Na3V2(PO4)3 battery using the g-C3N4-coated separator exhibits better cycling stability and higher rate capability. These results prove that the g-C3N4-coated paper-based separator is expected to become the next generation of low-cost and high-safety separator in sodium metal batteries.

In this paper is reported the energy generated in a paper-based microfluidic fuel cell (paper-based mFC) using Pd/CX100 as anode and glycerol from three sources: reagent grade glycerol, crude glycerol from sunflower oil biodiesel, and crude glycerol from used cooking oil biodiesel, as fuels. TEM, SEM, XRD, XPS, and cyclic voltammetry were employed for the Pd/CX100 characterization. The paper-based mFC using Pd/CX100 as anode was evaluated employing 0.1 M and 0.5 M glycerol of each glycerol sample and achieving power densities of 0.242 and 0.160; 0.15 and 0.127; and 0.108 and 0.090 mW cm-2 for reagent grade glycerol, glycerol from sunflower oil biodiesel, and glycerol from used cooking oil biodiesel, respectively.

Natural cellulose paper is flame retarded using ammonium polyphosphate/montmorillonite (APP/MMT) nanocompound through coating method. Their morphologies are assessed by scanning electron microscopy, chemical components by energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy, chemical structure by Fourier transform infrared, thermal stability by thermo-gravimetric analysis and fire retardancy by 45° horizontal burning test. The results show that the thermal stability and flame retardancy of coated paper samples are enhanced obviously, and all samples are self-extinguishing during the tests due to the char formation reaction between APP/MMT and cellulose. Then the treated paper, AM-18.3, as surface flame retardant treatment for low specific surface area (SSA) polypropylene (PP) specimens (PP@AM-18.3) also is investigated using cone calorimeter. Compared with two controlled samples, PP@AM-18.3 shows significantly increased time to ignition, the lowest fire growth index and highest fire performance index. This may give a new flame retarded approach for low SSA polymer materials with little amount flame retardants.

Nanofibrillated films based on TEMPO-oxidized cotton linters were applied to reduce the hydrophilic properties of paper. For this purpose, aqueous dispersions of nanofibrillated cellulose of different composition: 1 and 3% of nanofibrillated cellulose, up to 13% of CaCO3 and/or Al(OH)3, up to 20% of propane-1,2-diol (glycol), and up to 21% of TEMPO-oxidized cotton linters were coated on the model paper, without additional adhesive. The pristine model paper and papers coated with nanofibrillated cellulose-based composite films were characterized in terms of water absorptiveness by COBB method and water drop contact angle measurements. The surface appearance was characterized by scanning electron microscopy (SEM) and surface chemistry by infrared spectroscopy with Fourier transform and attenuated total reflection (ATR-FTIR). Additionally, optical properties, i.e. measurement of reflection curves and CIE degrees of whiteness, were determined according to appropriate standards. For all papers coated with nanofibrillated cellulose-based films, depending on the composition of the dispersions, a decrease in sorption properties was achieved, without changes in optical properties and surface morphology of the paper compared to the pristine paper.

In this study, we developed ashless cellulose filter papers as calibration standards in laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to rapidly determine multi-element concentrations in airborne fine particulate matter (PM2.5). To achieve this, the papers were treated by immersion in standard solutions, followed by evaporation of the solutions. The homogeneity of the paper standards was studied, and the results demonstrated that the elements were homogeneously distributed at the paper centers with slight fluctuations (i.e., relative standard derivation ≦ 8%). The instrument signal drift and instability were compensated using a pseudo internal standard (197Au). The limits of detection established for LA-ICP-MS were obtained by the ablation of 11 lines on the procedural blank filter paper containing 0.5% HNO3, with values ranging from 0.01 (Sr) to 0.49 μg g−1 (Fe). The accuracy of the LA-ICP-MS determinations was validated using certified reference materials (CRMs) and analyzed using six line scans. The results showed acceptable analytical errors (

This study presents a paper-based thin-layer optical cuvette for absorption spectroscopy with a pneumatically driven pump for the introduction of an aqueous sample. The three major components, a sample reservoir, an open-channel as an optical path and a pneumatic pump, are patterned in polypropylene paper using an electronic cutting machine. When sealed with transparent tape, the patterned paper serves as the side walls of the paper-based cuvette with an integrated pneumatic pump. Due to the reduced pressure inside the open-channel caused by the depression of the pump with a finger, aqueous samples spotted onto the reservoir are introduced into the open-channel of the paper-based cuvette. We demonstrated that the paper-based cuvettes are compatible with conventional spectrophotometers for absorption spectroscopic measurements and capable of quantifying the concentrations of various colored dyes in aqueous samples.