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The rapid economic growth and environmental concerns have led to high demands on paper and paper-based products in terms of variety, quantity, quality, and specialty. Enhancement and functionalization with additives are constantly required. Moving away from traditional petroleum-based additives, researchers have attempted to use “green” nanoadditives by introducing renewable environmentally friendly nanocellulose. This article studies the functions of nanocellulose as bio-additives (enhancer, retention and filtration reagent, and coating aid) in paper and paper products, and overviews the research development of nanocellulose-based additives and their applications in the paper industry for both efficient production and paper functionalization. The review shows that (1) a variety of nanocellulose-based bioadditives have been reported for various applications in paper and paper-based products, while commercially viable developments are to be advanced; (2) nanocellulose was mostly formulated with other polymer and particles as additives to achieve their synergistic effects; (3) major interests have concentrated on the nanocellulose in the specialty papers as representing more value added products and in the efficient utilization of recycled fibers, which remains most attractive and promising for future development. This report shall provide most useful database information for researchers and industries for paper recycling and enhancement, and paper-based products innovation and application.

With the increased awareness of reusing solid wastes for higher sustainability and the concern of water pollution associated with phosphorus over-emission, there are strong interests in developing solid waste based adsorbents for purifying phosphorus-containing wastewater. As a rich calcium resource, paper mill sludge (i.e., a major solid waste from pulping industry) can be used as phosphorus removal adsorbent after calcination. Thus, in this work, a simple and clean thermally treating route has been proposed for preparing calcium-containing biochar from paper mill sludge. The effect of the physicochemical properties of paper mill sludge and its carbonization condition on phosphorus adsorption has been analyzed. Moreover, the influence of some key adsorption parameters, e.g., biochar dosage, initial pH of solution, co-existing anions, initial phosphorus concentration and contact time has also been investigated. The results showed that the phosphorus adsorption data could be fitted well with pseudo-second-order kinetic and Langmuir isothermal models. The calculated maximum adsorption capacity of the as-prepared optimal calcium-containing biochar could reach to 68.49 mg·g−1 at 25 °C. Combined with the characterization results, it can be reasonably inferred that the adsorption process was chemisorption-dominated. Lastly, the application of this spent adsorbent in agriculture field has also been discussed. In brief, this work provided a feasible strategy for converting paper mill solid waste to an environmental functional material (i.e., calcium-rich biochar) for remediation of eutrophic water.

We employed a microwave-assisted two-pot in-situ deposition technique to incorporate zinc oxide particulates in the structure of filter paper to produce antimicrobial paper. The process involved successive immersion of filter paper samples in ZnSO4 (precursor solution) and NaOH (precipitating agent) to form Zn(OH)2, which transformed into ZnO during microwave treatment. Successful deposition of ZnO particles on the filter paper was confirmed via X-ray diffraction and the corresponding morphologies were observed using field emission scanning electron microscopy. The ZnO-deposited papers were tested for antimicrobial activity and were found to be more effective against Staphylococcus aureus (gram-positive) than Escherichia coli (gram-negative). Bacterial populations were reduced by up to 92 ± 2% and 57 ± 4% for S. aureus and E. coli, respectively. Also, it was found that the samples prepared using higher concentrations of ZnSO4 and NaOH exhibited better antimicrobial 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.

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.

Cellulose paper, a material that is naturally derived, low cost, lightweight, eco-friendly, and mechanically deformable, plays important roles in producing next-generation flexible electronics. Following the booms in the development of functional electronics, the soft actuators built from cellulose paper have attracted great attention. In this focused review, the milestones and recent achievements of cellulose paper-based actuators are summarized. Electro-, thermal, moisture and magnetic actuation mechanisms are utilized to acquire energy from external stimuli. Corresponding functional materials and available fabrication techniques like film assembly and layer deposition are described. Programmable actions for the emerging applications in bionics, paper grippers and robots are realized by pursuing different strategies to control the responding deformation. Along with a conclusion, the existing challenges and possible solutions in evaluating and improving the performance of cellulose paper are summarized in the final section.

This study optimizes a novel surfactant-assisted green liquor dregs (GLD) pretreatment of paper mill sludge (PMS), both of which are wastes from the kraft pulping industry, using a combined Response Surface Methodology (RSM) design. Optimized conditions give a maximal reducing sugar release of 16.38 g/L. A substantial reduction in heavy metals aluminum, chromium, cobalt, arsenic, lead, and copper after pretreatment illustrates the enhancement of substrate digestibility by reducing toxic elements. Separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) for hydrogen production are assessed. SSF produced a hydrogen yield of 3.72 mL/g, displaying a 36.26% increase from pretreated PMS compared to SHF. These findings provide insights into possible methods of reducing process duration, energy input, and costs incurred with waste disposal within the paper industry. Furthermore, improved hydrogen yield using an SSF process demonstrates the potential beneficiation of pulp and paper GLD and PMS wastes.

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.

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.

Environmentally friendly and energy saving treatment of black liquor (BL), a massively produced waste in Kraft papermaking process, still remains a big challenge. Here, by adopting a Ni CaO Ca12Al14O33 bifunctional catalyst derived from hydrotalcite-like materials, we demonstrate the feasibility of producing high-purity H2 (∼96%) with 0.9 mol H2 mol−1 C yield via the sorption enhanced steam reforming (SESR) of BL. The SESRBL performance in terms of H2 production maintained stable for 5 cycles, but declined from the 6th cycle. XRD, Raman spectroscopy, elemental analysis and energy dispersive techniques were employed to rationalize the deactivation of the catalyst. It was revealed that gradual sintering and agglomeration of Ni and CaO and associated coking played important roles in catalyst deactivation and performance degradation of SESRBL, while deposition of Na and K from the BL might also be responsible for the declined performance. On the other hand, it was demonstrated that the SESRBL process could effectively reduce the emission of sulfur species by storing it as CaSO3. Our results highlight a promising alternative for BL treatment and H2 production, thereby being beneficial for pollution control and environment governance in the context of mitigation of climate change.

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.

Rewritable paper is meaningful to the recyclable and sustainable utilization of environmental resources and thus has been extensively investigated for several decades. In this work, we demonstrated an efficient and convenient strategy to fabricate rewritable paper based on reversible hydrochromism of donor-acceptor Stenhouse adducts (DASAs). The kinetics and efficiency of isomerization could be well-controlled by adjusting the surrounding temperature and humidity. Monocolored rewritable paper was prepared by coating cyclic DASA·xH2O on the paper surface. Writing, printing, stamping and patterning were realized on the rewritable paper. The information could be controllably erased by treatment in a humid atmosphere. More importantly, the rewritable paper was upgraded to multicolored by combination of two DASA materials. The color of chirography was switched by controlling the writing speed.

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.

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.

A high-barrier, strong, and antibacterial paper was fabricated by coating the acetylated cellulose solution with different contents of cinnamaldehyde (CIN) on Kraft paper. The antibacterial, antioxidant, mechanical, and barrier properties of coated paper were investigated. When the amount of CIN added in coating reached 6% v/v, the coated paper exhibited excellent antioxidant activity and antibacterial activity against Escherichia coli and Staphylococcus aureus. Notably, the dry and wet tensile strength of paper after coating was increased by 26.4 and 10.6 MPa, respectively. Furthermore, the coated papers' barrier properties against oil, water, water vapor, and oxygen were dramatically improved, especially for the water barrier rate up to 96.4%. Our coated papers with over 6% v/v CIN could extend beef's shelf-life for at least 4 days, which exhibited a promising prospect in eco-friendly antibacterial packaging.

Cellulose nanofibers isolated from unbleached pulp are characterized by different surface properties due to presence of lignin at their surface, in addition to lower cost than isolated from bleached pulp. In the current work, the effect of cellulose nanofibers isolated from unbleached neutral sulfite and bleached soda rice straw pulps (so called UBCNF and BCNF) on improving paper sheet properties of unbleached and bleached rice straw pulp (so called UBP and BP) was studied. The effect on mechanical properties (tensile strength, burst strength, and tearing resistance) and physical properties (porosity and water vapor permeability) was studied. Scanning electron microscopy (SEM) was used to assist in explaining the obtained results. The result showed that using BCNF and BP resulted in better improvement in mechanical properties and also more effective in reducing porosity of paper sheets than in case of using UBCNF and UBP. These results indicated stronger bonding between nanofibers and pulps’ fibers in case of using BCNF and BP (surfaces rich in cellulose hydroxyl groups) than in case of UBCNF and UBP (surfaces rich in lignin). Water vapor permeability of paper sheets made from unbleached or bleached pulps did not significantly affect by the addition the nanofibers.

The development of industry and of the Internet of Things (IoTs) have brought energy issues and huge challenges to the environment. The emergence of triboelectric nanogenerators (TENGs) has attracted wide attention due to their advantages, such as self-powering, lightweight, and facile fabrication. Similarly to paper and other fiber-based materials, which are biocompatible, biodegradable, environmentally friendly, and are everywhere in daily life, paper-based TENGs (P-TENGs) have shown great potential for various energy harvesting and interactive applications. Here, a detailed summary of P-TENGs with two-dimensional patterns and three-dimensional structures is reported. P-TENGs have the potential to be used in many practical applications, including self-powered sensing devices, human–machine interaction, electrochemistry, and highly efficient energy harvesting devices. This leads to a simple yet effective way for the next generation of energy devices and paper electronics.

Paper and pulp mills generate substantial quantities of cellulose-rich sludge materials that are disposed in landfills at a large scale. For sustainability purposes, sludge materials can be bioprocessed to produce renewable fuels and useful chemicals. The enzymatic hydrolysis of cellulose is the process bottleneck that affects the conversion economics directly by using zero-cost raw materials. In order to study and optimize the process, the characteristics of the sludge raw materials should be first evaluated. In this work, sludge samples were obtained from paper mills located at different locations in Wisconsin and Minnesota. Part of the sludge samples was washed (de-ashed) with hydrochloric acid while the other part remained unwashed. The samples were subjected to multiple spectroscopic analyses techniques to evaluate the morphological properties of cellulose fibers and to estimate the total structural carbohydrate content. The results showed that the de-ashing process changed some fiber characteristics and cellulose crystallinity structure in all sludge samples. Sludge sample A (obtained from Kraft pulp and recycled paper mill region) showed a high percentage of fiber, with crystalline cellulose, compared to the other two sludge samples suggesting that sludge A is a valuable source to make value-added products. Aspen Plus mass and energy calculations performed in view of the ‘zero’ cost and the reliable supply of sludge raw materials producing 2 mol H2/mol glucose. Moreover, the results showed that extracting crystalline cellulose from these sludge samples is more profitable than crystalline cellulose made from the other lignocellulosic feedstocks. The results reported here showed that the utilization of these sludge materials would be an economically attractive and promising alternative for the production of hydrogen.

By continuously varying the structure of graphene oxide paper (PRGP) using Joule heating annealing, we are able to tune its electrical conductivity (σ) and thermal diffusivity (α) in a very wide range: more than three orders of magnitude for σ (186–503009 S/m) and 10-fold for α (8.31 × 10−7 m2/s to 9.31 × 10−6 m2/s). Excellent coherency-linear relationship between σ and α is discovered although they are sustained by different carriers: electrons and phonons. Such coherency exists over two sections: σ > 2 × 104 S/m, and 103

We report a paper-based photodetector made from mixed cation organic perovskite halide MA1–xFAxPbI3 (MA = methylammonium (CH3NH3); FA = formamidium CH(NH2)2). The detector shows a substantial photo...

Achieving an efficient catalyst in the ATRP system with a simple design, preparation from available materials, and high recyclability is a significant challenging issue. To attain the goal, herein, we used chitosan (CS)-modified cellulose filter paper (FP) as a green support for the synthesis of dip catalyst. The preparation of this catalyst involved surface treatment of the FP strips by CS coating through a dipping method, which increased the affinity of the substrate for adsorbing copper ions in the next step. The Cu@CS-FP catalyst was prepared without the requirement of any ligands. The synthesized dip-catalyst, in the form of the strips, was employed for the first time in the ATRP reaction of methyl methacrylate to assay catalytic activity. Catalytic insertion/ removal (ON/OFF) experiments were carried out during the polymerization. A reasonable control over the molecular weight with high conversion (68%) and polydispersity index of 1.32 under mild reaction conditions were obtained. Significantly, because of the facile separation of the catalyst, the amount of copper that remained in the polymer was very low (2.7 ppm). Also, the recyclability of the catalyst was investigated for five runs. The conversion in the final run was 64% without a loss of catalyst efficiency.

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.

Compared with a single chemical indicator, the use of multivariate chemical indicators in aging status assessment of transformer cellulose paper insulation can improve the reliability of the evaluation. In this study, a non-destructive method based on multivariate chemical indicators was proposed to evaluate the remaining life of cellulosic paper insulation. The selected chemical indicators closely related to the aging of the insulating paper were analyzed. Additionally, by applying the subjective and objective weighting method, the evaluation information of each indicator was fully extracted to obtain reasonable comprehensive evaluation weights. Besides, the comprehensive evaluation index of multivariate chemical indicators was obtained by using the technique for order preference by similarity to ideal solution method, which is consistent with the deterioration law of paper insulation. Then, the correlation lifespan model between the comprehensive evaluation index of multivariate chemical indicators and the degree of polymerization of insulating paper under different aging stages was established. The effectiveness of the proposed model was verified by experiments. This promising model can increase the accuracy of the condition assessment for the transformer cellulosic paper insulation.

Flexible paper-based sensors may be applied in numerous fields, but this requires addressing their limitations related to poor thermal and water resistance, which results in low service life. Herein, we report a paper-based composite sensor composed of carboxylic carbon nanotubes (CCNTs) and poly-m-phenyleneisophthalamide (PMIA), fabricated by a facile papermaking process. The CCNT/PMIA composite sensor exhibits an ability to detect pressures generated by various human movements, attributed to the sensor's conductive network and the characteristic "mud-brick" microstructure. The sensor exhibits the capability to monitor human motions, such as bending of finger joints and elbow joints, speaking, blinking, and smiling, as well as temperature variations in the range of 30-90 °C. Such a capability to sensitively detect pressure can be realized at different applied frequencies, gradient sagittas, and multiple twists with a short response time (104 ms) even after being soaked in water, acid, and alkali solutions. Moreover, the sensor demonstrates excellent mechanical properties and hence can be folded up to 6000 times without failure, can bear 5 kg of load without breaking, and can be cycled 2000 times without energy loss, providing a great possibility for a long sensing life. Additionally, the composite sensor shows exceptional Joule heating performance, which can reach 242 °C in less than 15 s even when powered by a low input voltage (25 V). From the perspective of industrialization, low-cost and large-scale roll-to-roll production of the paper-based sensor can be achieved, with a formed length of thousands of meters, showing great potential for future industrial applications as a wearable smart sensor for detecting pressure and temperature, with the capability of electric heating.

The plasmonic properties of gold nanoparticles (AuNPs) are a promising tool to develop sensing alternatives to traditional, enzyme-catalyzed reactions. The need for sensing alternatives, especially in underdeveloped areas of the world, has given rise to the application of nonenzymatic sensing approaches paired with cellulosic substrates to biochemical analysis. Herein, we present three individual, low-step, wet-chemistry, colorimetric assays for three target biomarkers, namely, glucose, uric acid, and free cholesterol, relevant in diabetes control and their translation into paper-based assays and microfluidic platforms for multiplexed analysis. For glucose determination, an in situ AuNPs synthesis approach was applied into the developed μPAD, giving semiquantitative measures in the physiologically relevant range. For uric acid and cholesterol determination, modified AuNPs were used to functionalize paper with a gold-on-paper approach with the optical properties changing based on different aggregation degrees and hydrophobic properties of particles dependent on analyte concentration. These paper-based assays show sensitivity ranges and limits of detection compatible for target analyte level determination and detection limits comparable to those of similar enzymatic, colorimetric systems, relying only on plasmonic transduction without the need for enzymatic activity or other chromogenic substrates. The resulting paper-based assays were integrated into a single 3D, multiplex paper-based device using paper microfluidics, showing the capability for performing different colorimetric assays with distinct requirements in terms of sample flow and sample uptake in test zones using a combination of both horizontal and vertical flows inside the same device. The presented device allows for multiparametric, colorimetric measures of different metabolite levels from a single complex sample matrix drop using digital color analysis, showing the potential for development of low-cost, low-complexity tools for diagnostics toward the point-of-care.

Gelatine sizing was used extensively for western papermaking before the nineteenth century and this technique is still applied nowadays for restoration purposes. Despite its wide use, the relationships between gelatine types, the strength of the size and its distribution inside the paper sheet are still unclear. Different concentrations of three gelatines of various origins and types (A/B) were used to size model papers. The gelatine uptake, the strength of the size and the presence of gelatine at the papers surface were investigated by using a water drop test method and ATR-FTIR spectroscopy. At a given concentration, similar uptakes were found for all gelatines but great variations were observed in terms of size strength and of gelatine ability to cover the surface of paper sheets. In addition, Scanning transmission X-ray microscopy was performed on paper fibres cross sections to map the distribution of the organic compounds (both cellulosic and proteinaceous) on a nanometer scale. This showed that gelatine coats but does not penetrate the fibres. It can be inferred that the different size strengths observed between the tested gelatines are mainly due to different ways of filling holes between fibres inside the paper mat, some gelatines being more prone to go inside the sheet than others which remain mostly distributed near the surface.

Highly foldable and flexible energy materials are a requisite for actual applications in self-powered wearable electronics and complex environments. Unfortunately, thermoelectric (TE) materials showing excellent foldability and flexibility under external mechanical stresses have rarely been reported so far. Herein, foldable and flexible TE materials based on Chinese traditional Xuan paper (a bio-based material) and commercialized conducting polymer of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) are reported. With a facile dip-coating and subsequent drying process, PEDOT:PSS is wrapped on the surfaces of cellulose fibers of Xuan paper via hydrogen-bond interactions. The resulting composite films exhibit outstanding mechanical and decent TE properties. In particular, the PEDOT:PSS/Xuan paper composite films exhibit excellent foldability and flexibility, and can be easily processed into various shapes with no distinct damage to their electrical conductivity and TE performances. This work paves the way for imparting TE performance to insulating paper-based materials, and the unique foldability may widen the TE applications in complex and extreme environments.

Paper-based sensors open a new avenue to produce easy-to-handle, inexpensive and simple-use analytical devices for widespread application fields in biological systems involving diagnosis, drug discovery and biosensing. In this manuscript, we constructed a fluorescence sensor based on functionalized paper coupled with silver nanoparticles (AgNPs) etching for hydrogen peroxide (H2O2) determination in biological systems. A significant fluorescence signal was achieved by immobilizing CDs onto the surface of cellulose filter paper by covalent bonds. The CDs functionalized paper coupled with AgNPs composites platform (PCD/AgNPs) consisted of CDs functionalized paper (PCD) and a AgNPs layer which acted as a fluorescence quencher of CDs via a physical adsorption mechanism. With the introduction of H2O2, the AgNPs were etched accompanied by the fluorescence recovery. As the target, a good linear relationship of a fluorescence turn-on response toward H2O2 between 10 and 120 μM was obtained with a limit of detection of 1.38 μM in our sensor. The designed sensor demonstrated good specificity and would have broad application prospects in the detection of milk samples and determination of H2O2 released from cancer cells.

Detecting vascular endothelial growth factor C (VEGF-C), a kind of tumor biomarker, is of significant clinical importance in evaluating the prognosis of patients with cancer. However, laboratory analyses are usually not suitable for point-of-care testing because they are expensive and time consuming. In response to these challenges, we fabricated an origami paper-based microfluidic electrochemical device. To improve the specificity of VEGF-C detection, nanocomposites, synthesized by new methylene blue (NMB), amino-functional single-walled carbon nanotubes (NH2-SWCNTs), and gold nanoparticles (AuNPs), were used to modify the surface of working electrodes. Results of electrochemical detection showed that the immunosensor had excellent linearity, ranging from 0.01 to 100 ng mL−1 (R2 = 0.988), and the limit of detection was 10 pg mL−1. To confirm the high specificity of the device under real-world conditions, we evaluated the device using clinical serum samples from our hospital. The results demonstrated that the device had an excellent performance and could provide a platform for real-time detection of cancers., Sun, Wang et al. report an origami paper-based immunosensor for the electrochemical detection of the VEGF-C biomarker in blood serum. The immunosensor is made by modifying the surface of working electrodes with new methylene blue, amino-functional single-walled carbon nanotubes, and gold nanoparticles and demonstrates excellent performance with a limit of detection in the range of picograms per milliliter.

Cellulose bromo-isobutyl ester was prepared using filter paper as raw material through esterification reaction with 2-Bromoisobutyryl bromide (BIBB) in N, N-Dimethyl-formamide (DMF). Cellulose esters with different degree of substitution were obtained. FTIR result indicated the successful introduction of bromo isobutyryl group in cellulose to obtain cellulose ester (Cell-Br). The surface of modified filter paper become rough and grooves could be observed by SEM. The thermal stability of the cellulose ester decreased in comparison with unmodified filter paper. Besides, the hydrophobicity of the filter paper was improved and the water contact angle increased from 73.4° to 116.5° with increasing degree of substitution. The water vapor barrier property was improved by 26 %. Furthermore, it was also found the modified filter paper possessed antibacterial activity against S. aureus bacteria. The modified filter paper obtained could be potentially used in food packaging fields and the results provide a simple method to prepare functional filter paper.

Eco-friendly and cost-effective materials and processes to manufacture functional substrates are crucial to further advance the area of printed electronics. One potential key component in the printed electronics platform is an electrically functionalized paper, produced by simply mixing common cellulosic pulp fibers with high-performance electroactive materials. Herein, an electronic paper including nanographite has been prepared using a standardized and scalable papermaking technique. No retention aid was needed to achieve a conducting nanographite loading as high as 50 wt %. The spontaneous retention that provides the integrity and stability of the nanographite paper, likely originates partially from an observed water-stable adhesion of nanographite flakes onto the fiber surfaces. The resulting paper exhibits excellent electrical characteristics, such as an in-plane conductivity of 107 S/cm and an areal capacitance of 9.2 mF/cm(2), and was explored as the back-electrode in printed electrochromic displays. Funding Agencies|Digital Cellulose Centre, a competence center set up by the Swedish Innovation Agency VINNOVA; consortium of Swedish forest industries; Wallenberg Wood Science Center (Knut and Alice Wallenberg Foundation); VINNOVA "EPIC" projectVinnova [2017-05413]; Karl-Erik Onnesjo Foundation

An industry compatible chemo-refining approach was tested for preparation of micro-nanofibrillated cellulose (MNFC) from bleached softwood pulp using sodium meta-periodate and sodium chlorite as oxidizers followed by refining in Valley beater. SEM and FTIR analyses confirmed micro-nano scale fibrillation and chemical functional group modification in laboratory prepared MNFC, respectively. The water retention value, carboxyl content and viscosity of MNFC were found comparable with imported NFC as reference (R-NFC). To evaluate MNFC as strength enhancer for paper properties, 5% MNFC addition to bleached mixed hardwood pulp showed 6% reduction in bulk with 36%, 24% and 97% increment in breaking length, burst index and double fold of the handsheets, respectively without affecting tear index and optical properties than the control. Surface properties were also improved. Pulp drainability (37°SR) after MNFC addition was found suitable for papermaking. These laboratory results confirmed the potential of MNFC as a suitable strength additive for paper quality improvement.

Photocatalytic materials have been widely used to remove dyes from printing and dyeing wastewater. However, difficulty in recycling of photocatalysts is the great concern in the real catalytic applications, which significantly raises the application cost. This study developed a low-cost catalyst by loading magnetic Ni onto filter paper (FP) via an easy going in-situ reaction. The characterization results displayed that the Ni particles were uniformly anchored onto the FP. The Ni@FP material presented a strong magnetic ability which was evidenced by a saturation magnetization (Ms) of 5.014 emu·g−1, a remanent magnetization (Mr) of 2.067 emu·g−1 and a coercivity (Hc) of 133.868 Oe. Meanwhile, the magnetic Ni@FP material displayed a recyclable advantage in photocatalytic degradation of methyl orange (MO) via an external magnetic field. There existed an optimal photocatalytic degradation rate of 93.40% within 5 min when MO concentration was 15 mg·L−1 at pH 8.0. Three cycle experiments confirmed that the Ni@FP possessed a satisfied stability and recycling ability. Moreover, the Ni@FP material presented a strong antibacterial activity which can prevent it from being contaminated by microorganisms. The versatility of the newly proposed photocatalyst in this study demonstrated its great application prospect in dyeing wastewater treatment.

Human papillomavirus (HPV) is one of the most common sexually transmitted infections which causes cervical cancer in women. In order to avoid the development of cancer and the onset of the disease, a reliable and on-site diagnosis for early screening of HPV is still required. To achieve this goal, a smartphone-assisted paper-based colorimetric assay using pyrrolidinyl peptide nucleic acid (acpcPNA) as a probe for the detection of HPV DNA was developed. Dextrin-stabilized gold nanoparticles (d-AuNPs) were used as the colorimetric reagent. The aggregation of the d-AuNPs can be induced by the outstanding properties of the positively charged acpcPNA, generating a distinctive color change. After the duplex formation between the acpcPNA probe and the HPV DNA target, the acpcPNA probe was depleted and the residual probe can cause different degrees of d-AuNPs aggregation, resulting in a detectable color change. The different color change before and after the introduction of the DNA target as a function of the DNA concentration was quantified by analyzing the color intensity through a smartphone application. Under the optimal conditions, the linearity in the range from 1 to 1000 nM with a correlation coefficient of 0.9996 and an experimental limit of detection of 1 nM was obtained. In addition, the acpcPNA probe exhibited high selectivity for the DNA target over single-base-mismatch, two-base-mismatch, and non-complementary DNA. Moreover, this DNA sensor was successfully applied for the detection of HPV DNA from cell line samples. The proposed smartphone-based colorimetric DNA sensor offers a simple, sensitive, and selective way of detecting HPV DNA. Therefore, this DNA sensing device can be utilized as an alternative tool for the point-of-care (POC) screening of HPV.

Lightweight yet strong paper with high toughness is desirable especially for impact protection. Herein we demonstrated electrically conductive and mechanically robust paper (AP/PB-GP) made of reduced graphene oxide via interfacial crosslinking with 1-aminopyrene (AP) and 1-pyrenebutyrat (PB) small molecules. The AP/PB-GP with thickness of over ten micrometer delivers a record-high toughness (∼69.67 ± 15.3 MJ m−3 in average), simultaneously with superior strength (close to 1 GPa), allowing an impressive specific penetration energy absorption (∼0.17 MJ kg−1) at high impact velocities when used for ballistic impact protection. Detailed interfacial and structural analysis reveals that the reinforcement is synergistically determined by π-π interaction and H-bonding linkage between adjacent graphene lamellae. Especially, the defective pores within the graphene platelets benefit the favorable adsorption of the pyrene-containing molecules, which imperatively maximizes the interfacial binding, facilitating deflecting crack and plastic deformation under loading. Density functional theory simulation suggests that the coupling between the polar functional groups, e.g., −COOH, at the edges of graphene platelets and −NH2 and −COOH of AP/PB are critical to the formation of hydrogen bonding network.

Neotame is an artificial sweetener with increasing consumption in recent years, excessive intake of it may bring potential health risk. In this work, a rapid method was developed to detect neotame in instant grain beverages, which was based on surface-enhanced Raman scattering (SERS) technique and filter paper-based silver nanoparticles (AgNPs@FP) substrates. The designed substrate exhibits good SERS activity with an enhancement factor of 105 because of the synergistic effect of the concentrated silver nanoparticles and filter paper. Meanwhile, the stability and repeatability of this fabricated substrate have been investigated with the relative standard deviation of 6.1%. In addition, it shows an excellent linear relationship (R 2 = 0.997) between the SERS signal and the logarithm concentration of neotame with a wide concentration range (0.05–5 g/kg) in the quantitative analysis. The limit of detection of neotame can be as low as 0.01 g/kg in instant grain beverages, which is below the maximum allowable addition level for neotame in instant grain beverages set in China (GB2760-2014, 0.16 g/kg). The proposed method has great potential for the identification and quantification of neotame in food safety applications with high sensitivity.

The growing need for reliable analytical tools to perform measurements at the point-of-need has prompted the development of novel sensors that are low cost, portable, sensitive, easy to use, and capable of multiplexed analysis. Miniaturization of the sensors into microfluidic platforms has become a promising approach to achieve these self-contained sensors. However, traditional microfluidics often require relatively expensive and complicated pumping mechanisms that increase the cost and limit the portability of the sensors. From a material perspective, paper is an attractive substrate for constructing point-of-need sensors because of its affordability, vast availability, and self-pumping ability, particularly when combined with electrochemical detection. In this mini-review, we discuss various strategies to achieve multiplexing or simultaneous detection of multiple analytes in electrochemical paper-based devices and provide a brief guide on selecting the detection strategy based on the electrochemical property of the analytes.

A novel nacre-like flame-retardant paper based on graphene oxide (GO), and phytic acid (PTA) is fabricated via evaporation-induced self-assembly. This facile method is time saving and low energy consuming. A facile approach is proposed to improve thermal oxidative stability of GO paper by in situ phosphorus doping during flame exposure. Then fire-alarm system is designed based on the high-temperature thermal reduction characteristic of GO. The GO paper functionalized with PTA (GO-PTA) can provide ultrasensitive, reliable and longtime fire early-warning signal. Fire alarm can be triggered at approximately 0.50 s when GO-PTA samples are attacked by fire. Phosphorus atoms are in situ doped into graphene layers during fire exposure, endowing GO-PTA paper with outstanding thermal oxidative stability, and thus alarm duration time of GO is greatly improved. The work develops advanced fire detection and early-warning sensors that provide reliable and continuous signals, which provide more available time for fire evacuation.

Paper-based products are similar to paper wasps’ “nests” built by “biofiber separation” and “biofiber reassembly”, where they add “saliva” for structural reinforcement and waterproofing. Rice leave...

We demonstrate a versatile and easily fabricated paper-based CO2 sensor. The sensor consists of a specially designed fluorescent color-shift chromophore infused into standard filter paper. The emission color of the resulting fluorescent paper changes upon exposure to CO2 due to the formation of carbonic acid, which underlies the sensing mechanism. By using a ratiometric method, the undesirable effects of photobleaching can be eliminated, leading to a stable and repeatable sensor performance. These multiuse sensors have a response time on the order of 1 min and feature low detection limits for a paper-based CO2 gas sensor, suggesting possible low-cost applications in smart buildings or other facilities in which CO2 levels are required to be continuously monitored.

The study describes the preparation of pulp and nanocellulose from non-wood plant materials, as well as an improved properties of paper and cardboard for mass production. The pulps from wheat straw, kenaf and flax fibers were prepared by the environmentally friendly organosolv method—cooking in a solution of isobutanol or peracetic acid. The organosolv pulps used to prepare nanocellulose had traces of lignin and mineral substances. The process of hydrolysis of the investigated organosolv pulps was optimal when carried out under the following conditions: 43% sulfuric acid, temperature 60 °C, hydrolysis time 90 min and ultrasonic treatment 60 min. Using the methods of SEM, XRD, TEM, AFM and TGA, the structure and properties of organosolv pulps and nanocellulose were studied. The use of nanocellulose in bulk and on the surface of mass types of paper and cardboard—paper for corrugation, offset paper, recycled containerboard and cardboard for flat layers of corrugated cardboard were investigated. We established the positive effect of nanocellulose application on the physical and mechanical properties of paper and cardboard. Low consumption of nanocellulose allows production of the paper and cardboard with properties that meet the requirements to appropriate standards and replacement of synthetic reinforcing materials.

A paper-based electrode is a very attractive component for a disposable, nontoxic, and flexible biosensor. In particular, wearable biosensors, which have recently been attracting interest, not only require these characteristics of paper-based electrodes but must also be able to detect various ions and biomolecules in biological fluids. In this paper, we demonstrate the detection ability of paper-based metal electrodes for wearable biosensors as part of a wireless potentiometric measurement system, focusing on the detection of pH and sodium ions. The paper-based metal electrodes were obtained by simply coating a silicone-rubber-coated paper sheet with a Au (/Cr) thin film by sputtering then modifying it with different functional membranes such as an oxide membrane (Ta2O5) and a fluoropolysilicone (FPS)-based Na+-sensitive membrane, corresponding to the targeted ions. Satisfactory and stable detection sensitivities of the modified paper-based Au electrodes were obtained over several weeks even when they were bent to a radius of curvature in the range of 6.5 to 25 mm, assuming use in a flexible body patch biosensor. Moreover, the Na+ concentration in a sweat sample was evaluated using the paper-based Au electrode with the FPS-based Na+-sensitive membrane in a wireless and real-time manner while the electrode was bent. Thus, owing to their complex mesh structure, flexible paper sheets should be suitable for use as potentiometric electrodes for wearable wireless biosensors., Graphical abstarct

The potential application of graphene as a filter paper for selectively removing cationic and anionic dyes from aqueous solutions is demonstrated herein. A surface-tailored graphene paper was fabricated by the vacuum filtration technique on a microporous substrate to remove two different classes of dyes. A negatively charged graphene paper was fabricated from graphene oxide (GO) solution, and a positively charged graphene paper was fabricated from polyallylamine-functionalized GO solution. The solutions of methylene blue (MB) and methyl orange (MO) were filtered through the negatively charged graphene paper (GO−) and positively charged graphene paper (GO+). The stacking structure of the GO− and GO+ paper successfully removed the MB and MO mixtures from the solution. The GO− and GO+ paper demonstrated a high retention rate of 99.8% for MB dye and 99.5% for MO dye. The pore size of the paper was found to be less than 7 nm, providing more insights into the rejection mechanism. The rejection mechanism involves the adsorption and electrostatic interaction (i.e., cationic–anionic interaction) between the dye and graphene sheets, which result in the fast and efficient removal of the dye. The GO paper displayed adsorption capacities as high as 311 and 340 mg g−1 for MB and MO dyes, respectively. The results indicate that the surface-tailored graphene paper is a great alternative for the next generation cost-effective filters in practical water purification applications.

The inorganic core-shell pigment CaCO 3 {\mathrm{CaCO}_{3}} @ SiO 2 {\mathrm{SiO}_{2}} was synthesized using a sol-gel method, and the pigment was applied as a surface coating on inkjet paper to study the influence of inorganic core-shell pigments on the dynamic permeability, surface properties, optical properties and inkjet-printing performance of coated paper. CaCO 3 {\mathrm{CaCO}_{3}} @ SiO 2 {\mathrm{SiO}_{2}} prepared using carboxymethyl cellulose (CMC) had better coverage than that prepared using polystyrene sodium sulfate (PSS) dispersant. The CMC-prepared CaCO 3 {\mathrm{CaCO}_{3}} @ SiO 2 {\mathrm{SiO}_{2}} -a had improved dispersibility, and the solids content of the coating reached 35 %. Inorganic core-shell pigments improve the surface and optical properties of the coated paper, making them similar to those of a reference calcium carbonate-coated paper. The smoothness and gloss improved by 60.8 % and 78.4 %, respectively, compared with those of silica-coated paper. The inkjet solid density and dot definition increased by 28.8 % and 4.1 %, respectively, compared with those of the calcium carbonate-coated paper. Preparing inorganic core-shell pigment CaCO 3 {\mathrm{CaCO}_{3}} @ SiO 2 {\mathrm{SiO}_{2}} is an effective method to fabricate inkjet printing coatings with advantageous microstructures for ink absorption.

Paper‐based microfluidics is characteristic of fluid transportation through spontaneous capillary action of paper and has exhibited great promise for a variety of applications especially for sensing. Furthermore, paper‐based microfluidics enables the design of miniaturized electrochemical devices to be applied in the energy sector, which is especially attractive for the rapid growing market of small size disposable electronics. This review gives a brief summary on the basics of paper chemistry and capillary‐driven microfluidic behavior, and highlights recent advances of paper‐based microfluidics in developing electrochemical sensing devices and miniaturized energy storage/conversion devices. Their structural features, working principles and exemplary applications are comprehensively elaborated and discussed. Additionally, this review also points out the existing challenges and future opportunities of paper‐based microfluidic electronics., Paper‐based microfluidics emerges as a powerful and versatile platform for constructing simple, inexpensive, environmentally‐friendly and high‐performing miniaturized electrochemical devices for various applications. This review summarizes the basics of paper‐based microfluidics and highlights some recent advances of paper‐based microfluidics in developing electrochemical sensing and energy storage/conversion devices. Their structural features, working principle and exemplary applications are comprehensively elaborated and discussed. This review also points out the existing challenges and future opportunities of paper‐based microfluidic electronics.

Flexible thin-film solar cells with high weight-specific power density are highly desired in the emerging portable/wearable electronic devices, solar-powered vehicles, etc. The conventional flexible metallic or plastic substrates are encountered either overweight or thermal and mechanical mismatch with deposited films. In this work, we proposed a novel substrate for flexible solar cells based on graphene paper, which possesses the advantages of being lightweight and having a high-temperature tolerance and high mechanical flexibility. Thin-film amorphous silicon (a-Si:H) solar cells were constructed on such graphene paper, whose power density is 4.5 times higher than that on plastic polyimide substrates. In addition, the a-Si:H solar cells present notable flexibility whose power conversion efficiencies show little degradation when the solar cells are bent to a radius as small as 14 mm for more than 100 times. The application of this unique flexible substrate can be extended to CuInGaSe and CdTe solar cells and other thin-film devices requiring high-temperature processing.

This study demonstrates a method for patterning paper-based microfluidic devices. An octadecyltrichlorosilane (OTS) solution is used to coat a chromatography paper to make it hydrophobic. A low-temperature (~ 32.9 °C) atmospheric-pressure dielectric-barrier-discharge jet with a shadow mask is then used to pattern hydrophilic stripes on the OTS-coated hydrophobic paper. In this manner, 1-mm-wide hydrophilic stripes are patterned successfully. Liquids are demonstrated to be transported and mixed in the hydrophilic stripes. Water contact angle measurement, X-ray photoelectron spectroscopy, surface profiler, optical emission spectroscopy, and scanning electron microscopy are used to characterize effect of pattering.

In this paper hemicellulose was separated by using 1-ethyl-3-methylimidazolium acetate (EmimAc, an ionic liquid) -water mixtures from a paper grade market bleached hardwood kraft pulp to produce dissolving pulp. Pure EmimAc dissolves pulp fibers completely in 30 min at ambient temperatures. By adding water (as an antisolvent to EmimAc system) the cellulose dissolution decreases and by optimizing the conditions, hemicellulose is largely removed while cellulose remains as the solid residue (dissolving pulp). At optimal conditions: molar ratio of water to EmimAc of 2, 60 °C, an alpha-cellulose content of 92.2%, with a high yield (78 wt%) was obtained. The viscosity of the solvent mixture decreases by increasing water to EmimAc molar ratio, which improves the mobility of ions, thus, facilitating their penetration into pores and lumens of the fibers during the dissolution process. Cellulose purity increases and purified cellulose yield decreases with the increases in temperature and water content (up to 2 wt%) in the mixture. This study implies that the optimal EmimAc/water mixture is an effective system to separate hemicellulose from hemicellulose/cellulose matrix.

Simultaneous enhancement in water flux and removal efficiency during the filtration process remains a big challenge for separation membranes. The porous structure of the filter paper can provide many channels for water transportation, but the separation performance is generally poor. The purpose of this study is to develop a new kind of filter paper consisting of ultralong hydroxyapatite (HAP) nanowires, cellulose fibers (CFs) and double metal oxide (LDO) nanosheets, and to achieve the simultaneous enhancement of both water flux and removal efficiency for high-performance dye separation. In this work, a novel kind of LDO/HAP/CF nanocomposite filter paper consisting of ultralong HAP nanowires and CFs and LDO nanosheets has been developed for rapid water filtration and highly efficient dye adsorption. Positively charged LDO nanosheets can adsorb on the surface of negatively charged ultralong HAP nanowires and embed in the porous networked structure of the LDO/HAP/CF nanocomposite filter paper, which can provide a porous structure for rapid water transportation and can adjust the pore size of the nanocomposite filter paper. As a result, the pure water flux of the LDO/HAP/CF nanocomposite filter paper can be adjusted. The optimized pure water flux of the LDO/HAP/CF nanocomposite filter paper can reach 783.6 L m-2 h-1 bar-1, which is 1.51 times that of the HAP/CF filter paper without LDO nanosheets (518.6 L m-2 h-1 bar-1). More importantly, the adsorption capacity of LDO nanosheets is high for dye molecules, the rejection percentage of Congo red (CR) by the as-prepared HAP/CF filter paper is only 59.8%, and its water flux is 534.7 L m-2 h-1 bar-1. The optimized rejection percentage and water flux of the LDO/HAP/CF nanocomposite filter paper for CR are significantly enhanced (98.3% and 736.8 L m-2 h-1 bar-1, respectively) compared to those of the HAP/CF filter paper. The size of LDO nanosheets has a significant effect on the water flux and dye rejection percentage of the LDO/HAP/CF nanocomposite filter paper. The as-prepared LDO/HAP/CF nanocomposite filter paper is promising for the applications in highly efficient purification of wastewater containing dye molecules.