Search

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 study, Taguchi experimental design was used to the optimize operating parameters for the degradation of paper mill effluent using electrochemical (EC) process with two-dimensional concentric aluminum tube electrodes (CATE). For this purpose, four significant experimental factors were used in four levels pH (6–9), electrolysis time (10–40 min), voltage (6–12 V) and surface area (357–624 cm(2)). The process parameters were optimized, through performing L16 orthogonal array of Taguchi technique, for the removal of chemical oxygen demand (COD) and turbidity. The percent COD and turbidity reductions were transferred into an accurate S/N ratio for a larger value is the better (LBT) response. The study presents a unique method of finding optimum combination of process parameters to illustrate their effect on the turbidity and COD reduction. The treatment conditions for the maximum elimination of the pollutants were second level of pH (7), third level of ET (30 min), fourth level of voltage (12 V) and second level of surface area (446 cm(2)). The confirmation experiment results were within the confidence intervals (CI) indicating an acceptable agreement between predicted and observed values. Based on the p-values, the electrolysis time and voltages were found to be the most significant factors for both COD and turbidity reduction. The findings of research indicated, that the Taguchi method can be used successfully for the treatment of paper industry effluent by electrochemical technique.

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.

Currently, most of the collected waste medium-density fiberboards (MDF) is incinerated or landfilled, as economically viable recycling methods are yet to be developed. By steam refining waste medium-density fiberboards (MDF), it is possible to hydrolyze the incorporated resins and isolate a high yield fiber fraction. Further refining of the steam treated fibers might enable the fibers to be utilized in applications such as paper packaging, facilitating a cascading use of the waste material stream. To this end, intimate knowledge of the material is needed. In this study, the steam refined fibers of two waste MDF samples containing differing amounts of softwood and hardwood underwent refining and beating. The resulting fibers were characterized regarding their morphology and paper test sheets were produced to evaluate their strength (compression-, tensile- and tear-strength). Distinct differences in response to refining between the MDF samples were apparent. For the sample with the higher hardwood share an increase in strength properties with increasing steam treatment severities could be observed and it was possible to produce test sheets with comparable compression strength to recycled pulp for industrial corrugated paperboard. For the sample with a higher share of softwood, the steam treatment severity did not show any influence on fiber morphology or paper properties, and the resulting paper strength was low in comparison to the other steam refined waste MDF sample. Graphic Abstract

In traditional deinking process, large amounts of chemicals are required which makes these methods expensive and polluting. Also, application of sustainable material implies the use of green processes to reduce waste and pollution. Green enzymatic deinking processes are alternatives to those technologies that have negative effects on the environment. In this work, we applied response surface methodology for deinking the electrophotography-printed paper based on a systematic experimental pattern. The individual and interactive effects of enzymatic deinking parameters including time, temperature, and enzyme dosage on the handsheet properties were investigated. Different analyses were carried out to determine the best process conditions of enzymatic deinking to optimize the handsheet properties (i.e., tensile, burst, whiteness, and brightness). The obtained responses of an oven-dried fiber at 45 min, 43 °C and the enzyme concentration of 1 mg/15 g were 12.44, 0.65, 72.20, and 87 for tensile strength, burst strength, whiteness, and brightness, respectively. Measuring the optical density of the deinked handset after printing showed that the printability of the deinked paper is in the desired range.

Thermochemical parameters of A4-sized printing paper (AP), filter paper (FP), newspaper (NP), writing paper (WP), and reed pith (RP) samples were estimated using standard protocol to identify its fuel characteristics, and thermal degradation of the same was studied using thermogravimetric analysis (TGA) and differential thermogravimetric (DTG) techniques in the temperature range of 30–800 °C at the heating rates of 10, 15, and 20 °C/min under nitrogen atmosphere. The curves of TGA and DTG exhibited four significant stages. Maximum weight loss was found to be in the second stage. Kinetic analysis was carried out in the conversion range of 0.1 to 0.7 using iso-conversational models of Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), Vyazovkin, and Vyazovkin AIC (V.AIC). The average activation energies were found to be 139.90, 115.93, 212.52, 257.41, and 241.63 kJ/mol using FWO; 129.73, 103.06, 202.46, 248.38, and 231.55 kJ/mol using KAS; 145.57, 134.00, 195.29, 256, and 241.63 kJ/mol using Vyazovkin; and 140.71, 133.86, 193.14, 247.57, and 190.14 kJ/mol using Vyazovkin AIC model. Thermodynamic parameters (enthalpy change (ΔH), Gibbs free energy change (ΔG), and entropy change (ΔS)) using these models have been evaluated.

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.

This study investigated the feasibility of utilizing paper sludge (PS) as feedstock in the production of composite boards that are lightweight, durable and environmentally friendly. PS samples were collected from recycled newsprint (RN), corrugated recycled (CR) and virgin pulp (VP) pulping mills in South Africa. The PS was dried and mixed with magnesium phosphate cement to produce boards in a central composite design. Three different fillers including fly ash, calcium carbonate and silica fume were also added to the mix as binder replacement. The PS was characterized before use, and the produced composite board was evaluated for mechanical and physical properties. The boards produced had medium to high density (0.52—1.12 g/cm3) that could be used for non-structural interior applications. The results showed that boards containing RN had the highest mean value for modulus of elasticity (MOE) of 769 MPa. The mean MOE for boards containing CR- and VP-PS was 357 and 411 MPa, respectively. Calcium carbonate had the best effect on the board properties. Techno-economic analysis was simulated for four different types of feedstock scenarios at different locations including a combined scenario. Sensitivity analysis revealed that decreased feedstock cost resulted in decreased minimum required selling price. The analysis also revealed that the combined scenario proved to be the most cost-effective and profitable option for the future.

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.

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.

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.

The study examines the potential of Mauritian hemp (Furcraea foetida L.), a lignocellulosic non-wood biomass, as a more environmental friendly substitute to virgin wood for printing paper production. The best pulping method for Mauritian hemp was first investigated. A4 sized papers were then produced using 100% Mauritian hemp fibres and mixtures of Mauritian hemp fibres with Elephant grass fibres and wastepaper. Using Standard tests, the physical (thickness, grammage, apparent density, water absorbency) and mechanical (tensile strength, burst strength, crease recovery, abrasion resistance) properties of the papers produced were evaluated and compared with those of an 80 gsm A4 commercial printing paper used as control. Lastly, internal sizing was done by adding different proportions of starch to the paper whose properties were closest to the control (judged most printable) to investigate any property enhancement. Soda cooking with 12% Wt/V NaOH solution at a temperature of 90 °C for 90 min was found best for pulping Mauritian hemp. The 100% Mauritian hemp paper had characteristics closest to the control, with apparent density 141.54 kg/m3, water absorbency time 1.436 s, burst strength 0.323 kPa m2/g, tensile strength 10.97 Nm/g, abrasion resistance 37.5 cycles before rupture and crease recovery angle 34.8°. Increasing the starch content from 10 to 40% caused the 100% Mauritian hemp paper’s characteristics to increasingly approach those of the control, thus showing printability improvement. The methodologies adopted for papermaking and testing demonstrated that Mauritian hemp is a suitable alternative to wood to produce good quality printing paper.

The study is a first investigation of the feasibility to preserve recycled fillers (e.g. calcium carbonate, kaolin) from deinking paper sludge for newspaper production using an alternative approach respect to the actual methods. Deinking paper sludge was incinerated at 575 °C. The thermal stability of the incinerated sludge (ash) was evaluated by infrared analysis. Subsequently, the resulting ash was bleached by sodium dithionite. The particle size of the ashes was analysed by laser diffraction. The effect of recycled fillers on recycled paper pulp, after blending, was evaluated by the analysis of the physical and optical properties of the obtained paper sheets. Analysis showed the conservation of the calcium carbonate and other fillers’ molecular structure, both after incineration of the sludge and after bleaching. The dithionite treatment of the ashes resulted in ISO brightness levels of more than 70. The brightness was stable over one month. Paper sheets made by blending the bleached ashes with recycled paper showed an improvement of brightness and opacity but a decrease in terms of porosity and breaking length compared to paper sheets made without any filler. The proposed method still requires further studies to evaluate the economical application but offers an opportunity for the recycling of inorganic materials and valorisation of the sludge.

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.

Loop-mediated isothermal amplification or LAMP has been identified to be an efficient technology for point-of-care diagnostics. Paper-based LAMP technique has tremendous potential in replacing the existing tube-based technology as the manufacturing cost of a paper-based device is comparatively lower and easy-to-use. LAMP-based paper diagnostic device for Mycobacterium tuberculosis (MTB) detection is of extreme importance as it will help in early and rapid diagnosis of the affected patients. The fabrication of these devices requires assessment of design parameters on the extent of LAMP amplification reaction. Hence, CFD studies would be extremely beneficial from the design perspective. The current work presents an insight into the CFD simulations for LAMP amplification reaction on a porous paper membrane (nitrocellulose membrane). The convection-diffusion-reaction model is solved on a COMSOL Multiphysics 5.0 platform. Studies on effect of pore size, aspect ratio and initial DNA concentration on the extent of DNA amplification reaction have been carried out. The current paper-based technique is effective in detecting a minimum of 5 copies of DNA contrasting the previous semi-quantitative technique which demonstrated the detection of minimum 98 copies. Overall, the simulation results displayed almost 96% enhancement in the DNA amplification rate on paper membrane. Graphical abstract Graphical abstract for the computational study of DNA amplification reaction via LAMP technique on a porous paper membrane.

In order to improve the efficiency of disease diagnosis and environmental monitoring, it is desirable to detect the concentration of proteins and metal ions simultaneously, since the current popular diagnostic platform can only detect proteins or metal ions independently. In this work, we developed a colorimetric microfluidic paper-based analytical device (µPAD) for simultaneous determination of protein (bovine serum albumin, BSA) and metal ions [Fe(III) and Ni(II)]. The µPAD consisted of one central zone, ten reaction zones and ten detection zones in one device, in which reaction solutions were effectively optimized for different types of chromogenic reactions. Fe(III), Ni(II) and BSA can be easily identified by the colored products, and their concentrations are in good accordance with color depth based on the established standard curves. The detection limits are 0.1 mM for Fe(III), 0.5 mM for Ni(II) and 1µM for BSA, respectively. Best of all, we demonstrated the efficiency of the µPAD with accurate detection of Fe(III), Ni (II) and BSA from river water samples within 15 minutes. The µPAD detection is efficient, instrument-free, and easy-to-use, holding great potential for simultaneous detection of cross type analytes in numerous diagnostic fields.

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.

The sensitive quantitative analysis of trace heavy metallic elements (Cd, Mn, Cr, and Cu) in aqueous solutions was achieved successfully through the combination of filter paper enrichment with laser-induced breakdown spectroscopy. Filter paper was enriched with 0.4 mL aqueous solutions to form a homogeneous sample layer on the surface of the metallic target. Considering the limits of detection, the values deduced with calibration curves already exhibited the high performance of the proposed method at several hundred or 10 μg/L (Cd 0.165, Mn 0.035, Cr 0.012, and Cu 0.078 mg/L), lower than or comparable to those using other similar methods. The LIBS results agreed reasonably well with those from ICP-MS for real samples. All results showed that our method was suitable and accurate for rapid on-site detection of trace metals in aqueous solutions. This indicates that filter paper enrichment combined with laser-induced breakdown spectroscopy is a feasible approach to wastewater quality monitoring.

Abstract Tissue paper softness relies on two major factors, the bulk softness, which can be indicated by the elasticity of the sheet, and surface softness. Measurement of surface softness is complicated and often requires a multi-step process. A key parameter defining surface softness is the topography of the surface, particularly the crepe structure and its periodicity. Herein, we present a novel approach to measure and quantify the tissue paper surface crepe structure and periodicity based on the detection of waviness along the sample using laser scanning confocal microscopy (LSM) and X-ray tomography (XRT). In addition, field emission scanning electron microscope (FESEM) was used to characterize the tissue paper surface. We demonstrate that surface topography is directly correlated to the erosion of the doctor blade, which is used to remove the dry tissue paper from the Yankee cylinder. Because of its accuracy and simplicity, the laser confocal microscopy method has the potential to be used directly on the production line to monitor the production process of the tissue paper. XRT revealed more structural details of the tissue paper structure in 3D, and it allowed for the reconstruction of the surface and the internal structure of the tissue paper. Graphic abstract

A superhydrophobic paper with excellent robustness was fabricated by roll coating with modified nano-TiO2. First, nano-TiO2 particles were hydrophobically modified by γ-aminopropyltriethoxysilane and 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane (POTS). Then the paper coating composed of modified nano-TiO2 particles as pigments and epoxy resin (EP) as adhesives was coated on a paper surface to create the desired surface morphology and surface energy. Compared with the uncoated filter paper, the prepared paper showed an improved rough surface morphology owing to the uniform layer of TiO2 microclusters deposited on the fiber network. The superhydrophobic paper exhibited water contact angles (WCA) about 153° ± 1.5°, and water sliding angles (WSA) about 3.5° ± 0.5°, low surface adhesion and excellent bounce ability. The superhydrophobic paper can withstand a variety of wear and tear, such as tape stripping and knife scraping. The as-prepared superhydrophobic paper showed mechanical durability even after 20 wear cycles with sandpaper,thus sustaining excellent superhydrophobicity on the filter paper surface. Moreover, it remains fully functional even in environments with high concentrations of acid and alkali for 96 h. The superhydrophobicity was not affected after storage for 6 months in a natural environment. It was confirmed that the superhydrophobic paper surface exhibited excellent chemical stability, long-term stability and self-cleaning properties. The entire production process was operated under normal environment, without complex equipment; and, as such, has the possibility for large-scale production and application in industry.

In the present analysis, a new experimental pilot plant system for exploring resin-impregnated paper (RIP) bushing technology was conducted. Experimental and numerical studies were carried out on the resin infusion and impregnation processes in the paper condenser core of a RIP bushing. An innovative approach for the molding process (named molding method B) of a commercial RIP bushing was implemented. For this method, the homogeneity of the paper winding process was controlled precisely. The filling process was conducted by gravity due to the difference of heights between two vacuumed chambers and from bottom to top in the mold. The flow front position and infusion time were measured experimentally and used to obtain the axial permeability of the paper condenser core analytically and numerically. The results indicate that the molding methods have a significant effect on the RIP bushing quality, homogeneous filling, and impregnating process time. Also, it was found that homogeneity of the paper winding process and, consequently, uniform axial velocity of resin flow in the radial direction is the most effective factor to eject the air. Finally, it was recognized that the determination of axial permeability in the case of transient flow is novel in comparison with conventional procedures such as Darcy relation of steady flows. By decreasing the paper thickness from 0.3 to 0.2 mm, the permeability decreased from 8.84 × 10−10 to 4.52 × 10−10 m2. The microstructure of the core illustrates that the axial permeability of the crepe paper condenser core is considerably affected by the variation of the paper thickness.

We present a high resolution, ultra-frugal printing of paper microfluidic devices using in-house paraffin formulation on a simple filter paper. The patterns printed using an office inkjet printer formed a selective hydrophobic barrier of 4 ± 1 µm thickness with a hydrophilic channel width of 275 µm. These printed patterns effectively confine common aqueous solutions and solvents, which was verified by solvent compatibility studies. SEM analysis reveals that the solvent confinement is due to pore blockage in the filter paper. The fabricated paper-based device was validated for qualitative assessment of Candida albicans (pathogenic fungi) by using a combination of L-proline β-naphthylamide as the substrate and cinnamaldehyde as an indicator. Our studies reveal that the pathogenic fungi can be detected within 10 min with the limit of detection (LOD) of 0.86 × 106 cfu/mL. Owing to its simplicity, this facile method shows high potential and can be scaled up for developing robust paper-based devices for biomarker detection in resource-limited settings. Graphic abstract

Water–oil separation from their emulsions and mixtures has been a prominent topic in fundamental research and in industries. A superhydrophobic/oleophilic membrane (SHP) was obtained by dipping a cellulose filter paper in an acetonitrile solution of toluene diisocyanate (TDI) and in that of N-(2,4-diaminophenyl) maleimide, alternatively and repeatedly for three times, to make the paper coated by maleimide-containing polyurea (PU), which was then reacted with n-dodecanethiol (DAT) through Michael addition to obtain the superhydrophobic porous membrane (SHP). All the involved reactions were confirmed by different techniques. SHP membrane as prepared was demonstrated to be superhydrophobic and oleophilic and of high performance in separation of oil and water from their emulsions and mixtures. This study provides a new route to the fabrication of new materials of high superhydrophobicity and oleophilicity, featured by ease of fabrication, low-cost and versatile availability of the starting materials, both synthetic and natural.

Fluorine-free cellulosic paper was successfully obtained by coating the glassine base paper with eco-friendly cellulosic coating, which was made from dissolving cellulose in 8 wt% NaOH/12 wt% urea aqueous solution. Then the coated paper was severally immersed into CH3COOH, Na2SO4, and H2O solution to coagulate and regenerate. Benefiting from the compact matrix and fully covered surface, the resultant cellulosic paper exhibited favorable barrier properties and mechanical performance. Notably, the paper coagulated with CH3COOH displayed the reduction in water–vapor transmission rate, air permeability, and uptake of organic solvents due to its low porosity (26.8%) and narrow pore size distribution (0.1–0.36 µm). The tensile strength and elongation at break of papers treated by CH3COOH at coating weight of 5 g/m2 were increased by 72.1% and 34.0%, respectively. In summary, the fluorine-free cellulosic paper with high oil and grease resistance is attractive for the development of high-performance materials for food packing applications. Fluorine-free paper was obtained from the glassine base paper coated with eco-friendly, non-fluorinated, and degradable cellulosic coating, then coagulated with CH3COOH, Na2SO4, and H2O solution, respectively. The resultant functional papers displayed enhanced barrier properties (oil, organic solvent, vapor, and gas) and mechanical performance.

The use of nanocelluloses is being conducted for the most diverse applications. Their performance as coating agent has been mainly explored to improve barrier properties, as they emerge as perfect candidate for plastic substitution, but it is also important to explore their potential to improve printing quality. In the present work, the influence of different nanocelluloses, obtained through mechanical, enzymatic, TEMPO-mediated oxidation and carboxymethylation treatments, in the coating process and inkjet printability of office papers was assessed. The results revealed that the cellulose nanofibrils are better for printability than the microfibrils. But the size and charge of the former must be taken into account, since fibrils of very small size penetrate the paper structure, dragging the pigments from the surface, and very anionic nanofibrils can also have negative influence on the optical density. Besides, an interesting synergy between surface-sizing starch and the cellulose nanofibrils was found to occur as the latter closed the paper structure, which prevented starch from penetrating, while potentiating both of their positive effects on ink pigment entrapment. An additional study of characterization of inkjet pigments was also performed.

Chitosan is a biopolymer that has shown promising results for surface treatment of paper to enhance barrier and mechanical properties. Commercially, chitosan is available with a wide range of degree of deacetylation (DD). Herein, effect of DD on performance of chitosan in surface application of paper is investigated. Surface application of chitosan of different DD (77%, 84% and 94%) was done at a dose of 1.0 ± 0.2 g/m2 on kraft paper and comparison in terms of strength, structural, surface and barrier properties of paper was performed. Different DD of chitosan was confirmed by FTIR analysis. Results showed that breaking length of paper maximally increased by 15.2%/26.6% in machine direction (MD)/cross direction (CD), respectively after surface application of 94% DD chitosan followed by 77% DD and 84% DD. The maximum increase in burst index, stretch in MD and TEA in both directions of paper was found after surface application of 94% DD chitosan. Results attained by 77% DD and 84% DD chitosan for improvement in burst index, stretch and tensile energy absorption of paper were also encouraging. Maximum increase in stiffness was observed in CD with application of 84% DD chitosan. Double fold of paper also increased the maximum after surface application of 84% DD chitosan. The best results of contact angle, surface energy, Cobb60 and water vapor transmission rate were attained after surface application with 94% DD chitosan whereas the results attained by 77% DD and 84% DD chitosan for contact angle, surface energy, Cobb60 were also encouraging.

Green/sustainable cellulose paper-based platforms at point-of-care testing have received much interest in biomedical fields at resource-limited settings. In such platforms, biomolecules would have to be immobilized onto paper substrate to achieve detection. Therefore, effective molecule immobilization is critical for the performance of paper-based testing, especially the detection sensitivity. Although various methods have been developed to improve the detection sensitivity, the immobilization capacity of biomolecules has not been considered yet. In this study, we developed a facile method for modifying paper materials by incorporating chitosan into NC membrane, which has positive effect on the pore size, porosity, and surface groups of NC membrane, hence, enhancing the immobilization capacity of biomolecules on paper substrate. We demonstrated the effectiveness of the above mentioned approach by using nucleic acid lateral flow assay (NALFAs) as a model paper-based platform; in comparison with the unmodified NALFAs, the results showed ten-fold increase in the detection sensitivity for HBV. We envision that this facile modification method will have a great potential for developing other highly sensitive paper-based detecting platforms.

We report a smartphone–paper-based sensor impregnated with cetyltrimethylammonium bromide modified silver nanoparticles (AgNPs/CTAB) for determination of Fe3+ in water and blood plasma samples. The methodology for determination of Fe3+ is based on the change in signal intensity of AgNPs/CTAB fabricated on a paper substrate after the deposition of analyte, using a smartphone followed by processing with ImageJ software. The mechanism of sensing for detection and determination of Fe3+ is based on the discoloration of AgNPs which impregnated the paper substrate. The discoloration is attributed to the electron transfer reaction taking place on the surface of NPs in the presence of CTAB. Fe3+ was determined when the paper was impregnated with 1 mM AgNPs for 5 min of reaction time and the substrate was kept under acidic conditions. The linear range for determination of total iron in terms of Fe3+ was 50–900 μg L−1 with a limit of determination (LOD) of 20 μg L−1 and coefficient of variation (CV) of 3.2%. The good relative recovery of 91.3–95.0% and interference studies showed the selectivity of the method for determination of total iron in water and blood plasma samples. Smartphone–paper-based sensors have advantages of simplicity, rapidity, user-friendliness, low cost, and miniaturization of the method for on-site determination of total iron compared to methods that require sophisticated analytical instruments.

Cellulose is the main component of transformer insulating paper. In this paper, the pyrolysis mechanism of cellulose is studied by means of computational chemistry. This study is aimed at exploring the generation process of the methanol from cellulosic insulating paper at the atomic level. A simulation scheme of cellulose pyrolysis with detailed reaction pathways for methanol production has been obtained that is not readily accessible by experiments. The molecular dynamics method based on reactive force field (ReaxFF) is adopted to simulate the pyrolysis of cellobiose. A model composed of 40 cellobioses simulated at 500–3000 K was established, and the force biased monte-carlo is mixed into ReaxFF to make it closer to the actual situation and ensure the reliability. The result reveals that the –CH2– group from the C5 (or $${\text{C}}_{ 5}^{{\prime }}$$) group in cellobioses grabbed the nearby H atom to form methanol. In the pyrolysis process of cellobioses, methanol is stable at the early stage but unstable even disappeared in the later stage. The pre-exponential factor A and activation energy Ea of the ReaxFF-MD simulation are consistent with previous experimental results. Thus, this study provides an effective theory of the methanol as an indicator to evaluate the aging condition of cellulosic insulating paper in the early stage at the atomic level.

In this study, we developed a simple, inexpensive and easily fabricable paper-based SERS substrate with high sensitivity and reproducibility. The filter paper has natural pleats and small pores that allow the metal nanoparticles to be deposited and arranged on the paper to form large area SERS ‘active sites’. Silver nanoparticles can be embedded and grown on cellulose nanocrystals framework through the in situ reduction to form cellulose nanocrystal–silver (CNC–Ag) composites, which are coated on the filter paper to form composite paper-based substrates. The CNC–Ag composites further filled the pores on the surface of the filter paper and improved the adhesive rate of metal nanoparticles, thus the reproducibility of the SERS sensor has been improved. At the same time, because it has the agglomerating effect on samples, the hydrophobic dodecyl mercaptan covered on paper-based substrates can improve detection limit of analyte. Furthermore, we demonstrate that paper-based SERS substrates can efficiently detect two substances, including phenylethanolamine A and metronidazole. The limits of detection for phenylethanolamine A and metronidazole were found to as low as 5 × 10−9 M and 2 × 10−7 M, respectively. The paper-based SERS substrates offer great potential for label-free and on-site detection of trace substances.

Effective separation of oil and water has always been a long-term challenge. Here we introduce a facile and fluorine-free method to fabricate superhydrophobic and superoleophilic filter paper without the decoration of solid particles for robust oil/water separation. After chemically bonding octadecanoyl and α-bromoisobutyryl groups on the surface of filter paper through simultaneous esterification with stearoyl chloride and α-bromoisobutyryl bromide (BiBB) to obtain C18-FP-g-Br, superhydrophobic poly(styrene-co-acrylonitrile) (SAN) grafted filter paper (C18-FP-g-SAN) was fabricated via surface-initiated atom transfer radical polymerization. The obtained C18-FP-g-SAN showed a water contact angle of 153° and achieved a separation efficiency exceeding 98.5% after ten different typical oil/water separation processes due to the synergistically combined contributions of bonded octadecanoyl chain and grafted SAN. C18-FP-g-SAN remained high separation efficiency after 10 cycles of use and treatment with strong acidic or basic solution. The excellent reusability and chemical stability of C18-FP-g-SAN promise its practical applications of continuous oil/water separation and oil spillage cleanup.

The use of dielectric nanofluids has been recently proposed as a method to improve the insulation system of transformers. It has been widely reported that these liquids present superior dielectric properties than conventional dielectric liquids and have a better behavior as cooling agents. Nevertheless some aspects need to be addressed before these materials are applicable to real equipment. This paper analyzes the interaction between dielectric nanofluids and the cellulose materials that constitute the solid insulation of transformers. The impregnation process of a transformer has been emulated in order to obtain samples of solid insulation impregnated with a Fe3O4 based nanofluid. The samples have been subjected to ICP testing and CryoSEM observation, complemented with the determination of the EDX sprectrum. The interaction between the nanoparticles and the cellulose fibers has been investigated finding that bonds are established between them when cellulose is impregnated with nanofluids. This research was funded by the Spanish Ministry of Economy and Competitiveness. Grant Number DPI2015-71219-C2-2-R and Spanish Ministry of Innovation. Grant Number PID2019-107126RB-C21.

Polyhedral oligomeric silsesquioxane (POSS) has eight substituent groups, which can be substituted with various substances to obtain different modification effects. In order to study the effect of different substituents on the modification of cellulose by POSS and its internal mechanism, the pure cellulose model and the modified cellulose with three kinds of POSS derivatives, polyoctamethyl silsesquioxane (PMSQ), polyoctaphenyl silsesquioxane (PPSQ) and polyoctaaminophenyl silsesquioxane (OAPS), were established by molecular dynamics method. The thermal stability parameters and polarizability were calculated. The simulation results showed that different POSS derivatives can improve the thermal stability of insulating paper cellulose, and the modified effect of OAPS is the best. Compared with the unmodified model, the glass transition temperatures of the modified cellulose models of PMSQ, PPSQ and OAPS increased by 58 K, 63 K and 71 K, respectively. The mean square displacement of the modified models is significantly reduced, and the free volume is increased. The addition of POSS derivatives increase the entanglement between the cellulose chains, and compresses the gap between the cellulose molecular chains to suppress the movement of the cellulose chain. It is also found that the addition of POSS derivatives can effectively reduce the polarizability of cellulose, even the electric field distribution in oil paper insulation system, so as to enhance the insulation of transformer.

Cellulose-based material has been increasingly used as a suitable substrate for depositing metal–organic frameworks (MOFs) in recent years. In this work, MOFs (Cu-BTC) were deposited onto carboxymethylated filter paper (CMP) using four different preparation procedures: one-pot, two-step, layer-by-layer-organic (LbL-org), and layer-by-layer-water-organic (LbL-wtr-org). The products (Cu-BTC@CMP) were comparatively characterized by SEM, ATR FT-IR, XRD, and BET specific surface area analyses. The Cu-BTC crystals were immobilized on the CMP surface, where different deposit ratios (1.31% for one-pot, 4.23% for two-step, 31.49% for LbL-org, and 39.38% for LbL-wtr-org, respectively) were obtained when different preparation procedures were used under the precondition of the same chemical dosage and reaction time. The Cu-BTC crystals were found to grow in the main solution rather than on the substrate surface and the layer-by-layer method would contribute to a remarkable quantity of MOFs depositing onto the substrate surface. The crystals on Cu-BTC@CMP surface prepared by LbL-wtr-org procedure presented a much larger particle size and rougher surface compared to those prepared by the LbL-org procedure due to the aqueous solution of copper precursor. Depositing more Cu-BTC onto CMP surface also endowed the composite prepared by LbL-wtr-org procedure with the highest gas adsorption capacity (1.59 × 102 m2/g of BET specific surface area). Hence, the LbL-wtr-org procedure will be an optimal pathway for depositing metal–organic frameworks onto cellulose-based materials with the advantages of saving organic solvents and best gas adsorption ability.

There is a growing interest on recycling of waste fibres as an alternative to landfill disposal. The aim of the study was to investigate the durability and mechanical properties of waste paper–cement composite panels reinforced with varying kenaf fibre content (FC, 2–10%). The panels produced were evaluated for properties including modulus of rupture (MOR) and apparent modulus of elasticity (MOE). The resistance of the panels was tested in the field for both termite damage and fungi decay for a period of 24 weeks. Accelerated decay test was also performed on selected samples. The results showed that the mean MOR ranged from 3.17 MPa for samples with 10% FC to 4.84 MPa for samples with 8% FC. The mean MOE ranged from 248 MPa for samples with 10% FC to 1298.1 MPa for samples with 8% FC. Statistical analysis showed that the effect of the fibre content was significant on the properties evaluated (p

In this work, the mechanical properties of Kraft paper (KP) coated with a coating formulated with recycled polystyrene dissolved in the solvent lime limonene (rEPS/LL) are investigated. These mechanical properties are compared with those of KP coated with three different commercial coatings: oil-based alkyd coating (ALKY), oil-based phenolic coating (PHEN) and water-based acrylic coating (ACRY). The morphology characterization via scanning electron microscopy showed the KP coated with rEPS/LL resembles a layered structure, in which, part of the coating remained on the surface and part of the coating was absorbed by the KP. The KP coated with rEPS/LL exhibited the highest tensile stiffness and compression strength when compared to the uncoated KP and KP coated with commercial coatings. The remarkable compression properties of the KP coated with rEPS/LL coating may be explained by the bending and crushing mechanisms observed during the ring crush test. The excellent mechanical performance of rEPS/LL combined with an environmentally friendly process to obtain recycled EPS using a bio-based solvent presents several advantages for coating applications. These results warrant further research to fully understand the properties of KP coated with rEPS/LL.

In this article, we report the development and optimization of a cost-effective, biodegradable, disposable, and lightweight conductive polymer deposited on exfoliated graphite paper battery. The anode is made of aluminum foil and the cathode using electrochemically deposited anthraquinone conductive polymers on exfoliated graphite paper. Concentrated sodium chloride salt is used as the electrolyte. The battery shows a maximum capacity of 235 mA h g−1 and a superior cyclability of up to 500 cycles at 50.0 mA cm−2 current density.

A comparison between uncreped and creped handsheets was performed to study the effect of fiber morphology and creping process on fiber web structure and tissue properties. Four wood and non-wood pulps refined at different levels were used to manufacture uncreped and creped handsheets using a creping simulator. A characterization of the fiber web structure using scanning electron microscopy (SEM) and evaluation of tissue properties (e.g. tensile strength, water absorbency, softness) was performed on the uncreped and creped handsheets. The results obtained with the creping simulator were compared with commercial products to evaluate the significance of the creping simulator results. The SEM images of the fiber web structure showed that the creping process promoted buckling and distortion of fibers, delamination of surface fiber layer, development of free fiber ends and creation of crepe folds, which enhanced water absorbency and softness at the expense of reduced tensile strength. Short and thin fibers seemed to be more effectively creped than long and coarse fibers. Long and coarse fibers seemed to offer higher resistance to the compressive forces acting at the creping blade. A reasonable correlation between the performance of uncreped and creped handsheets made with different fibers was observed. The results indicate that the performance of uncreped handsheets can be used as a semi-quantitative indication of the performance of creped handsheets. The performance of the creped handsheets were similar to commercial products, which indicates that the creping simulator can be used as an alternative to study the creping process at laboratory scale.

构建基于有机材料的高性能柔性储钠电极面临诸多挑战. 本 工作通过可控组装及还原的方式, 实现了铁基配位聚合物纳米线/还原氧化石墨烯柔性薄膜的构筑. 多维复合薄膜可直接用作钠离 子电池自支撑负极, 且具有较高的储钠容量(200 mA g−1电流密度 下可逆容量为319 mA h g−1)和优异的倍率性能(3000 mA g−1大电 流密度下比容量可保持在∼120 mA h g−1). 研究表明有机配体(氨 三乙酸)中的羧基及氨基为储钠活性位点, 而配位金属离子(Fe2+)不 参与电化学反应.

Owing to the increasing amount of industrial wastewater and ocean pollution, separation of water and oil from their mixtures and emulsions has been an active area in water treatment industry and in academic research. Using cellulose filter paper as the substrate, a porous superoleophobic membrane (OP) was easily prepared by immersing the paper in an acetonitrile solution of toluene diisocyanate and that of N-(2,4-diaminophenyl) maleimide, alternatively and repeatedly, coating the paper with maleimide-containing polyurea (PU). PU coated paper was then functionalized by 2-[(tris(hydroxymethyl)methyl)amino]-1-ethanesulfonic acid through aza-Michael addition. The formation of PU coating and the subsequent functionalization were confirmed by FTIR, NMR and XPS analyses. The produced OP paper was shown to be superoleophobic and had excellent performance for oil–water separation from their mixtures and emulsions. This study provides therefore a novel protocol for preparation of superoleophobic materials, featuring easy operation, low cost, and in particular, versatile applicability to different natural and synthetic materials.

Tissue paper that is prepared from bamboo has a very promising future in the world, especially in China, thanks to the various merits of bamboo fibers. However, the water absorption behavior and mechanical properties of bamboo pulp based tissue paper need to be improved due to the inherent drawbacks of bamboo fiber, such as high stiffness, weak interaction between bamboo fibers etc. Hence, cellulose nanofibers (CNFs) were combined with bamboo fibers before the tissue paper-making process, to improve the water absorption behavior and mechanical properties of tissue paper. The hypotheses are that: (1) CNFs themselves possess large specific surface area and abundant hydroxyl groups as well, thus enhancing the hydrophilicity of tissue paper; and (2) the added CNFs can form 3D structures in tissue paper, thus providing abundant pores with uniform small size, which would facilitate the capillary effect for water absorption; and (3) more hydrogen bonds will be formed between CNF and bamboo fibers, thus improving the strength properties of tissue paper, thanks to the excellent mechanical and physical properties of CNF. The results from water absorption and tensile strength tests of bamboo handsheets indicated that the addition of CNFs can increase the water absorption capacity from 6.6 to 8.7 g/g when the CNF dosage was 10 wt% (based on the dried pulp). The water retention value of prepared bamboo fibers increased from 163 to 190% at the same CNF dosage, the tensile index increased from 18.5 to 24.5 N m/g as well. The results from the bulk and pore size analyses, FTIR, as well as SEM images of tissue paper also evidenced the conclusions above. Cellulose nanofiber (CNF) as a versatile filler for the preparation of bamboo pulp based tissue paper with improved water absorption behavior and mechanical properties

Recycled paper and some hardwood paper often display poorer mechanical properties, which hinder its practical applications and need to be addressed. In this work, cellulose nanofibrils (CNFs) obtained by a combined process of enzymatic hydrolysis and grinding (EG-CNFs), grinding and microfluidization (GH-CNFs) or TEMPO-mediated oxidation and grinding (TE-CNFs) were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Moreover, CNFs were made into films on which some characterizations including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and UV–Vis transmittance spectroscopy were implemented. Results showed that CNF fibrillation was promoted as times of passes increased in microfluidization, and CNFs pretreated by enzyme possessed shorter length. Crystallinity of CNFs was related to CNF manufacturing methods, while CNF films’ transparency was correlated to CNF diameter distributions. Moreover, CNFs were applied with different dosages on recycled and hardwood paper. Lengths of CNFs, strength of CNF network, and pulp properties were critical factors affecting the mechanical strength of CNFs-enhanced paper. GH-CNFs showed better strengthened effect on tensile strength of paper than TE-CNFs and EG-CNFs. The best overall improvement was achieved at GH-CNF10 dosage of 5.0 wt% on hardwood paper. The increment of tensile index, burst index, and folding endurance were 108.32%, 104.65%, and 600%, respectively. This work aims to find out the relationship between production methods and morphologies of CNFs and how the morphological characteristics of CNFs affecting the mechanical performance of paper when they are added as strength additives.

Tissue furnish optimization plays a key role in enhancing tissue properties, making the process cost-effective. Typically, this furnish is composed of a mixture of hardwood eucalyptus fibers (HW) and softwood (SW) fibers, which ensure strength and tissue machine runnability. However, the tissue paper production with the maximization of eucalyptus fibers achieves softer papers at less cost, since SW fibers are often more expensive than HW fibers. From this perspective, this study aims to investigate the effect of micro/nano-fibrillated cellulose (MFC/NFC) as an additive, on structural, softness, strength, and water absorption properties of tissue papers, promoting partial or total removal of SW fibers to produce 100% eucalyptus materials. MFC/NFC was characterized in terms of morphological, chemical, and water interaction properties. The results showed that MFC/NFC presents a high bonding surface area, high carboxyl group content and, when incorporated into tissue furnishes, it promotes strong inter-fiber bonds. This evidence was also supported by SEM image analysis methods and FTIR. Additionally, laboratory tissue handsheets with low basis weight were produced and used in the characterization assays. Overall, the results indicated that MFC/NFC improved strength, at the expense of bulk, porosity, softness, and absorption properties. Compared to typical industrial furnish mixtures (75%HW + 25%SW), MFC/NFC enhanced the production of bulkier, porous, and softer structures, but with reduced strength and absorption. It was possible to optimize the furnish composition by using fiber modeling to obtain 3D structure computation simulations with predictive capability. The MFC/NFC proved to be a high-quality additive to improve softness and strength properties.

The copper(II) ion (Cu2+) has played an indispensable role in diverse kinds of functional physiological processes of organisms, which has become of growing interest. Despite the fact that numerous Cu2+ test papers using fluorescent probes have been fabricated, sensors featuring the ratiometric property that integrates quenched probes and an inner standard dye are rarely reported. Herein, a two-component ratiometric sensor in a paper-based device is proposed to realize highly selective Cu2+ detection. To overcome shortcomings such as low signal-to-noise ratio and incorrect response of the quenching probe, a novel BODIPY-based turn-off probe (P2017) is designed and introduced into the paper-based device with better water solubility and selectivity for Cu2+ detection. Furthermore, a reference dye (B001), exhibiting an emission at 690 nm when the excitation wavelength is 480 nm, is also introduced into the paper-based device. These two components can enhance the quality of the signal as P2017 is sensitively quenched by Cu2+, while B001 with a photostable property, serving as an internal benchmark, is unable to react with Cu2+. The results indicated that the two components provided a new concept for optimizing paper-based device fabrication and developing accurate, simple, and inexpensive Cu2+ detection methods, which could be potentially applied to monitor human health and the environment in remote areas.

This study aims to decrease the dielectric constant of cellulose insulating paper by octa(aminophenyl)silsesquioxane (OAPS) grafting. OAPS was grafted onto the primary hydroxyl group of cellulose molecules via amino groups and epichlorohydrin. The dielectric constant and dielectric loss of insulating paper before and after modification were investigated. Relative to the unmodified paper, the dielectric constant of 15 wt% OAPS-grafted paper decreased from 5.27 to 4.28, and the dielectric loss decreased by 37.5% at 50 Hz. The movement and orientation polarization of the cellulose chains could be restricted due to the porous macromolecular structure and nano quantum interface effect produced by OAPS, thereby resulting in the reduction of cellulose polarizability. Moreover, the OAPS grafting modification does not degrade the other properties of cellulose insulation, i.e., its thermal stability, mechanical performance, fire-resistant properties, and electrical strength. OAPS grafting has promising potential application for preparing low dielectric constant insulating paper.

Hairy cellulose nanocrystalloids (HNC) are a brand new family of nanocellulose characterized by having functionalized amorphous poles joined by a crystalline shaft. In this paper we hypothesize that cationic HNC (CNCC) could be used as an effective retention agent in papermaking. To investigate this, we first flocculated a suspension of only fillers, namely kaolinite and CaCO3, and second, a suspension of recycled fibers, with CNCC. It was monitored by photometric dispersion analysis and laser focused beam reflectance. The flocculation mechanism was assessed by means of zeta potential, reflocculation efficiency, flocculation stability and optical microscopy. Finally, the effect of CNCC on drainage, retention and paper mechanical properties was studied. CNCC were found to heteroflocculate fillers at a wide range of dosages, finding a maximum floc size at a dosage of 30 mg/g. On the other hand, the maximum floc size when flocculating the pulp suspension, was found at a lower CNCC dosage (20 mg/g). In this case, fillers were being attached to the exterior surface of the fibers. In both systems, the maximum size increment was observed at the isoelectric point, so a charge neutralization mechanism was proposed. The addition of CNCC not only improved filler retention, but also pulp drainage by reducing these times. Moreover, although mechanical properties of the handsheets were affected by the presence of CNCC, this effect was much lighter than that caused by traditionally used retention systems. Hence, CNCC could replace many additives used in the wet-end of a paper machine, thus simplifying its operation.

We investigated treatment of cellulose paper with a phosphoric acid–urea solution for increasing the wet strength. First, a filter paper was immersed in a phosphoric acid–urea solution (phosphoric acid: urea mole ratio = 1:0, 3:1, 1:1, or 1:3). Next, the filter paper was put between glass plates and heated at 80–140 °C for 15 min to 3 h. Then, the filter paper was washed for 1 h in distilled water. After washing, the filter paper was dried in a hot press at 110 °C and 1.1 MPa for 1 h. We investigated disintegration by immersing the prepared filter papers in distilled water. The paper treated with the 1:3 phosphoric acid–urea solution did not disintegrate. The optimum concentrations for developing the wet strength of the paper were 1.2–2.5 M phosphoric acid and 3.7–7.5 M urea. The optimum treatment time and temperature were 1.5 h and 140 °C, respectively. The wet strength of the paper increased after treatment with the phosphoric acid–urea solution. This method is a viable alternative to treatment with chemicals such as polyamidoamine epichlorohydrin.

The development of point-of-care (POC) devices for the detection of environmental contaminants and the early monitoring of disease outbreaks in the health and food sectors has steadily grown in recent times. The real-time analysis offered by POC devices is pivotal in developing areas where access to skilled labor is often lacking. Chelating agent–based signal amplification methods have previously been employed in conjunction with electroplated metallic films to improve electrode sensitivity in trace metal analysis. Here, we describe a method for the dry storage of electrochemical reagents: ammonia/ammonium chloride (NH3/NH4Cl) buffer as a supporting electrolyte, dimethylglyoxime (DMG) as a chelating agent, and mercury in paper-based electrochemical cells (PECs), fabricated from commercial filter paper. The stored PECs were applied to the trace, microliter analysis of nickel in water samples by adsorptive cathodic stripping voltammetry (AdCSV) in conjunction with screen-printed electrodes. The method relies on the single-step accumulation/adsorption of microvolumes of the metallic analyte onto stored DMG ligands to form [Ni(dmgH)2] complexes in the presence of mercury films. By integrating the AdCSV techniques with paper-based analytical devices, detection of Ni2+ in water samples with good resolution was achieved at 20 μL sample volumes in the low parts per billion range. The mechanism for pre-concentration and its subsequent reduction was demonstrated as it differs from bulk electroanalysis. Instrumental parameters of the PECs, accumulation time, and deposition potential were optimized along with reagent storage introduction and concentrations. Further, the PECs were investigated in the absence and presence of mercury and had shown good possibility for metal-free sensors in future work. The prepared PECs showed good reproducibility (4.36%, n = 4) and no intermetallic interferences in the presence of 100 μg L−1 Zn2+, Cd2+, Pb2+, Co2+, and In2+. Detection and quantitation limits were calculated and recorded as 6.27 μg L−1 and 18.8 μg L−1, respectively, for Ni2+ determination and 13.1 μg L−1 and 39.3 μg L−1 for the Hg-free derivative at the 90-s accumulation time. The pre-stored paper-based electrochemical cells were then applied to the detection of Ni2+ in real tap water samples and showed good recovery values of ± 94%. Further, the infusion of PECs with a range of chelating agents (dimethylglyoxime, nioxime, and morin hydrate) demonstrates the possibility for tuning PECs to specific applications and improving selectivity in metal analysis applications.

Superamphiphobic surfaces generally need a specific combination of low surface energy and re-entrant surface structure. Herein, we have created a hexane suspension of trichloro(1H,1H,2H,2H-tridecafluoro-n-octyl) silane, tetraethyl orthosilicate, silicon dioxide and titanium dioxide nanoparticles and modify a series of filter papers by one-step immersion in 10 min. Superhydrophobic and quasi-superoleophobic properties are obtained for the optimal filter papers, which repel both of polar and non-polar liquids such as water, glycerol, 1,4-butanediol, soybean oil and 1-octadecene with the contact angles of 168°, 158°, 154°, 145° and 121°, respectively. More importantly, the respective contribution of each component to the superhydrophobic and oleophobical property is explicated through a series of comparative experiments based on the optimal suspension prescription. The wettability transformation from quasi-superamphiphobicity to superhydrophilicity after UV irradiation is evaluated and illustrated. What’s more, the patterned paper is successfully used for the colorimetric detection of glucose using a simple paper-based analytical device. A linear correlation between gray intensity (GI) and glucose concentration (C), GI = − 10.7C + 161.8 is achieved with a correlation coefficient of 0.991, indicating the potential for semi-quantitative analysis of real sample in the field.