Cellulose Paper Research Articles

Advances in Paper‐Based Photodetectors: Fabrications, Performances, and Applications

AbstractWith the development of wearable electronic technology, the flexible photodetectors have attracted widespread attention, and it is of great significance to develop flexible, eco‐friendly and low‐cost photodetectors. Cellulose paper, as a flexible, eco‐friendly, low‐cost, lightweight, customizable, biodegradable and renewable material, has received enthusiastic attention and rapid development in the field of photodetectors in recent years. In this review, it is focused on the research progress of paper‐based (PB) photodetectors. First, the fabrication methods of PB photodetectors are discussed, including electrode materials and optoelectronic functional materials. Then, this review systematically summarizes and analyzes the achievements of PB photodetectors on photoelectric performances (spectral response range, responsivity, detectivity, response/recovery times and on/off ratio) and flexibility characteristics (bending angle and bending cycle). In terms of key performance indicators, the PB photodetectors reported so far can detect multiple wavelengths of light from UV to near‐infrared with the maximum detectivity of 1013 Jones. In addition, the various applications of PB photodetectors is reviewed and discussed. Finally, it is look forward to the future development of PB photodetectors in terms of fabrication methods, photoelectric and flexible performances, and applications. With this review, it is hope that it will promoted the future development of PB photodetectors.

Controllable self-cleaning FET self-assembled RNA-cleaving DNAzyme based DNA nanotree for culture-free Staphylococcus aureus detection

Staphylococcus aureus (SA) poses a serious risk to human and animal health, necessitating a low-cost and high-performance analytical platform for point-of-care diagnostics. Cellulose paper-based field-effect transistors (FETs) with RNA-cleaving DNAzymes (RCDs) can fulfill the low-cost requirements, however, its high hydrophilicity and lipophilicity hinder biochemical modification and result in low sensitivity, poor mechanical stability and poor fouling performance. Herein, we proposed a controllable self-cleaning FET to simplify biochemical modification and improve mechanical stability and antifouling performance. Then, we constructed an RCD-based DNA nanotree to significantly enhance the sensitivity for SA detection. For controllable self-cleaning FET, 1 H,1 H,2 H,2 H-perfluorodecyltrimethoxysilane based-polymeric nanoparticles were synthesized to decorate cellulose paper and whole carbon nanofilm wires. O2 plasma was applied to regulate to reduce fluorocarbon chain density, and then control the hydrophobic-oleophobic property in sensitive areas. Because negatively charged DNA affected the sensitivity of semiconducting FETs, three Y-shaped branches with low-cost were designed and applied to synthesize an RCD-based DNA-Nanotree based on similar DNA-origami technology, which further improved the sensitivity. The trunk of DNA-Nanotree was composed of RCD, and the canopy was self-assembled using multiple Y-shaped branches. The controllable self-cleaning FET biosensor was applied for SA detection without cultivation, which had a wide linear range from 1 to 105 CFU/mL and could detect a low value of 1 CFU/mL.

Metal ion-crosslinked thermoconductive sugar-functionalized graphene fluoride-based cellulose papers with enhanced mechanical properties and electrical insulation

Thermally conductive papers with electrical insulation and mechanical robustness are essential for efficient thermal management in modern electronics. In this study, we introduced a metal ion-assisted interfacial crosslinking strategy to strengthen sugar-functionalized graphene fluoride (SGF) and cellulose nanofibers (CNF) by hydrogen bonding and metal ion crosslinking that leads to simultaneous enhancements in thermal conductivity and mechanical properties. The facile sugar-assisted ball-milling exfoliation method was developed to achieve the exfoliation of graphite fluoride and hydroxyl group functionalization on the surface of graphene fluoride. Thanks to the good dispersibility of the SGF sheets in water, the flexible SGF/CNF composite papers with hydrogen bonding were prepared via vacuum-assisted filtration. We introduced hydrogen bonding and metal ion crosslinking into SGF/CNF papers to obtain densely packed composite papers. Ca2+ or Al3+ ion-crosslinked SGF/ CNF papers exhibited superior thermal and mechanical properties owing to hydrogen bonding and metal ion crosslinking. SGF/CNF-Ca2+ and SGF/CNF-Al3+ papers at 50 wt% of SGF yield in-plane thermal conductivities of 72.93 and 75.02 W m–1 K–1, and tensile strengths of 121.5 and 135.7 MPa, respectively. A thermal percolation value was observed at 12.6 vol% of SGF filler content. In addition, the SGF/CNF papers exhibited electrical insulation properties. These remarkable characteristics of the metal ion-crosslinked SGF/CNF papers are attributed to the densely packed structures caused by the strong interfacial interactions from hydrogen bonding as well as metal ion-crosslinking that could promote phonon transport. High-performance metal ion-crosslinked SGF/CNF papers with these fascinating advantages offer great potential for the thermal management of flexible electronics.

An ultrasensitive paper-based SERS sensor for detection of nucleolin using silver-nanostars, plastic antibodies and natural antibodies

A state-of-the-art, ultrasensitive, paper-based SERS sensor has been developed using silver nanostars (AgNSs) in combination with synthetic and natural antibodies. A key component of this innovative sensor is the plastic antibody, which was synthesized using molecularly imprinted polymer (MIP) technology. This ground-breaking combination of paper substrates/MIPs with AgNSs, which is similar to a sandwich immunoassay, is used for the first time with the aim of SERS detection and specifically targets nucleolin (NCL), a cancer biomarker. The sensor device was carefully fabricated by synthesizing a polyacrylamide-based MIP on cellulose paper (Whatman Grade 1 filter) by photopolymerization. The binding of NCL to the MIP was then confirmed by natural antibody binding using a sandwich assay for quantitative SERS analysis. To facilitate the detection of NCL, antibodies were pre-bound to AgNSs with a Raman tag so that the SERS signal could indicate the presence of NCL. The composition of the sensory layers/materials was meticulously optimized. The intensity of the Raman signal at ∼1078 cm−1 showed a linear trend that correlated with increasing concentrations of NCL, ranging from 0.1 to 1000 nmol L−1, with a limit of detection down to 0.068 nmol L−1 in human serum. The selectivity of the sensor was confirmed by testing its analytical response in the presence of cystatin C and lysozyme. The paper-based SERS detection system for NCL is characterized by its simplicity, sustainability, high sensitivity and stability and thus embodies essential properties for point-of-care applications. This approach is promising for expansion to other biomarkers in various fields, depending on the availability of synthetic and natural antibodies.

Cellulose–derived carbon scaffolds with bidirectional gradient Fe3O4 distribution: Integration of green EMI shielding and thermal management

Cellulose papers (CPs) possess a pore structure, rendering them ideal precursors for carbon scaffolds because of their renewability. However, achieving a tradeoff between high electromagnetic shielding effectiveness and low reflection coefficient poses a tremendous challenge for CP-based carbon scaffolds. To meet the challenge, leveraging the synergistic effect of gravity and evaporation dynamics, laminar CP-based carbon scaffolds with a bidirectional gradient distribution of Fe3O4 nanoparticles were fabricated via immersion, drying, and carbonization processes. The resulting carbon scaffold, owing to the bidirectional gradient structure of magnetic nanoparticles and unique laminar arrangement, exhibited excellent in-plane electrical conductivity (96.3 S/m), superior electromagnetic shielding efficiency (1805.9 dB/cm2 g), low reflection coefficients (0.23), and a high green index (gs, 3.38), suggesting its green shielding capabilities. Furthermore, the laminar structure conferred upon the resultant carbon scaffold a surprisingly anisotropic thermal conductivity, with an in-plane thermal conductivity of 1.73 W/m K compared to a through-plane value of only 0.07 W/m K, confirming the integration of thermal insulation and thermal management functionalities. These green electromagnetic interference shielding materials, coupled with thermal insulation and thermal management properties, hold promising prospects for applications in sensitive devices.

Anisotropy and Fiber Orientation: A Key Player in the Lateral Imbibition of Cellulose Paper

In this article, we delve into the influence of fiber orientation (structural anisotropy) on paper imbibition, with a particular focus on in-plane imbibition. Utilizing the XLPA experimental method, we analyze several papers with different anisotropies, employing a constant volume of ethanol as the imbibing fluid. Our findings contribute novel insights into the anisotropic behavior of imbibition, a topic not extensively covered in the literature. We analyze how the orientation of fibers significantly influences lateral imbibition, providing a deeper understanding of the microfluidic properties of paper. The anisotropies found for imbibition fit perfectly with the existing data found in the literature, indicating the influence of fiber orientation. Furthermore, the kinetics are shown to be linked directly with the porosity.

Flexible UV photodetector based on graphite/titanium dioxide through facile transfer of pencil drawn graphite films on desired substrates

Assembly of graphite structures through pencil drawn method is considered among the most facile and inexpensive approaches for a wide range of electronic and optoelectronic applications. However, the typical limitation of this methodology is that the films and structures can be drawn on a very limited number of substrates. Here, we report a novel methodology for the transfer of pencil drawn graphite films on desired substrate. The graphite films are transferred from cellulose paper, textile and wood paper onto flexible and transparent acrylic tape. The novel wood paper substrate is also used for the fabrication of bar device using a mask which is then transferred onto the acrylic tape. TiO2 nanoparticles paste is coated on the surface of transferred bar device. Scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction analysis, and UV–visible spectroscopy of graphite and graphite/TiO2-NPs electrodes are performed respectively to study their morphological, compositional, structural and optical features. The fabricated device acts as a UV photodetector and delivers a photocurrent as higher as 197.68 μA, photoresponsivity of 8.94 mA W−1, detectivity of 4.16 × 109 Jones at bias voltage of 5 V, response time of ∼860 ms and recovery time of ∼890 ms. The flexibility of the demonstrated photodetector is evaluated through recording changes in photocurrent under bending positions from 0 to 150°, and after employing bending cycles up to 1000. The results show that the fabrication of photodetector is facile and low-cost, and it offers valuable working compatibility under bending strains. Moreover, the flexibility of photodetectors enables their effective integration with human skin and clothes for human health monitoring applications.

Ultrafast and Sustainable Catalyst-Free Chemical Functionalization of Cellulose Paper with Diazo Compounds-Application to Hydrophobic Materials

Ultrafast and Sustainable Catalyst-Free Chemical Functionalization of Cellulose Paper with Diazo Compounds-Application to Hydrophobic Materials

Aging characterization of thermally aged transformer paper based on its reflectance

In this contribution, a simple non-destructive characterization of aging degree of oil-paper insulation materials based on the reflectance is proposed. Samples of cellulose Kraft paper having different thicknesses, were thermally aged in a mineral insulating oil and a synthetic ester with a controlled aging history. The degree of polymerization of the non-aged and aged paper samples was measured according to ASTM D4243 to monitor the cellulose degradation. In addition, the samples were optically analyzed to assess changes in paper’s reflectance. The reflectance spectra of the thermally aged paper samples were statistically analyzed using linear, single variable, and multi-variable analyses by considering eight popular variables. This enables correlating the reflectance to the degree of polymerization and identifying a suitable regression model. Appropriate variable interaction has been performed among which two best-fit models with goodness of fit ≥ 0.9 have been identified. The estimation of the cellulose paper’s DP using the proposed models is reported. The experimental results show that the proposed approach can be used in characterizing aging degree of oil-paper insulation and has the potential to be implemented online as an effective monitoring technique.

Paper-supported polystyrene membranes for micro-solid phase extraction of date-rape drugs from urine: A sustainable analytical approach

BackgroundThe rapid development of micro-solid phase extraction (μ-SPE) procedures with new sorption materials, in particular, based on using natural materials, is currently reported. The production of these sorbents and the entire extraction procedure should support the implementation of Green Analytical Chemistry (GAC) principles. Promising materials are sorbents based on paper, which can be relatively easily modified, among others: by covering it with a polymer membrane. In this work, the practical application of paper-supported polystyrene used in the analysis of urine samples containing selected date-rape drugs (DRD) substances, and evaluation of the entire procedure using GAC metrics is presented. ResultsThe paper-supported polystyrene membranes were successfully fabricated and characterized. The successful polystyrene coating on the paper was confirmed through ATR-FTIR measurements, ensuring even coverage. The μ-SPE procedure using this material facilitated extraction with a throughput of approximately 120 samples per hour in just a few steps. Throughout the research, a mixture of 100 mM acetic acid:methanol:acetonitrile (70:15:15, v/v/v) was selected as an optimal background electrolyte for capillary electrophoresis – mass spectrometry analysis. Validation results of this method demonstrated its suitability, exhibiting good linearity (R2 > 0.95), low limits of detection (3.1–15 ng mL−1), acceptable precision (<15 %), and recovery for all tested analytes. Furthermore, the greenness evaluation conducted with six different metrics: AGREEprep, AGREE, ComplexGAPI, SPMS, hexagonal metric, and WAC indicated the overall eco-friendliness and sustainability of the method, with minor concerns regarding energy consumption. SignificanceThe use of cellulose paper with polystyrene membranes for μ-SPE provides a versatile and eco-friendly extraction method for detecting DRDs in urine samples. The presented work is an example of the use of GAC metrics in the evaluation of the analytical procedure. The optimized PT-μ-SPE/CE–MS method allows for minimized reagent usage and waste production. Moreover, the method proves to be sustainable and efficient for forensic toxicology analysis.

Paper-based immunosensor integrated with bioinspired Cu-polydopamine nanozyme for voltammetric detection of CA-15-3 tumor marker

This manuscript describes the fabrication and characterization of a highly conductive paper-based nanoplatform for immobliztion of anti-CA 15-3 antibodies. For this purpose, cellulosic filter paper (FP) was first coated with Cu nanosponges (CuNSs) through ion beam sputtering deposition (IBSD) method and then covered with Cu-doped polydopamine nanospheres (Cu-PDA). Polydopamine doped with copper exhibited laccase (multi-copper oxidase)-mimicking properties. Bioinspired by the structure of the active site and the electron transfer mechanism of laccase, Cu-PDA nanozyme catalyzed the oxidation of hydroquinone (HQ) signal probe. In this design, CA-15-3, a prognostic biomarker in the breast cancer, was chosen as a model target. To the best of our knowledge, this is the only paper on the design of an electrochemical biosensor based on dense and uniform CuNSs produced by IBSD. More importantly, Cu-PDA is biocompatible and biodegradable, which makes it a potential competitor in the point-of-care (POC) biosensing applications. Thus, this paper-based sensing strategy can be used in designing cost-effective flexible chips consisting of electrodes printed on paper for in-situ and real-time monitoring biomarkers under clinical conditions. In addition to these outstanding features, the LOD (1.3 mU mL 1) and LOQ (4.3 mU mL 1) of the Ab/HQ/Cu-PDA/CuNSs/FP-based immunosensor was significantly lower than the clinically relevant cut-off level (30 U mL 1). In the practical applications, one of the key superiorities of this immuosensor is the wide DLR (5 mU mL 1–280 U mL 1) which covers the ultimate value of healthy and patient individuals.

Laser-based synthesis of silver nanoparticles embedded in cellulose paper for catalytic reduction of azo dyes and SERS sensing of pesticides

In this study, highly reactive bare silver nanoparticles (Ag NPs) are synthesized using the Pulsed Laser Ablation in Liquid (PLAL) technique. Ag NPs are then coated on the filter paper using the dip coating method. This process converts filter paper into a versatile substrate for catalysis and surface-enhanced Raman Spectroscopy (SERS) based sensing. The successful synthesis of spherical Ag NPs and their effective embedding into the filter paper was confirmed using UV–visible absorption spectroscopy, scanning electron microscopy (SEM), and Energy Dispersive x-ray analysis (EDX). SEM images revealed that the Ag NPs were embedded in the filter paper and attached to the cellulose fibers. The use of Ag NPs embedded filter paper as a catalyst substrate for the reduction of both cationic and anionic dyes demonstrated that higher concentrations of Ag NPs on the filter paper resulted in a faster reduction. In particular, filter paper impregnated with 52 μg of Ag NPs demonstrated a complete reduction of methylene blue and methyl orange in less than a minute and 4 min, respectively. To demonstrate the practical sensing capability of the Ag NPs embedded filter paper, it was utilized as a SERS substrate. This enabled the detection of trace levels of Rhodamine 6G (R6G) and the pesticide molecule chlorpyrifos, demonstrating its potential real-world applications.

Effect of molecular weight of PEI on the strength and hydrophobic performance of fiber-based papers via PEI-KH560 surface sizing

In recent years, researchers have put much attention on the improvements and upgrades of novel wet strength agent in the papermaking fields, especially in the usage of household paper. Herein, PEIM-KH560 by polyethyleneimine (PEI) and γ-glycidyl ether propyl trimethoxysilane (KH560) was synthesized with five molecular weights (Mw) of PEI at 600, 1800, 10,000, 70,000 and 750,000. Results showed that the molecular weight greatly influenced the physicochemical properties of PEI-KH560, such as the size and thermal stability. The intrinsic cationic charge of PEI-KH560 provided the bonding sites with the paper fibers, forming strengthened fiber-fiber joints. It was shown that the dry, wet strength and hydrophobicity of cellulosic paper sheets were obviously improved. When the m (PEI):m(KH560) is 1:2, the strength of papers after sizing by Mw of PEI at 600 and 1800 is the most obvious, with the dry strength increased by 227.9 % and 187.5 %, and the wet strength increased by 183.8 % and 207.8 %, respectively. The maximum hydrophobicity was found at the PEI1800-KH560 with the contact angle value of 130.6°. The resultant environmental-friendly agent (PEI-KH560) obtained in this work provides valuable significance for the preparation of household and food packaging paper.

Green synthesis of MIL53(Al)-modified paper-based analytical device for efficient extraction of neonicotinoid insecticides from environmental water samples

BackgroundThere is a need to develop low-cost, reliable and portable devices to enhance the efficiency of microextraction techniques in complex samples. Metal-organic frameworks (MOFs) have proven to be promising sorbents due to their well-documented properties. However, their green preparation and combination with paper-based substrates have not been satisfactorily explored to fabricate sustainable sorptive phases. ResultsIn this work, the hybridization of a paper substrate (as a sustainable support) with MOFs (as a sorptive phase) was carried out by one-pot approach. Concretely, the selected MOF, MIL-53(Al), was in-situ growth onto the paper surface in aqueous solution without the need for high temperature or pressure, thereby aligning with the Green Analytical Chemistry principles. The optimized composite (MIL-53(Al)@cellulose paper) was characterized and evaluated as extraction sorbent for five neonicotinoids (NEOs) (thiamethoxam, clothianidin, imidacloprid, acetamiprid, and thiacloprid). Furthermore, its feasibility was demonstrated by isolating these pollutants from environmental water samples, followed their determination by HPLC coupled to diode array detection. The whole method showed satisfactory analytical performance with recoveries between 86 and 114 %, suitable precision (with RSD lower than 14 %), and limits of detection ranged from 1.0 to 1.6 μg L−1. Besides, the greenness of the method was assessed by application of different existing metrics. The developed extraction device was affordable (<0.08 €/device) and mechanical and chemically stable, being possible its reuse more than 11 cycles, thus demonstrating its suitability for rapid screening of pesticides in environmental samples. SignificanceThis report presents, for the first time, the green synthesis of MIL-53(Al)cellulose paper composite and its application as a sorptive phase for the extraction of NEOs from environmental water samples. We believe that the proposed strategy for fabricating these sustainable paper-based sorptive phases paves the way for further hybridizations with other MOFs or materials. Additionally, it opens up large possibilities for their application in extraction of pollutants or other hazardous compounds in aquatic environments.

Simple Synthesis of Cellulose-Based Nanocomposites as SERS Substrates for In Situ Detection of Thiram.

There is a growing interest in the use of flexible substrates for label-free and in situ Surface-enhanced Raman Spectroscopy (SERS) applications. In this study, a flexible SERS substrate was prepared using self-assembled Au/Ti3C2 nanocomposites deposited on a cellulose (CS) paper. The Au/Ti3C2 nanocomposites uniformly wrapped around the cellulose fibers to provide a three-dimensional plasma SERS platform. The limit of detection (LOD) of CS/Au/Ti3C2 was as low as 10-9 M for 4-mercaptobenzoic acid(4-MBA) and crystal violet (CV), demonstrating good SERS sensitivity. CS/Au/Ti3C2 was used for in situ SERS detection of thiram on apple surfaces by simple swabbing, and a limit of detection of 0.05 ppm of thiram was achieved. The results showed that CS/Au/Ti3C2 is a flexible SERS substrate that can be used for the detection of thiram on apple surfaces. These results demonstrate that CS/Au/Ti3C2 can be used for the non-destructive, rapid and sensitive detection of pesticides on fruit surfaces.

The diffusion behavior of H3O+ in insulation systems composed of paper cellulose and modified natural ester insulating oil

The oil-paper insulation system will be affected by the synergistic effects of moisture and acids during long-term stable operation of the transformer. The moisture in the oil can be combined with the H+ionized from the acid molecules in the form of H3O+ by coordination, thus changing the proportion of acid distribution in the insulating oil and paper cellulose. Natural ester insulating oil, as a new development trend to replace mineral oil, can be significantly improved by adding nanoparticles to them. The diffusion behavior of H3O+ in paper cellulose and nano-SiO2-modified soybean oil-based natural ester insulating oil insulating system has been investigated using molecular dynamics in this article. The results indicate that the incorporation with nanoparticles is effective in mitigating the impact of temperature on the diffusion behavior of H3O+ in oil-paper insulation. Compared with the unmodified model, the nano-modified model results in a significant reduction in the concentration distribution of H3O+ in paper cellulose. The hydroxyl and ether bonds in paper cellulose will interact with H3O+ to generate hydrogen bonds and destroy its original hydrogen bonding network, while nanoparticles can inhibit diffusion by adsorbing H3O+ through hydroxyl oxygen atoms.

Colorimetric sensor for copper and lead using silver nanoparticles functionalized with fluoresceinamine isomer I

Chemical sensing of heavy metals in aqueous environments offers significant advantages, including a rapid and cost-effective method for estimating their concentrations. In this study, silver nanoparticles (AgNPs) were functionalized with fluoresceinamine (FLA) to detect Cu2+and Pb2+in water. Cysteamine (Cyt) was subsequently added to detect these metals with the naked eye. UV–Vis and fluorescence spectroscopy were conducted to determine the limits of detection (LODs) of each method. All AgNPs were characterized using transmission electron microscopy and Fourier transform infrared spectroscopy. The lower LODs using Cu2+and Pb2+ were 4.40 × 10−6 and 1.15 × 10−6 M for UV–Vis titration and 6.53 × 10−6 and 1.39 × 10−6 M for fluorescence, respectively. The recovery percentage for the spectroscopic methods was high at 87 %. Subsequently, cellulose paper sensors were impregnated with AgNPs-FLA and AgNPs-FLA-Cyt to analyze both cations with a limit of quantification (LOQ) of 10−3 M. The cellulose paper sensors were characterized using drop shape analysis and fluorescence. These findings demonstrate the potential of colorimetric sensors composed of AgNPs-fluorophores for the rapid estimation of the concentration of specific heavy metals in solution using UV–Vis and fluorescence spectroscopy. Further, the incorporation of an additional molecule, such as Cyt, linked to AgNPs-fluorophores enabled detection with the naked eye, offering potential utility in water analysis for mining industries characterized by high concentrations of contaminants.

A New Bioactive Thiazolidinone-based Azo Dye for Naked-eye Colorimetric Detection of Cyanide Ions

Abstract: A new bioactive azo dye embedding a thiazolidinone heterocyclic core was designed and synthesized for antibacterial application and colorimetric sensing of cyanide ion (CNˉ) in organic solutions. The structure of the prepared dye was elucidated from its 1H NMR, FT-IR and UV-Vis spectral data. It proved to be a fast and sensitive colorogenic sensor for detection of CNˉ. Spectroscopic studies were carried out to investigate the effect of different CNˉ concentrations on the detection efficiency. Moreover, the studies revealed no significant competition or influence of other anions on the sensitivity of CNˉ detection by the synthesized dye. A Job's plot indicated a 1:1 stoichiometry of the dye and CNˉ in their colorful complex. Further development of the method for naked-eye detection of CNˉ in low-concentration aqueous solutions was achieved by using the cellulose papers painted with the dye. The as-prepared testing paper allowed CNˉ sensing in concentrations as low as 2 μM. Evaluation of the dye for antibacterial activities using the well diffusion technique displayed that its inhibitory activity is at least as good as and in some cases superior to ampicillin against the bacterial strains employed in the zone assay. In response to CN¯, the dye changes color from yellow to reddish brown which accounts for its significant interactions with CNˉ and affords a naked-eye sensing method without resorting to any spectroscopic instrumentation.

Bionic silanized cellulose superhydrophobic paper for efficient oil-water separation

With the frequent occurrence of oil spill accidents and the increasing discharge of industrial oily wastewater, oil–water separation has become a global challenge to protect the ecological environment. Simple, fluorine-free preparation of high-throughput superhydrophobic materials is important for realizing efficient separation of oil/water mixtures. Paper-based materials have several advantages, such as low price and renewability, which make them valuable for applications. In this work, we propose a simple and economical two-part immersion technique to prepare superhydrophobic cellulose paper, which is modified with octadecyltrichlorosilane (OTS) directly and then assembled hydrophobic silica. The prepared functionalized paper is not only superhydrophobic (static water contact angle up to 157°) and superoleophilic, but also exhibits acid and alkali resistance and abrasion cycle resistance. After 10 separation cycles for a variety of heavy oil/water mixtures, the separation efficiency was as high as 99.31 % with fluxes greater than 5100 L/(m2·h). This simple, scalable, low-cost superhydrophobic paper shows great potential in the field of oil/water separation.

In-situ construction of stable and efficient superhydrophobic MOFs-based cellulose paper for oil–water separation

In recent years, separating oil-water mixed pollutants has emerged as an increasingly significant part of sustainable development due to oil-containing wastewater discharged and offshore oil spills. Therefore, developing stable and efficient materials for the separation of oily wastewater has garnered significant attention in current research. Herein, a novel superhydrophobic functionalized MOFs-based cellulose paper (PDMS/UiO-66-NH2@CP) was successfully synthesized by integrating cellulose paper (CP) with UiO-66-NH2 via solvothermal method and further modifying with polydimethylsiloxane (PDMS), which was used as an oil-water separation material to purify oily wastewater. The reaction procedure is facile and simple, and the preparation method is efficient. Notably, the as-synthesized PDMS/UiO-66-NH2@CP showed excellent superhydrophobicity/superlipophilicity, with a water contact angle up to 162° and an oil contact angle (OCA) of approximately 0º, and it can still maintain superhydrophobic stability under strong acid or alkali conditions. Furthermore, the surface of superhydrophobic paper cannot been adhered by dye solution and powder, indicating its good self-cleaning and anti-fouling ability. Moreover, the composite paper displayed exceptional UV blocking property with the ability to block 99% ultraviolet. Attributed to these characteristics, PDMS/UiO-66-NH2@CP as an oil-water separator demonstrated exceptional performance in separating oil-water mixtures and emulsions, achieving efficiencies exceeding 98% and fluxes in the range of 105.26−412.14 L·m-2·h-1. More importantly, it displayed remarkable recyclability and its separation efficiency was still above 98% after 50 cycles. This study not only develops a facile and effective strategy for preparing superhydrophobic papers, but also provides innovative and instructive guidance for developing efficient oil-water separation materials.