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Currently, there is significant competition in recycling waste paper and using it for producing various types of paper used in the packaging sector. The paper derived from recycled pulps lacks good strength due to the gradual shortening of fibers and the reduction in bonding characteristics. Considering this challenge, in this study, after converting old corrugated containers (OCC) into pulp and then refining them, they were oxidized in an alkaline environment using hydrogen peroxide at varying percentages of 0, 0.5, 1, 2, 3, and 4 to create diversity and increase reactive groups. Sodium caseinate was then added to the pulp suspension at levels of 0.5, 1, 2, 3, 4, 5, 6, 7, 8, and 9 percent as a cross-linking agent. Finally, standard handmade papers were produced from them. The status of the formed functional groups was measured by FTIR spectrum, and the mechanical strength and water absorption of the produced papers were measured according to the standards of the Technical Association of the Pulp and Paper Industry (TAPPI). FTIR results showed that the oxidized pulp samples had high absorption at the wavenumber 1650, which corresponds to the carboxyl group. Additionally, the calculation of the carboxyl groups using the methylene blue absorption method indicated that the highest amount of carboxyl groups was in the 1 percent hydrogen peroxide treatment. The addition of sodium caseinate to the pulp suspension significantly increased the mechanical strength of the resulting papers. [ABSTRACT FROM AUTHOR]

As air pollution escalates, the need for air filters increases. It is better that the filters used be based on natural fibers, such as non-wood fibers, which cause low damage to the environment. However, the short fiber lengths, low apparent densities, and high volumes of non-wood materials can make it challenging to prepare filter paper with the required mechanical and physical properties. In that context, this study focused on utilizing bamboo fibers to fabricate filter paper by employing the anthraquinone soda pulping method. The pulp underwent bleaching and oxidation processes, with the incorporation of cationic starch (CS) and polyvinyl alcohol (PVA) to enhance resistance properties, resulting in the creation of handmade filter papers. The findings revealed that the tear, burst, and tensile strength of filter paper increased with the oxidation and addition of CS and PVA. Air permeability increased with addition of PVA and combination of CS and PVA. FTIR demonstrated the conversion of hydroxyl groups in cellulose chains to carboxyl groups due to oxidation. SEM images illustrated alterations in the fiber structure post-oxidation treatment, with CS reducing pores while PVA and the CS-PVA combination enlarged pore size and enhanced porosity. The BET surface area surface area expanded with oxidation and the addition of the CS-PVA blend, indicating heightened filter paper porosity. Notably, the combined inclusion of CS and PVA not only augmented mechanical strength but also increased porosity while maintaining pore size. [ABSTRACT FROM AUTHOR]

• Starch paste was destroyed more easily than the paper fibers under UV-A irradiation. • Paper coated with high concentration of paste could cause fiber breakage due to the photodegradation of paste. • Paper coated with low concentration of paste could damage both the paste and paper fibers. • It's important to keep an appropriate concentration of starch paste to improve the irradiation stability of paste-restored paper artifacts. Starch paste has been the main adhesive of choice for paper conservation until now. Studies evaluating the properties of paste-coated paper under UVA irradiation conditions are limited but necessary to enable conservators for a proper choice of materials in terms of durability. In this paper, SEM, FTIR, Raman, and measurements of mechanical properties were used to investigate the aging features of UVA-irradiated paste-coated paper. The increased macro and micro physical and chemical changes with increasing UVA exposure time indicated the degradation of paste and paper polymers. The pH and spectroscopic analyses indicated that the carboxyl groups, which led to the acidity of the sample, were slowly produced with increasing irradiation, and the pH of the paste was lower than that of the paper samples when exposed for the same amount of time. The change in crystallinity also affected the degradation rate of paste-coated papers. SEM observations showed that the paste was destroyed more easily than the paper fibers, a higher concentration of paste caused the paper fibers to break, and a lower concentration of paste damaged both the paste and paper fibers. The present study suggests that an appropriate concentration of paste coated on the paper surface could improve the irradiation stability of paper samples for paste-restored paper artifacts. [ABSTRACT FROM AUTHOR]

Natural yellow plant dyes and traditional medicines were used widely on historical papers in ancient China for religious reasons and conservation considerations. This study aims to evaluate some traditional yellow botanical sources of dyes that contain different chemical colorant compositions in order to understand their effects on the properties of traditional handmade paper. The physical and chemical changes in paper specimens treated with plant dyes were studied by examining properties such as the color, pH, thermogravimetric (TG) characteristics, tensile strength, folding endurance and microstructure by scanning electron microscopy (SEM). The results indicated that different colorants had different toning effects and that the main components, including carboxyl and ketone groups, could affect the paper stability at high temperatures. The results also revealed that the mechanical properties of paper specimens were improved after treatment with plant dyes. The significant improvements in the tensile strength and folding endurance and the slightly higher decomposition temperature of Amur cork tree-dyed paper could be ascribed to the strong interaction between the colorants' main components and the fibers. The scientific evaluation of the property changes is therefore valuable information for weighing the advantages and disadvantages of the various yellow toning materials for paper conservation treatment. [ABSTRACT FROM AUTHOR]

Generation of lignin-carbohydrate complex (LCC) between dehydrogenation polymer (DHP) and pulp fibers may have an important impact on the properties of pulp. In this work, the benzyl ester-type LCC was formed between oxidized cellulose and DHP. The effect of pH on the addition reaction of oxidized cellulose to quinone methide in the synthesis of DHP-cellulose complex (DHPCC) was investigated. The structure of the product was characterized by Fourier Transform Infrared (FTIR), Carbon 13-Nuclear Magnetic Resonance (13C-NMR), and 2-Dimensional Heteronuclear Single Quantum Coherence Nuclear Magnetic Resonance (2D HSQC NMR) analyses. The results indicated that cellulose was indeed oxidized and carboxyl groups were introduced into cellulose by the oxidation process. The formed DHPCC was connected by benzyl ester linkage. In addition, the pH of the reaction system had an important role in the formation of the benzyl ester bonds. The acidic condition (pH = 4.0) was conducive to the addition reaction of quinone methide with carboxyl groups of cellulose. Overall, this study provides helpful guidance for the generation of LCC between DHP and paper pulp fibers. [ABSTRACT FROM AUTHOR]

This article describes how crystalline or fibrous nanocellulose influences the mechanical properties of paper substrate. In this context, we used commercially available cellulose nanocrystals, mechanically prepared cellulose nanofibers dispersed in water or ethanol, and carboxy cellulose nanofibers. Selective reinforcement of the paper treated with the nanocellulose samples mentioned above was observed. The change in the fibre structure was assessed using scanning electron microscopy, roentgenography, and spectroscopy techniques. In addition, the effect of nanocellulose coating on physical properties was evaluated, specifically tensile index, elongation coefficient, Elmendorf tear resistance, Bendtsen surface roughness, Bendtsen air permeability, and bending strength. It can be concluded that the observed decrease in the strength properties of the paper after applying some NC compositions is due to the loss of potential disturbances in hydrogen bonds between the nanocellulose dispersed in ethanol and the paper substrate. On the other hand, significantly increased strength was observed in the case of paper reinforced with nanocellulose functionalized with carboxyl groups. [ABSTRACT FROM AUTHOR]

The present study employed powdered activated coke (PAC) for the adsorptive removal of refractory COD from the bio-treated paper wastewater (BTPW). The adsorption reached equilibrium after 3 h, resulting in a decrease in the COD concentration from 98.9 mg L−1 in BTPW to 42.6 mg L−1 when utilizing a PAC dosage of 5 g L−1. The dominant fractions of dissolved organic matter in BTPW were hydrophilic acids (HIA), hydrophilic neutrals (HIN), and hydrophobic acids (HOA), accounting for 48.8%, 34.2%, and 17.0% of the total dissolved organic carbon, respectively. Three fractions were all predominantly composed of humic/fulvic acid-like substances, while the HOA fraction exhibited highest susceptibility to adsorption by PAC, followed by the HIA and HIN fractions. FT-ICR MS data revealed PAC preferentially adsorbed the unsaturated and oxygen-rich substances containing more carboxyl groups. Additionally, the spent PAC was regenerated through ozonation and subsequently utilized in the adsorption cycles. The regeneration was successfully conducted under an ozone concentration of 1 mg L−1 for a duration of 10 min, and the regeneration efficiency remained about 87.0% even after undergoing five-cycle of adsorption-regeneration. The findings of this study demonstrate that PAC adsorption is a viable and efficacious treatment technology for efficiently removing refractory COD from BTPW. [Display omitted] • Powdered activated coke was effective for advanced treatment of refractory fractions. • Acidic fractions showed preferential adsorption compared to neutral fractions. • Unsaturated and oxygen-rich substances containing were easily removed by adsorption. • The adsorption capacity of the adsorbent was recovered after ozone regeneration. • Regeneration efficiency was 87.0% after five-cycle of adsorption-regeneration. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to restore the lost mechanical properties of the prints with carrageenan, methyl hydroxyethyl cellulose (Tylose) and hydroxypropyl methylcellulose (Methocel). Design/methodology/approach: The effect of these materials on the properties of the printed paper (modern and historical samples) has been evaluated under the influence of accelerated aging using pH measurement, the mechanical properties (tensile and elongation), FTIR and color changes. Findings: The three consolidates reduced the acidity of treated samples significantly, but after ageing, it was observed that the pH of aged treated samples decreased slightly as compared to the untreated samples. The results of the mechanical properties showed the superiority of hydroxypropyl methylcellulose (Methocel) in improving the tensile and elongation forces of the samples compared to carrageenan and methyl hydroxyethyl cellulose even during the accelerated aging. Consolidation materials succeeded in reducing ΔE of the paper samples under accelerated aging, especially carrageenan. The IR spectra confirmed that no dramatic difference was observed in topically function vibrations of samples after treatment beside that the O-H stretching band intensity increased observably after treatment with the three consolidates, after ageing the treatment, and it protected the treated paper from oxidation processes as the infrared spectrum analysis showed a decrease in intensities of carbonyl and carboxyl groups as compared to aged untreated samples. Originality/value: The research provides new biopolymers in strengthening the historical printed paper, where printed papers lack studies related to their conservation. This makes the current study a promising step for treating historical printed paper. [ABSTRACT FROM AUTHOR]

In this work, zinc-doped carbon dots (Zn-CDs) were anchored on a three-dimensional wheel type paper-based microfluidic chip, and were decorated with 6-mercaptonicotinic acid (MNA) and L -cysteine (L -Cys) for highly sensitive and rapid fluorescence detection of Cu2+. Zn-CDs were first anchored on paper through the amide bonds between the carboxyl groups of the Zn-CDs and the amino groups of the paper. Afterwards, Zn-CDs were decorated with MNA and L -Cys, effectively preventing the Zn-CDs from aggregation. The nitrogen atom on the pyridine ring and the carboxylic acid groups in MNA and L -Cys coordinated with Cu2+ to form a nonfluorescent ground-state complex, causing the fluorescence quenching of the Zn-CDs. The three-dimensional rotary design could simplify the operation process and achieve simultaneous analysis of multiple samples with different concentrations. Under optimal conditions, the fluorescent sensor exhibits linear response for the determination of Cu2+ in the range from 0.1 to 60 μg L−1 with the detection limit (LOD) of 0.018 μg L−1. The proposed strategy provides a novel way for the highly sensitive detection of Cu2+ in a complex water environment. [ABSTRACT FROM AUTHOR]

TEMPO‐oxidized nanofibrillated cellulose (ONFC) with charged carboxyl groups is introduced for the efficient exfoliation of two‐dimensional (2D) MoS2/graphene composites. As an effective dispersant agent, ONFC can be easily absorbed between the adjacent layers, so as to prevent the accumulation of the exfoliated nanosheets. With the assistance of charged ONFC, the exfoliated MoS2/graphene is gradually increased in the aqueous dispersions with the elongated sonication time. After dewatering, self‐standing MoS2/Graphene/ONFC/CNTs composite films are rationally constructed using ONFC as flexible fibrous skeleton, and CNTs/graphene as 1D/2D interpenetrating electrical networks. Ultrathin MoS2 nanosheets anchored on the 1D/2D heterogeneous networks is directly acted as an ideal paper‐anode for lithium‐ion batteries (LIBs) without using traditional metallic current collector. The self‐standing flexible electrode materials based on natural cellulose will promote the future green electronics with high flexibility, miniaturization, and increased portability. [ABSTRACT FROM AUTHOR]

Exploring an appropriate immobilization approach to enhance catalytic activity and reusability of cellulase is of great importance to reduce the price of enzymes and promote the industrialization of cellulose-derived biochemicals. In this study, Fe3O4 magnetic nanoparticles (MNPs) were functionalized with meso-2,3-dimercaptosuccinic acid to introduce carboxyl groups on the surface (DMNPs). Then, melamine–glutaraldehyde dendrimer-like polymers were grafted on DMNPs to increase protein binding sites for the immobilization of processive endoglucanase EG5C-1. Moreover, this dendrimer-like structure was beneficial to protect the conformation of EG5C-1 and facilitate the interaction between substrate and active center. The loading capacity of the functionalized copolymers (MG-DMNPs) for EG5C-1 was about 195 mg/g, where more than 90% of the activity was recovered. Immobilized EG5C-1 exhibited improved thermal stability and increased tolerability over a broad pH range compared with the free one. Additionally, MG-DMNP/EG5C-1 biocomposite maintained approximately 80% of its initial hydrolysis productivity after five cycles of usage using filter paper as the substrate. Our results provided a promising approach for the functionalization of MNPs, enabling the immobilization of cellulases with a high loading capacity and excellent activity recovery. [ABSTRACT FROM AUTHOR]

Hanji paper, the paper material traditionally used in Korea, is in the focus of the present aging and mechanistic study. As raw materials and historic recipes for paper making are still available for Hanji today, specimen resembling historical material at the point of production can be prepared. While from that starting point, historical material had taken the path of natural aging, newly prepared samples-prepared according to both historic and current recipes-were artificially aged, and both aging modes can be compared. For the first time, an in-depth chemical and mathematical analysis of the aging processes for Hanji is presented. The aging of Hanji paper, resulting in hydrolysis and oxidation processes, was addressed by means of selective fluorescene labeling of oxidized groups in combination with gel permeation chromatography, providing profiles of carbonyl and carboxyl groups relative to the molar mass distribution. Starting Hanji showed the highest molecular weight (>1,400 kDa) ever reported for paper. We have defined two critical parameters for comparison of the paper samples: half-life DP (the time until every chain is split once on average) and life expectancy (the time until an average DP of failure is reached and no further mechanical stress can be tolerated). The two values were determined to be approximately 500 and 4,000 years, respectively, for the Hanji samples, provided there is no UV radiation. The rate of cellulose chain scission under accelerated aging (80 °C, RH 65 %), was about 600 times faster than under natural conditions. In addition, cellulose degradation of Hanji paper under accelerated aging condition was about 2-3 times slower than that of historical rag paper as those used in medieval Europe. [ABSTRACT FROM AUTHOR]

This research attempts to fabricate a novel type of pressure‐sensitive adhesive (PSA) tape utilizing epoxidized linseed oil (ELO) as the primary component in an effort to reduce reliance on petrochemical polymers. This raw material comes from the natural renewable resources, making this tape a more environmentally friendly choice in reducing impact on the environment and alleviating resource pressure. The ester groups on ELO are subjected to hydrolysis in order to yield a combination of epoxy linseed oil fatty acids (ELFAs) containing both epoxy and carboxyl groups. By controlling the temperature and catalyst conditions, the epoxy and carboxyl groups undergo a ring‐opening reaction, resulting in the self‐polymerization of the ELFA mixture and the formation of hydroxy‐functionalized polymers. These polymers are then applied as a coating on kraft paper and subsequently cut to produce PSA tapes. The tapes produced using this method exhibit a peak peel strength of 20.538 N per 25 mm. Moreover, the incorporation of glycerol ester of rosin serves to enhance the peel strength, resulting in a higher value of 21.883 N per 25 mm. The utilization of sealing the cardboard box by the tapes also serves as validation for the immense capabilities of the tapes in practical applications. [ABSTRACT FROM AUTHOR]

The large use and emission of p -nitrophenol (p-NP) seriously pollute the environment and endanger human health. In this work, a hydrazone-linked fluorescent covalent organic framework (BATHz-COF) was simply synthesized at room temperature and covalently linked N-acetyl-L-cysteine (NALC) via the "thiol-ene" click reaction, where carboxyl groups were introduced to improve dispersion and fluorescence intensity. As a rapid, good selectivity and reusability fluorescence sensor, the obtained COF-NALC has been used for quantitative analysis of p-NP predicated on the internal filtering effect (IFE). Under optimal conditions, COF-NALC enabled quantitative detection of p-NP with a linear range of 5–50 μM and the detection limit was 1.46 μM. The application of COF-NALC to the detection of p-NP in river water samples was successful, and the satisfactory recoveries were 98.0%–109.3%. Furthermore, the fluorescent COF paper chips constructed by in situ growth were combined with a smartphone to build a visual platform for the quick and real-time detection of p-NP, providing an excellent illustration for the development of intelligent fluorescence sensing in environmental analysis. [Display omitted] • Covalent Organic Frameworks are modified with N-acetyl- l -cysteine to improve dispersion and fluorescence performance. • The obtained hydrophilic framework is highly selective for the detection of p -nitrophenol. • Paper-based sensors with in-situ immobilization of frameworks are prepared for visual analysis of p -nitrophenol. [ABSTRACT FROM AUTHOR]

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This study presents a simple, fast, and sensitive method for multiplexing heavy metal detection. Using a chemically patterned microfluidic paper-based analytical device (C-μPAD), silane compounds terminating in amine (NH 2 ), carboxyl (COOH), and thiol (SH) were immobilized on a patterned chromatography paper via condensation reactions. Three chromogenic reagents that react distinctly with Ni(II), Cr(VI), and Hg(II) were then covalently coupled to these functional groups. These functionalized C-μPADs were then evaluated for heavy metals ions detection with spiked water samples. Using a single-plex platform, we achieved detection limits as low as 0.24 ppm for Ni(II), 0.18 ppm for Cr(VI) and 0.19 ppm for Hg(II). The detection limits for this single-plex platform were twice as good as those obtained in previous studies using colorimetric analysis due to the formation of homogeneous metal complexes from immobilized chromogenic reagents. Furthermore, by minimizing cross-reaction with chelating agents and maximizing reaction uniformity, multiplex heavy metal ion detection was successfully demonstrated for lake-water samples spiked with various concentrations of heavy metal ions with high precision. This functionalized C-μPAD provides a highly portable and rapid on-site monitoring platform for multiple heavy metal ions detection with extremely high repeatability, which is useful for resource-limited areas and developing countries. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Generally, the mechanical strength and stiffness of old corrugated cardboard (OCC) waste paper are decreased after multiple recycling procedures. Surface sizing starch, which is extensively used in the surface sizing of paper making, accumulates after dissolving from the fibers and is transformed into pollutant during the OCC re-pulping process. To overcome the pollution and reutilization problem of the waste starch during the recycling process of OCC paper, waste starch was ionized using hydrogen peroxide (H 2 O 2) to improve the mechanical properties of OCC paper during the reutilization. The results showed that the carboxyl group of waste starch increased with an increasing degree of ionization, resulting in enhanced copper ion adsorption capacity. Furthermore, the retention rate of the modified starch in the wet-end increased from 18.0% to 48.2%. The OCC paper presented the highest burst index and tensile strength of 8.94 kPa m2/g and 112.5 N m/g, respectively, when MS-2 was added. This work has great significance for implementation of the cleaning production of OCC waste papers and the reutilization of the waste starch. Image 1 • Waste starch was ionized to improve the mechanical properties of OCC paper. • The starch content in OCC pulp wastewater reached 4.5–4.8 g/L. • The waste starch was oxidized by H 2 O 2 to give anion carboxylic groups. • The retention rate of the modified starch was 30.2% higher than waste starch. [ABSTRACT FROM AUTHOR]

Carbon paper (CP) used for proton exchange membrane fuel cells (PEMFCs) are improved using carboxyl-terminated butadiene-acrylonitrile (CTBN)-modified phenolic resin (PF) for impregnation of CP preform. The effect of CTBN ratio on the properties of CP, which is fabricated by the processes of impregnation, molding and heat treatment, is investigated. The results show that compared with the CP without CTBN addition, the CTBN-modified CP exhibits significantly improved overall properties. With the increase of CTBN ratio in the mixture, porosity and permeability of the modified CP increase because of the low carbon yield of CTBN after heat treatment. Mechanical strength and conductivity also increase because of the chemical reactions between the CTBN and resin that lead to robust interfacial bonding in the CP product. However, excessive CTBN addition causes decreased tensile and bending strength of the CP. Single cell tests show that the increased conductivity of the CP enhances the polarization performance in the Ohm polarization region, while the CTBN-induced nearly spherical micro/macro-pores in the CP matrix improve the performance in the concentration polarization region. At an optimum CTBN ratio of 50 wt%, the membrane electrode assemble with the modified CP exhibits a current density of 1606.5 mA cm −2 at 0.608 V. [ABSTRACT FROM AUTHOR]

Advancements in health care monitoring demand a rapid, accurate and reliable early diagnosis of "Heart Attack" (acute myocardial infarction) with an objective to develop a cost-effective, rapid and label-free point of care diagnostic test kit for the detection of cardiac troponin I (cTnI) on paper-based multi-frequency impedimetric transducers. Paper based sensing platforms were developed by integrating carboxyl group functionalized multi-walled carbon nanotubes (MWCNT) with antibodies of cardiac troponin I (anti-cTnI) biomarker and was characterized using Electrochemical Impedance Spectroscopy (EIS). Various concentrations of cTnI with anti cTnI were studied as a function of impedance change. The suitability of the proposed immunosensor is demonstrated by spiking cTnI in blood serum samples. The limit of detection (LoD) and sensitivity of the proposed sensor was determined to be 0.05 ng/mL and 1.85 mΩ/ng/mL respectively, with a response time of ~1 min. The shelf life of the fabricated sensor was nearly 30 days. The rapid response, very low detection limit, and cost effectiveness offer a portable platform to detect cTnI in blood serum samples. The proposed immunosensor, therefore, offers an affordable healthcare diagnostic platform in resource limited areas. [ABSTRACT FROM AUTHOR]

The macroscopic and microscopic properties of old newsprint pulp with xylanase, MLac/Glu (modified laccase-glutamate system), and X-MLac/Glu (xylanase synergistic modified laccase-glutamate system) pretreatment was investigated by means of fiber quality measurements (FQA), attenuated total reflectance-infrared spectroscopy (ATR-IR), headspace gas chromatography (HSGC), X-ray diffract ion method (XRD), Low-temperature nitrogen absorption and scanning electron microscopy (SEM). Results showed that, compare with the control pulp, the brightness and lightness ( L ∗ {L^{\ast }}) of hydrogen peroxide bleached pulp after X-MLac/Glu pretreatment increased by 5.86 % ISO and 3.58 %, respectively. FQA analysis revealed that coarseness and fine fiber content increased slightly. The content of carboxyl groups and water retention value increased remarkably by 31.11 % and 39.22 %, respectively. The paper physical analysis showed that the paper strength properties have improved significantly. The crystallinity of cellulose decreased by 3.82 % due to X-MLac/Glu pretreatment. ATR-IR analysis indicated some non-cellulose components are removed. The BJH average pore size and BET specific surface area increased after enzyme pretreatment. The SEM analysis showed that through X-MLac/Glu treatment the fiber surface becomes rough and the connections between the fibers become tighter, more fibrils appeared. [ABSTRACT FROM AUTHOR]

Bacterial cellulose (BC) was functionalized applying the Laccase/TEMPO oxidative treatment, leading to a five-fold increase of the concentration of carboxyl groups. Paper produced with this cellulose showed improved mechanical properties while maintaining barrier function against water and greases as compared to paper produced with non-oxidized BC. Also, the negative charge provided by the carboxyl groups on functionalized BC was used to generate silver nanoparticles (AgNPs), obtaining a BC paper and Ag composite. The presence of AgNPs in the composites was validated by SEM, EDS and ICP analysis, showing spherical, uniformly sized particles stabilized in the BC nanofibers matrix. Additionally, antimicrobial property of composites containing AgNPs was tested. The results showed the strong antimicrobial activity of the composites against Gram-positive and Gram-negative bacteria and fungi. The generation of Ag nanoparticles in a matrix that combine the physical characteristics of the BC nanofibers with the stiffness and the mechanical properties of paper produced composites that may have applicability in technological and biomedical uses. [ABSTRACT FROM AUTHOR]

Graphene papers (GP) modified with alkaline earth metal ions (Mg 2 + , Ca 2 + ) were prepared by reduction of graphene oxide papers, which were obtained through a facile vacuum filtration of graphene oxide solution aqueous. The thermal conductive properties of graphene paper and its modified analogues were measured with a laser flash method. The thermal diffusivities of Mg-modified GP and Ca-modified GP are 1003.4 mm 2 /s and 2232.2 mm 2 /s, respectively, which is significantly improved compared with unmodified graphene paper (694.9 mm 2 /s). The corresponding thermal conductivities are 100.4 W/mK (GP), 147.7 W/mK (Mg-GP) and 331.8 W/mK (Ca-GP), respectively, from which a substantial enhancement in thermal conductivity of M-modified GP is also observed. It is found that the ion chelating between carboxyl groups of graphene oxide and alkaline earth metal ions will bridge the small graphene oxide sheets, and it will decrease the thermal resistance of the boundary and increase the contact surface of graphene sheets. The reduction of M-modified graphene oxide can partly recover the structure of graphene, thus can further improve the heat transfer property of graphene paper. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new kind of hydrophobic grafted cellulose paper was facile synthesized. • A one-pot metal-free catalyzed tandem reaction strategy was developed. • The polysulfonamide grafting ratio was up to 136 wt%. • The grafted cellulose paper separated oil/water mixtures effectively. A facile and effective "grafting from" method by ROP of N -sulfonyl aziridines toward cellulose- g -polysulfonamides has been developed for efficient oil/water separation. The cellulose paper was initially succinylated to transform the hydroxyl to carboxyl acid groups, which act as the initiating sites for the ring-opening copolymerization of fluorescent 2-methyl-1-dansylaziridine and 2-methyl-1-tosylaziridine (TsMAz) towards the grafted cellulose. Both steps are catalyzed by the same compound, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD). The grafted polysulfonamide ratio was up to 136 wt%, and the surface contact angle up to 147°. A one-pot tandem strategy was applied to produce the grafted cellulose paper with a grafting ratio ranging from 96 to 150 % and a contact angle over 127°. The modified cellulose paper material showed promising properties for efficient oil/water separations. [ABSTRACT FROM AUTHOR]

Fibers obtained from dissolved air flotation rejects were oxidized using a TEMPO oxidation system to prepare oxidized recovered fibers. The effects of oxidization time on carboxyl content, water retention value, and physical properties of handsheets were evaluated. The effects of pH, amount of oxidized recovered fibers, and aluminum sulfate on paper properties were also considered. The results showed that carboxyl content and water retention values increased with the increasing of oxidized time. FTIR analysis indicated that carboxyl groups were connected to the surface of fibers. SEM micrographs showed that fibers were integrated more closely in the paper sheet, benefiting from the addition of the oxidized recovered fibers. Tensile index, burst index, and folding endurance were respectively increased by 71.7%, 38.5%, and 600% when 3% of oxidized recovered fibers was added to the pulp at pH 5, with 0.5% aluminum sulfate addition, based on the original pulp. Tensile index and folding endurance were increased by 40.2% and 433.3%, respectively, when 1% oxidized recovered fibers (the oxidized time was 60 min) were added into pulp for recycled pulp. This finding may lay the foundation for greater re-use of fiber obtained from dissolved air flotation rejects. [ABSTRACT FROM AUTHOR]

Cross-linked polyvinyl alcohol (AZ-CIPVA) for effective paper sizing was prepared by using N-(isobutoxymethyl)acrylamide (IBMA) and aziridine cross-linker (AZ) as modifiers. The structure and the performances of the AZ-CIPVA with different dosage of AZ were characterized. The enhancing mechanism of paper sized by AZ-CIPVA was clarified. The results show that cross-linking structure is formed by the reaction between AZ and carboxyl groups in CIPVA molecules. With the increase of AZ content, the gel content, cross-linking density and thermal stability of the AZ-CIPVA film are increased. When the AZ dosage is 3.5%, both tensile strength and modulus of AZ-CIPVA film reach maximum, and the value are 68.34 MPa and 1037.02 MPa, respectively. The water absorption of the film reaches minimum and the folding endurance of the sizing paper reaches maximum when the content of AZ is 2.8%. When applied to the surface of the paper, the maximum dry and wet tensile indexes of the paper are increased by 223.77% and 432.56%, respectively. Roughness of the sizing paper increases slightly and the surface becomes uneven. The micro-structure shows that larger pores between the paper fibers are filled and cross-linked after sizing, which is beneficial to improve the mechanical strength of paper. • A series of cross-linked polyvinyl alcohol (AZ-CIPVA) modified by IBMA and AZ are successfully prepared. • The increasing of AZ can improve the degree of cross-linking and comprehensive performance of both AZ-CIPVA film and sizing paper. • The enhancing mechanism of paper by AZ-CIPVA is proposed. [ABSTRACT FROM AUTHOR]

For more cost-effective and/or value-added utilization of cellulosic fibers in pulp and paper industry, fiber engineering is an important concept. Essentially, fibers can be engineered via various mechanical, chemical, and biological processes. In the current study, the combined use of laccase and TEMPO was applied to introduce carboxyl and aldehyde groups to softwood-derived cellulosic fibers (bleached softwood kraft pulp). The process conditions in preparation of the engineered fibers were optimized. Under the conditions studied, the maximum increases in carboxyl and aldehyde contents were 360 % and 225 %, respectively. The effectiveness of the laccase/TEMPO system could be well explained by the reaction cycles in catalytic oxidation pathways. The findings of the current work may provide useful insights into the enzymatic modification of cellulosic fibers for papermaking applications. [ABSTRACT FROM AUTHOR]

In this work, cellulose nanofibrils (CNF) were produced from a Eucalyptus globulus bleached kraft pulp by TEMPO-mediated oxidation and mechanical homogenisation, and their effects in papermaking, namely filler flocculation and retention, dry and wet-web strength and structural properties, were studied in detail. Cellulose nanofibrils possessing 0.6 mmol/g carboxyl groups and a degree of polymerisation (DP) of ca. 550 were found to promote filler flocculation and retention in the fibre mat, whereas the same amount (3 wt%) of CNF having 1.5 mmol/g of carboxyl groups, a DP of ca. 200 and a similar mean diameter exhibited the opposite effect. These results were interpreted with the help of flocculation studies of precipitated calcium carbonate (PCC) in the presence of CNF carried out by laser diffraction spectrometry. In addition, the mechanical and structural properties of the handsheets were analysed, revealing that the less charged CNF led to more closed matrices and, even increasing the filler retention, had a positive role on the tensile strength. A bonding mechanism among eucalypt fibres, PCC, CNF and a linear cationic polyacrylamide is proposed, consistent with the flocculation, retention and paper strength and structural property results. It is concluded that, to be used in papermaking, the CNF must not have a high charge (or a small length) to be able to flocculate the filler particles and, at the same time, to increase the filler-to-cellulosic fibres bonding. A complementary study on the wet-web resistance of handsheets produced with the less charged CNF was conducted for moisture contents between 10 and 70%, showing that these CNF can significantly improve the handsheet wet tensile strength (nearly 100%) even for water contents above 50%. The use of CNF in the paper machine may thus contribute, through the higher wet-web tensile resistance, to reducing breaks and increasing the operating speeds and, through the higher filler retention, to important fibre and cost savings. [ABSTRACT FROM AUTHOR]

• The chemical aspects of alum rosin sized paper degradation were described. • Direct influence of H 3 O+ ions formed during hydrolysis of aluminium(III) species. • Influence of pH variation on the redox potential of reactive oxygen species acting as oxidizing agent. In Europe, the use of aluminium(III) compounds, namely AlK(SO 4) 2 ·12H 2 O and later on Al 2 (SO 4) 3 ·18H 2 O for hardening gelatin sizes was recorded as early as the 16th century. This review is focused on the critical assessment of published data concerning the following chemical aspects of paper degradation: direct influence of H 3 O+ ions formed during hydrolysis of aluminium(III) species; influence of low-molecular organic acids formed within degradation processes; influence of pH variation on the redox potential of reactive oxygen species acting as oxidizing agent; consequences of the absorption of gaseous NO 2 and SO 2 present in the air for paper degradation; involvement of aluminium species in redox radical oxidation catalytic processes; possible effect of the coordination of Al(III) with small radius and high charge on oxygen atoms of cellulose carboxyl or hydroxyl groups. It is indicated how the understanding of the above mentioned effects can help slow down paper degradation. [ABSTRACT FROM AUTHOR]

Paper‐based surface‐enhanced Raman scattering (SERS) substrates have gained growing interest as an eco‐friendly and low‐cost tool for chemical and biosensing. However, paper‐based SERS substrates often suffer relatively low signal spatial homogeneity because of their nonuniform hot‐spot distribution. In this paper, a nanofibrillated cellulose paper (nanopaper) based SERS multiwell plate is developed for trace chemical detection with high sensitivity and high signal homogeneity. The SERS plate is fabricated from ultrasmooth (2,2,6,6‐tetramethylpiperidin‐1‐yl)oxyl‐oxidized NFC paper (TO‐nanopaper) through wax‐printing‐based multiwell patterning followed by silver nanoparticle (AgNP) growth based on a successive ionic layer adsorption and reaction (SILAR) process. Taking advantage of the abundance of carboxyl groups on the TO‐nanopaper, uniformly distributed and densely arranged AgNPs are successfully synthesized through the SILAR process on the NFC multiwell surface under ambient conditions. The SERS performance of the device is evaluated for testing two Raman marker chemicals, rhodamine B and 2‐naphthalenethiol, and picomolar detection limit and high Raman enhancement factor (up to 1.46 × 109) are achieved. The Raman signal mapping results show superior signal spatial homogeneity of the device with low variations (≤11%). The nanopaper‐based SERS device represents a promising SERS platform for chemical and biomolecule detections with high sensitivity and high repeatability. [ABSTRACT FROM AUTHOR]

Background and purpose: In the production of pulp, materials such as sodium hypochlorite, chlorine dioxide, ozone, hydrogen peroxide, etc. are used in the bleaching process. In addition, the above-mentioned materials can be used as oxidizing materials to increase the surface charge of fibers, and can help the paper to be more resistant. Therefore, this research was conducted to investigate the effect of fiber oxidation with hydrogen peroxide and sodium hypochlorite on the characteristics of NSSC and OCC pulps as vigin and recycled pulps, respectively. Materials and methods: The pulps required for this research, unbleached NSSC pulp and OCC pulp were obtained from Mazandaran wood and paper factory. First, the consistency, initial freeness and brightness of the pulp were measured. Also, the required chemicals were all of industrial grade, hydrogen peroxide (in liquid form 52%) from Chlor Pars Tabriz Company and sodium hypochlorite (in liquid form 16.4%) from Kleran Semnan Company and sodium silicate from Bawand Shimi Qazvin Company, caustic soda (Liquid soda) with a purity of 47% for bleaching with peroxide was obtained from Arvand Abadan Petrochemical, and soda ash (solid soda) with a purity of 90% for bleaching with hypochlorite was obtained from Chloran Pars, Semnan. In order to control the destructive effects of transition metals, all pulps were treated with 0.2% DTPA, in 2% consistency, time 30 minutes, temperature 90 degrees Celsius and pH=5.5-5, before bleaching. At the end of this step, the pulp is thoroughly washed with distilled water and used for the next steps. For the oxidation of both types of pulp, 3, 4, 5% hydrogen peroxide and sodium hypochlorite were used for oxidation of NSSC pulp using the above ratios (similar to peroxide) and for OCC pulp, 0.5, 1 and 1.5% hypochlorite ratios were used. Then the structural characteristics of the fibers such as pulp freeness, kappa number, WRV, viscosity, carboxyl groups were investigated and finally, the pulps were evaluated by FT-IR spectroscopy. Results: The results showed that with the increase in the consumption of hypochlorite, freeness increased in the oxidized NSSC pulps, but the trend of freeness decreased in the oxidized OCC pulp. This issue shows the situation regarding the use of peroxide. Also, the oxidation of pulp by sodium hypochlorite compared to peroxide has resulted in the release of more lignin, and in this sense, the effectiveness of OCC pulp has been higher compared to NSSC pulp. The amount of water retention value in the pulp fibers in the NSSC pulp treatments has increased compared to the control pulp, and in the case of the OCC treatments, it has not changed significantly compared to the control treatment, and only in one case (OC-Na1) has a significant decrease. With the increase of peroxide consumption in the oxidation process of both types of NSSC and OCC pulp, despite the increase in viscosity, there is no significant difference between different consumption levels. In addition, with the increase in the level of hypochlorite consumption, a significant increase in the viscosity of the aforementioned pulps is observed. The amount of carboxyl groups of pulps treated with peroxide increased in both types of NSSC and OCC pulps compared to the control sample. Compared to peroxide, hypochlorite has been more effective in creating carboxyl groups in both types of pulp. The evaluation of FT-IR spectroscopy also shows that the oxidation treatment with peroxide and hypochlorite has increased the carboxyl groups on both types of pulp compared to the control samples. Conclusion: The effectiveness of hypochlorite compared to peroxide in the creation of carboxyl groups in both types of pulp was more, which seems that the increase of carboxyl groups on the cellulose chain occurred more on C6 by peroxide and more on C2 and C3 by hypochlorite. The oxidation process increases the viscosity of paper pulp by increasing the carboxyl groups and due to the creation of a higher molecular weight. In addition, the increase of carboxyl groups due to higher chemical activity has made them able to absorb higher water and thus higher WRV. [ABSTRACT FROM AUTHOR]

[Display omitted] • A functional DES with lignin stabilization and functionalization were synthesized for biomass fractionation. • Lignin depolymerization resulted phenolic monomer with a bio-oil yield of 55.40%. • Lignin-based O/W emulsions were prepared using the functionalized lignin. • Curcumin-encapsulated microcapsules with excellent UV resistance and control release capacity was obtained using lignin-based O/W emulsion template. • Pretreated cellulose-rich substrate were used for papermaking and enzymatic saccharification. This study synthesized a functional deep eutectic solvent (DES) using betaine and glyoxylic acid (GA) for lignocellulosic biomass pretreatment. The Betaine/GA DES pretreatment resulted a high delignification efficiency of 81.89% and xylan removal of 83.25% while preserving most of cellulose. During pretreatment, lignin was stabilized by GA, preventing its condensation and introducing carboxyl groups onto its molecular backbone. The GA stabilized lignin (GASL), with a high β-O-4 linkage content of 62.92%, was depolymerized for phenolic monomer production with a bio-oil yield of 55.40%. Additionally, the functional lignin was used as a surfactant for GASL-based O/W emulsion (GA-O/W emulsion) preparation. With 0.5% of lignin addition and an optimal O/W ratio of 6:4, the resulting GA-O/W emulsion exhibited a high cream index value of 100% and excellent storage stability without any phase transition or emulsion aggregation. When using the lignin to prepare curcumin-encapsulated microcapsules, a cumulative curcumin remaining of 74.19% under UV radiation and an extraordinary encapsulation efficiency of 62.86% were achieved. Furthermore, this DES pretreatment promoted enzymatic saccharification of the pretreated cellulose substrate, resulting in a glucose yield of 91.49%. After adding 15 wt% of the fibers in soft wood pulp for papermaking, the tear index, ring crush strength index, and tensile index of the produced paper-sheets reached 112.04%, 98.58%, and 83.55% of those of the pure softwood pulp papers, respectively. [ABSTRACT FROM AUTHOR]

The valorization of lignocellulosic biomass by-products holds significant economic and ecological potential, considering their global overproduction. This paper introduces the fabrication of a novel wheat-straw-based hydrogel and a new microcellulose-based hydrogel through 2,2,6,6-tetramethylpiperidinyl-1-oxy (TEMPO) oxidation. In this study, Fourier transform infrared (FTIR) analysis was employed for the detection of carboxyl groups, neutralization titration was conducted using a conductivity meter, viscosity analysis was performed using a rheometer, and transmittance analysis was carried out using a spectrophotometer. Two novel hydrogels based on TEMPO oxidation have been developed. Among them, the bio-based hydrogel derived from oxidized wheat straw exhibited exceptional printability and injectability. We found that the oxidation degree of microcellulose reached 56–69%, and the oxidation degree of wheat straw reached 56–63%. The cross-linking of 4% oxidized wheat straw and calcium chloride was completed in 400 seconds, and the viscosity exceeded 100,000 Pa·s. In summary, we have successfully created low-cost hydrogels through the modification of wheat straw and microcellulose, transforming lignocellulosic biomass by-products into a sustainable source of polymers. This paper verifies the future applicability of biomass materials in 3D printing. [ABSTRACT FROM AUTHOR]

In this paper, N-vinylpyrrolidone was copolymerized with acrylic acid and itaconic acid by free radical polymerization, and a series of polyacrylic acid-co-itaconic acid-co-N-vinylpyrrolidone (PAIN) dispersants with different pyrrolidone ligand contents were synthesized and characterized. Then, the cobalt blue nano-pigment slurry (20 wt%) was prepared through a water-based grinding method, and the optimum grinding technology was explored and determined as follows: PAIN2 as a dispersant, a dispersant dosage of 10 wt%, and a grinding time of 480 min. According to this optimum grinding technology, the prepared pigment slurry had a significantly decreased agglomeration, the D90 of which was 82 nm, and separately increased to 130 nm and 150 nm after heat storage for 3 and 7 days, exhibiting excellent heat storage stability. Additionally, its TSI value was also the lowest (1.9%), indicating good dispersion stability. The QCM and adorption capacity measuring results showed PAIN2 had a larger adsorption capacity, and the formed adsorption layer had a higher rigidity and was not easy to fall off. This was caused by both the interaction of carboxyl groups and the pyrrolidone ligand (strong coordination interaction) in PAIN2 with cobalt blue. The XPS and FT–IR measurements further proved the above-mentioned adsorption mechanism. [ABSTRACT FROM AUTHOR]

Wood specimens were dyed by boiling them in the presence of walnut shells and dye to penetrate the dyestuff into the sample. Specimens prepared from Scots pine, oak, and beech woods were boiled separately in walnut shell, water, and NaOH environment, and the penetration of the dyestuff into the samples was ensured. Sodium hydroxide solution was preferred because it facilitates the dissolution of the hemicelluloses in the wood and the dyestuffs in the walnut shell. Alum was added in other samples to reveal the mordant effect on the adhesion of dyestuffs to wood. Thermogravimetric (TG) analysis revealed that wood degradation primarily occurs due to evaporation of free water at 50 to 120 ℃, followed by lignin and cellulose breakdown across a wide temperature range of 160 to 600 ℃. Treatment with NaOH and NaOH+alum notably reduced the peak temperatures in differential-thermogravimetric analysis by indicating an effect on lignin. This was supported by Fourier transform infrared analysis, particularly in the disappearance of carboxyl groups at 1710 cm-1 and significant decreases in peak intensities at 1027, 1247, 1315, and 1501 cm-1. Based on the findings, it was concluded that the dyed parts obtained can be used in the wooden toy industry. [ABSTRACT FROM AUTHOR]

In this paper, a preparation method of superhydrophobic composites of oxidized multi-walled carbon nanotubes modified by stearic acid (SA) is proposed. Hydroxylated multi-walled carbon nanotubes (HMWCNTs) were obtained by oxidizing multi-walled carbon nanotubes with potassium dichromate to give them hydroxyl groups on the surface. Subsequently, the carboxyl group in the SA molecule was esterified with the hydroxyl group on the HMWCNTs. SA molecules were grafted onto the surface of multi-walled carbon nanotubes. SA modified oxidized multi-walled carbon nanotubes (SMWCNT) superhydrophobic composites were obtained. The results show that the water contact angle (WCA) of superhydrophobic composites can reach up to 174°. At the same time, the modified nanocomposites have good anti-icing and corrosion resistance. After low temperature delayed freezing test, the freezing extension time of the nanocomposite film is 30 times that of the smooth surface. Under strong acid and alkali conditions, the superhydrophobic nanocomposites still maintain good superhydrophobicity. The nanocomposites may have potential applications in the preparation of large-scale superhydrophobic coatings. [ABSTRACT FROM AUTHOR]

This paper presents the results of a study of the effects of the lanthanide ions Ce3+, Pr3+, Nd3+ and Sm3+ on the electronic structure and antioxidant and biological (antimicrobial and cytotoxic) properties of p-coumaric acid (p-CAH2). Structural studies were conducted via spectroscopic methods (FTIR, ATR, UV). Thermal degradation studies of the complexes were performed. The results are presented in the form of TG, DTG and DSC curves. Antioxidant properties were determined via activity tests against DPPH, ABTS and OH radicals. The reducing ability was tested via CUPRAC assays. Minimum inhibitory concentrations (MICs) of the ligand and lanthanide complexes were determined on E. coli, B. subtilis and C. albicans microorganisms. The antimicrobial activity was also determined using the MTT assay. The results were presented as the relative cell viability of C. albicans, P. aeruginosa, E. coli and S. aureus compared to controls and expressed as percentages. In the obtained complexes in the solid phase, lanthanide ions coordinate three ligands in a bidentate chelating coordination mode through the carboxyl group of the acid. Spectroscopic analysis showed that lanthanide ions increase the aromaticity of the pi electron system of the ligand. Thermal analysis showed that the complexes are hydrated and have a higher thermal stability than the ligand. The products of thermal decomposition of the complexes are lanthanide oxides. In the aqueous phase, the metal combines with the ligand in a 1:1 molar ratio. Antioxidant activity tests showed that the complexes have a similar ability to remove free radicals. ABTS and DPPH tests showed that the complexes have twice the ability to neutralise radicals than the ligand, and a much higher ability to remove the hydroxyl radical. The abilities of the complexes and the free ligand to reduce Cu2+ ions in the CUPRAC test are at a similar level. Lanthanide complexes of p-coumaric acid are characterised by a higher antimicrobial capacity than the free ligand against Escherichia coli bacteria, Bacillus subtilis and Candida albicans fungi. [ABSTRACT FROM AUTHOR]

Examples of labeling polysaccharides at hydroxyl groups are described in this paper, which are especially in demand for molecules with a blocked reducing end. The protocols presented are suitable for the microscale synthesis of labeled polysaccharides that do not require a chromatography step for isolation. Examples of hydroxyl labeling include (1) direct modification with fluorescein isothiocyanate; (2) reaction with a fluorescein-dichlorotriazine derivative; (3) reaction with biotin-dichlorotriazine; (4) indirect two-step modification (given for glycosphingolipid) with glutaric anhydride followed by amidation with aminospacered BODIPY or SuCy5. The labeling of carboxyl groups of hyaluronic acid with BODIPY is also described. The staining of plant tissue sections with biotinylated polysaccharide versus being fluorescein labeled is compared. [ABSTRACT FROM AUTHOR]

In this paper, response surface methodology (RSM) was used to study the optimised process conditions of lotus root starches modified by treatment with sodium hypochlorite (NaOCl). Based on the Box-Behnken design, quadratic models were developed to correlate the reaction variables. Analysis of variance (ANOVA) revealed that the active chlorine content was the most significant variable for the response. Under the experimental conditions in this paper, the calculated carboxyl content (CNCOOH) of obtained samples was approximately 0.98% ± 0.02% (n = 5). The spectra of Fourier transform infrared (FTIR) spectroscopy displayed that the formation of carboxyl groups successfully occurred on the oxidised lotus root starches. Scanning electron microscope (SEM) analysis showed that the oxidised lotus root starch (CNCOOH, 0.98%) granules were mostly spherical in shape and their surfaces were slightly rougher than those of native lotus root starch. This work may contribute to providing technical support and theoretical guidance for the production of oxidised lotus root starches using NaOCl as an oxidising agent. [ABSTRACT FROM AUTHOR]

Powder lignocellulose modifiers for vulcanized rubbers were prepared from secondary paper resources (recycled cardboard) treated with TiCl4 in hexane. The diffraction patterns, IR spectra, and morphological characteristics of the materials obtained, including the geometric characteristics and length distribution of fibers, were analyzed. The content of titanium, lignin, and carbonyl and carboxyl groups and the bulk density of the material were determined. The presence of up to 5 wt parts of powder modifiers per 100 wt parts of rubber in the rubber stock favors preservation of physicomechanical properties of vulcanized rubbers both before and after accelerated thermal oxidative aging at 100°C for 72 h, enhancing the resin–metal cord adhesion and thus prolonging the operation life of the vulcanized rubbers. [ABSTRACT FROM AUTHOR]

In this paper, functionalized nanotube-reinforced cementitious composites were prepared, and the mechanical property test results showed that the 28d flexural strength of the composite was increased by 41.58% at a hydroxylated carbon nanotube mass fraction of 0.08 wt.% compared to the original cement mortar. Carboxylated carbon nanotubes with a mass fraction of 0.02%, on the other hand, increased the 28d compressive strength by 99.12%. Probing the effect of the presence of functional groups on carbon nanotubes on the CNT/C–S–H interface by first principles. The results showed that the shear strengths (11.392 MPa and 14.130 MPa) of hydroxylated carbon nanotubes and plain carbon nanotubes at the interface with cementitious (CNT-OH/CSH and CNT/CSH) were lower than the shear strengths (21.584 MPa) of carboxylated carbon nanotubes at the interface with cementitious (CNT-COOH/CSH). The adsorption of functional groups on carbon nanotubes changes the electron distribution on the surface of carbon nanotubes. The introduction of carboxyl groups exacerbates the charge transfer between carbon nanotubes and cementitious groups and promotes the generation of solid chemical bonds. This is the reason that carboxylated nanotubes added as reinforcement to cement mortar give better strength to the composite than hydroxylated nanotubes. [ABSTRACT FROM AUTHOR]

In this paper, the effect of elemental chlorine free fully bleached eucalyptus kraft pulp alkali treatment with 25% w/v of sodium hydroxide (NaOH) solution on the absorption behavior of the resultant air-laid absorbent pads is investigated. The results showed that after an hour of alkali treatment at room temperature, fiber charge (based on carboxyl group content) decreased to more than half. As a result, eucalyptus fibers have lost some of their hydrophilicity, as shown by the contact angle and water retention value (WRV) measurements, where the contact angle increased and the WRV decreased. Parallel cellulose I is converted into antiparallel and thermodynamically stable cellulose II by removing hemicellulose from inter-fibrillar spaces and fibrils' surfaces. In line with these molecular changes, fibril aggregation occurred. This was confirmed by the increase in hydrogen bond intensity and decrease in total crystallinity index calculated from ATR-FTIR data like the wrinkled surface of modified eucalyptus fiber from FESEM images. Also, fiber biometry measurements revealed a decrease in weighted average length and linear density making the air-laid absorbent pad thinner. A strike-through time decrease for artificial urine was achieved by improving the wet resiliency of fiber networks after alkali treatment. Essentially, after wetting, structural stability, and preserved porosity compensated for hydrophilicity loss, which played a crucial role in the performance of an air-laid fiber network. [ABSTRACT FROM AUTHOR]

Nowadays, afterglow materials with long-lifetime phosphorescence are mainly prepared from metal-containing substances. It is necessary and challenging to find a simple, green and feasible approach to generate afterglow materials with excellent phosphorescence from biomass materials. Herein, a facile strategy is proposed to construct afterglow materials via confining fluorescence carbon dots from lignin into silica (SiO2). Specifically, a microwave-assisted carboxymethylation process was adopted for the lignin precursor, which endowed the lignin with abundant carboxyl groups (3.69 mmol g−1) and maintained its benzene ring structure. Subsequently, N-doped lignin-based carbon dots (NL-CDs) with nanoscale size (6.07 nm) and excellent fluorescence (quantum yield = 30.6%) were prepared through the hydrothermal treatment of carboxymethylated lignin. Finally, the NL-CDs were confined in SiO2 and the generated NL-CDs@SiO2 exhibited excellent phosphorescence behavior in both solid-state and aqueous solution. The obtained afterglow materials achieved 5.97% of phosphorescence quantum yield and 834 ms of lifetime, which could be observed for 6 s by the naked eye. Meanwhile, a multi-modal information encryption strategy was designed based on the phosphorescence characteristics of the afterglow materials. The proposed strategy in this paper will pave the way to generate afterglow materials from lignin biomass and provide guidance for high-value utilization of lignin. [ABSTRACT FROM AUTHOR]

In the current study, the cyclopeptide alkaloid discarine D-derived tri-peptides fragments were synthesized and then investigated for their inhibitory potential against krait (Bungarus sindanus) venom acetylcholinesterase (AChE) enzyme. The tri-peptides L-Leu- threo-D-Pheser-L-Phe and L-Leu- threo-L-Pheser-L-Phe were chemically synthesized by a conventional method using the benzyloxycarbonyl group for the alpha-amino (α-amino) safety and the methyl esters an amino acids derivative used for the safety of carboxyl group. The present paper described that the general synthetic strategy of tri-peptide allows the tri-peptide sequence to be acquired with the N-terminal extreme protected. Kinetic studies using the Lineweaver Burk plot indicated that tri-peptides fragments cause an un-competitive type of inhibition i.e. both Km and Vmax values decreased with the increase of tri-peptides fragment concentration (13.5–22.5 µM). The estimated Ki and IC50 for krait venom AChE were found to be 17.5 µM and 19.5 µM, respectively. Thus the present paper, clarified that the freshly produced tri-peptides fragment can be deliberated as a beneficial mediator for the inhibition of krait venom AChE. [ABSTRACT FROM AUTHOR]

Bi4Ti3O12 ferroelectric nanomaterials are mainly used in the manufacture of biosensors, biomedical imaging reagents, or other biomedical applications. Due to the different arrangements of Bi4Ti3O12 ferroelectric nanoparticles, complex nanofibers with specific geometries can be obtained. In this paper, Bi4Ti3O12 ferroelectric nanomaterials were used to study the volatilization state of the acrylic paint used in the coating process. This article explains that some Bi4Ti3O12 nanoparticles were difficult to be dispersed in spinning solution, which made the preparation of composite fibers difficult. Therefore, these issues need further research and resolution. This work proposes to selectively reduce the use of graphene oxide by using an environmentally friendly water solvent to prepare water-reduced graphene oxide (rGO) and then inject octadecylamine into the selectively reduced graphene oxide to prepare octadecylamine-grafted reduced graphene oxide (rG-ODA). The experimental results in this paper showed that through seeding and reduction, functional groups such as carboxyl groups and epoxy groups on the surface of graphene oxide disappeared, and graphene oxide was well reduced. The presence of oxygen-containing functional groups increased the distance between the graphitic layers to 0.713 nm. GS-EDA had a characteristic diffraction peak close to 2θ = 24.3°, indicating that GO was effectively reduced after inoculation reduction. [ABSTRACT FROM AUTHOR]

Carbon-based materials incorporated with oxygen functional groups (OFGs-Gr) exhibit outstanding electrocatalytic performance for hydrogen peroxide (H2O2) production via the two-electron oxygen reduction reaction (2e− ORR). Currently, the nature of the active functional group and the underlying reaction mechanism are still under debate. Herein, we constructed the OFGs-Gr structures and systematically investigated the effect of the aqueous environment (including pH and electrode potential) on the catalyst performance in combination with ab initio molecular dynamics (AIMD). The carboxyl group (COOH-Gr structure) plays a key role in the neutral solution environment. The water molecules on COOH-Gr effectively modified the interaction of the C sites with OOH. The adsorption strength of OOH increases with increasing pH, resulting in an ether group (dopant-Gr in the C–O–C structure), maintaining excellent properties in alkaline media. Furthermore, our calculations demonstrate that the selectivity of H2O2 generation for dopant-Gr is increased by an elevated electrode potential, while the selectivity for COOH-Gr is decreased. These findings provide a dynamic perspective that elucidates that both pH and electrode potential synergistically influence the catalytic properties for H2O2 synthesis. [ABSTRACT FROM AUTHOR]