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A new glutamic acid-modified cellulose was prepared and investigated as a bioadsorbent used for the simple and rapid removal of Cu2+ and Hg2+ from single and binary aqueous solutions. The effects of the initial concentration of heavy metal ions, pH of the solution and temperature on the adsorption capacity of the bioadsorbent were investigated. Equilibrium studies demonstrate that the adsorption of Cu2+ and Hg2+ follows the Langmuir model in a single aqueous solution system. Meanwhile, the adsorption kinetics were found to follow the pseudo-second-order model well. Competitive adsorption in the binary component system indicates the mutual inhibitation adsorption between the two metal ions. The FTIR and SEM–EDS results reveal that Cu2+ and Hg2+ are successfully adsorbed on the bioadsorbent by coordination and static interactions.

A biodegradable and robust fluorogenic cellulose material for simultaneous fluoride recognition and adsorption at environmentally significant levels is presented. The fluorescent modified cellulose (FMC) containing a boronic acid-based anthracene group as a fluorescent signaling unit displays a selective fluorescence enhancement with F−. On the other hand, Cl−, Br−, SO42−, H2PO4−and ClO4− did not induce significant changes in fluorescence. Furthermore, FMC shows excellent F− adsorption over a wide range of pH with a low dosage. Equilibrium studies demonstrate that the adsorption of F− follows the Langmuir model in an aqueous solution. While, adsorption kinetics were found to follow the pseudo-second-order model. The simplicity of the method and the ability to detect and remove fluoride in waste water is noteworthy given the problems associated with fluoride pollution in drinking water.

Sulfur dioxide (SO2) emission has become a crucial problem, especially in developing countries since it is one of the main reasons for the formation of acid precipitation and the secondary formation of fine particulate matter (PM2.5). Wet magnesia desulfurization stands out as a widely used practical approach for the control of SO2 due to its high removal efficiency, low operating cost and potential valuable by-products. However, the effluent of magnesium sulfite (main by-product) can reemit SO2 and cause water pollution. Thus, it is important, but challenging, to enhance the oxidation rate to improve the utilization of MgSO4 for sustainable resources and meanwhile downsize the absorbing tower. Herein, we report a series of graphitic carbon nitride (g-C3N4)-assembled transition metal catalysts (M–C3N4) for the first time via a facile and environmentally friendly synthetic route as a new generation of catalysts for the oxidation of magnesium sulfite. We have performed both theoretical evaluation and deep experimental validation of the series of M–C3N4 materials, and in particular, the cobalt–C3N4 material since it possesses the best catalytic activity reported to date, which is comparable to that of aqueous precious metal benchmarks but only with a 2.4 wt% cobalt loading. Additionally, the ability to recycle the Co–C3N4 complex is investigated to facilitate its practical application. This fabrication method is expected to provide a new concept for the construction of multifunctional nanocomposites for a large variety of industrially relevant desulfurization applications.

We have developed a green and robust fluorogenic (λex = 410 nm, λem = 510 nm) cellulose membrane using graphene oxide (GO) as a construct for simultaneous copper ion recognition and filtration at environmentally relevant levels. The detection limit and removal limit of Cu2+ are 7.3 × 10−7 M and 1000 ppm, respectively. The simplicity and scalability achieved for the detection and removal of metal ions in waste water is particularly noteworthy given the significant problems associated with metal ion pollution of drinking water., The present work was supported by the National Key Research and Development Program of China (Grant #: 2017YFC0210201 and 2016YFC0204102) and the National Natural Science Foundation of China (Grant #: 21607044, 51378204, and 51379077). This work was also supported by the Natural Science Foundation of Hebei Province (Grant #: B2017502069 and E2016502096) and the Fundamental Research Funds for the Central Universities (Grant #:2016MS108). T. D. J. wishes to thank the Royal Society for a Wolfson Research Merit Award. All data supporting this study are provided as supplementary information accompanying this paper (ESI†).

Penetration of adhesive into the wood cell and lumens is an important factor that may enhance the durability of the adhesive bonds. In this study, the diffusion of adhesive polyvinyl acetate (PVAc) into the cell wall of various types of wood was evaluated making use of micro-CT. Compression shear block tests were also applied to examine the mechanical performance of the bond. In adhesive assemblies examined, cell walls at the immediate surface which were damaged during machine planning were full of adhesives. As the penetration of PVAc increased, the variation in the observed bind strengths was not substantial. Bonded with the same type of glue, black spruce appeared to have lower shear strength than Douglas fir and lodgepole pine. Moreover, gravity seemed to play a role in the glue penetration. During clamping and adhesive curing, the substrate on the lower of the shear block specimen had a deeper glue penetration. There are some correlations between glue penetration and glue line thickness measured using micro-CT.

Cyclodextrins (CDs) can form inclusion complexes with a variety of molecules making them very attractive in different areas, such as pharmaceutics, biochemistry, food chemistry and papermaking. In this communication the preparation of β-cyclodextrin-grafted cellulose fibers was carried out by reacting β-cyclodextrin with cellulose fiber via citric acid (CA). Both fourier transform infrared (FTIR) and cross polarization magic angle spinning solid state nuclear magnetic resonance (CP-MAS NMR) indicated that β-CDs had been chemically attached to cellulose backbone through the formation of ester bonds. Furthermore, the β-CD-grafted cellulose fibers formed inclusion complexes with ciprofloxacin hydrochloride (CipHCl). And the β-CD-grafted cellulose fibers loaded with CipHCl showed excellent antibacterial activity against E.coli and S.aureus.

Both water repellency and water vapour barrier properties were endowed at paper surface by coating with beeswax-chitosan latex. It was found that the water vapour transmission rate of coated paper decreased as the drying temperature increased. However, water contact angle was not affected with it. Although the surface morphology deformed at high drying temperature, the roughness values maintained at micro-scale. Further analysis indicated that the water vapour barrier property of coated paper was influenced by the density of the coating layer.

Novel antimicrobial PVP-GP hydrogels were prepared by polycondensation of hexamethylenediamine and guanidine hydrochloride, followed by cross-linking reaction using N-vinyl pyrrolidone (NVP) and N,N’-methylene bisacrylamide (MBAm). The products were characterized by 1H NMR, FTIR, SEM, and their performances for wound dressing applications were also evaluated. Swelling study showed that the water absorptivity of the hydrogels decreased as the cross-linking density increased either in water or in physiological saline solution. Both PVP and PVP-GP hydrogels possessed excellent mechanical strength which could address the requirements for wound dressing. The water vapor transmission rates (WVTR) of PVP and PVP-GP hydrogels were in the range of 1727–2320 g/m2/day, indicating that the prepared hydrogels were suitable for wound dressings without dehydrating the wound surface or accumulating exudates. Kirby-Bauer inhibition zone test and microbe penetration assay proved that the PVP-GP hydrogels had high antimicro...

Poly (butylenesadipate-co-terephalate) (PBAT) was modified by melt grafting glycidyl methacrylate (GMA) in the presence of benzoyl peroxide (BPO) in a Haake mixer; and the various properties of blends of PBAT/thermoplastic starch (TPS) using GMA-grafted PBAT (PBAT-g-GMA) as compatibilizer were investigated. The blends comprising TPS content ranged from 20wt% to 50wt%. Thermal properties and thermal stability were characterized with DSC and TGA, respectively. The morphologic results indicated that the interfacial adhesion of PBAT/TPS blends was improved by PBAT-g-GMA. In comparison with the uncompatibilized blends, the tensile properties of compatibilized blends were significantly enhanced, particularly at a high content of TPS (i.e., 40wt% and 50wt%).

In this work, the innovative starch microcapsules enclosed with hydrophobic carnauba wax were developed, which were applied to the modification of cellulose fibers, thus increasing the water resistance of paper by reducing water vapor transmission rate (WVTR). Carnauba wax being encapsulated by crosslinking starch was confirmed by thermogravimetric analysis. The sizes of carnauba wax-starch microcapsules depended on the weight ratio (R) of starch to carnauba wax and concentration of crosslinker. The best performance on water vapor barrier of the paper was achieved by the fibers treated with the microcapsules of larger size. The lowest WVTR was given by the handsheet treated by wet-end addition with carnauba wax-starch microcapsules at Rstarch/ carnauba wax=5%, and R crosslinker/ carnauba wax=50%, and had a value of 348 g/m2day, a 70% drop from untreated original paper which has a WVTR value of 1176 g/m2day.

Two approaches of improving the toughness of polypropylene (PP)-based composites reinforced by natural cellulose fibers were developed. The surface modification of cellulose fibrils (CMF) or fiber by either in-situ grafting polymerization of butyl acrylate (BA) on CMF surface via an atom transfer radical polymerization (ATRP) or adsorbing the cationic polymeric latex with core-shell structure on fiber surfaces was performed; and resulting fibers or CMF were used as reinforments in an attempt to enhance the toughness of the PP-based composites. The results of mechanical properties indicated that the flexure, tensile, and impact strengths of the CMF-g-PBA reinforced composites were all improved. The cellulose fibres treated by cationic latex also showed the same trend. The optimal dosage of latex for hydrophobic-modifying fibers was also identified.

In this work polyvinyl alcohol (PVA) was modified via grafting or coupling with the guanidine-based antimicrobial polymer using epichlorohydrin as a crosslinking agent. The resulting polymer was tested for its charge density and inhibition against E.coli. The modified PVA adsorbed onto cellulose fibres via electrostatic association; thus resulting in the hand-sheets (or paper) with improved antimicrobial activity. As a further extension of this work, the temperature-responsive antimicrobial polymers were prepared based on acetalyzed PVA (APVA) grafted with guanidine-based polymer chains. In conjunction with anionic APVA copolymer (APVA copolymerized with sodium acrylate), the cationic and responsive APVA formed a unique antimicrobial polymer system via layer by layer (LbL) assembly, which could adsorb on fibre surfaces and be incorporated into cellulose fibre networks, leading to the functionalizing of cellulose fibres. The lower critical solution temperature (LCST) of APVA copolymer could be tailored by controlling the degrees of acetalysis (DA) and co-monomer ratios. AFM images obtained to reveal the roughness of the surfaces; while the antimicrobial test proved that cellulose fiber assembled with APVA-based multilayers exhibited excellent antimicrobial activity against E.coli.

Hydrophobic modification of cellulose fibres was conducted by plasma-induced polymer grafting in an attempt to increase the hydrophobicity of paper. Two hydrophobic monomers, i.e., butyl acrylate (BA) and 2-ethylhexyl acrylate (2-EHA) were grafted on cellulose fibres, induced by atmospheric cold plasma. Various influencing factors associated with the plasma-induced grafting were investigated, including the contact time and reaction temperature with monomers, and the dosage of monomers. Contact-angle measurement, infrared spectrum (IR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) were used to ascertain the occurrence of the grafting. The results showed that the hydrophobic property of the modified paper sheet was improved significantly after the plasma-induced grafting. The water contact angle on the surface of the paper reached up to higher than125°.

Due to its buffer property, activity, absorbability and safety, magnesium hydroxide is widely used in environmental protection, pharmaceutics, pulp and paper industry, and as flame-retardant filling in composite materials. The hydrothermal synthesis of magnesium hydroxide at low temperature (< 100°C) needs only simple equipment and is environmentally friendly and energy-saving, so the process is promising and easy for industrialization. In this study, we have investigated the effects of hexamethylenetetramine and ammonia additives on the hydrating synthesis of superfine Mg (OH)2 particles at 70°C. Mg (OH)2 particles formed were of platelet shape and the mean diameter was approximately 200nm. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were applied to characterize the crystal phase, size distribution and morphology of the crystal particles. Different morphologies of Mg (OH)2 particles were formed in hexamethylenetetramine and ammonia solutions. The generation velocity of hydroxyl (OH-) was found to play an important role in the distribution and morphology of Mg (OH)2 particles.

In this paper, two guanidine derivative polymers were synthesized by reacting polyhexamethylene guanidine hydrochloride (PHGH) with starch and epichlorohydrin (EP) respectively and used as potential functional additives in papermaking. The molecular structure of the guanidine derivative polymers were characterized by FTIR and 2D NMR. PHGH- modified starches exhibited high antimicrobial activities against E. coli and the growth inhibition reached almost 100% in the presence of 1.0 wt.% PHGH in wood fibers. UV260 absorption was applied to reveal the dynamic antimicrobial process of guanidine derivative polymer obtained with PHGH and EP. Results showed that most of bacteria was deactivated within a few mins and the intracellular components were leaked when the concentration of the guanidine derivative polymer were higher than the minimum inhibitory concentration (MIC).

A thermal-responsive polymer was prepared by partially acetalyzing poly(vinyl alcohol) (PVA). The completely reversible polymer aggregation and dissolution occur above and below a low critical solution temperature (LCST) for the aqueous solution of the modified PVA. The partially acetalized PVA (APVA) with higher molecular weight and higher degree of acetalysis exhibited a lower LCST transition and was used as an anionic polymer for polymer complexation. Water-soluble polymer, cationic polyhexamethylene guanidine hydrochloride (CPHGH) with antimicrobial property, was also prepared. In conjunction with APVA, CPHGH created the unique antimicrobial polymer multilayers on the surfaces of rayon fibres via layer by layer (LbL) assembly. AFM images revealed that the particles generated by multilayers became larger after the material was treated at 60°C; while the roughness of the surfaces was increased as the layer number increased and then decreased. Moreover, antimicrobial tests also demonstrated that the rayon fiber assembled with (CPHGH/APVA) multilayers exhibited higher antimicrobial activity against E. coli and s. aureus.

Cationic β-cyclodextrin polymer (CPβCD) and its complexes with butylparaben and triclosan were reported in this paper. 2D NMR confirmed that the host-guest complexes were formed by including antibiotics inside the cavities of CPβCDs, which significantly improved the water solubility of the antibiotics. Results of inhibition zones and shaking flask methods of antimicrobial-modified cellulose fibres showed that both antibiotics/CPβCD complexes had excellent antimicrobial activities when applying on the cellulose fibers whereas triclosan appeared to more effective. Morphology of untreated and treated bacteria revealed by AFM suggested that the antibiotics/CPβCD complexes inhibited bacteria through affecting the metabolism of the bacteria instead of damaging the cell membrane. Due to the strong electrostatic association, CPβCD polymers adsorbed on the surface of cellulose fibres almost completely within the range of dosages investigated.

Antimicrobial-modified starch was synthesized by covalently bonding guanidine polymer (PHGH) with potato starch via coupling reaction. Orthogonal tests were applied to optimize the reaction conditions. The coupling efficiency could reach 90.21% at the optimal conditions: temperature, 70 °C; time, 2 h; PHGH/starch, 120 wt.%; GDE/starch, 8 wt.%; pH, 11. PHGH modified starches exhibited high antimicrobial activities against both E. coli and S. aureus. Shaking flask method was more suitable for current non-released modified starches than diffusion method to evaluate the antimicrobial activities. In the presence of 1.0 wt.% PHGH in wood fibers, the growth inhibition reached almost 100%. The AFM results also demonstrated that the antimicrobial mechanism of PHGH was to destroy the membrane of the cells.

The adsorption of guanidine polymer modified starches on cellulose fibers was investigated along with the systematic studies on various influencing factors including temperature, pH, ionic strength and charge density of the starches. The AFM results revealed the relationship between the adhesion force and adsorption capacity. The adsorption capacity is not necessarily proportional to the adhesion force. The conditions for achieving the maximum adsorption were: temperature, 40 °C; pH, 6; CNaCl, 0 mM and charge density, 0.4 meq/g. The corresponding the normalized adhesion force is approximate 1 mN/m. In terms of the surface roughness determined by AFM, it has been proved that adsorbed starches of high charge density tend to form train structure, whereas those of low charge density tend to form tails and loops. Due the comb molecular structure, the adsorption capacity of the novel cationic starch reaches 124.3 mg/g, which is much greater than those reported previously.

A methacrylate monomer containing ciprofloxacin (CPF) was synthesized, followed by the free-radical co-polymerization of the methacrylate monomer, acrylamide and diallyl dimethyl ammonium chloride (DADMAC). The resulting antimicrobial cationic tripolymers were characterized by (1)H-NMR, gel-permeation chromatography, thermogravimetric analysis and differential scanning calorimetry. The in vitro antibacterial activity of the monomer, as well as of the polymers, was investigated against E. coli. The CPF pendant tripolymer exhibited excellent antibacterial activities, thus permitting the cationic tripolymers to be used as antibacterial intensifier, retention or filtration aid for various hygiene products, including those based on cellulose fibres.

The preparation of a cationic beta-cyclodextrin polymer (CPbetaCD) and its complexes with butylparaben and triclosan were reported in this paper. FT-IR and 2D 1H-1H gCOSY NMR spectra confirmed that the antibiotics could be included inside of the lipophilic cavities of CPbetaCD. The formation of complexation of CPbetaCD with the antibiotics significantly improved the water solubility. The solubility of the antibiotics linearly increased with the concentration of CPbetaCD, and the values of the association constant K1:1 of the butylparapben/CPbetaCD and triclosan/CPbetaCD complexes were 3800 and 3082 M(-1), respectively. The results also suggested that it was easier for butylparaben, which had relative smaller molecular size, to form the complexes with CPbetaCD than triclosan. Due to the targeting effect after the complexation with CPbetaCD, the antimicrobial activity of butylparaben can be significantly improved. Meanwhile, this improvement effect was not obvious for triclosan.