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This study promotes the use of nanobiochar (NBC) as an environmentally friendly substitute to conventional fillers to improve various properties of biopolymers such as their mechanical strength, thermal stability and crystallization properties. TGA analysis showed a slight increase in onset thermal degradation temperature of the composites by up to 5 °C with the addition of 4 wt% NBC. Non-isothermal DSC analysis determined that the addition of NBC into PHBHHx increases the crystallization temperature and degree of crystallinity of PHBHHx while isothermal DSC analysis demonstrated higher crystallization rate in PHBHHx/NBC composited by up to 54%. PHBHHx incorporated with NBC also exhibited superior tensile strength and modulus versus neat PHBHHx. Increase in mechanical strength was further proven via DMA where PHBHHx/NBC composites maintained higher storage modulus at higher temperatures when compared to neat PHBHHx. PHBHHx/NBC also exhibited no cytotoxicity effect against HaCat cells. This study demonstrates the ability of biochar to act as both nucleating agents and reinforcing agents in biodegradable polymers such as PHBHHx, which could be suitable for packaging application., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)

A W/ZSM-5 zeolite was successfully prepared by incorporating tungsten transition metal into a zeolite structure using a conventional impregnation method. The as-obtained W/ZSM-5 zeolite was characterized using several characterization techniques such as XRD, IR and SEM-EDS. The catalyst was then applied to a cascade, single-batch reaction to synthesize bio-polyol from sunflower oils using H 2 O 2 in isopropanol solvent. The obtained results indicated that the W/ZSM-5 zeolite had high catalytic efficiency in the epoxidation of the double bond of vegetable oil and the epoxy ring opening reaction to form bio-polyol. The effect of different reaction conditions on bio-polyol synthesis, such as the dosage of the catalyst and reaction time, were investigated. Bio-polyol was obtained from sunflower oil with a hydroxyl number of 160 mg KOH per g and functionality of 2.9 OH groups per mol. The as-synthesized sunflower oil-based polyol was used to replace fossil-based polyol in the fabrication of a bio-polyurethane-based composite with high oil uptake capacity. The oil adsorption capacity of the porous polyurethane-corn stalk composite was relatively high, up to 15.07 g g -1 . In comparison with neat polyurethane and lignocellulosic materials, the new porous bio-composite had higher oil uptake capacity., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Environment-friendly and biodegradable packaging materials have attracted widespread attention. Development of green solutions to extend the fruit shelf life and address fruit preservation thus has a far-reaching impact. In this study, high-barrier white cardboard (WC) was prepared by a facile coating method. Compared with the WC substrate, the WVP value of the polyvinylidene chloride (PVDC) emulsion-coated WC (3.46 × 10 -11 g m m -2 s -1 kPa -1 ) decreased 73.8% and the OP value (14.8 cm 3 m -2 day -1 ·Pa -1 ) decreased 61.9%. In addition, the mechanical properties of the PVDC emulsion-coated WC increased significantly. The weight loss rate and decay rate of the stored fruits packaged with PVDC emulsion-coated WC decreased by about 5%. The high barrier PVDC emulsion-coated WC with excellent mechanical properties, good barrier effect, and preservation function was successfully prepared. Benefitting from these investigated characteristics, the obtained coated WC can be used to package fruits to reduce water loss and delay ripening, and thus extend their shelf life, exhibiting a favorable effect on blueberry and grape storage. Overall, the fabricated eco-friendly coated white cardboard has shown great potential for biodegradable packaging applications. We believe the current work presents an approach to address perishable fruit preservation and provide a supplement alternative., Competing Interests: The authors declare no conflict of interest., (This journal is © The Royal Society of Chemistry.)

Paper-based materials with precisely designed wettabilities show great potential for fluid transport control, separation, and sensing. To tune the wettability of paper, paper sheets are usually modified after the paper manufacturing process. This limits the complexity of the local wettability design. We combined the wettability design of the individual fibres with subsequent paper sheet fabrication through either fibre deposition or fibre printing. Using silica-based cellulose fibre functionalization, the wettability of the paper sheets, containing only one specific fibre type, could be gradually tuned from highly hydrophilic to highly hydrophobic, resulting in water exclusion. The development of a silica-functionalized fibre library containing mesoporous or dense silica coatings, as well as silica with varying precursor compositions, further enabled the variation of the paper wettability and fluid flow. By combining this fibre library with the paper fabrication process by (i) fibre deposition or (ii) fibre printing, the paper wettability architecture and thus the local fibre composition were adjusted without any further processing steps. This enabled the fabrication of papers with wettability integration, such as a wettability pattern or a Janus paper design, containing wettability gradients along the paper sheet cross section. This asymmetric wettability along all three spatial dimensions enabled side-selective oil-water separation., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Reversed-electrowetting based droplet electricity generator (REWOD-DEG) shows merits in high power densities, tunable output formats, and wide adaptability to diverse mechanical energies. However, the surface charge trapping and dielectric failure, which are also common challenges for electrowetting system, hinders the development of reliable REWOD-DEGs for long-term running. We innovatively introduce a slippery lubricant-infused porous surface (SLIPS) into REWOD-DEG. Benefits from the significant inhibitory effect for surface charge trapping and ambient contamination, self-healing characteristic given by SLIPS, and robust reversed-electrowetting based energy harvesting were achieved. The SLIPS enhanced REWOD-DEG experienced 100 days of intermittent energy harvesting without deterioration. In addition, the device shows robust performances when exposed to a variety of extreme working conditions, like low temperature, pH, humidity, fouling, and even scratching. This work may address the core application challenges of REWOD based devices, and inspire the development of other robust droplet-based electricity generators., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Sustainable bimetallic nanoparticles (NPs) have attracted particular attention in the past decade. However, the efficiency and environmental concerns are associated with their synthesis and properties optimization. We report herein biosynthesis of bimetallic ZnO@SeO NPs based on green and ecofriendly methods using pomegranate peel extract (PPE). Pyrochemical ultraviolet-visible (UV-vis), Fourier-transform infrared (FTIR) and X-ray diffraction (XRD) spectroscopy as well as TEM and EDX supported successful synthesis. Antibacterial, antifungal, and cytotoxic activities were indicative of biological worth of sustainable bimetallic ZnO@SeO NPs, exhibiting antibacterial activity compared to monometallic ZnO and SeO NPs. The values of Minimum Inhibitory Concentration (MIC) of bimetallic ZnO@SeO NPs toward E. coli , P. aeruginosa , B. subtilis and S. aureus were 3.9, 15.62, 3.9 and 7.81 μg ml -1 , respectively. Likewise, a promising antifungal activity against Candida albicans , Aspergillus flavus , A. niger and A. fumigatus was achieved (MICs: 31.25, 1.95, 15.62 and 15.62 μg ml -1 , respectively). The cytotoxicity results suggest that bimetallic ZnO@SeO NPs are non-toxic and biomedically safe, evidenced by in vitro anticancer activity against human liver carcinoma (Hep-G2) cell line (with a half-maximal inhibitory concentration (IC50) > 71 μg ml -1 ). The bimetallic ZnO@SeO NPs successfully biosynthesized using PPE showed a high potential for biomedical engineering., Competing Interests: The authors declare that they have no conflict to interests., (This journal is © The Royal Society of Chemistry.)

Fluorobenzoic acids (FBAs) are used as chemical tracers in enhanced oil recovery and reduction in their limit of detection is a crucial issue. GC-MS is a versatile tool to detect and quantify FBAs at very low limits of concentration, but they require esterification prior to analysis by GC-MS. The present article presents a study of the catalytic methyl esterification of fluorinated aromatic carboxylic acids (FBAs) using methanol as methyl source and UiO-66-NH 2 as a heterogeneous catalyst. The reaction time was reduced to 10 hours which is a 58% reduction in time over the traditional BF 3 ·MeOH complex as derivatizing agent. The yield of the esterification reaction was evaluated with respect to the BF 3 -MeOH complex and determined by GC-EI-MS. The catalytic procedure was optimized by the Taguchi model with a 99.99% fit. Good catalytic performance was observed for 23 different isomers of fluorinated aromatic acids showing a relative conversion yield of up to 169.86%, which reduced the detection limit of FBAs up to 2.60 ng mL -1 ., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The photo-Fenton reaction provides an effective strategy for the removal of organic pollution in water environments. However, it remains a great challenge to develop photo-Fenton catalysts with high photocatalytic activity, low catalyst losses and excellent recyclability. In this work, a β-FeOOH/TiO 2 /cellulose nanocomposite aerogel was fabricated as an efficient and convenient heterogeneous catalyst in the photo-Fenton system via in situ synthesis of TiO 2 and β-FeOOH NPs on a cellulose-based aerogel. The cellulose aerogel not only acted as a microreactor to prevent aggregation of particles, but also acted as a supporting material to improve the stability and reusable performance of the catalyst. Meanwhile, the synergy between TiO 2 and β-FeOOH endowed the cellulose-based nanocomposite aerogel with highly efficient photo-Fenton degradation of dyes. As a result, the composite β-FeOOH/TiO 2 /cellulose aerogel displayed high photocatalytic performance. Its removal efficiency of MB reached 97.2% under weak UV light for 65 min. There is no obvious decrease in the catalytic efficiency after 5 cycles, suggesting the stability and recyclability of the composite aerogel. This study provides a novel strategy for the preparation of efficient green heterogeneous catalysts by using renewable resources, and shows composite catalyst processes have great potential in wastewater treatment., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Multifunctional integration is the focus of hydrogel-based flexible sensors, and formation of a dual network (DN) could shed light on the fabrication of hydrogels with multifunctionality and enhanced properties. In this study, a DN hydrogel was fabricated by the self-assembly of herbal molecule glycyrrhizic acid (GA) as the first hydrogel network and subsequent photocrosslinking of methacrylated sodium alginate (SA-MA) to form the second network. Profiting from the good compatibility between the two hydrogel networks, the obtained DN hydrogels with a homogeneous porous microstructure were endowed with remarkably enlarged stretching (114.5%) and compression (74.4%) strains. In addition, they were demonstrated to display excellent bacteriostatic activity (>99.9%) against Escherichia coli and Staphylococcus aureus owing to the synergetic antibacterial effect of GA and SA-MA. The DN hydrogels as strain sensors possessed high sensitivity (GF = 1.39), linear sensing ( R 2 > 0.99), rapid response (180 ms), and good stability (1300 times) for human motion detection. Besides, the DN hydrogels could also be used to conduct pressure sensing such as application of heavy weights and even human pulses. All results suggest that the developed DN hydrogels have great potential in serving as epidermal and implantable flexible sensors for human health monitoring., Competing Interests: The authors declare no conflict of interest., (This journal is © The Royal Society of Chemistry.)

This study explores adsorptive removal measures to shed light on current water treatment innovations for kinetic/isotherm models and their applications to antibiotic pollutants using a broad range of biomass-based adsorbents. The structure, classifications, sources, distribution, and different techniques for the remediation of antibiotics are discussed. Unlike previous studies, a wide range of adsorbents are covered and adsorption of comprehensive classes of antibiotics onto biomass/biochar-based adsorbents are categorized as β-lactam, fluoroquinolone, sulfonamide, tetracycline, macrolides, chloramphenicol, antiseptic additives, glycosamides, reductase inhibitors, and multiple antibiotic systems. This allows for an assessment of their performance and an understanding of current research breakthroughs in applying various adsorbent materials for antibiotic removal. Distinct from other studies in the field, the theoretical basis of different isotherm and kinetics models and the corresponding experimental insights into their applications to antibiotics are discussed extensively, thereby identifying the associated strengths, limitations, and efficacy of kinetics and isotherms for describing the performances of the adsorbents. In addition, we explore the regeneration of adsorbents and the potential applications of the adsorbents in engineering. Lastly, scholars will be able to grasp the present resources employed and the future necessities for antibiotic wastewater remediation., Competing Interests: The authors declare no conflict of interest., (This journal is © The Royal Society of Chemistry.)

Lapindo mud (LM) is a volcanic mud from a natural disaster that occurred 16 years ago in Sidoarjo District, East Java, Indonesia. The high amount of silica in the local materials of LM has been extracted for silica gel synthesis via hydrometallurgy methods, followed by sol-gel methods. The presence of ethanol in the synthesis process generated a unique textural property at different ratios between ethanol and sodium silicate (e/ss). Sol-gel mediated silica gel synthesis exhibited mesoporous properties with an amorphous structure, which is a characteristic of the silica gel. The silica gel exhibits silica nanoparticles over the average diameter of 2.08 nm with a spherical morphology and is connected to form an agglomeration structure. Increasing the e/ss ratio enhanced the amount of the hydroxyl group and the specific surface area ranged from 57 to 103 m 2 g -1 . The moisture adsorption performance of each silica gel showed that the silica gel with an e/ss ratio of 5 : 5 exhibited the highest adsorption capacity measured by conventional gravimetric methods and thermogravimetric analysis of 10.56% and 11.20% g water g silica -1 , respectively. These results indicated that the silica gel with an e/ss ratio has a high number of hydroxyl groups and more surface-active sites, which is beneficial for the adsorption process. The adsorption capacity of the synthesized silica gel is also higher than that of the commercial silica gel, indicating an excellent performance for desiccant applications., Competing Interests: The authors have no competing interests., (This journal is © The Royal Society of Chemistry.)

Amitrole is a non-selective triazole herbicide that is widespread used to control a variety of weeds in agriculture, but it may pollute the environment and do harm to organisms. Thus, it is of critical significance to enlist a low-cost, sensitive, stable and renewable method to detect amitrole. In this paper, electrochemical experiments were carried out using carbon fibers/reduced graphene oxide/cellulose paper electrodes, which demonstrated good electrocatalytic performance for amitrole detection. The electrochemical process of amitrole on the surface of the reduced paper electrode was a quasi-reversible reaction controlled by diffusion. Cyclic voltammetry and the amperometric i - t curve method were used for amitrole determination at a micro molar level and higher-concentration range with the following characteristics: linear range 5 × 10 -6 mol L -1 to 3 × 10 -5 mol L -1 , detection limit 2.44 × 10 -7 mol L -1 . In addition, the relative standard deviation of repeatability is 3.74% and of stability is 4.68%. The reduced paper electrode with high sensitivity, low detection limit, good stability and repeatability provides novel ideas for on-site amitrole detection in food and agriculture., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)

Lignin, one of the main components of lignocellulose, can be used as an alternative to chemical polyols in the production of polyurethane because of its abundant phenolic and alcohol hydroxyls. Traditionally, lignin is directly applied in the preparation of polyurethane; however, modified lignin has been proved to be superior, especially that obtained by the oxypropylation reaction. Therefore, lignopolyol obtained by mild and efficient oxypropylation was utilized in the production of rigid polyurethane foam in this study. Specifically, the effects of the content of lignopolyol on the chemical structure, morphological structure, mechanical properties and thermal stability of the lignin-based rigid polyurethane foam were investigated. It was found that the compressive strength of the rigid polyurethane foam was significantly improved with the addition of lignopolyol compared with that of the pure polyurethane foam, which was attributed to the fact that oxypropylation made lignin into highly branched and functionalized polyols by transforming all phenolic hydroxyls into aliphatic hydroxyls. Moreover, when the molal weight of lignopolyol accounted for 40% of the added polyols, the generated foam showed optimal uniformity and regularity, and the compressive strength reached 0.18 MPa, meeting the requirements of industrial application, below which, the amount of undesired reactions is bound to increase. As a consequence, the added amount of lignopolyol was increased as much as possible on the basis of guaranteeing the desired properties, which was more conducive to realizing the green degradation and economic synthesis of rigid polyurethane foam., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)

The poor mechanical properties of chitosan physical hydrogels seriously hinder their application in the biomedical field. Inspired by the structure of cell tissues, a novel chitosan nanofiber (CSNF)/Hyaluronic acid (HA)/β-glycerophosphate disodium (β-GP) drug-loaded hydrogel was prepared by micro-dissolution and physical crosslinking. The hydrogel has a "Branch-Fruit" structure and exhibits excellent mechanical properties, good biocompatibility and cell-adhesion properties. Human cancer cells (HeLa) can adhere to the hydrogel surface, which might facilitate tumor site-specific administration of drugs. This material also exhibits high pH sensitivity, with which drug release can be triggered under acidic conditions at pH 4.00. The mechanical strength and drug release behavior of this hydrogel can be easily adjusted by varying the CSNF content., Competing Interests: The authors declare no competing financial interest., (This journal is © The Royal Society of Chemistry.)

Biochar is conventionally and widely used for soil amendment or as an adsorbent for water treatment. Nevertheless, the need for transition to renewable materials has resulted in an expansion of biochar for use as a filler for polymer composites. The aim is to enhance the physical, chemical, mechanical and rheological properties of the polymer composite. The reinforcement of biochar into a polymer matrix however is still new, and limited reports are focusing on the effects of biochar towards polymer composite properties. Hence, this review highlights the unique properties of biochar and its effect on the crystallization, thermal, flammability, electrical conductivity, and mechanical properties of polymer composites. This review does not solely summarize recent studies on biochar-polymer-based composites, but also offers insights into a new direction of biochar as a renewable and superior polymer filler in the future., Competing Interests: The authors have no conflict of interest to declare., (This journal is © The Royal Society of Chemistry.)

The prevention of grain storage pests is a universal concern all over the world. It is in high demand to explore novel, safe and green insecticidal techniques to address such concerns. In this work, both raw and calcined diatomite were used as a natural insecticide to remove common grain storage pests with improved lethal effect on the saw-toothed grain beetle. Interestingly, the raw diatomite showed higher insecticidal efficiency than the calcined diatomite, and its associated insecticidal properties and preparation conditions were also optimized through orthogonal tests. The optimal conditions for processing the raw diatomite insecticide were identified as follows: the diatomite dust was 500 mesh ( A 3 ), the temperature was 25 °C ( B 1 ), the relative humidity was 65% ( C 2 ), the diatomite dosage was 20 g m -2 ( D 2 ), the influence factor order was C ≥ D > A > B . The observation of surface morphology indicated that the raw diatomite had a complete, multi hole surface morphology and good adsorption performance, whereas the structure of the calcined diatomite was uncomplete with collapsed pores, resulting in poor adsorption performance. The special pore structure and excellent adsorption capacity of diatomite make the stored grain pests lose water to lethal effect. Acute toxicity and long-term toxicity tests in mice showed that diatomite has no harmful effects on mammals. The findings from our work led to a green and effective approach in producing a highly efficient and safe storage grain insecticide., Competing Interests: The authors declare no competing financial interest., (This journal is © The Royal Society of Chemistry.)

A convenient and sensitive reversible-fluorescence sensing platform for accurate monitoring of high-valence metal ions is still very challenging. As a green kind of fluorescent carbon nanomaterials, carbon dots (CDs) have captured considerable attention because of the stable fluorescence property and low cost. Herein, we fabricated a type of nitrogen-functionalized carbon dots (N-CDs) from CMC as a fluorescent reversible sensing platform for detecting various high-valence metal ions. N-CDs with a mean size of 2.3 nm were obtained and possessed 22.9% quantum yields (QY). A label-free fluorescent probe for detection of high-valence metal ions (Fe 3+ , Cr 6+ , Mn 7+ ) was established via the fluorescence quenching response. Among them, the detection limit (LOD) toward Fe 3+ ions reached 0.8 µM. We have explored the quenching mechanism of N-CDs to explain the valence state-related electron-transfer fluorescence quenching between high-valence metal ions and N-CDs. Moreover, the valence state-related fluorescence quenching phenomenon of N-CDs in aqueous solution could be effectively recovered by introducing a reducing agent (Ti 3+ ). This "turn off-on" fluorescence recovery system of N-CDs could be applied in different applications covering the selective detection of environmental high-valence metal ions and cellular imaging., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Currently, it is challenging to prepare uniform hollow-structured hydrogels with tailorable comprehensive properties. Herein, making full use of the different gelation routes of polyvinyl alcohol (PVA), we propose a distinctive two-stage method for preparing hollow-structured hydrogels, which is to arrange the microstructure of the hydrogel through segmented adjustment. The mechanical properties, macrostructure, and functions of the obtained hollow hydrogel can be easily designed and edited. Specifically, the mechanical properties of the hollow hydrogel can be improved from "soft" to "hard" by changing the preparation conditions. In addition, hollow hydrogels with diverse macrostructures can also be developed through different templates, such as tubes, gloves, and rings. More importantly, the hollow hydrogels can be endowed with conductive, anti-drying, anti-freezing, and photothermal-converting functions due to the great system compatibility of the gel precursor. Benefiting from the advantages of the hollow hydrogel, the conductive gel ring-based bioelectrodes and sensors were developed. Interestingly, the adaptive gel ring-based electronics can stably record the electrophysiological and strain signals of the human body without the help of adhesive tape. This study opens more opportunities for development and applications of other hydrogel-based hollow materials., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

In this study, granular activated carbon (GAC) and Fe-modified granular activated carbon (FeGAC) prepared by ultrasonic impregnation method were added into respective up-flow anaerobic sludge blanket (UASB) reactors to explore their effects on the anammox process start-up. The results showed that the time of anammox system start-up could be reduced from 108 d in R1 (control group) to 94 d in R2 (GAC reactor) and to 83 d in R3 (FeGAC reactor). After 120 days of operation, the nitrogen removal rates (NRR) of all reactors could reach more than 0.8 kg-N m -3 d -1 . Extracellular polymeric substance (EPS) amount, heme c content and the anammox bacterial functional gene copy numbers gradually increased in all reactors with the passage of culture time, and manifested the superiority in R3 especially. High throughput sequencing revealed that Candidatus Kuenenia was the dominant species in all reactors in the end. It was also demonstrated that FeGAC markedly strengthened the growth and aggregation of anammox bacteria, which is promising for the practical application of the anammox process., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

In this study, we prepared chemical staple fibers (CSFs) by plasticizing bleached coniferous pulps (BCPs) with 1-allyl-3-methylimidazolium chloride (AMIMCl) under high temperature and pressure. It became a transparent paper after hot-pressing when the mass ratio of AMIMCl to BCPs was 4 : 5. Interestingly, it could be hot-pressed into a new transparent paper after the transparent paper prepared above was torn into pieces. The morphologies of fibers showed that BCPs could be plasticized with AMIMCl. The glass transition temperature ( T ) occurred in CSFs when the mass ratio of AMIMCl to BCPs was 4 : 5 and the corresponding temperature was 149 °C, which was lower than the initial decomposition temperature, therefore, CSFs could achieve workability to a certain extent. The plasticizing effect of AMIMCl on BCPs was further verified by testing the properties of the paper. The plasticizing effects of 1-butyl-3-methylimidazolium chloride (BMIMCl) and 1-ethyl-3-methylimidazolium acetate (EMIMAc) on BCPs showed the universality of the method for preparing CSFs with AMIMCl.g ) occurred in CSFs when the mass ratio of AMIMCl to BCPs was 4 : 5 and the corresponding temperature was 149 °C, which was lower than the initial decomposition temperature, therefore, CSFs could achieve workability to a certain extent. The plasticizing effect of AMIMCl on BCPs was further verified by testing the properties of the paper. The plasticizing effects of 1-butyl-3-methylimidazolium chloride (BMIMCl) and 1-ethyl-3-methylimidazolium acetate (EMIMAc) on BCPs showed the universality of the method for preparing CSFs with AMIMCl., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The effective and safe capture and storage of radioactive iodine ( 129 I or 131 I) are of significant importance during nuclear waste storage and nuclear energy generation. Herein, a porous silicon-carbon (pSi-C) composite derived from paper mill sludge (PMS) is synthesized and used for rapid iodine capture. The influences of the activator type, the impregnation ratio of the paper mill sludge to the activator, carbonization temperature, and carbonization time on the properties of the pSi-C composite are investigated. The pSi-C composite produced in the presence of ZnCl 2 as the activator and at an impregnation ratio of 1 : 1, a carbonization temperature of 550 °C, and a carbonization time of 90 min has a surface area of 762.13 m 2 g -1 . The as-synthesized pSi-C composite exhibits promising iodine capture performance in terms of superior iodine adsorption capacity ( q t ) of around 250 mg g -1 and rapid equilibrium adsorption with in 15 min. The devised method is environmentally friendly and inexpensive and can easily be employed for the large-scale production of porous silicon-activated carbon composites with excellent iodine capture and storage from iodine-contaminated water., Competing Interests: The authors declare that they have no competing financial interests., (This journal is © The Royal Society of Chemistry.)

Air filter paper with a high filtration efficiency that can remove small-size pollutant particles and toxic gases is vital for human health and the environment. We report a nanofiltration paper that is based on wood fiber filter paper with good mechanical properties and a three-dimensional network structure. The filter paper was prepared by impregnation with multi-walled carbon nanotubes (MWCNTs) and phenol-formaldehyde (PF). The results showed that MWCNTs were present on the surfaces of the fibers and between the pores, which increased the specific surface area of the fibers and enhanced the effective interception of the particles. The optimum impregnation concentration of the MWCNT was 0.1%. Compared with the cellulose fibers (CFs), the average pore diameter of the 0.1% MWCNT-CF filter paper was reduced by 8.05%, the filtration efficiency was increased by 0.64%, and the physical properties were slightly enhanced. After impregnation with PF, the mechanical properties of the air filter paper were significantly enhanced. The PF on the fiber surfaces and at the junction of the fibers covered the MWCNTs. Based on the change in the filter paper properties after impregnation, the optimal filter paper strength index and filtration performance were observed at a solid PF content of 8.4%., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

In this study, several representative deep eutectic solvents (DESs) were designed to evaluate the solubility for alkali lignin (AL). It was found that DESs with lactic acid (LA) as hydrogen bond donors (HBDs) had good solubility for AL, in which lactic acid(LA) : choline chloride(ChCl) 10 : 1 showed excellent solubility with more than 17 wt% under a relatively mild condition of 60 °C. The results of gel permeation chromatography (GPC), FTIR and 1 H and HSQC NMR spectroscopies revealed an important possible dissolution mechanism of AL in LA-ChCl, that is, AL could be depolymerized under the action of LA when dissolved in LA-ChCl. Then, a new connection would form between the phenolic groups on the lignin fragments and ChCl, which is similar to that between ChCl and LA in DES, leading to an increase in the molecule weight of lignin. The new connections could be easily broken under the action of heat (150 °C) or microwave to the redispersion of lignin fragments. The results would provide a theoretic base for the high-value application of lignin in bioresources., Competing Interests: There are no conflicts of interest to declare, (This journal is © The Royal Society of Chemistry.)

Photothermal effects in SiO 2 @Au core-shell nanoparticles have demonstrated great potential in various applications for drug delivery, thermo-photovoltaics and photothermal cancer therapy, etc. However, the photothermal conversion of SiO 2 @Au nanoparticles partially covered by disconnected gold clusters has rarely been investigated systematically. Here, we control the surface morphology of gold clusters on the photothermal conversion performance of SiO 2 @Au core-shell nanoparticles by means of chemically adjusting the synthesis parameters, including amounts of gold salts, pH value and reducing agent. The macroscopic variations of the photothermal heating of different nanoparticle dispersions are significantly influenced by the nanoscale differences of gold cluster morphologies on the silica core. The temperature rise can be enhanced by the strong near-field coupling and collective heating among gold clusters with a relatively uniform distribution on the silica core. A numerical model of the simplified photothermal system is formulated to interpret the physical mechanism of the experimental observation, and shows a similar trend of temperature rise implying a reasonably good agreement with experimental data. Our work opens new possibilities for manipulating the light-to-heat conversion performance of SiO 2 @Au core-shell nanoparticles and potential applications of heat delivery with spatial resolution on the nanoscale., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

In this study, effects of catalyst types, reaction temperatures, reaction times, reaction solvents and ultrasound frequencies were carefully investigated to improve the yields and characteristics of various depolymerization products of organosolv lignin. Generally, both catalyst types and ultrasound frequencies played important roles in promoting lignin depolymerization and reducing char yield. In particular, the yield and distribution of phenolic monomer (PM) products were greatly influenced by pore structure and acidity of the catalyst. The optimal reaction condition was got in isopropanol at 310 °C for 6 h with 30% ultrasound frequency and 50% phosphotungstic acid (PTA)/MCM-41 catalyst. The highest yields of PM, bio-oil, liquid fuels and lignin conversion were reached as 8.63 wt%, 86.89 wt%, 95.52 wt% and 98.54 wt%, respectively. The results showed that ultrasound acoustic cavitation could enhance the depolymerization of lignin, thus greatly enhancing production of liquid fuels. Simultaneously, the hydrogen composition and high heating value of various lignin depolymerization products improved, and the oxygen content decreased, indicating that hydrogenation and/or hydrodeoxygenation happened during the depolymerization process. Finally, we also found that the 50% PTA/MCM-41 catalyst had high stability; it could be reused for up to five cycles without loss of catalytic activity., Competing Interests: The authors declare no competing financial interest., (This journal is © The Royal Society of Chemistry.)

Environmentally friendly cellulose/GO/TiO 2 hydrogel photocatalyst has been successfully fabricated via a green, simple, and one-step method and evaluated as the photocatalyst and adsorbent for the removal of methylene blue (MB). The XRD and FTIR analysis suggested the strong interaction among cellulose, GO and TiO 2 , resulting from the formation of hydrogen bonds. Due to the unique porous structure of cellulose hydrogel and introduction of GO, the cellulose/GO/TiO 2 hydrogel showed superior (degradation ratio ∼ 93%) and reproducible (no significant change during the ten consecutive cycles) performance in the removal of MB under UV light. Consequently, the prepared cellulose/GO/TiO 2 hydrogel can be applied as an eco-friendly, high-performance, reproducible, and stable photocatalyst and adsorbent for the removal of MB. This green hydrogel is a promising candidate for dye wastewater treatment. Moreover, this work is expected to extend the scope of bio-templated synthesis of other nanomaterials for various applications., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

As the most widely used insulator materials in the electrowetting (EW) systems, amorphous fluoropolymers (AFs) provide excellent hydrophobicity, dielectric properties and chemical inertness; however, they suffer from charge trapping during electrowetting with water and the consequent asymmetric phenomenon. In this study, an ultra-thin oil-lubricated AF surface was proposed to release the charge trapping in the dielectric layer and further suppress the polarity-dependent asymmetry during electrowetting. The negative spontaneously trapped charges gathering on the dielectric/water interface with aging time were characterized by various measurements and calculations, which explained the polarity dependence of the asymmetric electrowetting. Approximately symmetric EW curves withstanding water aging were obtained for the oil-lubricated AF surface, confirming the blocking effect on charge trapping induced by the lubricated surface. The improved reversibility of EW with low contact angle hysteresis brought by the oil-lubricated surface was also demonstrated. This study reveals the mechanism behind the asymmetric EW phenomenon and offers an attractive oil-lubricated EW material system for suppressing the charge trapping on the dielectric/water interface, which can significantly improve the manipulation of the EW devices., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

A high monosaccharide conversion rate of hemicellulose in a green solvent and under moderate reaction conditions for industrialization is one of the most important keys in a lignocellulosic biorefinery. The behavior of Populus tomentosa hemicellulose polysaccharides, crystallinity and the furfural formation in the autohydrolysis process under moderate subcritical water conditions (160-180 °C, 0.618-1.002 MPa) were studied. The results have shown that the hemicellulose was converted to corresponding monosaccharides at an ultra-high hydrolysis rate. Factor analysis indicates that the temperature is the most important factor affecting hemicellulose autohydrolysis. When the autohydrolysis temperature increased from 160 to 180 °C for 2 h, the hydrolysis rate of xylose, rhamnose, galactose, mannose, and glucose from hemicellulose increased from 70% to 91%, 71% to 100%, 82% to 95%, 42% to 58%, and 34% to 37%, respectively. Arabinose was completely dissolved in 30 min. The xylose, rhamnose, galactose, and arabinose from hemicellulose could be almost completely removed under the conditions. The hemicellulose removal rate obtained herein exceeded the values reported for most acid, alkali, ionic liquid, or deep eutectic solvent treatments. It is notable that almost all glucose in hemicellulose was dissolved and the glucose in cellulose was partially hydrolyzed. An analysis of the sugar composition and the crystallinity change in the process at 180 °C demonstrate that hydrolysis reaction started to shift from amorphous regions to crystalline regions, due to the partial hydrolysis of crystalline cellulose after 90 min at 180 °C. Overall, these results show that the moderate subcritical water autohydrolysis of hemicellulose in Populus tomentosa may be a potential bio-refinery process., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Oil-in-water food emulsions consisting of natural emulsifiers has been an active field of green scientific inquiry. Here, we extract two types of new hemicellulose-based emulsifiers (H H and H L ) from holocellulose and dewaxed materials of bamboo ( Phyllostachys pubescens ), as well as compare their emulsifying soy oil ability, respectively. The main content of H H is arabinoxylan, while the primary composition in H L is glucan. The emulsifying capacity of these two types of hemicellulose-based emulsifiers are evaluated by droplet size distribution, surface charge and optical microscopy. Since H L possesses higher lignin and protein residual contents, the resultant emulsion exhibits smaller droplets and higher emulsion stability. In comparison, H H emulsifier has almost no emulsifying capacity due to the lack of non-polar groups. This study provides insight into the choice of hemicelluloses-based emulsifiers for the formation of stable oil-in-water food emulsions., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

In this paper, a solution-processed zirconium oxide (ZrO 2 ) dielectric was deposited by spin coating with varying pre-annealing temperatures and post-annealing temperatures. The thermal effect of the pre-annealing and post-annealing process on the structural and electrical properties of ZrO 2 films was investigated. The result shows that the pre-annealing process had a significant impact on the relative porosity and internal stress of ZrO 2 film. A pre-annealing process with a low temperature could not effectively remove the residual solvent, while a high pre-annealing temperature would lead to large internal stress. As for post-annealing temperature, it was found that the post-annealing process can not only reduce internal defects of the ZrO 2 dielectric, but also optimize the interface between the semiconductor and dielectric by lowering the surface defects of the ZrO 2 film. Finally, the TFT with a pre-annealing temperature of 200 °C and post-annealing temperature of 400 °C showed optimized performance, with a mobility of 16.34 cm 2 (V s) -1 , an I on / I off of 2.08 × 10 6 , and a subthreshold swing (SS) of 0.17 V dec -1 ., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

This paper reported a novel method for the determination of total phosphorus (TP) content in soil and sludge by a headspace gas chromatography (HS-GC) method. It was based on a reaction between the soluble phosphate in the digestion solution and calcium oxalate solid to form a calcium phosphate precipitate and release oxalate ions, which can react with permanganate to form carbon dioxide, which was then measured by HS-GC. The results showed the complete conversion of phosphate (meanwhile to free oxalate ions in calcium oxalate) in 15 min at 60 °C. The present method has good repeatability (RSD < 2.6%) and good accuracy (RD < 7.3%) compared to the reference method. Therefore, the present HS-GC method can become a more effective method for determining the TP content in soil and sludge samples., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

In this study, we investigated the effect of liquid viscosity and surface tension for inkjet printing on porous cellulose sheets. We used five model liquids, representing the operational field of an industrial high speed inkjet printer, as specified by Ohnesorge- and Reynolds number. Drops with 30 pl and 120 pl drop size were jetted with a commercial HSI printhead. We printed on four uncoated papers representing the most relevant grades on the market in terms of hydrophobisation and surface treatment. We are presenting a quantitative analysis of viscosity and surface tension on the print outcome, evaluating dot size, liquid penetration (print through) and surface coverage of the printed dots. The most important finding is that for liquids within the jetting window the variation of the liquid viscosity typically has a 2-3 times higher impact on the print outcome than variation of the liquid surface tension. Increased viscosity in all cases reduces dot area, liquid penetration and liquid surface coverage. Surface tension plays a smaller role for liquid spreading and penetration, except for hydrophobised substrates, where both are reduced for higher surface tension. Interestingly, higher surface tension consistently increases liquid surface coverage for all papers and drop sizes. A detailed analysis on the competing effect of dot spreading and liquid penetration is presented, in terms of viscosity, surface tension and surface coverage of the liquid., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

In this study, a graphene-based composite 4HQ-rGO/Cu 2+ was prepared via the supramolecular assembly of graphene nanosheets with 4-hydroxyquinoline (4HQ) and copper(ii) ions. The as-prepared supramolecular assembly exhibited an excellent and enhanced sensing performance towards acetic acid at room-temperature, which was due to the fact that the D-π-A molecules, i.e. 4HQ, were able to accelerate the charge transfer between the graphene nanosheets and 4HQ molecules when acetic acid was attached. In addition, at room temperature, the copper(ii) ions also played a critical role as the main active site for gas adsorption, and thus the as-fabricated sensor exhibited a high response, outstanding selectivity, and ultra-fast response/recovery time. To examine the selectivity of the Cu 2+ ions for the supramolecular assembly, various other transition metal ions such as Mn 2+ , Fe 3+ , Co 2+ , Ni 2+ , Cu 2+ , and Cd 2+ were attached to the 4HQ-rGO assembly, and their acetic sensing performance was determined. Interestingly, the supramolecular assembly with the Cu 2+ ions (4HQ-rGO/Cu 2+ ) exhibited the best sensing performance compared to other metal ion-based 4HQ-rGO materials. Compared with the typical acetic acid gas sensors reported in the literature, it is noteworthy to mention that the as-prepared 4HQ-rGO/Cu 2+ supramolecular assembly exhibited the shortest gas response time (within 5 s) at room temperature. The presented study demonstrates that the as-prepared supramolecular assembly is a promising material as a room temperature acetic acid gas sensor in practical applications., Competing Interests: The authors declare no competing financial interest., (This journal is © The Royal Society of Chemistry.)

Liquid crystal (LC) smart windows with adjustable reflectivity have been gradually applied in green and intelligent building materials for energy saving needs, but their applications are limited by their fundamental defects. In this study, we developed local photo-induced in situ polymerization to rapidly fabricate the infrared reflection microsheets of a cholesteric LC polymer as functional units. With the exception of the LC formula, the photo mask, liquid crystal cell, polymerization inhibitor, and the preparation conditions were specifically managed to control the extent of in situ polymerization, namely the microsheet morphology. The circular, triangular and oval-shaped microsheets were precisely obtained and were slightly bigger than the light hole. This easy, controllable, continuous and recyclable technology is expected to promote the industrialization of a high quality LC smart window with an adjustable reflection band and state., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Herein, thermo-sensitive lignocellulose hydrogels with varying lignin contents were fabricated with N -isopropylacrylamide (NIPAAm) by a semi-interpenetrating polymer network (SIPN) strategy using a LiCl/DMSO solvent system. Soda lignin mixed with the lignocellulose/LiCl/DMSO solution was also used to prepare the composite hydrogels, and the influence of the existential state of lignin on the hydrogel properties was analyzed objectively. The SIPN hydrogels exhibited more favorable mechanical properties due to the physical entanglement of poly-NIPAAm and lignocellulose. The presence of externally added lignin in the composite hydrogels is beneficial for mechanical improvement. Both the mechanical properties and the morphologies of the SIPN hydrogels can be tuned by varying the existential state and content of lignin. Furthermore, the prepared SIPN hydrogels showed rapid conversion from being hydrophilic at 20 °C to being hydrophobic at 45 °C. All SIPN hydrogels exhibited obvious oil absorbency in an oil/water mixture at 45 °C. Moreover, the different lignin existential states in the hydrogels resulted in different lower critical solution temperatures (LCST). This study provides a feasible route to produce reinforced thermo-sensitive hydrogels and develops a method for tailoring the morphology and the absorption properties of hydrogels by controlling the existential state and content of lignin., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The synthesis process of the phenolic resin adhesive was developed in the 19th century, and its excellent environmental resistance and high bonding strength make it one of the main wood adhesives. With the development of industry, phenolic resin adhesive is not only used in plywood, wood processing and laminate, but also in automobile, aerospace, composite materials and other fields. Herein we review the main synthetic processes and latest research progress for phenolic resin adhesives, the capacity distribution of major domestic phenolic resin enterprises, analysis of domestic phenolic resin consumption, import and export volume and price, Chinese plywood production, and the main production and export markets. Furthermore, research and discussion on the commercial application of domestic phenolic resin adhesives in plywood were carried out, which provides a reference for development of better phenolic resin adhesives that meet the development needs of the country, along with quality and economic competitiveness., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Waste newspaper is one of the most common cellulosic materials. Therefore, effective utilization of this commonly available biomass resource to prepare high-value carbon-based solid acid catalysts is an interesting and meaningful task. In this study we propose a new route for waste newspaper valorization, in which sulfonic-acid-functionalized carbon fiber can be directly produced from waste newspaper as a recyclable carbon based solid acid catalyst (WCSA) for the hydrolysis of cellulose. The as-prepared sulfonic-acid-functionalized carbon fiber contained -SO 3 H, -COOH, and phenolic -OH groups and exhibited good catalytic activity for the hydrolysis of cellulose. WCSA prepared under sulfonation conditions at a temperature of 100 °C and for a duration of 10 h has a higher sulfonic acid content. A total reducing sugars (TRS) yield of 58.2% was obtained with a catalyst/microcrystalline cellulose (MCC) ratio of 4 at 150 °C using a reaction time of 6 h. The recycling performance of the WCSA catalyst indicated that the TRS remained almost stable for five cycles during the hydrolysis of cellulose., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

In this research, nanometer size aggregates (clusters) of titanium dioxide (TiO 2 ) quantum dot clusters (QDs) have been successfully prepared via a convenient hydrolysis method at a low temperature (80 °C). Then different amounts (0-5%) of Ag were further decorated on the TiO 2 QDs via dipping and annealing under a nitrogen atmosphere. After Ag decoration, the TiO 2 QD sensing materials were synthesized, and characterization and NH 3 gas sensing performance studies were carried out. Analysis via XRD and EDS was conducted, and the results showed that Ag + ions were successfully reduced to Ag and decorated on the surface of the anatase TiO 2 QDs. Noble metal Ag acted as the sites for adsorbates, catalysts, or promoters during the surface reactions, and as the element improving the thermal stability of the nanostructure. Therefore, the Ag-decorated gas sensor possessed better gas sensing performance than an undecorated gas sensor, and 3% Ag dopant proved to be the optimal amount of addition. The fabricated 3% Ag-decorated TiO 2 QDs gas sensor, compared with the undecorated TiO 2 QDs sensor, displayed a 6-times-higher sensing response at room temperature and demonstrated excellent gas sensing properties toward 10-100 ppm NH 3 gas, good selectivity, gas sensitivity and stability, rapid response/recovery time, and a linear relationship between the response and the target gas concentration. In particular, the excellent performance of the Ag decorated-TiO 2 QDs gas sensor was achieved at room temperature, which suggests the great possibility of a prompt gas sensing response, with the use of paper as a substrate, that requires a low operation temperature., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)

The effect of acetylene black (ACET) as additives on methane production, extracellular polymeric substances (EPS), microbial community structure and methanogenesis pathway during sludge anaerobic digestion (AD) was investigated in this study. The results indicated that the addition of 2 g L -1 ACET resulted in a 44.36% increase in methane accumulation. ACET, which resulted in the increase of EPS and VSS/TSS by 4.71-50.64%, effectively improved the physicochemical properties of anaerobic granular sludge (AnGS). During anaerobic digestion, the high throughput sequencing presented direct evidence that the ACET increased microbial diversity and enriched functional microorganisms such as norank&#95;f&#95;&#95;Synergistaceae , norank&#95;f&#95;&#95;Anaerolineaceae , and unclassified&#95;f&#95;&#95;Clostridiaceae&#95;3 , which can improve the hydrolysis acidification process and the acetotrophic pathway. These results were reaffirmed by applying metagenome inference and gene content inference (16S function prediction). Microscopically, significant enhancement in the AD efficiency can be due to the methanogenesis promoted by the ACET that can construct direct interspecies electron transfer (DIET) between the unclassified&#95;f&#95;&#95;Clostridiaceae&#95;3 , norank&#95;f&#95;&#95;Anaerolineaceae , and Methanosaeta . These results were expected to provide primary research data for improving the performance of anaerobic reactors and the development of microbial fuel cells., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Gastrodin, a bioactive compound extracted from the plant source of Gastrodia elata Blume, has a wide range of therapeutic effects on central nervous system (CNS) diseases, but suffers from poor brain permeability and short half-life in plasma. In this study, fatty acid esters of gastrodin were successfully synthesized by a whole cell-based biocatalytic method. Aspergillus oryzae cells showed different catalytic activities in the organic solvent systems tested. Tetrahydrofuran was confirmed as the most suitable pure organic solvent, with the highest substrate conversion of 98.0%. Addition of ionic liquids (ILs) into pyridine dramatically accelerated the reaction with conversion increased from 5.9% to 84.2%, and also changed the selectivity of the cells, mainly due to the use of IL-containing systems altering cell permeability and contact of the enzymes with solvent molecules possessing different polarities. The ester products were characterized by 13 C-NMR and ESI-MS as gastrodin monoester and diester., Competing Interests: None., (This journal is © The Royal Society of Chemistry.)

Surface-enhanced Raman scattering (SERS) technique has emerged as a potentially powerful tool for the detection of trace amounts of environmental contamination and pollutants such as various antibiotics and their active metabolites in the surface aquatic ecosystem (drinking water). In this study, we report the detection method for ciprofloxacin and norfloxacin analytes, two largely used antibiotics in the world, at a very low detection concentration based on the enrichment and efficient delivery of analytes after the evaporation of the solvent on slippery-SERS substrates. The slippery-SERS substrates were fabricated in a very efficient and cost effective way by simply spin-coating the silicone oil onto the widely used glass slides followed by annealing. The analyte particles with gold nanorods (GNRs) were efficiently delivered to the active site by evaporating the aqueous solvent on the slippery surface via the suppression of the coffee ring effect caused by the smooth contraction motion of the base contact radius of the droplet without any pinning. Thus, the detection limits of ciprofloxacin and norfloxacin analytes were reduced to 0.01 ppm, which is the lowest limit of detection achieved by any SERS technique. Finally, this study suggests that the fabricated silicone oil-coated slippery surface and GNRs based combinational approach for the SERS detection technique might be a powerful strategy for the reliable detection of the aqueous pollutant analytes even at very low concentrations., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

In this study, a dual-wavelength spectroscopic method for rapid determination of organic matter in sludge was developed. The contents of the organic matter were calculated by determining the consumption of potassium dichromate (K 2 Cr 2 O 7 ) based on the production of trivalent chromium ions (Cr 3+ ). Cr 3+ could be determined by subtracting the absorption at 800 nm (spectral interference) from the absorption at 650 nm (only contributed by Cr 3+ ). The results showed that the relative standard deviation in the test was less than 5%. The same set of samples was used and when the content of organic matter was more than 150 g kg -1 , the relative difference between the spectroscopic method and titration method was within 1%. Furthermore, the method does not require calibration based on the standard samples. In conclusion, the present method is simple, reliable, accurate and suitable for application in mass testing for sludge samples., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Two-dimensional (2D) nanosheets are a class of fascinating host material that demonstrates a high specific surface area for the immobilization of functional molecules. Herein, we describe a layered photochromic film using montmorillonite 2D nanosheets immobilized with spiropyran units, which demonstrates a remarkable and reversible photochromic behavior. The synthesis of the layered photochromic film includes the intercalation and exfoliation of montmorillonite powders into 2D nanosheets using a spiropyran-modified surfactant and a subsequent vacuum filtration. The photochromic units of spiropyran-modified quaternary ammonium groups are immobilized on the surface of montmorillonite 2D nanosheets through an electrostatic interaction after exchanging with the native cations in montmorillonite during the intercalation and exfoliation. The photoisomerization of the spiropyran units between closed-ring spiropyran and open-ring merocyanine upon visible/UV irradiation contributes to the photochromic behavior of the layered film. The color contrast between the coloration and decoloration states of photochromic film is optimized by increasing the amount of spiropyran-modified cationic surfactant during the intercalation and exfoliation process. Our layered films with a visual photochromic behavior may promote their applications for optical data storage, optical switching and chemical sensing., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Herein, we report a rapid screening method for evaluating the hydrocarbon contamination in paper samples by headspace gas chromatography (HS-GC). This method was based on conducting the near-complete migratable release of hydrocarbons from a paper matrix to the headspace in 35 min at 98 °C. By programming the GC column temperature, other co-existing volatile organic compounds in the sample can be effectively separated from the migratable hydrocarbons. To simplify the method calibration, the concept of total migratable hydrocarbons was introduced and n -pentadecane was used as the standard hydrocarbon compound in the calibration. The results indicate that the present method offers good precision (the relative standard deviation < 9.8%) and accuracy (recovery between 94.3 and 101%). The present method can be a valuable tool for the quality assessment of total migratable hydrocarbons of paper products, aiming at providing a good guidance for safely using the recycled paper-based materials in various applications., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Poly(3-hydroxybutyrate- co -3-hydroxyvalerate)/polyhedral oligomeric silsesquioxane (PHBV/POSS) hybrids with different POSS contents of 5, 10, 15, 20, 25 and 30 wt% were prepared by solution casting. The composition, crystallization and melting behavior, crystal structure, spherulite morphology, surface morphology, and tensile properties of PHBV/POSS hybrids were characterized by EDS, DSC, FTIR, XRD, HSPOM, AFM and a tensile testing machine. The results showed that POSS was well dispersed in the PHBV matrix. PHBV and POSS crystals coexisted in the hybrids. The crystallinity of pure PHBV was larger than that of PHBV/POSS hybrids. POSS restricted the crystallization of PHBV in PHBV/POSS hybrids. With the increase of POSS content, the crystallinity of PHBV/POSS hybrids decreased from 56.8 (pure PHBV) to 33.6% (PHBV/POSS hybrid with 30 wt%). However, the introduction of POSS did not affect the spherulite morphology of PHBV. The Avrami equation was used to describe the isothermal crystallization kinetics of PHBV/POSS hybrids. The results showed that as the crystallization temperature increased, the crystallization rate became slow. In addition, POSS can improve the tensile properties of PHBV., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

In this study, the effects of chitosan hydrochloride (CTSCL), lysozyme (LZM) and cationic polyacrylamide (CPAM) as conditioners on the dewatering performance of activated sludge were comparatively investigated in terms of the capillary suction time (CST), specific resistance to filtration (SRF) and water content after conditioning and subsequent dewatering. CTSCL showed nearly the same capacity to improve the sludge dewaterability as CPAM, with CTSCL and CPAM conditioning resulting in the SRF of sludge decreasing by 95.82% and 96.15%, CST decreasing by 78.22% and 84.88%, and water content of the dewatered sludge decreasing by 10.84% and 8.5%, respectively. However, LZM conditioning exhibited the best improvement in the dewatering extent, which could decrease the water content of dewatered sludge by 19.84%. In addition, the evolution of the physical properties, extracellular polymeric substance content and composition, and the sludge floc morphology were analyzed to explain the sludge conditioning mechanism. Both CTSCL and CPAM could extrude sludge surface bound water into free water, produce sludge flocs with a larger size and more surface pores and finally improve the sludge filterability. In comparison with chemical flocculants, the conditioning mechanism of LZM was distinctly different, which effectively decomposed cell walls, released the internal bound water beneficial for improving the sludge dewatering extent, while the released organic substances clogged the floc surface, and the high proportion of fine particles in the flocs resulted in poorer filtration., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The difficulties in sludge dewatering are associated with the high organic content, colloidal materials in sludge solids and the high hydrophilicity of extracellular polymeric substances (EPS). Based on the principle of advanced oxidation processes, waste pulping activated sludge was subjected to potassium permanganate (KMnO 4 ) oxidation pretreatment and then the influence and mechanism on sludge dewatering were comprehensively investigated in the present study. At lower KMnO 4 dosage, changes of the physicochemical and rheological characteristics were that: (1) as the sludge disintegration degree increased, the total extractable EPS increased and then the bound water were released; (2) the rheological behavior showed that the yield stress and viscosity decreased while flowability increased and the positive thixotropic behavior weakened; (3) the particle size and microscopic structure were changed insignificantly. These changes resulted in damaging the gel-like environment and making the surface of sludge floc stripped but did not completely induce the floc breakage as a result of KMnO 4 with lower redox potential. Thus, sludge dewaterability was improved with the optimum dosage of 16 g kg -1 dry solid. On the perspective of environmental safety, KMnO 4 conditioning on sludge dewatering is feasible., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

In this work, three-dimensional (3D) aerogels and hydrogels based on lignin-containing arabinoxylan (AX) and cellulose nanofibers (CNF) were prepared. The effects of the CNF and the crosslinking with citric acid (CA) of various contents (1, 3, 5 wt%) were evaluated. All the aerogels possessed highly porous (above 98%) and lightweight structures. The AX-CNF hydrogel with a CA content of 1 wt% revealed a favorable network structure with respect to the swelling ratio; nanofiber addition resulted in a five-fold increase in the degree of swelling (68 g of water per g). The compressive properties were improved when the higher CA content (5 wt%) was used; when combined with CNF, there was a seven-fold enhancement in the compressive strength. The AX-CNF hydrogels were prepared using a green and straightforward method that utilizes sustainable resources efficiently. Therefore, such natural hydrogels could find application potential, for example in the field of soft tissue engineering., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Pretreatments have been successfully used to shorten the HRT of anaerobic digestion (AD) of sewage sludge, but they become ineffective for low-organic sewage sludge, with HRT > 10 days. Herein, a new process using alkaline hydrolysis-anaerobic digestion has been developed to solve this problem. Firstly, maximum organic matter in the sludge was dissolved by strong alkaline hydrolysis (pH > 11) in a two-stage alkaline hydrolysis system (TSAHS). Secondly, only the supernatant of the sludge that contained most of the methane potential was applied for AD. The operational conditions were optimized and the process mechanism was also analyzed. The results showed that under optimum operational conditions, above 19% of the organic matter in the sludge was released into the supernatant after alkaline hydrolysis in TSAHS, and the supernatant for AD achieved a methane production of 392 mL CH 4 per g COD. The process attained a methane production of 0.26 m 3 CH 4 per kg VS and a VS reduction of 43.5%, while the HRT was only 12 h. The advantage of the mechanism was that the alkaline neutralization capacity of the sludge maintained a proper pH value for the supernatant from TSAHS, which benefited subsequent AD. It is concluded that the new process based on the dissolution of organic matter can attain a short digestion time for low-organic sludge., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)