Content Of Hydrophilic Groups Research Articles

Experimental and simulation studies on the improvement of coal dust pollution by an aqueous solution of sodium α-alkenylsulfonate and amino acid-based surfactants

The use of surfactants is crucial for the prevention and control of coal dust pollution in coal mining operation areas, yet there still exist many challenges in the control of coal dust pollution. In this paper, the green biomass-based amino acid surfactant sodium myristoyl glutamate (SMG) and the anionic surfactant sodium α-alkenyl sulfonate (AOS) were selected to investigate the improvement of coal dust wettability by single and binary solutions from the macroscopic and microscopic perspectives. Molecular simulations were used to reveal the microscopic mechanism of the wettability of coal dust by the different solutions. Experimental measurements showed that the contact angle of the AOS + SMG aqueous solution was as low as 13.8° on a coal surface. Coating the coal dust with the AOS + SMG solution reduced the surface tension by 12.02% compared to coating the coal with a single component solution. Additionally, the use of the binary AOS + SMG solution increased the hydrophilic group content in the coating by 11.77% compared to a single component solution, and the linkage between hydrophilic groups was enhanced, which pulls the water molecules to wet the coal dust. These research results should provide a new way to promote more environmentally friendly coal dust pollution control technology.

Ultrasonication Improves the Flotation of Coal Gasification Fine Slag Residue

Coal gasification fine slag (CGFS) is a significant source of solid waste requiring improved treatment methods. This study primarily investigates the mechanism of ultrasonic treatment in optimising flotation-based decarbonization of CGFS and its impact on CGFS modified with surfactants. The objective is to maximise the carbon ash separation effect to support the clean and efficient utilisation of CGFS. Flotation experiments revealed optimal conditions at an ultrasonication power of 180 W for 2 min and a slurry concentration of 60 g/L, resulting in a residual ash content of 82.59%. Particle size analysis, scanning electron microscopy (SEM), and Brunner−Emmet−Teller (BET) measurements demonstrate the efficacy of ultrasound in extracting inorganic minerals from the surface and pores of residual carbon, consequently reducing both pore and particle sizes. Fourier transform infrared spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS) analyses indicate alterations in the surface chemistry of CGFS induced by ultrasound treatment. The content of hydrophilic groups decreased from 31.64% to 29.88%, whereas the COO- group content decreased from 13.13% to 8.43%, consequently enhancing hydrophobicity. Adsorption experiments demonstrate an increase in surfactant adsorption capacity following ultrasonic treatment. Furthermore, ultrasonic treatment facilitates the desorption of surfactants previously adsorbed onto the surfaces of CGFS residue. Therefore, optimal flotation is obtained by applying ultrasonic pretreatment to CGFS before adding flotation chemicals. Upon the addition of Polysorbate (Tween-80), the residual ash content increased 90.17%.

High solid content waterborne polyurethane with high foaming rate to artificial leather: Synthesis and characterization

A type of high solid content waterborne polyurethane (HSWPU) dispersions applied to foamed artificial leathers were designed and prepared by prepolymer method. The solid content of the waterborne polyurethane dispersions could reach 53 %, and the foaming ratio could reach an astonishing 2.50 by adjusting the parameters. The influence of synthesis parameters, including R value (molar ratio of -NCO/-OH), D value (hydrophilic group content), trimethylol propane (TMP) content (degree of crosslinking) and ethylenediamine (EDA) content (it was chain extender) on foaming ratio were investigated. Meanwhile, a series of properties of HSWPU dispersions, films and foamed artificial leathers were introduced in detail. The results demonstrated that R value, TMP content, D value and EDA content synergistically decided the foaming properties of HSWPU dispersions in three aspects: three-dimensional structure, surface tension and polarity, respectively. With optimized parameters of R = 2.0, TMP = 0.4 wt%, DMPA = 3.0 wt% and EDA = 60 wt%, the HSWPU dispersions had good appearance and stability, and the latex particles exhibited excellent water, acid and alkali resistance after films formation. The HSWPU dispersions with high foaming rate without collapsing in the foam-forming process and created uniformly bubble pores. In terms of application properties, the prepared foamed artificial leathers showed admirable air permeability and water vapor transmissions. All results distinctly demonstrate a feasible yet promising paradigm for applying the HSWPU on foamed artificial leathers had great potential applications.

Effect of Low-Temperature Plasma-Modified Carbon Fibers on Impact Load Damage of Low-Density Oil-Well Cement.

After large-scale exploitation of conventional oil and gas resources, most remaining resources are in highly depleted zones, where the fracture pressure of the formations is greatly reduced. Low-density oil-well cement prevents wellbore and formation fractures by reducing annular liquid column pressure and is one of the most commonly used cements in the oil and gas industry. However, cement sheaths made of low-density oil-well cement can be easily damaged due to the impact load generated during the well completion process. Incorporating carbon fibers into the cement matrix can effectively enhance the performance of cement sheaths. To ensure that carbon fibers can be closely combined with the cement matrix, low-temperature plasma modification technology was used in this study to pretreat the fibers. The mechanical properties of low-density oil-well cement incorporated with unmodified or modified carbon fibers were studied in detail under an impact load. The results of X-ray photoelectron spectroscopy revealed that the content of hydrophilic groups on the surface increased from 18.3 to 60.3% after the plasma treatment. The impact test results showed that the peak strengths of the cements cured at 60 °C for 14 days with 0.3% unmodified and modified carbon fibers could reach 37.01 ± 1.7 and 62.27 ± 1.7 MPa, respectively, under the impact load, i.e., an increase of 68.25% after the carbon fibers were treated with low-temperature plasma. Similarly, the absorbed energy increased from 15.59 to 44.31 J, and the energy absorption rate increased from 25.98 to 73.85%. Low-temperature plasma modification provided hydrophilic functional groups on the surface, significantly improving the interfacial bonding between the carbon fibers and cement matrix. The strengthened interaction was beneficial to extending the bearing time under the impact load and demonstrated a positive influence on the mechanical properties related to the impact resistance.

Lignin fractionation towards improved rosin emulsification behavior and advanced liquid packaging board sizing performance

The heterogeneity of lignin, due to its intricate chemical composition and inconsistent molecular weight distribution across various sources, would result in inconsistent materials with unpredictable characteristics, thus presenting a significant obstacle and impeding the advancement of lignin-based products. The need for innovative rosin/lignin-based sizing agents for liquid packaging board (LPB) products has yet to be fulfilled, stimulating ongoing research efforts in this area. Herein, to tackle the urgent challenge posed by the lignin inhomogeneity and its effect on sizing performance, we propose a comprehensive approach for the production of fractionated lignin-modified rosin sizing agents for liquid packaging board (LPB) with improved sizing characteristics. This study first fractionated three lignin components from wheat straw-derived lignin and utilized them as adaptable surfactants in the manufacture of cationic dispersion rosin sizing agents. The resulting agents were analyzed and evaluated for their utilization in LPB sizing process, exhibiting improved homogeneity, molecular weight, and hydrophilic group content. The obtained fractionated lignin-modified rosin sizing agents displayed outstanding sizing performance and desirable stability. Additionally, these agents enhance the mechanical and optical properties of LPB products. This study proposed a novel and valorized approach to apply lignin biomass with a fractionation and sustainable method to prepare series lignin-modified rosin sizing agents and their great potential in liquid packaging board applications.

Effects of ultrasonic and surfactant coupling treatment on the wettability of coal

Coal wettability has an important influence on the permeability of water-injected coal seam. The coal seam water injection effectively improves the ultrasonic excitation effect, and the surfactant can mitigate the water lock effect produced during water injection. To study the effect of ultrasonic and surfactant coupling treatment on the wettability of coal, the ultrasonic excitation fracturing system was used to perform excitation experiments on different coal samples. The coal microscopic properties were determined, and the coal wettability was characterized based on the contact angles. The experimental results demonstrate that the general decrease in the content of hydrophilic groups after the coal was coupled with ultrasonic and surfactant compared to the alkyl polyglycoside (APG) treatment, and the decrease in the content of oxygen-containing functional groups was more obvious; the pore size, pore volume and specific surface area (SSA) of coal all increased to different degrees, especially for pore size and pore volume; under the treatment of ultrasonic or surfactant, the coal wettability was enhanced, while the wettability was further enhanced by the coupling treatment; when ultrasonic was coupled with the surfactant, an advantageous complementary effect could be formed, which improved the final effect of the coupling treatment.

Facile fabrication of SWCNT film-based superhydrophobic cotton fabrics for oil/water separation and self-cleaning

With the increase of oily waste, oil-water separation has become an urgent and difficult task. However, the current challenge is to fabricate such efficient membrane materials for oil-water separation. Herein, superhydrophobic single-walled carbon nanotubes (SWCNTs)/cotton fabric (CF) was prepared via a dry process. In which the ultrathin SWCNT films with a low content of hydrophilic groups were prepared by a facile floating catalyst chemical vapor deposition method and directly deposited on CF without solvent dispersion. The obtained SWCNT@CF was further treated by 1 H,1 H,2 H,2 H-perfluorooctyltriethoxysilane (POTS). Due to the synergistic effect of SWCNTs and POTS, the POTS-modified SWCNT@CF displayed excellent superhydrophobicity with a water contact angle（WCA）of ∼163.3°, and consequently can be further used as a membrane for oil-water separation. These superhydrophobic fabrics have high oil/water separation efficiency (99.2% for dichloromethane/water) and high oil flux (28.71 ×103 L·m−2·h−1 for dichloromethane/water). Even after 25 separation cycles, oil/water separation efficiency and oil flux maintain 98.8% and 25.15 × 103 L·m−2·h−1, respectively. In addition, it exhibits high separation efficiency (∼99%) for water-in-oil emulsion. Moreover, under extreme environmental conditions, the contact angle of the obtained POTS-modified SWCNT/CF was maintained at ∼155°, keeping stable superhydrophobicity. This reported preparation strategy of superhydrophobic fabrics is environmentally friendly, low cost, sustainable, and easy to scale up, thereby exhibiting great potential in practical applications.

A Self-Matting Waterborne Polyurethane Coating for PVC Artificial Leather

A type of polyester-based self-matting waterborne polyurethane (ESMWPU) with an excellent matte effect of 0.8° and transmittance of 78.5% for PVC artificial leather was synthesized. The influence of synthesis parameters, including R value, crosslinking and hydrophilic group content, on coating gloss and transmittance was investigated. Meanwhile, the properties necessary for applying water-based resins to plasticized PVC were detailed. The results demonstrated that R value, crosslinking degree and hydrophilic group content synergistically decided the morphological changes of latex particles during their film-forming process in three aspects: particle stiffness, three-dimensional structure and particle size, respectively. With optimized parameters of R = 1.9, TMP = 2 wt% and DMPA = 1.75 wt%, ESMWPU latex particles stabilized their spherical shapes without collapsing in the film-forming process and created a rough surface, resulting in a matte effect. In terms of application performance, good wetting and adhesion for ESMWPU to a plasticized PVC surface was achieved with a 2 wt% leveling agent load. Moreover, due to the high cohesion energy of ester bonds and intermolecular hydrogen bonds, this type of polyester-based ESMWPU also depicted admirable thermal adhesion resistance. All aforementioned results distinctly demonstrate a feasible yet promising paradigm for applying ESMWPU on PVC artificial leather.

Experimental study on chemical structure and wetting influence of imidazole ionic liquids on coal

Three imidazole ionic liquid solutions were selected to handle coal with distinct degrees of metamorphism to research the influences of cation and anion ions in ionic liquids on functional groups and the relationship between functional groups and coal wettability. The chemical framework of coal was researched by FTIR and the wetting peculiarity of the coal was researched by contact angle meter. FTIR analysis showed that the cation and anion ions in ionic liquids significantly altered the framework of the coal. The contact angle measurement results demonstrated that compared with coal using pure water, the coal handled with ionic liquids showed a smaller contact angle. Finally, the relationship between contact angle and functional group content was analyzed. The results showed that the anions and cations of different ionic liquids can increase the content of hydrophilic groups in coal dust with different metamorphisms, such as OH···O, CO, and CO, and destroy the hydrophobic groups in the dissolved coal structure, such as CH2, CH and the benzene ring 3 substitutions. And 2 % [Emim][BF4] can effectively reduce the coal contact angle and improve the wettability of coal dust. The content of CO and OH···O groups had the greatest correlation with the contact angle, which were 0.845 and 0.754, respectively. By studying the influence of anions and cations in ionic liquids on the content of functional groups in coal, the effect of specific anions and cations on coal structure was further discovered, which provides a theoretical basis for the development of new ionic liquids with specific functions, and provides guiding significance for ionic liquid solutions to improve the wettability of coal and reduce the dust concentration.

An exploration of enhancing thermal stability of leather by hydrophilicity regulation: effect of hydrophilicity of phenolic syntan

Effect of retanning on the thermal stability of leather is eliciting increasing attention. However, the relationship between the hydrophilicity of retanning agents and the heat resistance of leather and the corresponding mechanism remain unclear. Herein, phenolic formaldehyde syntans (PFSs) were selected as models to explore the effect of the hydrophilicity of retanning agents on the thermal stability of retanned leather. The thermal stability of leather was closely correlated to the hydrophilic group content (sulfonation degree) of PFSs. As the sulfonation degree increased, the water absorption rate of PFSs and their retanned leathers decreased, whereas the thermal stability of leather increased. Molecular dynamics simulation results proved that the introduction of PFSs could reduce the binding ability of collagen molecules with water and thus decreased the water molecules around the PFS-treated collagen. These results may provide guidance for the tanners to select retanning agents reasonably to improve the thermal stability of leather.Graphical

High-purity lignin fractions and nanospheres rich in phenolic hydroxyl and carboxyl groups isolated with alkaline deep eutectic solvent from wheat straw

A combined pretreatment based on alkaline deep eutectic solvent (DES) of K2CO3 and glycerol and sequential acid fractionation was developed to extract reactive lignin from wheat straw biomass. This process exhibited excellent purification performance in lignin isolation, and the lignin fractionated at low pH displayed high reactivity, having hydroxyl and carboxyl groups up to 9.60 and 2.52 mmol/g, respectively. Silica was selectively separated and removed during the precipitation stage, avoiding the “silica interference”. Moreover, DES-lignin nanospheres created by self-assembly using lignin fractions obtained by acid precipitation possessed a high zeta potential, large particle size and high content of hydrophilic groups. Overall, the findings related to the dissociation mechanism and fractionation of reactive lignin during alkaline DES pretreatment and the acid sequence precipitation are crucial for facilitating lignin valorization in high-added value products.

A facile and sustainable hygroelectric generator using whole-cell Geobacter sulfurreducens

Hygroelectric generator (HEG) technology based on ambient humidity is a promising self-sustained energy harvesting system, but it usually suffers from the disadvantages of expensive materials, complicated device construction processes, and unfavorable short-term power output. Herein, we propose a facile whole-cell HEG, which was fabricated from an easily prepared film of whole-cell Geobacter sulfurreducens (G.S.) and a low-cost indium tin oxide electrode. The HEG produced an open-circuit voltage of 0.3 V and a load current of 0.3 μA with a power density of 2.5 μW/cm2 that lasted for longer than 2160 h. The performance of HEGs constructed from G.S. nanowires (NWs), whole-cell G.S., and G.S.-without NWs was compared, which indicated that the energy harvesting behavior of the HEG was highly dependent on surface hydrophilicity and the ionization level, as determined by the content of hydrophilic groups in the film. Our results demonstrate a facile and inexpensive whole-cell HEG technology that generates sustainable hygroelectricity from ambient humidity. This development will greatly promote the practical application of hygroelectricity technology.

Reduction of lignin heterogeneity using aqueous two-phase system: A facile and universal “one-step-three-fractions” approach

As the most abundant aromatic biopolymer, lignin presents great potential to produce valuable materials and chemicals. However, its large-scale value-added application is still facing many practical challenges and one of them is the unstable properties caused by lignin heterogeneity. Herein, we developed a novel “one-step-three-fractions” fractionation strategy to reduce lignin heterogeneity using aqueous two-phase system (ATPS) composed of (NH4)2SO4 and ethanol. In contrast to conventional step-wise fractionation processes, the proposed process subdivided heterogeneous lignin into three homogeneous fractions in only one step: the first fraction (F1) dissolved in the ethanol-rich top layer; the second fraction (F2) dissolved in the salt-rich bottom layer and the last fraction (F3) insoluble in both two layers. F2 presented the lowest molecular weight followed by F1 while F3 showed the highest molecular weight. With the increase of molecular weight, the contents of guaiacyl unit and β-O-4 linkage increased while the content of hydrophilic groups (carboxyl and aromatic hydroxyl) decreased significantly. Moreover, the ATPS exhibited satisfactory recyclability and the fractionation approach could be applied to different types/sources of lignin. Consequently, the work indicates that ATPS is a novel and effective way to fractionate lignin and reduce its molecular weight polydispersity and structural heterogeneity in one step.

Experimental investigation on molecular-scale mechanism of wettability alteration induced by supercritical carbon dioxide-water-rock reaction

Wettability is a deciding attribute in enhance oil recovery research, thus plays a vital role in unconventional reservoir development. Previous studies were focused on wettability modulation of the reservoir rocks by changing the properties of fluids. However, the wettability alteration mechanism of tight sandstones remains unclear. In this study, the influence of molecular groups on wettability is discussed by measuring the contact angle of samples from the Upper Triassic Yanchang Formation after being subjected to the supercritical carbon dioxide-water-rock dynamic reaction. The mineral composition of the samples under different reaction times was characterized by XRD. Zeta potential measurements and the Fourier-transform infrared spectroscopy (FTIR) technique were combined to determine the type and amount of molecular groups on the rock surface. Results show that the sample becomes more hydrophilic with the reaction time because of the varied composition of rock minerals induced by the chemical reaction. However, it is not easy to discern the influence of different mineral content on wettability only through the XRD experiment. The Supercritical carbon dioxide - water - rock dynamic reaction reduced the absolute value of zeta potential and weakened the effect of the electrostatic force on wettability, yet increased the content of hydrophilic groups (C–O and CO), and thus reduced the contact angle (altered the wettability towards more water-wet). This study can advance the understanding of the wettability alteration mechanism in tight sandstones and promote the development of carbon dioxide geologic sequestration and enhanced oil recovery technologies by the regulation of wettability.

Hydrophilicity Improvement of Quartz Glass Surface by a Large-Area Atmospheric Pressure Plasma Generator

In this article, experimental study of a device combining the advantages of dielectric barrier discharge (DBD) and atmospheric pressure plasma jet (APPJ) has been presented. This device with a total length of 500 mm was capable of generating stable uniform atmospheric pressure plasma (APP) with a length of 400 mm, which was operated using a 12-kV HV supply and the air flow rate of 20–30 L/min. The plasma spectra were obtained by optical emission spectroscopy (OES), in which N2(C-B) and N2+ can be observed, and the rotational temperature was calculated to be 360 K. The macroscopic temperature was measured by an infrared camera. The result showed that the central temperature was room temperature. In addition, quartz glass substrates were treated by this device. The surface properties of quartz glass were investigated by water contact angle (WCA), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). The results revealed that hydrophilicity and surface roughness of the quartz substrates were gradually increased with increasing treatment time. However, the results of XPS indicated that the content of hydrophilic groups at the surface had a slight change. Therefore, hydrophilicity of quartz glass improved effectively after APP treatment, which was due to the change in surface morphology and the increase in roughness.

Preparation and evaluation of lignite flotation collector derived from waste hot-pot oil

Due to poor hydrophobicity, large amounts of petroleum-based collectors are required for upgrading lignite. In this paper, Waste Hot-pot Oil (WHPO) collectors from the catering industry were prepared via filtration, heating, and catalysis. The catalytic experiment was optimized using the Design-Expert software. The optimum catalytic conditions were found to be a pyrolysis temperature of 85 °C, alcohol-oil ratio of 35:1, catalyst dosage of 2%, and reaction time of 1 h. The Separation Efficiency (SE) of WHPO was 3.04 percentage higher than that of the conventional collector (kerosene), while the ash content of Lignite Surface Treated with WHPO (LWHPO) was 1.14 percentage lower than that of kerosene. Response surface methodology was used to analyse the factors influencing the SE; the effect of the studied factors followed the order catalyst amount > alcohol-to-oil ratio > reaction temperature. GC–MS showed that WHPO contained both long-chain alkyl groups and other ester and hydroxyl groups. XPS tests confirmed that the hydrophobic group (CC, CH) content of LWHPO increased, while its hydrophilic group content (except CO) decreased, demonstrating the improved hydrophobicity of lignite after WHPO treatment. FT-IR analysis indicated that WHPO more effectively decreased the content of hydrophilic groups and increased the content of hydrophobic groups than kerosene. Contact angle (CA) analysis showed WHPO was more conducive to lignite surface hydrophobicity improvement than kerosene. WHPO possessed strong collecting ability and better selectivity, and could be used as an alternative collector for lignite flotation.

Synthesis of a water polyurethane emulsion with high solid content, low viscosity via core–shell method

In this study, the core–shell method was used to prepare water polyurethane (WPU). First, two different prepolymers were synthesized; one contained a hydrophilic group (prepolymer A), whereas the other one had none (prepolymer B). Then, the two prepolymers were mixed at a certain ratio and emulsified to obtain a WPU emulsion. The effect of hydrophilic group content in prepolymer A on the emulsion properties was investigated and compared with the WPU properties prepared via one-pot method. Transmission electron microscopy analysis showed that latex particles with core–shell structures were formed. Results showed that the WPU particle size distribution was narrow. As the content of hydrophilic groups in prepolymer A increased, the emulsion solid content decreased, and the viscosity increased, which was inconducive for the preparation of a WPU with high solid content and low viscosity. When the prepolymer A/prepolymer B mass ratio was 1.2:1, and the hydrophilic group content in prepolymer A was 3%, a WPU with good stability with the solid content of 55.3% and the viscosity of 187.4 mPa s was prepared via core–shell method.

Synthesis of self‐matting waterborne polyurethane coatings with excellent transmittance

AbstractThe effect of structural factors, including the type of diisocyanates and glycols, degree of crosslinking, hard‐segment content, crystallinity and hydrophilic group content, on optical properties of waterborne polyurethane (WPU) was investigated. Based on the relationship between structure and properties, a series of self‐matting WPUs with excellent transmittance were synthesized. Results demonstrated that refractive index of constituent groups was an important factor to influence the optical properties of coatings. For multiphase polyurethane, aromatic ring, ester bond, NHCOO and urea groups with high refractive index could decrease the matting effect and transmittance. Higher hard‐segment content resulting in an increase of the number of NHCOO or urea bonds also decreased the matting effect and transmittance. The aggregation structure of WPU was another factor to influence the optical properties of coatings. Crystalline soft and hard segment domains could decrease the transmittance and matting effect, whilst non‐crystalline segments, pendent groups and crosslinking destroyed the regularity or crystallinity of macromolecules, behaving as an auxiliary function to improve the transmittance. The particle size of WPU was of great importance for the matting effect. Smaller particle size (<5.0 µm) would endow the coating with a smoother surface and higher reflected light ratio, and thus the expected matting effect was hard to be achieved. A larger particle size could improve the matting effect but impart to the coating a coarse surface and hand‐feel. When the 2,2‐bis(hydroxymethyl)propionic acid content was 1.6 wt%, spherical particles with a size distribution of 7–8 µm were aggregated on the coating surface, giving the coating an excellent matting effect and hand‐feel. © 2017 Society of Chemical Industry

Green manure as part of organic management cycle: Effects on changes in organic matter characteristics across the soil profile

Green manure (GM) cultivation and incorporation (i.e., GM management) may change soil organic matter (SOM) composition and the agroecosystem functioning. However, the understanding of GM effects on SOM composition, specifically in deeper soil layers, is limited. The objectives of this study were to examine the effects of GM management (as part of an organic agriculture practice), following two years of various doses of compost application, on the changes in SOM and water-extractable organic matter (WEOM) compositional characteristics up to a soil depth of 60cm. Soil samples from a two years compost amended field that was subsequently subjected to GM management were taken in four intervals to a depth of 60cm (0–5, 5–15, 15–30 and 30–60cm) and characterized for organic C content and SOM composition, by FT-IR transmission. Characterization of WEOM included excitation-emission matrices (EEMs) of fluorescence, UV absorbance and dissolved organic C (DOC) measurements. The response of SOM and WEOM to GM management resulted in some opposite trends. The SOM became rather aromatic, with aliphatic CH-containing structures contributing to a greater extent to SOM composition at deeper layers following GM management. By contrast, GM management resulted in (i) a substantial increase in dissolved organic C concentration, (ii) WEOM becoming enriched by hydrophilic aliphatic organic compounds, and (iii) aromatic and fluorescent components increasingly being found at deeper soil layers and hydrophilic aliphatic components at the surface soil. Fluorescent portion of WEOM became enriched by relatively less biodegradable and weaker-soil adsorbing humic-like components; this enrichment increased in deeper soil layers. The effects of past compost application rates on the changes in SOM and WEOM characteristics were either non-significant or negative. In the latter case, an increase in application rate decreased the changes in SOM content of hydrophilic groups and in the fractions of fluorescent components in WEOM. Growing and incorporating plant biomass may mask, at least on a short time scale, the effects of earlier compost applications on changes in SOM and WEOM compositional characteristics.

Preparation of waterborne polyurethane with outstanding fluorescence properties and programmable emission intensity

AbstractThe hard segment content and hydrophilic group content of a fluorescent waterborne polyurethane (FWPU) were used to optimize the polymer structure which can influence the fluorescence properties. The synthesis of FWPU was based on 2,2′‐((4‐([3,3′:6′,2″‐terpyridine]‐4′‐yl)phenyl)azanediyl)diethanol (TPPDA) as fluorophore. The structure of FWPU was characterized using Fourier transform infrared and 1H NMR spectroscopies, and the polymer molecular weight and polydispersity were measured using gel permeation chromatography. The relationship between fluorescence properties and FWPU structure was studied using luminescence spectrometry. Compared to TPPDA, the maximum emission wavelength of FWPU showed a hypsochromic shift, and the fluorescence emission intensity and quantum yield of FWPU were increased obviously. Moreover, increasing the hard segment content led to an enhancement of the fluorescence lifetime of FWPU, and to the fluorescence intensity increasing at first and then decreasing. The fluorescence emission intensity and quantum yield of FWPU were increased nearly 11 and 7 times, respectively, compared to TPPDA when the hard segment content was 65%. With an increase of hydrophilic group content, the fluorescence emission intensity of FWPU increased. The fluorescence emission intensity of FWPU exhibited a response to pH, which facilitated its employment as a fluorescence probe. FWPU with excellent solid fluorescence is very suitable for processing into optical devices, with increasing hard segment content and hydrophilic group content both enhancing the solid fluorescence emission intensity of FWPU. © 2016 Society of Chemical Industry