Active Functional Groups Research Articles

Kinetic properties of non-caking coal spontaneous combustion by evolution of its functional groups

Coal spontaneous combustion (CSC) continues to generate huge economic losses and considerable casualties. Thew aim of this study is to further reveal the evolution of microstructures and coal spontaneous combustion mechanisms during natural oxidation. Coal samples with known CSC tendencies were selected to explore their microstructure and the characteristics of their reaction kinetics. This information is of great benefit to mine safety engineers and risk management professionals. Proper characterisation of risk leads to improved early warning detection, and the possibility of CSC retardant materials. A low-metamorphic type, non-caking coal sample was obtained from a Mengcun Coal Mine, and the relative content of the active functional groups and evolution of the key active groups were examined as temperature varied. Fourier transform infrared spectroscopy (FTIR) and the Coats-Redfern and Achar calculus methods were used to determine the reaction kinetics of the key active groups during CSC. The most probable mechanisms were determined, and the spontaneous combustion kinetic reaction mechanism was derived. Initial analysis of the sample revealed multiple active groups, active nuclear substances, a high calorific value, and a strong oxidative ability. There were a large number of oxygen containing functional groups and activity was high, due to the high intermolecular hydrogen bond content, and the apparent activation energy for ignition was low. Within the reaction, the aliphatic hydrocarbons were relatively stable; they had the largest apparent activation energy and were the least reactive. Methylene was the most important group consumed by aliphatic hydrocarbons in the CSC process. The reaction mechanism of the various groups were determined via Avrami-Erofeev equation. The large number of active groups produced and consumed was best described by the three-dimensional Ginstling-Brounshtein model.

Study on the Coal-Oxygen Intrinsic Reaction at Low Temperature by the Subtraction Method.

Coal oxidation involves complex physical and chemical processes as well as many reaction pathways. The subtraction method was used to investigate the law of the coal-oxygen intrinsic reaction at low temperatures. The subtraction method is to subtract the characteristic curve of the coal reaction in N2 from the characteristic curve of coal oxidation in air, which can remove the influence of pyrolysis reaction, water evaporation, and gas desorption on coal low-temperature oxidation, and ultimately obtain the coal-oxygen intrinsic reaction curve under the pure oxidation pathway. To reveal the internal relationship of the coal-oxygen intrinsic reaction between the release of gas products and the conversion of active functional groups, a temperature-programmed system was used to analyze the law of index gas products. Furthermore, Fourier infrared spectroscopy was used to analyze the conversion of active functional groups in the low-temperature reaction process of coal. The findings revealed that the coal-oxygen intrinsic reaction obtained through subtraction played a significant role in the release of gas and the conversion of aliphatic hydrocarbons in the overall process of the coal low-temperature reaction. However, the alterations in the N2 atmosphere were relatively weak. The gas release of CO and CO2 gradually increased with increasing temperature, as did the concentration of oxygen-containing functional groups, and there was a positive correlation between them.

The study of removal chromium (VI) ions from aqueous solution by bimetallic ZnO/FeO nanocomposite with Siltstone: Isotherm, kinetics and reusability

In this study, nanocomposites of Baghanwala Siltstone (BSS) with ZnO (BSS/ZnO), FeO (BSS/FeO), and BSS/ZnO/FeO were successfully prepared for the removal of hexavalent chromium [(Cr (VI)] from aqueous solutions via a batch adsorption process. The characterization studies by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX) found successful synthesis of the composites and demonstrated the occurrence of different active functional groups that played an active role in Cr ion adsorption. The effect of Cr initial concentrations (25–100 mg/L), adsorbent dose (0.5–2 g/L), pH (2–8), and contact time (0–160 min) on Cr remediation from contaminated water was examined. The order of Cr ion removal was BSS/ZnO/FeO (77-87%) > BSS/ZnO (74-83%) > BSS/FeO (71-77%) > BSS (68-74%). The as-synthesized BSS/ZnO/FeO led to successful Cr removal (87%) at a 25 mg/L Cr concentration at pH 4.0. The Cr ion adsorption by the BSS/ZnO/FeO nanocomposite was well explained by the Langmuir adsorption isotherm model (R2 > 0.99), while the kinetic experimental data was well fitted with the pseudo-second-order model (R2 > 0.99). Among the as-synthesized adsorbents, the BSS/ZnO/FeO nanocomposite showed excellent stability and reusability in seven sorption cycles. The results showed that the as-synthesized BSS/ZnO/FeO nanocomposite had the greatest adsorption potential for removing Cr ions from contaminated water.

Antimony(V) removal from water within ferrihydrite transformation: Influence of humic acid

Antimony (Sb), a widely distributed heavy metal pollutant, poses a formidable threat to human health and the delicate ecological environment. Anthropogenic activities such as mining, industrial processes and the widespread use of Sb-containing products aggravate the toxicity and potential risks of Sb to the environment. The mobility and fate of Sb(V) in the water environment is affected by ferrihydrite (Fhy) transformation and humic acid (HA). However, the key role of HA on Sb(V) removal in the transformation of iron minerals remains unclear. In this study, the transformation of Fhy into goethite was significantly inhibited as a result of HA structural coating, while active functional groups of HA enhanced the combination with iron minerals and Sb(V) under acidic conditions. Residual Sb(V) concentration in water was less than 5 µg/L, which meets the United States Environmental Protection Agency (USEPA) recommended Sb concentration of 6 µg/L. Under alkaline conditions, the dissociation of HA provided more negative charges for the surface of transformed hematite and magnetite. Due to the stronger electrostatic repulsion and steric effects of HA, further removal of Sb(V) was limited. This work provided multiple secondary mineralization pathways of Fhy under the impact of HA and mechanistic insights into the removal process of Sb(V), which could contribute meaningful information regarding the interaction between Sb(V) and iron oxyhydroxides.

Preparation and properties of tea polyphenol nanofoamed gel for preventing coal spontaneous combustion

The current technologies employed to prevent the spontaneous combustion of coal, such as grouting, inert gas, retardants, gels and foams have the disadvantages of high pollution, easy failure at high temperature, and high cost. In this study, in order to develop an environmentally friendly, efficient and low-cost composite gel material to inhibit coal spontaneous combustion, tea polyphenols were added to the gel for grafting, while nanomaterial halloysite nanotubes were introduced for intercalation reaction. Finally, sodium bicarbonate and acetic acid were used as foaming agents to produce tea polyphenol nanofoaming gels. The microscopic characterization of the composite gel was studied using X-ray diffraction experiments and scanning electron microscopy. Experiments on physical properties such as fluidity, thermal stability and adhesion were also carried out. In addition, fire performance studies such as thermogravimetric experiments, oxidation kinetic analysis, infrared spectroscopy of gas products, analysis of the change law of active functional groups and crossing-point temperature analysis were completed. The results show that composite gel renders the activity of active functional groups inert, which inhibits coal spontaneous combustion, while it can cover the surface of coal and plug the fissures efficiently. Therefore, it is an ideal material to inhibit the spontaneous combustion of coal.

Recent Advances in MXenes Based Composites as Photocatalysts: Synthesis, Properties and Photocatalytic Removal of Organic Contaminants from Wastewater

AbstractMXene has indeed gained significant attention in recent years as a promising photocatalyst for various applications, including photocatalytic degradation of pollutants. MXene possesses several unique physical and chemical properties that make it suitable for such applications, including its uniform planar structure, strong metal conductivity, effective functional groups, and numerous derivatives. These properties contribute to the excellent photodegradation performance and long‐term stability exhibited by MXene‐based photocatalysts compared to other photocatalysts. MXene‐based composites, which are formed by incorporating MXene with other materials, demonstrate even better photodegradation activity due to their abundant active sites and porous structure. One crucial factor influencing the photodegradation performance of MXene‐based photocatalysts is the presence of active functional groups on the surface of MXene. These functional groups play a significant role in the photocatalytic process and contribute to the overall efficiency of the catalyst. To provide a broader understanding of MXene‐based photocatalysts, the physicochemical properties of MXene are briefly described in this review. This includes its structural characteristics, electrical conductivity, and the presence of functional groups. This review also investigates the physical and chemical synthesis routes for preparing MXene, both in its natural state and as composites with other materials. These synthesis methods are essential for tailoring the properties of MXene‐based photocatalysts to meet specific requirements. Finally, the review discusses future work and challenges in MXene‐based photocatalysis. This field holds great promise for addressing environmental concerns and improving the degradation of organic compounds. However, further research is needed to optimize the synthesis methods, enhance the photocatalytic efficiency, and explore the practical applications of MXene‐based photocatalysts.

One-Pot Synthesis of Nitrogen-Doped Graphene Quantum Dots and Their Applications in Bioimaging and Detecting Copper Ions in Living Cells.

Two natural carbon sources, glutamic acid and tyrosine, were used to fabricate strong green emission nitrogen-doped graphene quantum dots (N-GQDs) with the one-pot pyrolysis method. The morphology of the prepared GQDs has been characterized by high-resolution transmission electron microscopy, showing a well-displayed crystalline structure with a lattice spacing of 0.262 nm. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy were used to analyze the surface functional groups and elemental composition, suggesting that the N-GQDs have active carboxylic and amino functional groups. Meanwhile, photoluminescence and ultraviolet-visible (UV-vis) spectroscopy were used to evaluate the optical properties of GQDs; the prepared N-GQDs show an excitation-dependent fluorescence behavior with a maximum excitation/emission wavelength at 460/522 nm, respectively. N-GQDs showed good photostability and the fluorescence intensity quenched about 10% after irradiating 2800 s in the experiment of time kinetic analysis. The MTT assay was utilized to assess the viability of N-GQDs; good biocompatibility with a relatively high quantum yield of 12% demonstrated the potential for serving as bioimaging agents. Besides, the selectivity study on metal ions indicates that the N-GQDs could be used in Cu2+ detection. The linear range is from 0.1 to 10 μM with a limit of detection of 0.06 μM. Overall, these proposed N-GQDs with one-pot synthesis showed their promising potential in cell imaging and Cu2+ monitoring applications involved in the biological environment.

Emerging two-dimensional (2D) MXene-based nanostructured materials: Synthesis strategies, properties, and applications as efficient pseudo-supercapacitors

Supercapacitors, which are essential for addressing modern energy challenges, possess outstanding energy storage capabilities without requiring manual maintenance. However, their low energy density and capacity limit their applicability for electrode materials. Recently, two-dimensional materials (2D), and particularly 2D transition metal carbonitrides (MXenes) have attracted considerable interest for developing energy storage devices because of their large specific surface area and fast ion-transport pathways. MXenes mainly comprise a transition metal (M) layer, carbon and/or nitrogen (X) layer, and active functional groups exterior to the layer. Metallic properties of the M layer offer excellent pseudocapacitance characteristics, while X layer is characterized by abundant active sites and conductivity similar to that of graphene. Compared with conventional materials, the existence of various functional groups on the surface of MXenes endows them with stronger hydrophilicity and higher wettability in aqueous electrolytes, which, combined with their diverse frame structures and functional group combinations, significantly augment their applicability for energy storage devices. Therefore, it is necessary to summarize and analyze the research results on MXenses. This review addresses the applications of MXenes in energy storage supercapacitors along with current challenges and solutions including intercalation, doping, surface modification methods, and heterogeneous structures. Finally, the prominent contemporary research trends are comparatively discussed to promote research and development in this field in the near future.

Enhanced removal performance of magnesium-modified biochar for cadmium in wastewaters: Role of active functional groups, processes, and mechanisms

In this study, a series of biochar products with different active functional groups were developed by one-pot coprecipitation method, including magnesium-modified biochar (MgBC) and functional group-grafted MgBC (Cys@MgBC, Try@MgBC, and Glu@MgBC), for effective adsorption of cadmium (Cd(II)) from wastewaters. These biochars exhibited excellent removal performance for Cd(II), particularly Cys@MgBC, whose maximum Cd(II) adsorption capacity reached 223.7 mg g−1. The highly active and weakly crystalline Mg could adsorb Cd(II) through precipitation and ion exchange, which was further promoted by the introduced functional groups through complexation and precipitation. After 120 d of natural process, the immobilization efficiency of Cd(II) by Cys@MgBC, Try@MgBC, and Glu@MgBC was still maintained at 98.7%, 95.2%, and 82.7% respectively. This study proposes and clarifies the complexation mechanism of functional group-grafted Mg-modified biochar for heavy metals, providing new insights into the practical application of these biochars.

Microstructure evolution and higher-molecular-weight gas emission during the low temperature oxidation of coal

The higher-molecular-weight gases (HMWGs) released from coal oxidation carry a wealth of information on the mechanism of coal spontaneous combustion. To explore the formation process of HMWGs, the emission of HMWGs and the evolution of active functional groups during coal oxidation were tested using gas chromatography and in-situ FTIR, and the relationship between them was further analyzed using grey relational analysis. It was found that the concentration of most HMWGs changed regularly with the increase in temperature and showed a significant correlation with oxygen concentration. As the temperature increased, the content of alkyl groups changed little at first and then decreased by more than 40%. The content of oxygen-containing functional groups increased gradually by 2–3 times. The production of straight-chain alkanes correlated most strongly with alkyl groups compared to other active groups. While branched alkanes, benzene, aldehydes and ketones showed a higher correlation with the increase of oxygen-containing functional groups. It indicated that the decrease of alkyl groups and the formation of aldehyde groups contributed to the emission of hydrocarbon HMWG. The formation pathways of benzene, aldehydes and ketone during coal oxidation need to be further investigated and verified.

Self-diffusion of aromatic compounds in the carbon tetrachloride – acetone binary system. NMR experiment and MD simulation

In this work, we studied the influence of the structure of molecules of aromatic compounds (methylparaben (MP), propylparaben (PP), syringic acid (SA), gallic acid (GA), protocatechualdehide (PAL), p-coumaric acid (p-CA), and caffeic acid (CA)) on their molecular association and self-diffusion in the binary carbon tetrachloride – acetone solvent. The self-diffusion coefficients of PAL, SA, and GA in the binary carbon tetrachloride – acetone‑d6 solvent were measured by the pulsed gradient spin-echo nuclear magnetic resonance (PGSE NMR) method at temperatures of 288, 298, and 308 K. The data obtained at 298 K were also compared with the data on the self-diffusion coefficients of MP, PP, CFA, and p-CA in the binary solvent available in the literature. According to the presented data, the self-diffusion coefficients of all the substances under consideration become greater with an increase in the acetone‑d6 concentration and decrease in the MP > PAL > PP > p-CA > SA > CA > GA series of compounds. Quantitative assessment of the degree of influence of molecular association on solute self-diffusion was carried out within the framework of a method based on the ratio of the self-diffusion coefficient of a solute to the self-diffusion coefficient of its monomers. The study shows that the degree of influence of molecular association of the solute on its self-diffusion is determined by the number and type of active functional groups in the structure of the solute molecules (MP < PP < PAL < SA < p-CA < CA < GA), but does not depend on the composition of the binary solvent. According to the results of molecular dynamics (MD) simulation, this effect correlates with the increase in the degree of self-association of solutes and decrease in the degree of solute – acetone heteroassociation observed when the carbon tetrachloride concentration becomes higher. This effect is also responsible for the similar concentration dependencies of the self-diffusion coefficients of active and inert compounds.

A thermodynamic framework for bulk–surface partitioning in finite-volume mixed organic–inorganic aerosol particles and cloud droplets

Abstract. Atmospheric aerosol particles and their interactions with clouds are among the largest sources of uncertainty in global climate modeling. Aerosol particles in the ultrafine size range with diameters less than 100 nm have very high surface-area-to-volume ratios, with a substantial fraction of molecules occupying the air–droplet interface. The partitioning of surface-active species between the interior bulk of a droplet and the interface with the surrounding air plays a large role in the physicochemical properties of a particle and in the activation of ultrafine particles, especially those of less than 50 nm diameter, into cloud droplets. In this work, a novel and thermodynamically rigorous treatment of bulk–surface equilibrium partitioning is developed through the use of a framework based on the Aerosol Inorganic–Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) model in combination with a finite-depth Guggenheim interface region on spherical, finite-volume droplets. We outline our numerical implementation of the resulting modified Butler equation, including accounting for challenging extreme cases when certain compounds have very limited solubility in either the surface or the bulk phase. This model, which uses a single, physically constrained interface thickness parameter, is capable of predicting the size-dependent surface tension of complex multicomponent solutions containing organic and inorganic species. We explore the impacts of coupled surface tension changes and changes in bulk–surface partitioning coefficients for aerosol particles ranging in diameters from several micrometers to as small as 10 nm and across atmospherically relevant relative humidity ranges. The treatment of bulk–surface equilibrium leads to deviations from classical cloud droplet activation behavior as modeled by simplified treatments of the Köhler equation that do not account for bulk–surface partitioning. The treatments for bulk–surface partitioning laid out in this work, when applied to the Köhler equation, are in agreement with measured critical supersaturations of a range of different systems. However, we also find that challenges remain in accurately modeling the growth behavior of certain systems containing small dicarboxylic acids, especially in a predictive manner. Furthermore, it was determined that the thickness of the interfacial phase is a sensitive parameter in this treatment; however, constraining it to a meaningful range allows for predictive modeling of aerosol particle activation into cloud droplets, including cases with consideration of co-condensation of semivolatile organics.

Facile Fabrication of Fluorescent Cellulose with Aggregation‐Induced Emission Characteristic in a CO2 Switchable Solvent

AbstractFabrication of fluorescent cellulose with aggregation‐induced emission (AIE) characteristics is usually achieved by grafting tetraphenylethylene (TPE) to the cellulose backbone using TPE derivatives with highly active functional groups such as carboxylic, isothiocyanate, and alkynyl groups. However, besides the complicated synthetic routes of these TPE derivatives, conversion of hydroxyl groups in the cellulose chain to more reactive groups such as amine or azide groups is usually involved, and the resulting products have a degree of substitution (DS) of TPE lower than 0.08. Herein, a facile one‐pot strategy for the grafting of a TPE group to the cellulose backbone with high DS of up to 0.22 in a CO2 switchable solvent under mild reaction conditions is reported. The hydroxyl groups in the cellulose are in situ converted to cellulose carbonate intermediately during the dissolution step. Subsequently, nucleophilic substitution between the intermediate and a halogenated TPE derivative with bromine atom as leaving group is carried out to achieve the effective grafting of TPE. The synthetic route for this promising TPE derivative is much more convenient than those of TPE derivatives reported in previous studies. This work suggests a new and facile pathway for the synthesis of high‐emission fluorescent cellulose with AIE functionality.

Compost-derived humic and fulvic acid coupling with Shewanella oneidensis MR-1 for the bioreduction of Cr(Ⅵ)

The compost-derived humic acids (HA) and fulvic acids (FA) contain abundant active functional groups with strong redox capacity, which can function as an electron shuttles for promoting the reduction of heavy metals, thus changing the form of the pollutants in the environment and reducing their toxicity. Therefore, in this study, UV–Vis, FTIR, 3D-EEM, electrochemical analysis were applied to study the spectral characteristics and electron transfer capacity (ETC) of HA and FA. Upon analysis, the results showed an increasing trend of ETC and humification degree (SUVA254) for both HA and FA during composting. However, the aromatic degree (SUVA280) of HA was higher than FA. After 7 days of culture, 37.95% of Cr (Ⅵ) was reduced by Shewanella oneidensis MR-1 (MR-1) alone. Whereas, only if HA or FA existed, the diminution of Cr (Ⅵ) reached 37.43% and 40.55%, respectively. However, the removal rate of Cr (Ⅵ) by HA/MR-1 and FA/MR-1 increased to 95.82% and 93.84% respectively. It indicated that HA and FA acted as electron shuttles, mediating the transfer of electrons between MR-1 and the final electron acceptor, effectively facilitating the bioreduction of Cr (Ⅵ) to Cr (Ⅲ) and also determined via correlation analysis. This study suggested compost-derived HA and FA coupling with MR-1 exhibited excellent performance for the bioreduction of Cr (Ⅵ) to Cr (Ⅲ).

Concurrent Dual-Contrast Enhancement Using Fe3O4 Nanoparticles to Achieve a CEST Signal Controllability.

Traditional T2 magnetic resonance imaging (MRI) contrast agents have defects inherent to negative contrast agents, while chemical exchange saturation transfer (CEST) contrast agents can quantify substances at trace concentrations. After reaching a certain concentration, iron-based contrast agents can "shut down" CEST signals. The application range of T2 contrast agents can be widened through a combination of CEST and T2 contrast agents, which has promising application prospects. The purpose of this study is to develop a T2 MRI negative contrast agent with a controllable size and to explore the feasibility of dual contrast enhancement by combining T2 with CEST contrast agents. The study was carried out in vitro with HCT-116 human colon cancer cells. A GE SIGNA Pioneer 3.0 T medical MRI scanner was used to acquire CEST images with different saturation radio-frequency powers (1.25/2.5/3.75/5 μT) by 2D spin echo-echo planar imaging (SE-EPI). Magnetic resonance image compilation (MAGiC) was acquired by a multidynamic multiecho 2D fast spin-echo sequence. The feasibility of this dual-contrast enhancement method was assessed by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, dynamic light scattering, ζ potential analysis, inductively coupled plasma, X-ray photoelectron spectroscopy, X-ray powder diffraction, vibrating-sample magnetometry, MRI, and a Cell Counting Kit-8 assay. The association between the transverse relaxation rate r2 and the pH of the iron-based contrast agents was analyzed by linear fitting, and the linear relationship between the CEST effect in different B1 fields and pH was analyzed by the ratio method. Fe3O4 nanoparticles (NPs) with a mean particle size of 82.6 ± 22.4 nm were prepared by a classical process, and their surface was successfully modified with -OH active functional groups. They exhibited self-aggregation in an acidic environment. The CEST effect was enhanced as the B1 field increased, and an in vitro pH map was successfully plotted using the ratio method. Fe3O4 NPs could stably serve as reference agents at different pH values. At a concentration of 30 μg/mL, Fe3O4 NPs "shut down" the CEST signals, but when the concentration of Fe3O4 NPs was less than 10 μg/mL, the two contrast agents coexisted. The prepared Fe3O4 NPs had almost no toxicity, and when their concentration rose to 200 μg/mL at pH 6.5 or 7.4, they did not reach the half-maximum inhibitory concentration (IC50). Fe3O4 magnetic NPs with a controllable size and no toxicity were successfully synthesized. By combining Fe3O4 NPs with a CEST contrast agent, the two contrast agents could be imaged simultaneously; at higher concentrations, the iron-based contrast agent "shut down" the CEST signal. An in vitro pH map was successfully plotted by the ratio method. CEST signal inhibition can be used to realize the pH mapping of solid tumors and the identification of tumor active components, thus providing a new imaging method for tumor efficacy evaluation.

Controllable synthesis of lignin nanoparticles with antibacterial activity and analysis of its antibacterial mechanism

As a kind of polyphenol substance, lignin is considered to have good biological activity and certain antibacterial properties. However, it is difficult to be applied because of its uneven molecular weight and difficulty in separation. In this study, by way of fractionation and antisolvent, we obtained lignin fractions with different molecular weight. Moreover, we increased the content of active functional groups and regulated microstructure of lignin, thereby increased lignin's antibacterial property. The classification of chemical components and the control of particle morphology also provided convenience for the exploration of lignin's antibacterial mechanism. The results showed that acetone with high hydrogen bonding ability could collect lignin with different molecular weights and increase the content of phenolic hydroxyl groups, up to 31.2 %. By adjusting the ratio of water/solvent (v/v) and stirring rate during the process of antisolvent, lignin nanoparticles (sphere 40–300 nm) with regular shape and uniform size can be obtained. Through observing the distribution of lignin nanoparticles in vivo and in vitro after co-incubation for different time, it could be found that lignin nanoparticles firstly damage structural integrity of bacterial cells externally, and then are swallowed into cells to affect their protein synthesis, which constitutes a dynamic antibacterial process.

SYNTHESIS AND PHOTOCHEMICAL PROPERTIES OF NOVEL AZOQUINOLINE CONTAINING POLYMERS

The development of modern technologies are constantly requires seeking new low-cost, efficient materials and establish new technical methods for application these materials. Synthesis of polymers with predicted and expected properties on the one hand and using specific features of interaction light with photoactive fragments in polymers, on the other hand, opens new prospects of application for new materials based on these polymers. The side chain methacrylic polymers with different active functional group have been well studied and widely applied in many fields, such as optoelectronics, nonlinear optics, optical storage materials, biochemicals, and medicine.&#x0D; The present work focused on synthesis new azostyrylcontaining methacrylic monomers and copolymers with methylmetacrylate (MMA) based on these monomers. The pre­sent study is a first reported notice of the synthesis and photochemical properties of methacrylic polymers with 6-azo-phenylquinoline frag­ments in side chain. Moreover in this work the features of syntheses have been described in detail for monomers and polymers based on new azocompounds. Absorption spectroscopic properties for new quinoline polymers with azo fragment were investigated with UV-Vi­sible spectrophotometry in THF solutions. All studi­ed polymers show a strong absorption band in the range of 300–375 nm resulting from π-π* electronic transition and a weak absorption band in the range of 400–490 nm assigned to n-π* transitions. Electron donating and electron withdrawing substituents at quinoline moity of azo-quinoline polymer solutions lead to bathochromic shift of the π-π*absorption band which agrees well with the result of work. We found that this red-shift increases with an increase of electron donating strength of the substituent as well as with an increase of electron withdrawing strength of the substituent. Based on of the result achieved we can suppose that irradiation of polymers with azo fragment lead to photoinduced trans-cis-isomerization.&#x0D; From the obtained and presented results one can conclude that novel quinoline polymers with azo fragment can be considered as promising materials for applications requiring photosensitivity in certain of range of wavelength.

Analysis of natural photocatalysts derived from spartina alterniflora with superior removal performance of pollutant

Spartina alterniflora, as an invasive alien species, has been studied in terms of its potential use in immobilization and synergistic photocatalysis against dye contaminants for the first time. Microscopic characterization and Fourier transform infrared (FTIR) spectroscopy results confirmed the presence of abundant 3D wormhole-like pore structures and active functional groups (-OH, –NH2, CO, Si–O–Si). Moreover, the existence of SiO2 was connected the metal oxides with polar groups, which could proceed entire reaction procedure subsequently. Transition metal oxides (such as Fe2O3, TiO2, MnO2 and NiO) contained in photocatalysts might effectively promote the organics decomposition by the visible light excitation. The highest dye removal efficiency of 92.03% could be reached with the addition of 0.02 g photocatalyst. The capture experiment confirmed that the h+ was the dominant active substance during the photocatalytic degradation process. Density functional theory (DFT) calculations verified that the functional groups (-COOH, –OH and –NH2) were exceptional adsorption sites for catalyst, and the calculated adsorption energy were all negative with the order of SRHH-NH2 (−2.712688 eV) < SRHH-OH (−2.075601 eV) < SRHH-COOH (−1.283141 eV), which confirmed that interface interaction effectively bound cationic dyes through the formation of hydrogen bonds at the catalysts-water interface, further accelerating the reaction rate of the entire photocatalytic reduction of dye molecules. Therefore, this work provides a feasible synthesis of natural photocatalysts using solid waste, which suggests excellent adsorption and photocatalysis properties for the treatment of organic industrial pollutant.

Mercury removal performance and mechanism of biochar co-modified with HNO3 and NH4Br under oxy-combustion atmosphere

ABSTRACT In order to meet the demand for mercury removal in the oxy-combustion atmosphere, a new mercury adsorbent was prepared by using rice husk char as raw material and co-modification of acid and halogen. The experimental results indicate that the specific surface area of the combined modified char is smaller than those modified by HNO3 and NH4Br alone, but it has better mercury removal performance. X-ray photoelectron spectroscopy (XPS) analysis shows that the co-modification can effectively promote the formation of C-O* and C-Br. The high activity of Br will induce the Hg0 adsorption, while C-O* will convert the easily decomposed HgBr2 into more stable HgO, which may be the reason why the combined modified char maintains high mercury removal efficiency. When the reaction temperature reaches 150°C, the mercury removal efficiency of RHC (Br+N) is almost 100%. Both above and below the optimum reaction temperature will affect the activity of chemical functional groups and inhibit mercury removal. According to the density functional theory (DFT) results, the addition of O and Br atoms can stably combine with the carbonaceous surface to form covalent compounds (C=O, C-Br), both of which can induce the charge transfer of surrounding C atoms, which makes the C atoms have stronger electronegativity and easier to chemically adsorb Hg0.

Progress in the Graphene Oxide-Based Composite Coatings for Anticorrosion of Metal Materials

Graphene oxide (GO), derived from the two-dimensional nanosheet graphene, has received unprecedented attention in the field of metal corrosion protection owing to its excellent barrier performance and various active functional groups. In this review, the protection mechanism “labyrinth effect” of composite coatings against metal corrosion was demonstrated systematically. The origination, structure and properties of GO were also analyzed. Their poor dispersion in polymer and tendency to aggregate as nanofillers in composite coatings are the main limitations during application of the coating fillers. In addition, a comprehensive overview on the perspectives of the surface modification of GO and the multi-functionalization of the composite coatings based on GO were given in particular. Green modification methods, reasonable arrangement of GO sheets in composites and development of multi-functional coatings remain challenges in current studies and should be a focus in the future development of GO-based anticorrosive coatings. This review is of value to researchers interested in the design and application of GO in corrosion protection coatings.