Phosphorus/Bromine Synergism Improved the Flame Retardancy of Polyethylene Terephthalate Foams.

Polyethylene terephthalate (PET) foams have the characteristics of being lightweight and high strength, as well as offering good heat resistance, minimal water absorption, etc., and they have been widely used in the wind power field. In addition, they are being promisingly applied in automotive, rail, marine, construction, and other related fields. Therefore, the flame retardancy(FR) of PET foams is an issue that requires investigation. The addition of flame retardants would affect the chain extension reaction, viscoelasticity, and foamability of PET. In this study, zinc diethyl hypophosphite (ZDP) and decabromodiphenylethane (DBDPE) were used to form a synergistic FR system, in which ZDP is an acid source and DBDPE is a gas source, and both of them synergistically produced an expanded carbon layer to improve the flame retardancy of PET foams. The ratio of ZDP and DBDPE is crucial for the carbon yield and the expansion and thermal stability of the char layers. At the ZDP/DBDPE ratios of 9/3 and 7/5, the thickness of the char layers is about 3-4 mm, the limiting oxygen index (LOI) values of FR modified PET are 32.7% and 33.6%, respectively, and the vertical combustion tests both reached the V-0 level. As for the extruded phosphorous/bromine synergism FR PET foams, ZDP/DBDPE ratios of 3:1 and 2:1 were applied. As a result, the vertical combustion grade of foamed specimens could still reach V-0 grade, and the LOI values are all over 27%, reaching the refractory grade.

The Resource Utilization of Poplar Leaves for CO2 Adsorption.

Every late autumn, fluttering poplar leaves scatter throughout the campus and city streets. In this work, poplar leaves were used as the raw material, while H3PO4 and KOH were used as activators and urea was used as the nitrogen source to prepare biomass based-activated carbons (ACs) to capture CO2. The pore structures, functional groups and morphology, and desorption performance of the prepared ACs were characterized; the CO2 adsorption, regeneration, and kinetics were also evaluated. The results showed that H3PO4 and urea obviously promoted the development of pore structures and pyrrole nitrogen (N-5), while KOH and urea were more conductive to the formation of hydroxyl (-OH) and ether (C-O) functional groups. At optimal operating conditions, the CO2 adsorption capacity of H3PO4- and KOH-activated poplar leaves after urea treatment reached 4.07 and 3.85 mmol/g, respectively, at room temperature; both showed stable regenerative behaviour after ten adsorption-desorption cycles.

Effect of Additives on CO2 Adsorption of Polyethylene Polyamine-Loaded MCM-41.

Organic amine-modified mesoporous carriers are considered potential CO2 sorbents, in which the CO2 adsorption performance was limited by the agglomeration and volatility of liquid amines. In this study, four additives of ether compounds were separately coimpregnated with polyethylene polyamine (PEPA) into MCM-41 to prepare the composite chemisorbents for CO2 adsorption. The textural pore properties, surface functional groups and elemental contents of N for MCM-41 before and after functionalization were characterized; the effects of the type and amount of additives, adsorption temperature and influent velocity on CO2 adsorption were investigated; the amine efficiency was calculated; and the adsorption kinetics and regeneration for the optimized sorbent were studied. For 40 wt.% PEPA-loaded MCM-41, the CO2 adsorption capacity and amine efficiency at 60 °C were 1.34 mmol/g and 0.18 mol CO2/mol N, when the influent velocity of the simulated flue gas was 30 mL/min, which reached 1.81 mmol/g and 0.23 mol CO2/mol N after coimpregnating 10 wt.% of 2-propoxyethanol (1E). The maximum adsorption capacity of 2.16 mmol/g appeared when the influent velocity of the simulated flue gas was 20 mL/min. In addition, the additive of 1E improved the regeneration and kinetics of PEPA-loaded MCM-41, and the CO2 adsorption process showed multiple adsorption routes.

Morphology and Compressive Properties of Extruded Polyethylene Terephthalate Foam.

The cell structure and compressive properties of extruded polyethylene terephthalate (PET) foam with different densities were studied. The die of the PET foaming extruder is a special multi-hole breaker plate, which results in a honeycomb-shaped foam block. The SEM analysis showed that the aspect ratio and cell wall thickness of the strand border is greater than that of the strand body. The cells are elongated and stronger in the extruding direction, and the foam anisotropy of the structure and compressive properties decrease with increasing density. The compression results show typical stress-strain curves even though the extruded PET foam is composed of multiple foamed strands. The compression properties of PET foam vary in each of the three directions, with the best performing direction (i.e., extrusion direction) showing stretch-dominated structures, while the other two directions show bending-dominated structures. Foam mechanics models based on both rectangular and elongated Kelvin cell geometries were considered to predict the compressive properties of PET foams in terms of relative density, structure anisotropy, and the properties of the raw polymer. The results show that the modulus and strength anisotropy of PET foam can be reasonably predicted by the rectangular cell model, but more accurate predictions were obtained with an appropriately assumed elongated Kelvin model.

Increased risk of colorectal adenomas with metabolic-associated fatty liver disease components.

BACKGROUND: Metabolic (dysfunction)-associated fatty liver disease is the most common liver disease related to various metabolic disorders. Colorectal adenomas are related to metabolic dysregulation. Despite the proposed association between non-alcoholic fatty liver disease and colorectal adenomas, the influence of metabolic-associated fatty liver disease on colorectal adenomas has yet to be investigated. Our study investigates the relationship between metabolic-associated fatty liver disease and colorectal adenomas and evaluates the predictive value of fatty liver index for colorectal adenomas. METHODS: A retrospective cross-sectional study was conducted on 650 inpatients at Qinghai Provincial People's Hospital. All participants underwent colonoscopy, abdominal ultrasound or CT, relevant laboratory tests, and physical examinations to ascertain baseline characteristics and overall health status. Multivariate logistic regression analysis examined the relationship between metabolic-associated fatty liver disease and colorectal adenomas. Lastly, the ability to identify, accuracy, and clinical applicability of predicting colorectal adenomas through fatty liver index were assessed using receiver operating characteristic curve area under the curve, calibration curve, and decision curve analysis. RESULT: In both the colorectal adenomas and control groups, the prevalence of metabolic-associated fatty liver disease was 62.1 % and 35.7 %, respectively. Multivariate analysis indicates that metabolic-associated fatty liver disease was independently correlated with an increased risk of colorectal adenomas (OR, 1.565; 95 % CI, 1.057-2.319; P < 0.05). Further analysis revealed that the risk of colorectal adenomas increased with an increasing quantity of metabolic components in metabolic-associated fatty liver disease (Ptrend < 0.001). The area under the curve of the fatty liver index predictive model was 0.838, with a 95 % CI of 0.807-0.869. The calibration curve indicated excellent agreement, and the decision curve analysis revealed a higher net benefit. CONCLUSION: The risk of colorectal adenomas was associated with metabolic-associated fatty liver disease, and the risk of developing colorectal adenomas increased with the presence of more metabolic-associated fatty liver disease metabolic components. Furthermore, fatty liver index served as a predictive indicator for screening colorectal adenomas.

Efficient oxidation of benzyl alcohol into benzaldehyde catalyzed by graphene oxide and reduced graphene oxide supported bimetallic Au-Sn catalysts.

A series of bimetallic and monometallic catalysts comprising Au and Sn nanoparticles loaded on graphene oxide (GO) and reduced graphene oxide (rGO) were prepared using three distinct techniques: two-step immobilization, co-immobilization, and immobilization. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), energy dispersive X-ray (EDX), and Inductively-coupled plasma optical emission spectroscopy (ICP-OES) were used to characterize the chemical and physical properties of prepared Au-Sn bimetallic and Au or Sn monometallic nanocatalysts. The catalytic performance of the prepared nanocatalysts was evaluated in the selective oxidation of benzyl alcohol (BzOH) to benzaldehyde (BzH) using O2 as an oxidizing agent under moderate conditions. To obtain the optimal BzH yield, the experimental conditions and parameters, including the effects of the reaction time, temperature, pressure, and solvent type on BzOH oxidation, were optimized. Under optimal reaction conditions, bimetallic Au-Sn nanoparticles supported on GO (AuSn/GO-TS, 49.3%) produced a greater yield of BzH than the AuSn/rGO-TS catalysts (35.5%). The Au-Sn bimetallic catalysts were more active than the monometallic catalysts. AuSn/GO-TS and AuSn/rGO-TS prepared by the two-step immobilization method were more active than AuSn/GO-CoIM and AuSn/rGO-CoIM prepared by co-immobilization. In addition, the AuSn/GO-TS and AuSn/rGO-TS catalysts were easily separated from the mixture by centrifugation and reused at least four times without reducing the yield of BzH. These properties make Au-Sn bimetallic nanoparticles supported on GO and rGO particularly attractive for the environmentally friendly synthesis of benzaldehyde.

Study on Chain Extension Blending Modification and Foaming Behavior of Thermoplastic Polyamide Elastomer.

In order to improve the melt foaming properties of thermoplastic polyamide elastomers and reduce the shrinkage rate of foamed materials, acid anhydride chain extenders SMA (styrene maleic anhydride copolymer) are used in this paper to in situ reactive blending thermoplastic polyamide elastomers (TPAE) and polyamide 6 (PA6). The rheological and crystalline properties of the modified samples were characterized by a rotational rheometer and differential scanning calorimeter, and the melt batch foaming experiment with CO2 as the foaming agent was carried out. The results showed that the melting enthalpy of modified TPAE reduced with the addition of content of PA6, which implied that the crystallinity of the hard phase of the system was depressed. Nevertheless, the reduction of crystallinity was beneficial to improve the penetration of gas and reduce the effect of the pressure difference inside and outside the cell on foam shrinkage. Additionally, the microcross-linked structure formed with the increase of PA6 content enhanced the storage modulus of modified TPAE, which could accelerate recovery of strain. The foaming temperature zone and recovery performance of all modified TPAE samples were significantly improved. The overall shrinkage rate was reduced to less than 10%, the maximum expansion ratio could reach 11-13 times with a more complete and uniform cell structure, and the resilience was improved by about 12%.

Development of Low-Cost Porous Carbons through Alkali Activation of Crop Waste for CO2 Capture.

To achieve the "double carbon" (carbon peak and carbon neutrality) target, low-cost CO2 capture at large CO2 emission points is of great importance, during which the development of low-cost CO2 sorbents will play a key role. Here, we chose peanut shells (P) from crop waste as the raw material and KOH and K2CO3 as activators to prepare porous carbons by a simple one-step activation method. Interestingly, the porous carbon showed a good adsorption capacity of 2.41 mmol/g for 15% CO2 when the mass ratio of K2CO3 to P and the activation time were only 0.5 and 0.5 h, respectively, and the adsorption capacity remained at 98.76% after 10 adsorption-desorption cycle regenerations. The characterization results suggested that the activated peanut shell-based porous carbons were mainly microporous and partly mesoporous, and hydroxyl (O-H), ether (C-O), and pyrrolic nitrogen (N-5) functional groups that promoted CO2 adsorption were formed during activation. In conclusion, KOH- and K2CO3-activated P, especially K2CO3-activated P, showed good CO2 adsorption and regeneration performance. In addition, not only the use of a small amount of the activator but also the raw material of crop waste reduces the sorbent preparation costs and CO2 capture costs.

The development of activated carbon from corncob for CO2 capture.

The accumulation and incineration of crop waste pollutes the environment and releases a large amount of CO2. In this study, corncob crop waste was directly activated using solid KOH in an inert atmosphere to prepare porous activated carbon (AC) to capture CO2, and to introduce N-containing functional groups that favour CO2 adsorption, urea was mixed with corncob and KOH to prepare N-doped AC. The physical and chemical properties of the AC were characterized, and the effects of the mass ratio of KOH and urea to corncob, the activation temperature and time as well as regeneration were investigated to explore the optimal preparation process. The pores in the AC are mainly micropores, with the specific surface area and pore volume reaching 926.07 m2 g-1 and 0.40 cm3 g-1 for KOH-activated corncob and 1096.70 m2 g-1 and 0.48 cm3 g-1 after N-doping; the C-O plus O-H ratio and the -NH- ratio, which favour CO2 adsorption in N-doped AC were 6.04 and 1.92%, respectively. The maximum adsorption capacities for KOH-activated corncob before and after N-doping were 3.49 and 4.58 mmol g-1, respectively, at 20 °C and remained at 3.44 and 4.52 mmol g-1 after ten regenerations. The prepared corncob-based AC showed good application prospects for CO2 capture.

Comparative Study of Pd-Ni Bimetallic Catalysts Supported on UiO-66 and UiO-66-NH2 in Selective 1,3-Butadiene Hydrogenation.

Selective hydrogenation of 1,3-butadiene (BD) is regarded as the most promising route for removing BD from butene streams. Bimetallic Pd-Ni catalysts with changed Pd/Ni molar ratios and monometallic Pd catalysts were synthesized using two differently structured metal-organic framework supports: UiO-66 and UiO-66-NH2. The effects of the structure of support and the molar ratio of Pd/Ni on the catalytic property of selective BD hydrogenation were studied. The Pd-Ni bimetallic supported catalysts, PdNi/UiO-66 (1:1) and PdNi/UiO-66-NH2 (1:1), exhibited fine catalytic property at low temperature. Compared with UiO-66, UiO-66-NH2 with a certain number of alkaline sites could reduce the catalytic activity for the BD hydrogenation reaction. However, the alkaline environment of UiO-66-NH2 is helpful to improve the butene selectivity. PdNi/UiO-66-NH2 (1:1) catalyst presented better stability than PdNi/UiO-66 (1:1) under the reaction conditions, caused by the strong interaction between the -NH2 groups of UiO-66-NH2 and PdNi NPs. Moreover, the PdNi/UiO-66-NH2 (1:1) catalyst presented good reproducibility in the hydrogenation of BD. These findings afford a beneficial guidance for the design and preparation of efficient catalysts for selective BD hydrogenation.

MIL-100(Fe) Supported Pt-Co Nanoparticles as Active and Selective Heterogeneous Catalysts for Hydrogenation of 1,3-Butadiene.

Superior catalytic performance for selective 1,3-butadiene (1,3-BD) hydrogenation can usually be achieved with supported bimetallic catalysts. In this work, Pt-Co nanoparticles and Pt nanoparticles supported on metal-organic framework MIL-100(Fe) catalysts (MIL=Materials of Institut Lavoisier, PtCo/MIL-100(Fe) and Pt/MIL-100(Fe)) were synthesized via a simple impregnation reduction method, and their catalytic performance was investigated for the hydrogenation of 1,3-BD. Pt1Co1/MIL-100(Fe) presented better catalytic performance than Pt/MIL-100(Fe), with significantly enhanced total butene selectivity. Moreover, the secondary hydrogenation of butenes was effectively inhibited after doping with Co. The Pt1Co1/MIL-100(Fe) catalyst displayed good stability in the 1,3-BD hydrogenation reaction. No significant catalyst deactivation was observed during 9 h of hydrogenation, but its catalytic activity gradually reduces for the next 17 h. Carbon deposition on Pt1Co1/MIL-100(Fe) is the reason for its deactivation in 1,3-BD hydrogenation reaction. The spent Pt1Co1/MIL-100(Fe) catalyst could be regenerated at 200 °C, and regenerated catalysts displayed the similar 1,3-BD conversion and butene selectivity with fresh catalysts. Moreover, the rate-determining step of this reaction was hydrogen dissociation. The outstanding activity and total butene selectivity of the Pt1Co1/MIL-100(Fe) catalyst illustrate that Pt-Co bimetallic catalysts are an ideal alternative for replacing mono-noble-metal-based catalysts in selective 1,3-BD hydrogenation reactions.

Enhancement of Hydrothermal Stability and CO2 Adsorption of Mg-MOF-74/MCF Composites.

Hierarchical porous composite Mg-MOF-74/MCFs were successfully synthesized using a simple and facile method under in situ solvothermal conditions. Textural structures and morphologies of the composites were characterized by X-ray diffraction (XRD), N2 adsorption-desorption isotherms, and scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The results demonstrate that a large amount of nanosized Mg-MOF-74 particles is incorporated into the pores of mesocellular siliceous foams (MCFs) without remarkable aggregation and the composites possess microporous and mesoporous characteristics of both components. In addition, CO2 adsorption properties of the composites were tested in a fixed bed with/without hydrothermal treatment. The total CO2 adsorption capacities were calculated by breakthrough curves. The CO2 adsorption capacity of the composites reaches 1.68 mmol/g, which is smaller than that of pristine Mg-MOF-74. However, the total CO2 adsorption capacity of the composites after hydrothermal treatment reaches 2.66 mmol/g, which is larger than that of Mg-MOF-74 (2.39 mmol/g) under the same condition. XRD patterns and SEM images of the composites demonstrate that the hydrothermal stability and CO2 adsorption performance of the composites were improved compared with those of pristine Mg-MOF-74 after hydrothermal treatment.

Rational Design of Monodisperse Mesoporous Silica Nanoparticles for Phytase Immobilization.

Monodisperse mesoporous silica nanoparticles (MMSNs) with fractal structures were synthesized via a facile, one-pot, surfactant-free process under the well-known Stüber synthesis condition. It was characterized by scanning electron microscope, transmission electron microscopy, and N2 adsorption-desorption isotherms. Phytase was immobilized on the MMSNs by physical adsorption. The enzyme loading capacity, activity, and release profile were measured by a faster and more reliable assay method, which was based on the hydrolysis of para-nitrophenylphosphate. The results show that the fractal structures have an important influence on the phytase capacity, and the releasing results also illustrated that phytase immobilized on MMSNs possessed the smallest releasing amounts under acidic conditions (pH = 3).

The dynamic CO2 adsorption of polyethylene polyamine-loaded MCM-41 before and after methoxypolyethylene glycol codispersion.

To reduce the cost of CO2 capture, polyethylene polyamine (PEPA), with a high amino density and relatively low price, was loaded into MCM-41 to prepare solid sorbents for CO2 capture from flue gases. In addition, methoxypolyethylene glycol (MPEG) was codispersed and coimpregnated with PEPA to prepare composite sorbents. The pore structures, surface functional groups, adsorption and regeneration properties for the sorbents were measured and characterized. When CO2 concentration is 15%, for 30, 40 and 50 wt% PEPA-loaded MCM-41, the equilibrium adsorption capacities were respectively determined to be 1.15, 1.47 and 1.66 mmol g-1 at 60 °C; for 30 wt% PEPA and 20 wt% MPEG, 40 wt% PEPA and 10 wt% MPEG, and 50 wt% PEPA and 5 wt% MPEG codispersed MCM-41, the equilibrium adsorption capacities were respectively determined to be 1.97, 2.22 and 2.25 mmol g-1 at 60 °C; the breakthrough and equilibrium adsorption capacities for 50 wt% PEPA and 5 wt% MPEG codispersed MCM-41 respectively reached 2.01 and 2.39 mmol g-1 at 50 °C, all values showed a significant increase compared to PEPA-modified MCM-41. After 10 regenerations, the equilibrium adsorption capacity for codispersed MCM-41 was reduced by 5.0%, with the regeneration performance being better than that of PEPA-loaded MCM-41, which was reduced by 7.8%. The CO2-TPD results indicated that the mutual interactions between PEPA and MPEG might change basic sites in MCM-41, thereby facilitating active site exposure and CO2 adsorption.

Anchorage of Au3+ into Modified Isoreticular Metal-Organic Framework-3 as a Heterogeneous Catalyst for the Synthesis of Propargylamines.

Postsynthetic modification of metal-organic framework is a general and practical approach to access MOF-based catalysts bearing multiple active sites. The isoreticular metal-organic framework-3 (IRMOF-3) was modified with lactic acid through condensation reaction of the carboxyl group of lactic acid and amino group present in IRMOF-3 frameworks. Au3+ was subsequently anchored onto the metal-organic framework IRMOF-3 using postsynthetic modification. The synthezized IRMOF-3-LA-Au (LA = lactic acid) was characterized by powder X-ray diffraction, N2 adsorption-desorption, infrared spectroscopy, liquid-state nuclear magnetic resonance, thermogravimetric analysis, H2-temperature programmed reduction, transmission electro microscopy, and inductively coupled plasma-optical emission spectrometry. IRMOF-3-LA-Au acted as an efficient heterogeneous catalyst in the synthesis of propargylamines by three-component coupling reaction of aldehyde, alkyne, and amine. Moreover, the catalyst is applicable to various substituted substrates, including aromatic and aliphatic aldehydes, alkyl- and aryl-substituted terminal alkynes, and alicyclic amines. In addition, the catalyst can be easily separated from the mixture and can be reused for four consecutive cycles.

Phase transition of silica in the TMB-P123-H2O-TEOS quadru-component system: a feasible route to different mesostructured materials.

Various siliceous structures were obtained using a nonionic block copolymer (Pluronic P123) surfactant and trimethylbenzene (TMB) as a hydrophobic additive by hydrolysis and condensation of tetraethoxysilane (TEOS) in a sol-gel process. The resultant materials were characterized by small-angle X-ray diffraction (SAXRD), nitrogen adsorption analysis, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results revealed the structure transformation from hexagonal structure (HEX) to multilamellar vesicles (MLVs) and then to mesocellular foams (MCFs) in the TMB-P123-H2O-TEOS quadru-component system. The morphology of the mesoporous silica was mainly controlled by the mass ratio of TMB/P123 resulted from the increasing volume of the hydrophobic chain of micelle of P123 that caused by more amount of TMB dissolved in the PPO segment of polymer. The fact that the occurrence of rod-like particles with curved ends and the coexistence of the MLVs and the HEX structure indicates that the MLVs are developed from the ends of HEX structures, rather than formed by a direct cooperative self-assembly mechanism. Further increasing of packing parameter of surfactant resulted from TMB addition transforms lamellar micelles to reversed micelles, leading to the formation of MCFs.