Water-resistant Ability Research Articles

Promoting effect of Ce doping on catalytic performance and water resistance ability for toluene catalytic combustion over the cheap and efficient Mn8Ni2CeaOx catalysts

A series of metal oxides Mn8Ni2CeaOx (a = 0–1.5) catalysts were prepared by hydrothermal co-precipitation to investigate the effect of Ce doping on manganese-based oxides for toluene catalytic combustion reaction. Activity evaluations show that Mn8Ni2CeOx (a = 1) catalyst exhibits highly efficient toluene oxidation activity and high yield to CO2 production. Durability tests reveal that it has remarkably superior water resistance ability and promising potential for practical application. Various characterizations were conducted to explore possible structure-activity correlations. Results show that Ce introduction could construct the strong Ce-Mn interactions, generate more oxygen vacancies, facilitate lattice oxygen mobility, and increase the content of surface active oxygen. These changes efficiently utilize active oxygen species and accelerate the deep oxidation of benzyl alcohol/benzoate intermediates, therefore render activity advantages. Otherwise, Ce doping can effectively maintain the catalyst's structural stability while simultaneously inhibiting H2O adsorption on the catalyst surface under humid atmosphere, thus being conducive to the outstanding durability and water resistance ability.

Fabrication of Hierarchical Porous Metal Oxides by the HPMC-Assisted Gel Combustion Strategy: Incorporation of Nanoceria into Cookie-like Mn2O3 with Enhanced Oxidation Activity and Excellent Water Resistance

Constructing nonprecious metal oxide catalysts with a hierarchical porous structure by a simple method for the deep catalytic oxidation of toxic volatile organic compounds at low temperatures is of great value and significance. In this work, a porous manganese trioxide catalyst (Mn2O3-H) was prepared by a hydroxypropyl methylcellulose-assisted combustion synthesis strategy for catalytic complete oxidation of gaseous toluene. Benefiting from the rich porous nanostructure, Mn2O3-H has much higher specific surface area and active site density, resulting in better low-temperature reducibility and oxygen activation ability than blank Mn2O3 formed by direct calcination. With this sol–gel combustion process, CeO2 nanoparticles could be successfully introduced to form cookie-like Ce–Mn composite oxide with a hierarchical porous nanostructure, which builds the strong interaction of CeO2–Mn2O3 to weaken Mn–O with more active defects. Among Ce-doped catalysts, 5%CeMn-H shows the best catalytic activity in toluene oxidation with 90% conversion temperature at 242 °C under a weight hour space velocity of 60,000 mL·g–1·h–1, which is about 30 and 133 °C lower than that of Mn2O3-H and Mn2O3-B, respectively. This advantage is also shown in other typical hydrocarbons such as propylene and propane. Moreover, the as-prepared Ce-doped catalyst exhibits excellent stability and water resistance ability. This simple robust sol–gel combustion method will provide valuable enlightenment for designing porous catalysts with high performance for related catalytic reactions.

SILICATE COATINGS FILLED WITH ZINC POWDER AND GRAPHENE NANOPLATES FOR STEEL CORROSION PROTECTION

The method is proposed to protect the carbon steel from corrosion by silicate coatings filled with powdered zinc and graphene nanoplates obtained by thermal splitting of graphite. The conditions for steel pre-treatment in an alkaline solution containing citrate ions and a nonionic surfactant, for the production of potassium liquid glass composition with the addition of zinc and graphene powders are selected. It is shown that coatings 70–80 µm thick, cured at room temperature for three days and containing 80–90 wt. % zinc, 7– 12 wt. % silicon dioxide and 0.2 wt. % carbon have the highest adhesion, water resistance and protective ability. The study of steel corrosion in 3.5% NaCl solution using methods of voltammetry and the dependence of open circuit potential on the test duration showed that silicate coatings filled with zinc and graphene provide cathodic polarization of steel and protect it from corrosion better than twice as thick coatings obtained by hot galvanizing. Graphene nanoplates enhance the contact of zinc particles with each other and with steel, promoting its cathodic polarization. Using scanning electron microscopy and X-ray spectral microanalysis, it has been shown that zinc corrosion products fill the pores of the near-surface layer of coatings, enhancing their protective ability.

Capture-bonding Super Assembly of Nanoscale Dispersed Bimetal on Uniform CeO2 Nanorod for the Toluene Oxidation.

Elimination of VOCs by catalytic oxidation is an important technology. Here, a general synergistic capture-bonding superassembly strategy was proposed to obtain the nanoscale dispersed 5.8% PtFe3 -CeO2 catalyst, which showed a high toluene oxidation activity (T100 =226 °C), excellent catalytic stability (125 h, >99.5%) and a good water resistance ability (70 h, >99.5%). Through the detailed XPS analysis, oxygen cycle experiment, hydrogen reduction experiment, and in-situ DRIFT experiment, we could deduce that PtFe3 -CeO2 had two reaction pathways. The surface adsorbed oxygen resulting from PtFe3 nanoparticles played a dominant role, due to the fast cycling between the surface adsorbed oxygen and oxygen vacancy. In contrast, the lattice oxygen resulting from CeO2 nanorods played an important role due to the relationship between the toluene oxidation activity and the metal-oxygen bonding energy. Furthermore, DFT simulation verified Pt sites were the dominant reaction active sites during this reaction.

Physical Simulation on Weakly Cemented Aquiclude Stability due to Underground Coal Mining

In northwest China, underground mining is frequently conducted in weakly cemented rock environments, including the aquiclude that protects the aquifer from dewatering. In this context, understanding the aquiclude responses to longwall mining is significant for assessing the reliability of water-conserved mining in the weakly cemented rock environment. Taking the Jurassic and Paleogene coal measure geology in Yili Mine in Xinjiang Province, China, as a case study, the paper conducted a laboratorial three-dimensional simulation by configuring a longwall operation and induced groundwater migration. The study analysed the aquiclude depressurisation and revealed the aquiclude stability in response to longwall mining. The results indicated that the aquiclude had a significant plastic strain and self-healing ability in the ground depressurisation condition. The aquiclude experienced tension and then compression, and, accordingly, fracture initiation, propagation, and convergence, during which the aquiclude had significant bending deformation. On the aquiclude horizon, tensile fracturing dominated above the set-up and longwall stop positions. The self-healing behaviour was correlated to the high content of clay minerals and disintegration proneness. The simulation results had a good agreement with field measurements, suggesting that the aquiclude had a satisfactory water-resisting ability and that the simulation results were practically reliable.

A Novel Protection Method for Carbonate Stone Artifacts with Gypsum Weathering Crusts

An innovative method using a methanol solution of barium hydroxide-urea as a protective agent was investigated for the conservation of stone artifacts with harmful gypsum weathering crusts. In this method, the methanol solution of barium hydroxide-urea and water were introduced into the gypsum crust in sequence by surface spraying. By doing so, the harmful gypsum crust is directly converted into a barium sulfate—calcium carbonate composite protective layer. The properties of the composite layer were characterized by SEM-EDX, XRD, ATR-FTIR, IC, water solubility, wetting angle, color difference, open porosity, capillary water absorption, and surface hardness. The results of the morphological and composition characterization (SEM-EDX, XRD, ATR-FTIR) indicate that the added urea can promote the carbonization reaction effectively. In addition, the methanol solution of barium hydroxide-urea can penetrate deep into the gypsum crust. The results of the physical properties characterization denote that the water stability of the specimens was significantly increased after the protection treatment; an approximate ten-fold stronger water resistance ability was achieved. Meanwhile, the intrinsic physical properties of gypsum crust, such as pore structure and original appearance, could basically be maintained. The presented conservative method has high facility and controllability and satisfying conservation effect, which means it has potential in the conservation of surface weathering carbonate stone artifacts.

Enhanced activity of plasma catalysis for trichloroethylene decomposition via metal-support interaction of Si[sbnd]O[sbnd]Co/Mn bonds over CoMnOX/ZSM-5

Metal-support interaction has a substantial influence on catalyst activity while little attention has been paid to it in the plasma catalytic system. Herein, the effect of support on the activity of CoMnOX-based catalysts was investigated for trichloroethylene removal by plasma catalysis, and CoMnOX/ZSM-5 exhibited the highest mineralization rate (36.93−94.24 %), HCl and Cl2 yield (19.66−94.37 %), energy yield (63.29–29 g/kWh), as well as the lowest export ozone concentration (18.72–108.83 mg/m3) under 6–10 kV. The excellent catalytic activity of CoMnOX/ZSM-5 was ascribed to the formation of abundant defects and oxygen vacancies, which was induced by the SiOCo/Mn hybridization promoting Co/MnO bonds cleavage. CoMnOX/ZSM-5 also exhibited superior adsorption ability, large amount of Co3+, Mn4+ and adsorbed oxygen species, high reducibility and suitable acidity. Moreover, CoMnOX/ZSM-5 maintained superior water-resistant ability and high catalytic activity after 50 h operation. The proposed TCE degradation mechanism suggested that the contribution of plasma active oxygen species was involved in TCE oxidation and oxygen cycle of catalyst. This work provides a novel strategy to design catalysts in plasma catalytic system.

PDMS – Coated pomelo peel carbon aerogel: Synthesis, characterization, and oil removal application

AbstractRaw pomelo peel (RPP) has been widely reported as a potential eco‐friendly adsorbent due to its porous structure. In this work, pomelo peel‐derived carbon aerogel (PCA) was synthesized by approaching simple methods: Hydrothermal treatment and freeze‐drying technique. The obtained PCA from RPP exhibits an abundance of honeycomb‐like open porous structure, ultralight density of 0.03 g/cm3, and porosity of 99.23 %. To enhance the hydrophobicity and selectivity for removal of oil in water, PCA was coated with Poly(dimethylsiloxane) (PDMS) by facile dip‐coating method. The as‐prepared hydrophobic PDMS‐coated pomelo peel carbon aerogel (PDMS/PCA) exhibits the water resistance ability via the water contact angle of 101.6 o and good adsorption capacity of 11.672 and 7.691 g/g for used cooking and lubricating oils, respectively. Furthermore, the pseudo‐first‐order and pseudo‐second‐order models were approached to predict the adsorption behavior of PDMS/PCA for both used cooking and lubricating oils. The obtained results illustrate the potential application of RPP for synthesizing eco‐friendly and low‐cost adsorbents for the removal of oil in water.

Enhancing oxygen/moisture resistance of quantum dots by short-chain, densely cross-linked silica glass network

Quantum dots (QDs) are facing significant photoluminescence degradation in moisture environment. In QDs-silicone composites, the poor water resistance of silicone matrix makes it easy for water and oxygen molecules to erode QDs. To tackle this issue, we proposed a new QDs protection strategy by introducing short-chain silica precursors onto the QDs’ surface, so that a dense silica passivation layer could be formed onto the QDs nanoparticles. Sol-gel method based on 3-aminopropyl triethoxysilane (APTES), 3-mercaptopropyl trimethoxysilane (MPTMS), and 3-mercaptopropyl triethoxysilane (MPTES) were adopted to prepare the uniform and crack-free QDs-silica glass (QD-glass). Because of the crosslinking of short-chain precursors, the formed silica glass possesses 38.6% smaller pore width and 68.6% lower pore volume than silicone, indicating its denser cross-linked network surrounding QDs. After 360 h water immersion, the QDs-glass demonstrated a 6% enhancement in red-light peak intensity, and maintained a stable full width at half maximum (FWHM) and peak wavelength, proving its excellent water-resistant ability. However, the conventional QDs-silicone composites not only showed a decrease of 75.3% in red-light peak intensity, but also a broadened FWHM and a redshifted peak wavelength after water immersion. QDs-glass also showed superior photostability after 132 h exposure to blue light. Red-light peak intensity of QDs-glass remained 87.3% of the initial while that of QDs-silicone decreased to 19.8%. And the intensity of QDs-glass dropped to 62.3% of that under 20 °C after thermal treatment of 160 °C. Besides, under increasing driving currents, the light conversion efficiency drop of QDs-glass is only one fifth that of QDs-silicone. Based on the QDs-glass, the white light-emitting diodes was achieved with a high luminous efficiency of 126.5 lm W−1 and a high color rendering index of 95.4. Thus, the newly proposed QD-glass has great significance in guaranteeing the working reliability of QDs-converted devices against moisture and high-power environment.

Cuttlebone-inspired magnesium oxychloride cement reinforced by biochar as green adhesive for wood industry

Design of eco-friendly, non-formaldehyde and flame retardant wood adhesives is in high demand for the wood industry, which can help to alleviate environmental stress and human health concerns. Magnesium oxychloride cement (MOC) can reduce CO2 emission and increase the value-added utilization of potash industry wastes, making it an ideal alternative to hazardous formaldehyde-based adhesives. However, its practical application usually suffers from poor water resistance and the filtering effect of wood. Inspired by the porous structure of cuttlebone, a facile yet powerful strategy is presented to prepare MOC adhesive with outstanding water resistance, compressive strength and adhesive ability to wood through introducing biochar. The naturally porous structure of biochar can form a protective core-shell structure and encapsulation with hydration products to stabilize phase 5 (5Mg(OH)2·MgCl2·8H2O), avoid crack extension and mitigate the filtering effect of wood. Meanwhile, the abundant functional groups of biochar can construct multiple interactions with Mg2+, which contributes to forming an internal network with excellent cohesion strength. Compared with pristine MOC, the obtained MOC/Biochar exhibited 102.33%, 32.33% and 31.45% increases in water resistance, compressive strength and wet adhesion strength, respectively. This work provides a promising strategy in preparing eco-friendly MOC-based adhesive from agricultural and industrial by-products to reduce environmental hazards.

Synergistic Effects of Nanoclay and Furfuryl Alcohol on Performance of Wood/Polymer Nanocomposites (WPNCs)

This study proposes a green and facile method by combining furfuryl alcohol (FA) and organic montmorillonite (OMMT) to solve the undesirable intrinsic properties and improve the performance of fast-growing wood. Wood/FA/OMMT nanocomposites (WPNCs) were fabricated by vacuum-pressure impregnation of FA/OMMT solution into wood cavities with the followingin situpolymerization to generate an interpenetrating network structure in cell structures. The FA and OMMT were distributed inside cell walls and transition areas between cell walls and cell lumens through SEM-EDXA and CLSM analyses. The resultant WPNCs had enhanced dimensional stability and water resistance ability. The incorporation of FA and OMMT could further improve the mechanical performance and the thermal stability of WPNCs. Therefore, FA/OMMT could synergistically enhance the performance of fast-growing wood.

Are zeolitic structure & Al necessary for Pd/zeolite being a superior passive NOx adsorber?

SiO2, Silicalite-2 and HZSM-11 were selected as the support to elucidate the necessity of long-range ordered zeolitic structure & composition for being a high-efficient zeolite-based PNA. It was found the silicalite zeolitic framework is favorable for the formation of small-sized PdOx with rare NOx adsorption ability but strong NO oxidation ability & very good water-resistant ability. The effective species of Pd2+ for NOx capture can only be formed in Si–Al zeolitic framework. The acidity endowed by Si–Al zeolitic framework also does a favor to the oxidation of NO to NO2 at release stage, however, only in dry condition. This work aims to provide some enlightment for designing a superior Pd/zeolite PNA material—possessing both considerable amount of Pd2+ for NOx storage and certain amount of tiny PdOx for partially oxidizing NO to NO2 for better reduction in the subsequent SCR during the release stage by adjusting the support materials' properties.

Pore Structure and Permeability of Cementitious Materials Containing a Carboxylic Acid Type Hydrophobic Agent

Integral hydrophobic treatment is the most effective method to prolong the service life of the concrete by resisting the transport of water containing aggressive ions. The hydrophobicity phenomenon of cementitious materials with carboxylic acid type admixture has been presented, and experimental studies, including water adsorption, amount of hydration products, and pore system, are conducted to reveal the hydrophobicity mechanism. It is reported that cementitious materials containing hydrophobic admixture present excellent water resistance ability, and the experimental results of nitrogen adsorption isotherm show that carboxylic acid type admixture addition increases pore volume and surface area of cement pastes. In addition, the fractal geometry theory is applied to reveal the relation between the pore structure and the permeability coefficient of cement pastes with a hydrophobic agent. In conclusion, the high tortuosity fractal dimension and the hydrophobicity of the pore surface result in water resistance when the cementitious system is mixed with a new type of hydrophobic admixture.

O-vacancy-rich porous MnO2 nanosheets as highly efficient catalysts for propane catalytic oxidation

Constructing non-noble robust catalysts for deep catalytic oxidation of obstinate light alkanes at low temperature is of great value and significance. Herein, we designed a facile solvent-thermal-reduction strategy to fabricate an O-vacancy-rich porous MnO2 nanosheet (MnO2−PS) catalyst for propane catalytic oxidation. The abundant vacancies in MnO2−PS catalysts can significantly promote its redox ability and oxygen activation capacity, and then provide more active oxygen species with enhanced oxygen mobility and reactivity, thus accelerate the cleavage of C-H bond and the decomposition of intermediates. Meanwhile, benefiting from the porous nanosheet structure, MnO2−PS catalyst possesses highly accessible surface and high density of exposed active sites, thus facilitating the adsorption and the activation of reactant molecule. At the same time, the catalyst also exhibits good thermal stability and water resistant ability. This robust and efficient catalytic system may provide some enlightenments for designing feasible catalyst with high-performance for deep catalytic destruction of VOCs.

Preparation and characterization of edible carboxymethyl cellulose films containing natural antibacterial agents: Lysozyme

Carboxymethyl cellulose (CMC) films containing lysozyme (Lys) were prepared in this study and changes in properties of the films were investigated. Enhancement in mechanical properties was observed with increased Lys, maximum (0.05 g/100 mL) reached to 39.07 MPa (TS) and 25.04 % (EAB). Meanwhile, water resistance ability improved, the minimum (0.05 g/100 mL) reached to 0.42 g·mm·(m2·h·KPa)-1, 84.62 % of pure CMC film. Thermogravimetric test showed better thermal stability of films. Scanning electron microscope illustrated that few cracks on surface of films. Fourier Transform infrared spectroscopy supported that more intermolecular hydrogen between Lys and CMC was formed with increased Lys, yet keeping increasing formed less intermolecular hydrogen. X-ray Diffraction observed the aggregated Lys by crystal structure. Antibacterial test showed an inhibitory effect on two common food-borne pathogens. Weight loss experiment indicated that films reduced the dry consumption of meat. Overall, the modification of CMC film by adding Lys was effective.

Ability evaluation of thiophenic sulfurs capture with a novel (MOF-818)-on-(Cu-BTC) composite in the presence of moisture

In view of unstable Cu-BTC could be destroyed by water molecules, causing a significantly performance decrease of adsorptive desulfurization, a (MOF-818)-on-(Cu-BTC) composite was innovatively designed and synthesized to achieve win-win for enhancing abilities of water-stability and desulfurization in this work. We approved that the novel (MOF-818)-on-(Cu-BTC) desulfurizer was achieved through nitrogen adsorption-desorption, powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS), etc. Thiophene (Th), benzothiophene (BT), and dibenzothiophene (DBT) capture performances from different simulated fuels in presence of moisture were systematic evaluated by means of batch tests. Further investigations demonstrated that the (MOF-818)-on-(Cu-BTC) exhibited remarkably sulfur capture ability, attributing to associative effects of specific surface area, nanopores, and acid-base interaction. Importantly, this (MOF-818)-on-(Cu-BTC) impressively retained sulfur capacity and its structural integrity even soaked in water for 7 days. Water-resistant ability was accordance with the order: (MOF-818)-on-(Cu-BTC)＞MOF-818＞Cu-BTC. This novel work would provide a new idea for adsorptive desulfurization by MOF-on-MOF in the presence of water environment.

Pt loaded manganese oxide nanoarray-based monolithic catalysts for catalytic oxidation of acetone

• Pt loaded MnNA monolithic catalyst were prepared for the removal of VOCs. • Pt-MnNA-P exhibited the best catalytic performance in the removal of acetone with a T 90 of 220 °C. • Pt-MnNA-P could keep its high catalytic activity for at least 48 h and exhibited excellent water resistance ability. • The reduction of Pt particle size and their high dispersion are the keys to the high activity of the Pt-MnNA-P. For large-scale application, increasing the activity of monolithic catalysts at low temperatures and achieving the high utilization efficiency of noble metal oxides remain formidable challenges. In this study, MnO 2 nanoarrays (MnNA) coated on honeycomb cordierite were prepared, and Pt nanoparticles were loaded on their surface. The probe reaction (oxidation of acetone) was set to explore their catalytic activities. By increasing the dispersion of Pt, the catalytic activity can be further improved with a T 50 of 189 °C and T 90 of 220 °C, which also exhibited water-resistance stability for 42 h. In this paper, the dispersed Pt particles can improve the activity of surface lattice oxygen of MnO 2 nanoarrays, and the possible reaction paths were subsequently discussed. This work offers a direct case for interpreting the catalytic behavior of MnNA coated on honeycomb cordierites, which could potentially promise broader insights into the construction and application of nanoarray structures in environmental engineering.

Effect of sodium alginate/phosphate-stabilized amorphous calcium carbonate nanoparticles on chitosan membranes

Biodegradable chitosan (CS) films can meet the demand for sustainable development. However, the performance of pure CS membrane still exists a particular gap compared with the traditional film. Inorganic nanomaterials with the controllable release are added to improve its physical and chemical properties. Herein, a series of CS/phosphate-stabilized amorphous calcium carbonate (CS/ACCP) and CS/sodium alginate/ACCP (CS/Alginate/ACCP) composite films were prepared by the flow method. The effects of ACCP and Alginate/ACCP nanoparticles on the physical and chemical properties of the composite membrane were investigated. The results showed that the composite nanoparticles could significantly improve CS film's compactness, hydrophobicity, and mechanical properties and enhance its ultraviolet (UV) blocking ability, water resistance, and water vapor blocking ability. When the number of nanoparticles was 8%, the mechanical properties of the CS composite membrane reached optimum value, and the comprehensive performance was better. In addition, the controlled-release properties of CS composite membranes were also studied, and the antioxidant, antibacterial, biocompatibility, and fresh-keeping effects of the composite membranes were explored. The results indicated that the CS composite membranes had not only excellent bacteriostatic (72%) properties (Escherichia coli) but also presented well fruit preservation (15 days) properties (sugar orange). In particular, the controlled release range of CS composite membrane at 12 h was between 30% and 90%, which provided a theoretical basis for its use as an edible membrane. Therefore, based on ACCP and Alginate/ACCP nanoparticles, CS composite membranes with more excellent application value in the biological field were prepared through further optimization design.

Enhanced antifouling and flux performances of a composite membrane via incorporating TiO2 functionalized with hydrophilic groups of L‐cysteine for nanofiltration

AbstractA new TiO2 nanoparticle modified via L‐cysteine is presented in this study. The L‐cysteine (cys) modified TiO2 nanomaterials impact as membrane modifier was examined in terms of pure water flux, hydrophilicity, morphology, and resistance ability. The mixed matrix membranes morphology investigated by using scanning electron microscope (SEM), atomic force microscopy (AFM), water contact angle measurement, porosity and pore size and Fourier transform infrared spectroscopy analysis. Membrane hydrophilicity and permeation flux were notably improved by introducing TiO2‐cys nanomaterials to the membrane matrix. The SEM image indicated the expanded finger‐like pores for the modified membranes comparing to the bare polyethersulfone (PES). The obtained AFM image exhibited lower surface roughness parameters for the modified membranes. In case of prepared membranes assessment, dye removal capability using the direct red‐16 and real liquorice wastewater were examined. The results confirmed that the modified membranes indicated high‐ranking dye rejection ability (more than 98% for direct red‐16 and 90% for real liquorice wastewater) comparing to the bare membrane (86 ± 2.58%). The antifouling tests were run based on milk powder (1000 mg/L) filtration and the best antifouling performance was obtained for 0.5 wt% of TiO2‐cys membrane (flux recovery ratio = 90.57 ± 2.71%, Rir = 9.43 ± 0.28%). Also, the results showed high potential of TiO2‐cys nanomaterials for membrane hydrophilicity enhancement.

Ptfe Modified Ti-Oms-2 Catalyst with Enhanced the Water-Resistance Ability and N2 Selectivity for Low-Temperature Nh3-Scr Reaction

Ptfe Modified Ti-Oms-2 Catalyst with Enhanced the Water-Resistance Ability and N2 Selectivity for Low-Temperature Nh3-Scr Reaction