Decomposition Ratio Research Articles

Sludge carbon promotes barium titanate piezoelectric property to activate persulfate degradation of enrofloxacin

AbstractBACKGROUNDPiezoelectric catalysis using perovskite‐type barium titanate (BaTiO3) has been applied to the decomposition of refractory organic pollutants through piezoelectric catalytic persulfate (PS). Nevertheless, challenges such as a limited specific surface area, poor electrical conductivity and a tendency towards agglomeration in BaTiO3 necessitate the exploration of novel methods to enhance its piezoelectric efficiency.RESULTSSludge carbon (SC) from sewage treatment and BaTiO3 was utilized to develop a novel piezoelectric catalytic material (BaTiO3/SC). The specific surface area of BaTiO3/SC reached 67.92 m2 g−1, which is nine times larger than that of BaTiO3 alone. The inclusion of SC in the composite enhanced the number of active sites and contributed to a higher degree of graphitization, improved electrical conductivity, and provided a more stable structure for BaTiO3/SC. This material was capable of harvesting mechanical vibration energy from ultrasound, thereby generating piezoelectric catalytic properties and activating PS to achieve a 93% decomposition ratio of enrofloxacin (ENR) in water within 80 min. The activation of PS by BaTiO3/SC piezocatalysis led to the production of reactive oxygen species (ROS), such as •OH and SO4−•. These ROS attack the quinolone ring of ENR, which is susceptible to cleavage, resulting in the decomposition of ENR into intermediates of lower toxicity.CONCLUSIONThe incorporation of SC has enhanced the piezoelectric performance of BaTiO3, rendering BaTiO3/SC a novel perovskite‐type piezoelectric catalytic material that improves piezoelectric efficiency. The BaTiO3/SC system, through its piezoelectric catalytic activation of PS, demonstrates potential for decomposition of refractory organic pollutants in water treatment. © 2024 Society of Chemical Industry (SCI).

A Gaussian process embedded feature selection method based on automatic relevance determination

In Gaussian Process, feature importance is inversely proportional to the corresponding length scale when applying the Automatic Relevance Determination (ARD) structured kernel function. Features can be selected by ranking them according to their importance. Among the ARD-based feature selection methods, no uniform score exists for quantifying the output variation explained by feature subsets. This study proposes two feature selection approaches using two cumulative feature importance scores, one titled derivative decomposition ratio and the other normalized sensitivity, to determine the optimal feature subset. The performance of the approaches is assessed to test if irrelevant features are accurately identified and if the feature rankings are correct. The approaches are applied to identify relevant dimensionless inputs for a hybrid model estimating liquid entrainment fraction in two-phase flow. The results reveal that the proposed methods can identify the optimal feature subset for the hybrid model without significantly worsening its Root Mean Squared Error.

Recovering high-quality glass fibers from end-of-life wind turbine blades through swelling-assisted low-temperature pyrolysis

The recycling of end-of-life wind turbine blades has become a global environmental challenge driven by the rapid growth of wind power. Pyrolysis is a promising method for recovering glass fibers from these discarded blades, but traditional pyrolysis is often operated at high temperatures, which degrades the mechanical properties of recovered fibers. To address this issue, a swelling-assisted pyrolysis method was proposed to recover high-quality glass fibers from end-of-life wind turbine blades at low temperatures. The results confirmed that the decomposition of the resin matrix within the blade was significantly promoted at low temperatures in the swelling-assisted pyrolysis process, achieving a resin decomposition ratio of 76.8 % at 350 °C. This improvement was attributed to enhanced heat transfer and co-pyrolysis with acetic acid. Swelling could physically disrupt the cross-linked structure of the blade, creating a more porous and layered structure, thereby enhancing heat transfer during the pyrolysis process. Simultaneously, the co-pyrolysis with acetic acid could generate hydrogen radicals, which promoted the cracking of macromolecular oligomers into lighter products or gaseous alkanes. Consequently, the formation of pyrolysis char within the solid pyrolysis product was reduced, shortening the oxidation duration to 30 min. In comparison to traditional pyrolysis, the swelling-assisted pyrolysis process effectively suppressed the diffusion of surface defects over the recovered fibers, leading to promising improvements in their flexibility, elasticity, and mechanical properties, with tensile strength notably increased by 27.5 %. These findings provided valuable insights into recovering high-quality glass fibers from end-of-life wind turbine blades.

Joule heat mediated by graphite felt enhances peroxymonosulfate activation and carbamazepine degradation: Efficiency and mechanism

Thermal activation of persulfate (PS) is a simple and effective method to generate sulfate radicals (SO4̇‾) for pollutant degradation but its practical application was severely restricted by the excessive energy consumption. In this study, a low energy consumption but efficient Joule heat-activation strategy was developed. The temperature of the reaction solution (TRS) rose to 76.9 °C within 30 min after 5 V external voltage (Uex) was applied onto the two sides of a graphite felt (GF) with the thickness of 6 mm (GF-6). Correspondingly, the peroxymonosulfate (PMS) decomposition ratio and the degradation efficiency of carbamazepine (CBZ) reached 82.6 % and 97.5 %. The catalytic activation of PMS on the surface of GF was the dominant pathway to generate free radicals during the Joule heating process rather than the heat-activation pathway. More importantly, removing per milligram of CBZ only consumed 5.6 kJ electric energy which was significantly lower than that of the common heating methods (namely, 80 °C water bath heating and electrical heating at 5 V using a commercially available ceramic electric heating rod). Impressively, this Joule heating system exhibited wide applicability and prominent reusability. Overall, this work developed an effective PMS thermal activation strategy with low power consumption using the widely available GF and realized efficient degradation of typical organic pollutants.

Magnetically-induced enhancement of photocatalytic dye decomposition in ferroelectric Hf0.5Zr0.5O2 films

The film photocatalyst is easily recycled and has attracted the widely research interesting. Here the ferroelectric Hf0.5Zr0·5O2(HZO) thin film synthesized through the atomic layer deposition (ALD) method is used as a photocatalyst for the rhodamine B (RhB) dye decomposition under visible light irradiation. The photocatalytic RhB dye decomposition performances with or without an external magnetic field excitation provided by a commercial NdFeB magnet are experimentally characterized. With the increasing of the external direct-current (DC) magnetic field from 0 to 3000 Gs, the photocatalytic RhB dye decomposition ratio by HZO film obviously increases from 87.20 % to 98.17 %, which is attributed to the enhanced separation of the photo-induced positive and negative carrier due to the magnetic Lorentz effect. The magnetically-induced enhancement of photocatalysis in the ferroelectric HZO film, provides a method with these advantages of simple external excitation method, remarkable promotion effect and friendly-environment to enhance the dye decomposition ratio, and is potential in the practical application of photocatalytic dye wastewater treatment through harvesting the clean solar energy in future.

Roles of vaporization and thermal decomposition in the dynamic evolution of laser-induced bubble on the surface of a submerged metal plate

This paper aims to explain when the vaporization or thermal decomposition prevails during laser-induced bubble growth and how they influence bubble morphology. Bubbles were generated by irradiating a 304 stainless steel plate submerged in degassed water using millisecond lasers with a pulse width of 0.4 ms and powers of 1.6 kW and 3.2 kW, respectively. The dynamic evolution of bubbles was recorded by a high-speed camera. Moreover, the numerical models were developed to obtain a vaporization model and a decomposition model by incorporating the source terms due to the vaporization and decomposition mass fluxes into the governing equations, respectively. The simulated dynamic bubble evolution is consistent with the experimental results. When the laser power is 1.6 kW, a thin-layer bubble is formed, which gradually shrinks and eventually disappears after the laser stops irradiating. When the laser power is 3.2 kW, a spherical bubble is formed, and its volume decreases significantly after the laser stops irradiating. Subsequently, it remains relatively stable during the observation period. The fundamental reason for the difference between the bubble morphologies obtained from the vaporization model and the decomposition model lies in the presence of a condensation zone in the gas phase. When water vaporization or thermal decomposition dominates, the temperatures obtained from the models align with the decomposition ratios at varying temperatures reported in the literature. Our findings are significant for understanding the dynamic behavior of bubbles, with implications for various laser processing underwater.

A functionalised interface for controllable decomposition of ammonium perchlorate by a self-assembly method

A functionalised interface construction strategy was developed by coating an ammonium perchlorate (AP) surface with quaternary ammonium cation surfactants using a self-assembly method. The functionalised interface transforms AP decomposition from high temperature decomposition into low temperature decomposition, and provides pressure-sensitive control over the mass ratio of AP decomposition in the two stages. Further study using molecular dynamics simulations and density functional theory reveal that the functionalised interface hinders the adsorption of NH3 molecules and promote the adsorption and decomposition of ClO4 on the AP surface, all of which could contribute to controlling AP decomposition.

Recovery of sulphur dioxide by converter dust synergistic coke decomposition of phosphogypsum

To further improve the decomposition ratio and sulfur dioxide mass yield of coke-reduced solid waste phosphogypsum (PG), converter dust (CD) is proposed as a novel additive. The effects of raw material ratio, time and temperature for roasting on the decomposition process of PG were inspected by simulation calculations and fluidized bed experiments. It turns out that the optimized reaction conditions are Fe3O4/Ca of 0.6, C/Ca of 0.4 at 1100 °C for 24 min, under which the PG decomposition ratio and SO2 mass yield are 99.56 % and 97.64 %, respectively. The addition of CD is able to reduce the initial reaction temperature from 975 °C to 914 °C, and promote the release of SO2. Kinetic analysis shows the mechanistic equation for this process is obtained as G(α) = [−ln(1 − α)]3/2, indicating that the decomposition reaction mechanism is a crystal nucleation and growth-controlled process. The chemical mechanism of the process is that coke and Fe3O4 in the CD convert CaSO4 to the intermediate CaS, and Fe3O4 is oxidized to Fe2O3. Then CaS and CaSO4 continue to react with Fe2O3 to form Ca2Fe2O5 and SO2. The presence of Fe2O3 accelerations the rate of CaS and CaSO4 roasting reaction and lowers the reaction temperature. Meanwhile, the self-decomposition of PG also produces CaO and SO2. Finally, a process for SO2 recovery from CD synergized with coke decomposition of PG is proposed.

Pure ammonia direct decomposition using rod-electrode-type microwave plasma source

This paper presents the experimental results of ammonia (NH3) decomposition without catalyst and dilution using a rod-electrode-type microwave plasma source (MPS) at atmospheric pressure. The direct decomposition ratio of pure NH3 was investigated in relation to the flow rate into the rod-electrode-type MPS and the average transmission power to the rod-electrode-type MPS. The decomposition ratio increased with decreasing the flow rate and with increasing the average transmission power. For example, the decomposition ratio was demonstrated to exceed 40 % at the flow rate of 0.2–0.8 L/min and the average transmission power of about 63–166 W. The highest decomposition ratio was approximately 84 % at the flow rate of 0.2 L/min and the average transmission power of approximately 112 W, and the hydrogen yield was approximately 90 %.

Thresholding of Polarimetric SAR Images of Coastal Zones Based on Three-Component Decomposition and Likelihood Ratio

Thresholding of Polarimetric SAR Images of Coastal Zones Based on Three-Component Decomposition and Likelihood Ratio

Process modelling and assessment of thermochemical sulfur-iodine cycle for hydrogen production considering Bunsen reaction kinetics

Thermochemical sulfur-iodine (SI) cycle is one of the large-scale, clean, and efficient hydrogen production routes. The Bunsen reaction process is always simulated by a stoichiometric reaction, without considering the realistic Bunsen reaction kinetic process. Herein, a user-defined Fortran module concerning Bunsen reaction kinetics was developed and embedded into a continuous stirred tank reactor (RCSTR), and then a SI flowsheet with 100 L/h hydrogen production was modeled. The key parameter optimization, mass and energy balance were analyzed, the internal heat exchange network was created using the pinch point temperature difference analysis and the principle of energy cascade utilization, along with thermal efficiency evaluation. Bunsen reaction process reaches equilibrium after a period, which is consistent with experiments. The increase of H2SO4 decomposition ratio is beneficial to reduce the energy consumption of system. Increase in temperature has less effect on increasing the equilibrium decomposition ratio of HI. The theoretical thermal efficiency of system reaches 14.0–57.4 % considering the recovery of exothermic heat. This work provides a theoretical basis for the optimization of SI cycle.

Strongly piezocatalytic dye decomposition of sol-gel synthesized PZT film

Piezocatalysis technology emerges as a promising solution for environmental protection and wastewater pollution treatment. This study focuses on the synthesis of Pb(Zr0.50Ti0.50)O3 (PZT) ferroelectric thin films as piezocatalysts through a sol-gel method. The piezocatalytic performance of these PZT films under vibration is also evaluated through utilizing Rhodamine B(RhB) dye as a model pollutant. When vibrations are applied to the RhB solution for 3 h, the RhB dye decomposition ratio reaches 90.22 %. The influence of pH values, vibration power and dye concentration condition on the decomposition ratio of RhB dye wastewater during the piezocatalytic process. Furtherly, these inhibitor experiments indicate that these middlle active species in piezocatalysis of PZT film are mainly the ·O2− and ·OH radicals. The study demonstrates the tremendous potential of PZT film's piezoelectric effect in treating dye wastewater through harvesting mechanical vibration energy.

Effects of ammonia combustion on skin friction characteristics for supersonic flow

Boundary layer combustion is an effective method to reduce friction in scramjet combustors. In existing research on drag-reducing fuels, hydrocarbons pose challenges related to carbon deposition and emissions. Meanwhile, hydrogen presents significant difficulties in storage and transportation. For the first time, this paper explores ammonia as a drag-reducing alternative. We employed the Reynolds-averaged Navier-Stokes (RANS) method to investigate the characteristics of drag reduction by ammonia combustion in supersonic flow. Numerical results indicate that the local drag reduction by ammonia combustion is better than hydrocarbon and worse than hydrogen compared to existing research. Ammonia exhibits superior potential for drag reduction. However, the overall drag reduction at room ammonia injection temperature is limited due to the significant distance between the ammonia self-ignition point and the injection port. To address this challenge, we proposed two optimization strategies: increasing the ammonia injection temperature and increasing the inlet ammonia decomposition ratio. As the ammonia injection temperature increases, the self-ignition position moves towards the inlet, and the combustion drag reduction region expands upstream. Interestingly, a higher ammonia inlet decomposition ratio does not necessarily lead to a better drag reduction effect. In fact, an excessively high decomposition ratio can inhibit the combustion drag reduction effect. The most effective drag reduction occurs when the ammonia inlet mass fraction is 50%, resulting in a 42.8% reduction in integrated drag compared to the case without NH3 injection. Overall, this paper offers critical insights into the utilization of ammonia combustion in scramjets to reduce drag.

Initiation of piezoelectricity expands the photocatalytic H2 production and decomposition of organic dye through g-C3N4/Ag/ZnO tri-components

The enhancement of photocatalytic reactivity through the internal electric field has received much attention. The combination of the piezoelectric effect and the photo-exiting process facilitates the segregation of the photogenerated carriers, thereby boosting the piezo-photocatalytic activity. We have constructed g-C3N4/Ag/ZnO tri-component composites; with various g-C3N4 precursors to achieve reliable photo/piezo-photocatalysis for H2 production and Rhodamine B (RhB) dye degradation. We observed that urea-based g-C3N4/Ag/ZnO (UCAZ) tri-components exhibit a superior H2 production rate of 1125.5 μmol h−1 g−1 under photocatalytic conditions. When piezoelectric-potential was introduced into the photocatalysis reaction via ultrasonic, the H2 rate increased dramatically to 1637.5 μmol h−1 g−1, which is approximately 145% greater than that light irradiation alone.Similarly, the catalytic decomposition ratio of Rhodamine B (RhB) under the coexistence of ultrasound and light, and degradation efficiency reached 99% in 120 min, which is higher than the value of (42%, 0.0031 min−1) for piezo-catalysis and (80%, 0.01 min−1) for photocatalysis condition alone. The rate constant under synergisticsimulation reaches 0.021 min−1, which is 200% and 645% times higher than the sole light and ultrasonic illumination. Additionally, RhB degradation of all the tri-components was performed under solar light (Sunlight) and ultrasound irradiation, and efficiency reached 99.5% in 45 min with a rate constant of 0.06 min−1, which is 300% higher than the piezo-photocatalytic under LED source. The enhanced performance of the g-C3N4/Ag/ZnO tricomponent is attributed to the high specific surface area (168 m2 g−1) and synergetic effect of piezo catalysis and photocatalysis.

Natural tourmaline for pyroelectric dye decomposition under 25–60 °C room-temperature cold-hot fluctuation

Tourmaline is a typical natural pyroelectric material. In this work, the pyroelectric property of tourmaline micro-powder is used to chemically deal with dyes wastewater under room-temperature cold-hot alternation. Under 25–60 °C heating-cooling cycles excitation, the decomposition ratio of Rhodamine B wastewater can achieve 84.7%. In the dye decomposition process, dissolved oxygen and hydroxide in the solution react with pyroelectrically induced positive and negative charges, respectively. This reaction triggers the production of superoxide radicals (O2–) and hydroxyl radicals (OH), which possess highly potent oxidation capabilities towards dye molecules. This work highlights the potential application of tourmaline mineral for dye decomposition in harvesting the environmental cold-hot alternation heat energy in future.

Experimental study on the activation of coal gasification fly ash from industrial CFB gasifiers

Coal gasification fly ash (CGFA) is an industrial solid waste from the coal circulating fluidized bed (CFB) gasification process, and it needs to be effectively disposed to achieve sustainable development of the environment. To realize the application of CGFA as a precursor of porous carbon materials, the physicochemical properties of three kinds of CGFA from industrial CFB gasifiers are analyzed. Then, the activation potential of CGFA is acquired via steam activation experiments in a tube furnace reactor. Finally, the fluidization activation technology of CGFA is practiced in a bench-scale CFB test rig, and its advantages are highlighted. The results show that CGFA is characterized by a high carbon content in the range of 54.06%–74.09%, an ultrafine particle size (d50: 16.3–26.1 μm), and a relatively developed pore structure (specific surface area SSA: 139.29–551.97 m2·g−1). The proportion of micropores in CGFA increases gradually with the coal rank. Steam activation experiments show that the pore development of CGFA mainly includes three stages: initial pore development, dynamic equilibrium between micropores and mesopores and pore collapse. The SSA of lignite fly ash (LFA), subbituminous fly ash (SBFA) and anthracite fly ash (AFA) is maximally increased by 105%, 13% and 72% after steam activation; the order of the largest carbon reaction rate and decomposition ratio of steam among the three kinds of CGFA is SBFA > LFA > AFA. As the ratio of oxygen to carbon during the fluidization activation of LFA is from 0.09 to 0.19, the carbon conversion ratio increases from 14.4% to 26.8% and the cold gas efficiency increases from 6.8% to 10.2%. The SSA of LFA increases by up to 53.9% during the fluidization activation process, which is mainly due to the mesoporous development. Relative to steam activation in a tube furnace reactor, fluidization activation takes an extremely short time (seconds) to achieve the same activation effect. It is expected to further improve the activation effect of LFA by regulating the carbon conversion ratio range of 27%–35% to create pores in the initial development stage.

Waste heat recovery optimization in ammonia-based gas turbine applications

E-fuels are promising alternatives to fossil fuels in the transition towards zero-emission energy system. In this study, a novel chemical-recuperated and humidified gas turbine concept aiming at the application of e-fuel ammonia is proposed to overcome the technical hitches and exploit the waste heat to enhance the cycle performance. The thermodynamic analysis shows that the highest net electrical efficiency (56.7%) under the design conditions exceeds that of the ammonia-fueled Brayton cycle by 20.6%-points. The chemical recuperation of fuel contributes to the efficiency improvement by 7%-points under dry condition, while steam injection provides 8%-points to 12%-points efficiency increase corresponding to the ammonia decomposition ratio of 5%–96%. A non-monotonic relation between the net electrical efficiency and steam-to-air ratio is found to be the result of the competition between the enthalpy change from to the varied steam and air mass flow rates. Analyzing the flame characteristics in the combustor under the design conditions, we found that conditions with high decomposition ratio (>88%) and high steam-to-air ratio (>0.3) exhibit similar flame speed with that of methane fueled combustor and thus existing designs can be reused. The prediction shows the NOx emission can be restricted when the steam-to-air ratio exceeds 0.4.

Strongly enhanced piezoelectric-catalysis of ZnSnO3/graphite hybrid materials for dye wastewater decomposition

In this study, the strongly-enhanced piezoelectric catalytic performance for dye decomposition was exhibited by sol-gel-synthesized ZnSnO3 with the addition of a certain proportion of graphite. With increasing graphite content from 0 to 5%, decomposition ratio of RhB dyes first increases and then decreases, reaching maximum value of ∼100% for the ZnSnO3 with 3% graphite addition. Reaction rate constant reached a maximum of ∼0.098 min−1 at 3% graphite content, while that of the pristine ZnSnO3 is only ∼0.02 min−1. Graphite particles can transfer piezoelectrically-negative charges, which helps to reduce the recombination of charges, thereby improving piezoelectric catalytic performance. Strong piezoelectric catalytic activity makes novel ZnSnO3/graphite hybrid materials potential for dye decomposition from wastewater.

Natural piezoelectric tourmaline mineral for piezocatalytic decomposition of organic dyes under vibration

AbstractPiezoelectric materials can convert mechanical energy into electrical energy, and further piezocatalysis can be designed based on the product between piezoelectric effect and electrochemical redox effect, which is hopeful for the actual dye decomposition. Tourmaline is a natural mineral with spontaneous polarization, which is an ideal piezocatalytic material and is rarely reported in dye decomposition. In this work, after 100 mg tourmaline powder is vibrated for 120 min, the piezocatalytic dye decomposition ratios of rhodamine B (RhB), methylene blue, and methyl orange are ∼95%, ∼46%, and ∼23%, respectively. The corresponding first‐order reaction kinetic values for these three dyes are 0.02681, 0.00639, and 0.00246 min−1, respectively. By adjusting the pH value of the initial RhB solution to 5, the decomposition ratio can reach ∼99% after only 60 min of vibration. In the process of dye decomposition, it is determined that the main active substances are hydroxyl radicals and superoxide radicals via electron spin–resonance spectra test. The spontaneous polarization performance of tourmaline can effectively adsorb dye molecules to promote the catalytic reaction. Natural tourmaline minerals are abundant, low cost, and environmentally friendly making them suitable for large‐scale piezocatalysis of mineral materials.

Efficient recycling of carbon fiber from carbon fiber reinforced composite and reuse as high performance electromagnetic shielding materials with superior mechanical strength

Carbon fiber reinforced boron phenolic resin composite (CF/BPR) is widely used. However, it is hard to decompose its waste for highly cross-linked networks. Herein, a solvothermal decomposition route was proposed to decompose CF/BPR and recycle carbon fibers. Decomposition ratio of resin (Dr) reached 99.78%. Possible decomposition mechanism was proposed based on characterizations of decomposition products. Composite was decomposed for synergistic effects of physical swelling, mechanical impact and chemical decomposition. Surface morphology and microstructure characterization of recycled carbon fibers (RCFs) confirmed that resin was highly removed while no significant harm was caused to RCFs. It was found that RCFs reinforced boron phenolic resin composite (RCFs/BPR) had superior punch type shear strength due to improved wettability and interfaces. Moreover, RCFs/BPR exhibited superior electromagnetic shielding performance in X-band frequency for improved conductive network. This work presents a facile and efficient pathway for decomposing composite waste and reuse as high performance electromagnetic shielding materials.