Asia-Pacific Journal of Chemical Engineering最新文献

Magnesium-based implants have garnered significant interest in orthopedic applications because of their favorable biodegradability, biocompatibility, and good mechanical strength. However, their rapid corrosion rate presents a considerable obstacle to widespread clinical adoption. This study investigates the application of a phosphate coating to pure magnesium substrates, exploring the impact of pH and hydrothermal temperature on phase composition to mitigate rapid degradation and preserve mechanical integrity. Although controlled temperature and pH in the precursor solution enabled the deposition of a uniform, dense, and defect-free magnesium phosphate coating via in situ conversion of pure magnesium, excellent corrosion resistance and minimized degradation led to vastly improved in vitro performance of these coatings on pure magnesium metal compared to the uncoated substrate.

This study investigates the development, characterisation and hydrolytic degradation of cellulose acetate and polyurethane-based bioactive food packaging wraps incorporated with spring onion leaf extract. Various ratios of wraps were formulated, and their physicochemical, mechanical, thermal and functional properties were evaluated. The incorporation of polyurethane improved the mechanical strength of the cellulose acetate matrix. At the same time, the addition of SO extracts further enhanced antioxidant and antibacterial properties because of the presence of phenolic compounds. Thermal analysis showed improved stability in composite wraps, and FTIR confirmed intermolecular bonding among components. SEM images revealed morphological compatibility, and water contact angle measurements reflected tunable surface wettability. The optimised wrap demonstrated significant free radical scavenging, high antibacterial efficacy and superior preservation performance when used for grape storage over 14 days, and it was aqueously degraded within 10 weeks. These results confirm the potential of composite wraps as sustainable, multifunctional food packaging materials that extend shelf life and enhance food safety.

The oscillation behavior of bubble plume in power-law fluids is investigated by using experimental and theoretical methods. The effects of gas phase conditions and liquid phase rheological properties on the oscillation characteristics and diffusion characteristics of bubble plume are analyzed. The results show that the amplitudes and core widths of the plume in tap water and sodium carboxymethyl cellulose (CMC) aqueous solutions both increase with the increase of the superficial gas velocity (u_g = 4.18 × 10⁻³ m·s⁻¹ ~ 1.67 × 10⁻² m·s⁻¹), and the diffusivity of tap water gradually increases from 0.011 to 0.013. The bubble clusters represent spiral oscillating upward movement in tap water and CMC aqueous solution. The oscillation period of the CMC aqueous solution is 0.9–1.39 times that of the tap water. The significant difference in liquid phase rheological properties between tap water and CMC aqueous solution significantly affects the oscillation mechanism of bubble plume. For the rheological properties, the oscillation period of plume is prolonged and the amplitude decreases; the oscillation period of plume in CMC aqueous solution is higher than that in tap water. Based on experimental characteristic parameters of the bubble plume, a mathematical model of plume oscillation period was established to predict the plume oscillation period.

Understanding the effect of inorganic cations on coal slurry conditioning is the premise of optimizing coal flotation. We studied the interaction between coal and dodecane via Materials Studio (MS) software. The difference in electrostatic potential energy was the essential factor of the different adsorption behavior of water and dodecane molecules at the coal surface. The interaction force, detachment force, and wettability of different coal types were measured using the interaction force test system. As the Ca²⁺ concentration increased, the interaction force between coal and the solution decreased while the wettability increased. The adsorption rate and contact angle of dodecane on the coal surface were measured via ultraviolet spectrophotometer. Both the adsorption rate and contact angle between coal and dodecane generally decreased as the Ca²⁺ concentration increased independently of coal type. Our results can provide valuable insight into the development of technology for coal slurry conditioning and flotation.

The present study unveils a novel approach in the facile fabrication of carbon soot-based electrodes for supercapacitor application. We utilize castor oil as a precursor material, a unique choice that has not been explored in this context. The soot derived from castor oil, with a major carbon composition of 95.5%, has a specific surface area of 114.99 m² g⁻¹. This work delves into the structural characteristics and electrochemical performance of the castor oil-derived soot-based electrodes for supercapacitors. The carbon soot electrode-based symmetric electric double-layer capacitor exhibits a specific capacitance of 50 F g⁻¹ at 0.5 A g⁻¹, with a remarkable capacitance retention of 95% and a columbic efficiency of 97% over 2000 cycles with excellent cyclic stability. It also has a high energy density of 4.44 W h kg⁻¹ at a power density of 400 W kg⁻¹. This study not only sheds light on the viability of castor oil-derived soot as a cost-efficient and sustainable material for supercapacitor technology but also introduces a new perspective by examining the effect of soot on the device's capacitance, charge–discharge properties, and overall efficiency.

Process intensification is essential for developing sustainable, efficient, and cost-effective processes in chemical and biological industries. Ultrasound, with its energy-saving, environmentally friendly, and safe characteristics, offers great promise in this regard. Ultrasound induces acoustic cavitation, leading to effects such as acoustic streaming and enhanced mixing, which can improve yields in various bioprocesses. The present study focuses on intensifying the fermentative production of erythromycin (EMC) using low-frequency ultrasound. Saccharopolyspora erythreae, the only known EMC-producing microorganism, offers limited nutrient flow due to its clumsy morphology, restricting EMC production. Controlled ultrasound treatment was applied during fermentation to improve the microorganism's morphological traits and enhance EMC yield. Optimized ultrasound (US) parameters were established using the one-factor-at-a-time (OFAT) methodology as 100 W power, 44 kHz frequency, 20% duty cycle, and 15 min treatment period. Under these conditions, EMC production increased significantly, achieving a 73.47% improvement over non-sonicated fermentation, with EMC yield rising from 0.49 to 0.85 g/L. The work clearly elucidated the process intensification benefits obtained by using ultrasound and also the need for detailed optimization of the operating conditions.

MIL-101(Cr) is considered a potential material for sorption-based storage applications; however, the chemicals and protocols used in its synthesis pose several environmental issues. This situation demands establishing a green synthesis protocol using eco-friendly chemicals while fulfilling the end application needs. Based on the life cycle assessment (LCA) concept, the present study examines the role of different protocols (mechanochemical and solvothermal) and washing solvents (N,N-dimethylformamide [DMF] and dimethyl sulfoxide [DMSO]) in synthesizing the MIL-101(Cr) and their impact on the environment. Towards this, four samples were synthesized using the aforementioned protocols and washing solvents and tested for carbon dioxide (CO₂) capture and thermochemical energy storage (TCES). At 25°C and 1 bar, the CO₂ uptake ranges from 1.4 to 2.33 mmol g⁻¹. These samples also demonstrated their suitability for a typical TCES application, with reaction enthalpies ranging from 186 to 1170.2 J g⁻¹. The LCA study suggests that the heating and drying processes contributed over 65% to the environmental impact, while the metal ion poses higher human carcinogenic toxicity and health risks. Replacing the DMF with DMSO helps reduce the impact on marine eutrophication by 91%. This comprehensive LCA study helped understand the role of the synthesis protocol and washing solvent in influencing the pore characteristics of MIL-101(Cr) and offers critical insights for sustainable MOF production.

Calcium phosphate (CaP) bioceramics like hydroxyapatite (HAP) are widely used for hard tissue repair due to their chemical and structural similarities to the mineral phase of bone. In order to improve their properties and expand their clinical applications, for example, to be used in the scaffold manufacturing process for bone tissue engineering, their structure was modified by introducing a biodegradable natural polymer like gelatin. This work aimed to study both the effect of adding different amounts of gelatin and calcination temperature on the microstructure of calcium phosphate–based bioceramics. Microstructural characterization indicated that the materials obtained after incorporation of different quantities of gelatin were chemically modified. They mainly contain the hydroxyapatite phase. Thermal degradation of gelatin incorporated in the bioceramic phase influenced its porosity. Indeed, the crystallinity of the gelatin-modified calcium phosphate materials varies depending on the quantity of gelatin added and the calcination temperature. For a volume of 50% of gelatin, the bioceramic calcined at 500°C exhibited the highest porosity corresponding to that of spongy bone. The in vitro test indicated the formation of CaP-like hydroxyapatite particles on the surface of the 50% bioceramic modified with gelatin calcined at 900°C.

The ammonia/coal co-combustion technology aligns with China's national energy condition, which is crucial for China to achieve carbon emission reduction in power plants and meet the “carbon peaking and carbon neutrality goals.” However, due to the distinct combustion characteristics of ammonia compared to traditional fossil fuels, blending ammonia into coal-fired power plants could lead to combustion instability and increase NO_x generation. In the present study, the combustion and NO_x emission characteristics of ammonia/coal co-firing in a 300-MW tangentially fired boiler were numerically investigated with elucidation on the impacts of NH₃ blending ratio, air distribution strategy, boiler load, load adjustment method and location of ammonia injection. The results indicate that ammonia injection can adversely affect coal burnout. When NH₃ blending ratio is 60%, the coal burnout rate decreases by about three percentage points compared with NH₃ blending ratio at 10%. Too high (more than 30%) or too low (less than 20%) NH₃ blending ratio could raise boiler NO_x emissions. The air distribution strategy is of great significance in reducing NO_x emissions. When α₁ rises from 0.95 to 1.0, the NO_x emissions increase by 223.2 mg·m⁻³ (6% O₂). The coal burnout rate and NO_x emissions can better meet energy conservation and emission reduction engineering requirements under the condition that the ammonia blending ratio is 20% and α₁ is 0.95. As the boiler load decreases, ammonia/coal co-combustion could efficiently decrease boiler NO_x emissions and increase the coal burnout rate, which is different from individual combustion of coal. The coal burnout rate increases by 2.2 percentage points with the boiler load reduced from 100% to 70%. In addition, compared with each burner evenly injected with ammonia, concentrated injection of ammonia can exert a significant rise in NO_x emissions, with a maximum increase of 449 mg·m⁻³ (6% O₂). The study can offer a certain reference for the low-carbon transformation of power plants in China.

In order to clarify the thermal reaction mechanism between iron/calcium (Fe₂O₃/CaO)-based oxygen carriers and coal char, the gas escape from the reaction process was resolved by TG-MS coupling, and the equivalent characteristic spectrum analysis (ECSA) method was used to determine the specific reactions occurring. Under Ar atmosphere, Fe₂O₃ starts to be reduced by graphite at 560°C, producing CO₂, and at 1040°C, CO is produced from the reaction between graphite and CO₂. When CaO is added to Fe₂O₃, CaO absorbs the CO₂ produced, affecting the path of the reaction. The reaction to produce CO₂ also occurs first in the two iron/calcium-based oxygen carrier conditions of sintered and pelletized ore, and CO production also occurs at high temperatures. In the case of air atmosphere combustion, only O₂ is consumed, and CO₂ is produced, no CO is formed. Graphite combustion consumes oxygen at a maximum value of 0.0393 mmol/min, and the addition of sintered ore reduces the maximum value of oxygen consumption to 0.0294 mmol/min, a decrease of about 25%, reflecting the oxygen buffering effect of oxygen carriers. Because the reaction of the coal char condition was concentrated at 300°C–700°C, this temperature interval, the addition of pelletized ore to coal char reduced the area of O₂ consumption from 3.36 to 3.01, indicating that the oxygen carrier provided additional oxygen in the reaction and reduced the oxygen consumption. The addition of iron/calcium oxygen carriers also reduces the reaction activation energy and makes the thermal reaction easier.