Chem & Bio Engineering最新文献

Additive manufacturing, normally referred to as three-dimensional (3D) printing, has been maturing rapidly in recent years and widely utilized in various industrial fields, because it can create predesigned functional products with sophisticated structures that are basically difficult to achieve using traditional methods. Among all 3D printing technologies, vat photopolymerization has attracted much attention because of its outstanding advantages such as fast printing speed, high precision, and ease of formulating. In recent years, many breakthroughs in photopolymerization based 3D printing have been achieved by photoreaction design regarding photopolymerizable monomers, photoinitiating systems, inhibition functions, light sourcs, etc., but challenges remain. This Perspective attempts to highlight these great advances regarding the promotion of printing efficiency, accuracy, and sustainability. At the end, several challenges, such as longer-wavelength printing, printing of functional materials, and multimaterial printing, are discussed, which must be carefully addressed to meet the increasing requirements of future high-performance additive manufacturing.

Chemical recycling of plastic wastes through pyrolysis, gasification, or partial oxidation is a promising alternative to landfill disposal and incineration which must be applied in a future circular economy. These technologies enable the chemical industry, which currently heavily relies on crude oil, to obtain necessary chemical feedstock from postconsumer plastic waste. Kinetic models of pyrolysis and gasification reactions are required to dimension and design these processes on an industrial scale. The creation of detailed kinetic networks is often not feasible due to their complexity in this application, which is when the lumped kinetic modeling approach is used. This work develops and compares five lumped kinetic models for the co-pyrolysis of LDPE with a heavy petroleum fraction in a tubular reactor. A priori lumping is used for four models, and the fifth is created using a posteriori principle whereby in each model the product mixture is defined by eight lumps distinguished by their boiling point. The aim of this work is to compare different approaches for modeling reaction pathways in lumped kinetic models and to identify their impact on the predictive accuracy of the model. It was shown that all of the modeling approaches and the resulting models have similar prediction accuracies and deviations but with different kinetic parameters. Each model was used for a scale-up of an industrial-sized reactor to check whether the model had an influence on the design or predicted operation of the reactor.

Chemical recycling of plastic wastes through pyrolysis, gasification, or partial oxidation is a promising alternative to landfill disposal and incineration which must be applied in a future circular economy. These technologies enable the chemical industry, which currently heavily relies on crude oil, to obtain necessary chemical feedstock from postconsumer plastic waste. Kinetic models of pyrolysis and gasification reactions are required to dimension and design these processes on an industrial scale. The creation of detailed kinetic networks is often not feasible due to their complexity in this application, which is when the lumped kinetic modeling approach is used. This work develops and compares five lumped kinetic models for the co-pyrolysis of LDPE with a heavy petroleum fraction in a tubular reactor. A priori lumping is used for four models, and the fifth is created using a posteriori principle whereby in each model the product mixture is defined by eight lumps distinguished by their boiling point. The aim of this work is to compare different approaches for modeling reaction pathways in lumped kinetic models and to identify their impact on the predictive accuracy of the model. It was shown that all of the modeling approaches and the resulting models have similar prediction accuracies and deviations but with different kinetic parameters. Each model was used for a scale-up of an industrial-sized reactor to check whether the model had an influence on the design or predicted operation of the reactor.

Adsorption desalination (AD) driven by low-grade renewable energy or waste heat is a sustainable solution to the water crisis. Recently, metal–organic frameworks (MOFs) with excellent water adsorption performances have been recognized as some of the most promising candidates for AD. However, previous studies mainly focused on MOFs in powder form, causing pipe clogging and a drastic pressure drop, which inspire the development of shaped MOFs for industrial use. In this work, MIL-100(Fe) with high water stability, high adsorption capacity, and mild synthesis conditions was chosen, and the optimal formulation of the shaped MIL-100(Fe) granules using different binders was explored. The high-performing MIL-100(Fe)@5PVB granule containing 5% polyvinyl butyral (PVB) with outstanding adsorption performance and mechanical strength was selected and massively prepared for AD system testing. It is found that, although binder content decreased the surface area, pore volume, and water uptake of MIL-100(Fe), the mechanical strength and adsorption kinetics of shaped MIL-100(Fe)@5PVB were enhanced, which favor its performance in an AD system. Moreover, system testing demonstrated that the desalination performance of the AD system based on the adsorption beds of MIL-100(Fe)@5PVB outperformed both silica gel and MIL-100(Fe) powder. The specific daily water production (SDWP) of the AD system based on MIL-100(Fe)@5PVB (28.74 m³/ton/day) is 30% higher than that based on MIL-100(Fe) powder (19 m³/ton/day). Such a phenomenon is mainly contributed by the improved water adsorption dynamics of MIL-100(Fe)@5PVB granules that favors the mass transfer efficiency in the adsorption bed. This work opens up the possibility for the development of high-performing shaped MOFs for adsorption desalination from the perspectives of formulation optimization and system testing.

Adsorption desalination (AD) driven by low-grade renewable energy or waste heat is a sustainable solution to the water crisis. Recently, metal-organic frameworks (MOFs) with excellent water adsorption performances have been recognized as some of the most promising candidates for AD. However, previous studies mainly focused on MOFs in powder form, causing pipe clogging and a drastic pressure drop, which inspire the development of shaped MOFs for industrial use. In this work, MIL-100(Fe) with high water stability, high adsorption capacity, and mild synthesis conditions was chosen, and the optimal formulation of the shaped MIL-100(Fe) granules using different binders was explored. The high-performing MIL-100(Fe)@5PVB granule containing 5% polyvinyl butyral (PVB) with outstanding adsorption performance and mechanical strength was selected and massively prepared for AD system testing. It is found that, although binder content decreased the surface area, pore volume, and water uptake of MIL-100(Fe), the mechanical strength and adsorption kinetics of shaped MIL-100(Fe)@5PVB were enhanced, which favor its performance in an AD system. Moreover, system testing demonstrated that the desalination performance of the AD system based on the adsorption beds of MIL-100(Fe)@5PVB outperformed both silica gel and MIL-100(Fe) powder. The specific daily water production (SDWP) of the AD system based on MIL-100(Fe)@5PVB (28.74 m³/ton/day) is 30% higher than that based on MIL-100(Fe) powder (19 m³/ton/day). Such a phenomenon is mainly contributed by the improved water adsorption dynamics of MIL-100(Fe)@5PVB granules that favors the mass transfer efficiency in the adsorption bed. This work opens up the possibility for the development of high-performing shaped MOFs for adsorption desalination from the perspectives of formulation optimization and system testing.

With inspiration from natural systems, various soft actuators and robots have been explored in recent years with versatile applications in biomedical and engineering fields. Soft active materials with rich stimulus-responsive characteristics have been an ideal candidate to devise these soft machines by using different manufacturing technologies. Among these technologies, three-dimensional (3D) printing shows advantages in fabricating constructs with multiple materials and sophisticated architectures. In this Review, we aim to provide an overview of recent progress on 3D printing of soft materials, robotics performances, and representative applications. Typical 3D printing techniques are briefly introduced, followed by state-of-the-art advances in 3D printing of hydrogels, shape memory polymers, liquid crystalline elastomers, and their hybrids as soft actuators and robots. From the perspective of material properties, the commonly used printing techniques and action-generation principles for typical printed constructs are discussed. Actuation performances, locomotive behaviors, and representative applications of printed soft materials are summarized. The relationship between printing structures and action performances of soft actuators and robots is also briefly discussed. Finally, the advantages and limitations of each soft material are compared, and the remaining challenges and future directions in this field are prospected.

A great deal of attention has been paid to lithium–sulfur (Li–S) batteries due to their high energy density (>2600 Wh kg^–1), elemental abundance, and environmental friendliness, which show great application prospects in a wide range of energy storage systems. However, the shuttle effect caused by traditional liquid electrolyte remains a problem handicapping the development of the Li–S battery. In-situ polymerized gel polymer electrolytes (GPEs) with high ionic conductivity, high-voltage stability, and interfacial compatibility are spotlighted to solve the shuttle effect for better electrochemical performance. Here, we use Al(OTf)₃ to initiate DOL ring-opening polymerization to form GPEs. A hierarchical carbon interlayer, comprised of superaligned carbon nanotubes and Super P, was rationally organized with size exclusion effect (0.76 nm) to strengthen the interface stability and conversion of soluble lithium polysulfides for higher sulfur utilization. GPEs with ionic conductivity up to 1.74 mS cm^–1 and low interfacial impedance at room temperature are proposed, which infiltrate into the demonstrated hierarchical carbon interlayer to form HC@PP separators. The Li–S battery using the HC@PP separator exhibits higher sulfur utilization and discharge capacities (1332 mAh g^–1), improved rate capability, and 80% capacity retention at 1 C after 150 cycles, greatly surpassing the interlayer-free solid-state Li–S battery. Our work provides a promising in-situ polymerization strategy of GPEs with compatible hierarchical carbon interlayers design and its intrinsic interface regulation for a high-performance solid-state Li–S battery.

The development of high-performance adsorbents is vital for adsorptive separation. Conventional adsorbents have limitations in combining selective adsorption and efficient desorption due to their fixed surface properties. In this work, we have constructed spiropyran (SP)-based visible-light-responsive adsorbents for controllable CO adsorption by synthesizing SP in situ in Y zeolite via the ship-in-the-bottle method. This avoids the drawbacks associated with the vast majority of systems that modulate adsorption capacity by UV light. SP molecules can undergo reversible isomerization within the Y zeolite, which exhibit the merocyanine (MC) state in the dark and revert to the SP form upon visible light stimulation. The results show that the isomerization of MC to SP leads to a tunable CO adsorption capacity of up to 34%. Simulations performed by density functional theory reveal that MC is more likely to trap CO molecules than SP due to its higher binding energy with CO. We further demonstrate that the isomerization-induced tunable adsorption capacity can be maintained during cycles without degradation.

The effective removal of radioactive iodine under harsh high-temperature conditions, akin to those encountered in real spent nuclear fuel reprocessing, remains a formidable challenge. Herein, a novel bismuth-based mesoporous silica nanoreactor with a distinctive hollow yolk–shell structure was successfully synthesized by using silica-coated Bi₂O₃ as a hard template and alkaline organic ammonia for etching (Bi@HMS-1, HMS = hollow mesoporous silica). In contrast to conventional inorganic alkali-assisted methods with organic template agents, our approach yielded a material with thinner and more disordered shell layers, along with a relatively smaller pore volume. This led to a significant reduction in the physisorption of Bi@HMS-1 onto iodine while maintaining a smooth passage of guest iodine molecules into and out of the shell channels. Consequently, the resulting sorbent exhibited an outstanding iodine sorption capacity at high temperatures, achieving a chemisorption percentage as high as 96.5%, which makes it extremely competitive among the currently reported sorbents.

Carbon dioxide (CO₂) can be reduced to a variety of value-added products by the electrochemical reduction of CO₂ (ERC). Modulating the coordination environment of the Cu sites can effectively optimize the selectivity and activity of the reduction process. In this work, we report a facile strategy to regulate the coordination environment of Cu sites for improving the Faradaic efficiency (FE) of ethylene. Room-temperature Ar plasma with different powers and treating times was employed to partially remove the 2,5-dihydroxyterephthalic moieties from the structure of Cu-MOF-74, thus resulting in more unsaturated coordinated Cu sites and lower oxidation state. The structure distortion and electron configuration change of Cu-MOF-74-P was observed from electron paramagnetic resonance (EPR). Meanwhile, the proportion of Cu⁺ in Cu-MOF-74-P has increased significantly. By combination of XAFS and in situ DRIFTS, it was shown that the coordination number of Cu-MOF-74-P has decreased from 2.7 to 1.6, thus facilitating the formation of more *CO intermediates on the surface during the reduction process. This modification strategy successfully increased the Faradaic efficiency of C₂H₄ in the product up to 48%, which was 3.2 times of its original performance. This work provides some guidance for the design of catalysts with tailored selectivity during CO₂ electroreduction.