Adsorption and Diffusion Properties of Functionalized MOFs for CO2 Capture: A Combination of Molecular Dynamics Simulation and Density Functional Theory Calculation.

The capture of carbon dioxide (CO2) from fuel gases is a significant method to solve the global warming problem. Metal-organic frameworks (MOFs) are considered to be promising porous materials and have shown great potential for CO2 adsorption and separation applications. However, the adsorption and diffusion mechanisms of CO2 in functionalized MOFs from the perspective of binding energies are still not clear. Actually, the adsorption and diffusion mechanisms can be revealed more intuitively by the binding energies of CO2 with the functionalized MOFs. In this work, a combination of molecular dynamics simulation and density functional theory calculation was performed to study CO2 adsorption and diffusion mechanisms in five different functionalized isoreticular MOFs (IRMOF-1 through -5), considering the influence of functionalized linkers on the adsorption capacity of functionalized MOFs. The results show that the CO2 uptake is determined by two elements: the binding energy and porosity of MOFs. The porosity of the MOFs plays a dominant role in IRMOF-5, resulting in the lowest level of CO2 uptake. The potential of mean force (PMF) of CO2 is strongest at the CO2/functionalized MOFs interface, which is consistent with the maximum CO2 density distribution at the interface. IRMOF-3 with the functionalized linker -NH2 shows the highest CO2 uptake due to the higher porosity and binding energy. Although IRMOF-5 with the functionalized linker -OC5H11 exhibits the lowest diffusivity of CO2 and the highest binding energy, it shows the lowest CO2 uptake. Accordingly, among the five simulated functionalized MOFs, IRMOF-3 is an excellent CO2 adsorbent and IRMOF-5 can be used to separate CO2 from other gases, which will be helpful for the designing of CO2 capture devices. This work will contribute to the design and screening of materials for CO2 adsorption and separation in practical applications.

Mussel-inspired polydopamine-modified biochar microsphere for reinforcing polylactic acid composite films: Emphasizing the achievement of excellent thermal and mechanical properties.

Having poor interfacial compatibility between biochar microsphere (BM) and polylactic acid (PLA) should be responsible for the unbalance of composite film strength and toughness. Elucidating the effect of polydopamine (PDA) on BM and BM/PLA composite films is the ultimate goal of this study based on the mussel bionic principle. It was found that the strong adhesion of PDA on the BM surface was achieved, which improved the surface roughness and thermal stability. Also, PDA modification can facilitate crystallization, increase thermal properties, improve interfacial compatibility, and enhance the tensile properties of BM/PLA composite films. Silane-based PDA modified BM/PLA composite film exhibited the best tensile strength, tensile modulus, and elongation at break with 77.95 MPa, 1.87 GPa, and 7.30%. These noteworthy findings, achieving a simultaneous improvement in PLA strength and toughness, hold promising implications for its sustainability.

Insights into Preparation Methods and Functions of Carbon-Based Solid Acids.

With the growing emphasis on green chemistry and the ecological environment, researchers are increasingly paying attention to greening materials through the use of carbon-based solid acids. The diverse characteristics of carbon-based solid acids can be produced through different preparation conditions and modification methods. This paper presents a comprehensive summary of the current research progress on carbon-based solid acids, encompassing common carbonization methods, such as one-step, two-step, hydrothermal, and template methods. The composition of carbon source material may be the main factor affecting its carbonization method and carbonization temperature. Additionally, acidification types including sulfonating agent, phosphoric acid, heteropoly acid, and nitric acid are explored. Furthermore, the functions of carbon-based solid acids in esterification, hydrolysis, condensation, and alkylation are thoroughly analyzed. This study concludes by addressing the existing drawbacks and outlining potential future development prospects for carbon-based solid acids in the context of their important role in sustainable chemistry and environmental preservation.

New strategy for reinforcing polylactic acid composites: Towards the insight into the effect of biochar microspheres.

Having even particle size and regular morphology of biochar microspheres (BM) provides the possibility for preparing polylactic acid (PLA) films. Hence, the novelty is proposing a strategy for reinforcing PLA by BM. It was found that BM exhibited regular morphology, higher thermal stability, even particle size, and better pore characteristics. Although adding BM decreased the toughness of PLA due to the poor compatibility between BM and PLA, the nucleation effect of BM facilitated the crystallization in the PLA system. The tensile strength and modulus of BM/PLA composite films increased first and then decreased with increasing BM content. The stress concentration formed by BM particle agglomeration was responsible for the tensile strength and modulus decreases of BM/PLA composite films under higher BM addition. 2% BM added and 3% added composite films exhibited the best tensile strength and modulus with 64.99 MPa and 1.59 GPa, which was mainly attributed to the proper proportion of BM to PLA and the uniform distribution of BM in PLA. The results of this study confirmed the positive reinforcing effect of BM in PLA and are expected to be available in the composite film field.

Improvement of the carbon yield from biomass carbonization through sulfuric acid pre-dehydration at room temperature.

The pre-dehydration of a woody biomass waste (Douglas fir, DF) with 4.6-32 wt% of diluted sulfuric acid solutions was carried out mainly at room temperature aimed to improve the carbon yield from the thermal carbonization of pre-dehydrated biomass at 500 °C. By comparison (based on the raw DF), the pre-dehydration at room temperature increased the biochar yield and carbon retention up to about 32 wt% and 54%, respectively from that of about 22 wt% and 39% without pre-dehydration. When the pre-dehydration temperature increased to 90 °C, the biochar yield and carbon retention were sharply promoted to about 44 wt% and 76%, which was about two times higher than that of the biochar obtained without pre-treatment. This work for the first time proved the effectiveness of improving the carbon yield from lignocellulosic biomass via diluted sulfuric acid-assisted pre-dehydration at low or even room temperature.

One-step synthesis of biomass-based sulfonated carbon catalyst by direct carbonization-sulfonation for organosolv delignification.

Biomass-based sulfonated carbon catalyst (SCC) was prepared from corncob via direct sulfuric acid carbonization-sulfonation treatment. Central composite design was used to evaluate temperature and time for optimizing SCC yield and sulfonic acid (SO3H) density. The SO3H groups were successfully introduced to the SCC as evidenced by FTIR and sulfur analysis. Numerical optimization results showed that 100 °C and 5.78 h are the optimal conditions for maximizing yield (61.24%) and SO3H density (1.1408 mmol/g). The highest ethanol organosolv lignin (EOL) yield of 63.56% with a substrate yield of 39.08% was achieved at 20% SCC loading in the ethanol organosolv delignification of lignocellulosic biomass. The FTIR spectra of the isolated lignin revealed typical features of G-lignin, indicating that no drastic changes took place in the lignin structure during the process. This study developed a simple one-step preparation method of SCC, which was successfully used as a catalyst in an organosolv delignification of biomass.

Production of high-density polyethylene biocomposites from rice husk biochar: Effects of varying pyrolysis temperature.

The novelty of this study is to explore the effect of temperature varied biochar on the properties of biochar/polymers composites. Rice husk biochar (RB) samples were prepared at different pyrolysis temperatures and injection molding was used to prepare RB/high-density polyethylene (HDPE) composites. Additionally, ultimate analysis, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), pore structure characteristics, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), tensile properties, and dynamic mechanical analysis (DMA) were used to characterize these RB and RB/HDPE composites samples. The results validated that RB obtained at 600 °C showed the highest carbon content, the most complete pore structure, and the largest specific surface area. Moreover, the thermal studies revealed that the addition of RB improved the thermal stability of HDPE. The best tensile strength (26.25 MPa) and Young's modulus (1.87 GPa) were obtained in 500 °C RB/HDPE composites and 600 °C RB/HDPE composites due to their good physical/mechanical interlocking structures shown in SEM. DMA revealed that the stiffness, elasticity, creep resistance and stress relaxation of the composites were improved by the addition of RB. The utilization of temperature varied biochars in biocomposites is important to manage wastes and optimize the properties of biocomposites in terms of reducing production cost and ensuring environmental safety.

Microwave-assisted synthesis of bifunctional magnetic solid acid for hydrolyzing cellulose to prepare nanocellulose.

The conventional studies on the preparation of nanocellulose used a high concentration of sulfuric acid that is difficult to remove and recover. A biochar-based solid acid with magnetic properties was developed to hydrolyze cellulose to prepare nanocellulose in this work. Two different methods were selected to investigate the properties of the synthesized magnetic carbon-based solid acids. The synthesized catalysts were characterized by SEM, TEM, XRD, NH3-TPD and FT-IR. The experimental results showed that two solid acids by the microwave-assisted synthesis had good magnetic properties by a magnet adsorption. Analysis by SEM and TEM showed that the two solid acids had rich pore structures. According to mineral element analysis, both solid acids contained high sulfur content. The solid acid was an amorphous carbon structural material with a surface rich in active groups. The catalytic activity of the biochar-based solid acids in cellulose hydrolysis to prepare nano-scale cellulosic material was evaluated. It was found that magnetic biochar-based solid acid (MBC-SA1) could achieve a high yield, which produced up to 57.68% for hydrolyzing cellulose into nanometers.

Jet fuel and hydrogen produced from waste plastics catalytic pyrolysis with activated carbon and MgO.

Catalytic pyrolysis of waste plastics to produce jet fuel and hydrogen using activated carbon and MgO as catalysts was studied. The effects of catalyst to waste plastics ratio experimental temperature, catalyst placement and activated carbon to MgO ratio on the yields and distributions of pyrolysis products were studied. The placement of catalysts played an important role on the catalytic pyrolysis of LDPE, and the pyrolytic volatiles first flowing through MgO and then biomass-derived activated carbon (BAC) could obtain an excellent result to produce H2 and jet fuel-rich products. The higher pyrolysis temperature converted diesel range alkanes into jet fuel range alkanes and promoted the aromatization of alkanes to generate aromatic hydrocarbons. BAC and MgO as catalysts had excellent performance in catalytic conversion of LDPE to produce hydrogen and jet fuel. 100 area.% jet fuel range products can be obtained in LDPE catalytic pyrolysis under desired experimental conditions. The combination of BAC and MgO as catalysts had a synergy effect on the gaseous product distribution and promoted the production of hydrogen, and up to 94.8 vol% of the obtained gaseous components belonged to hydrogen. This work provided an effective, convenient and economical pathway to produce jet fuel and hydrogen from waste plastics.

Synthesis and characterization of sulfonated activated carbon as a catalyst for bio-jet fuel production from biomass and waste plastics.

Sulfonated activated carbon-based catalysts were prepared by microwaved-assisted carbonization of phosphoric acid activated corncob followed by sulfonation using concentrated sulfuric acid. Sulfonation at different temperatures and times resulted in varied SO3H group density of the SAC catalysts. Sulfonation temperature showed a significant effect on the introduction of SO3H on the AC precursor while time had minor role. The SAC catalysts were characterized by means of N2 sorption analysis (specific surface area, pore-volume, average pore width), FTIR spectroscopy, SEM imaging, and sulfur analysis. The impact of catalysts SO3H density on the product distribution and bio-oil composition from the catalytic co-pyrolysis of Douglas fir and LDPE was evaluated. The highest bio-jet fuels (aromatics and C9-16 alkanes) obtained was 97.51% using the SAC catalyst sulfonated at 100 °C for 5 h. Results showed that SAC has great potential as catalyst in the co-pyrolysis of biomass and plastics for the production of jet-fuel range hydrocarbons.