Synthesis and application of carbon-based materials for the construction of an artificial nitrogen cycle with electrochemistry

This dissertation aims to contribute towards an artificial nitrogen cycle based on carbon-based materials design by electrochemical nitrogen reduction with an electrochemical activated C2N material and nitrate reduction with a single bismuth site material. These two parts include materials design and mechanism interpreting with experiments combined with density functional theory (DFT) calculations. By building well-defined catalytically active sites on heterogeneous carbon-based materials in different dimensions, it hopefully lights up a mild flame for the path to our ambitious goal, artificial nitrogen cycle

Chrome tanning process and the leather properties under microwave irradiation

Content: In leather making processes, the thermal and non-thermal effect of microwave, especially non-thermal effect, strengthen the combination between collagen and chemicals. Although tanning under microwave makes the leather have better thermal stability, the tanning process and leather properties have not been studied in detail. For illustrating the influence of microwave on chrome tanning process, pickled skin was tanned for 6h as penetration procedure and then basified for another 4h as fixation procedure. The tanning under microwave heating (MW) was experimental sample and under water bath heating was control. UVVis, ICP-OES and pH meter were used to measure the changes of tanning effluent during tanning, and Shrinkage temperature meter, DSC, TG, FT-IR, SEM, XRD and XPS were applied to determine the differences between MW and WB in aspect of leather property and structure. The results indicated microwave accelerated chrome tanning agent penetration and had better promotion effect on chromium complex hydrolysis and olation. The leather tanned with microwave assisting had special effect on improve tanning effect which led better thermal stability and resistance of leather, but the collagen structure, including triple helix structure, stayed as WB and the combination mechanism between collagen and chromium was also same with conventional. In sum, microwave had positive effect on accelerating tanning rate and resulting in better leather without any negative effect on leather structure. Therefore, microwave would be a potential for achieving clean and sustainable chrome tanning by making tanning much faster and more efficiency. Take-Away: Microwave promotes chrome tanning agent penetration and combination Microwave has positive effect on tanning effect further as the leather tanned by microwave assisting has higher thermal stability. Although microwave promotes chrome tanning process, the collagen structure and tanning mechanism remained as normal

Ti (III)-tannin combination tanning technology based on microwave irradiation

Content: Microwave is a fast, efficient and energy-saving thermal resource, hence an attempt has been made for applying this technology in the combination tanning using titanium (III) and tannin extracts. In this work, the microwave effects on the complex reaction of Ti (III) with tannin extracts and leather products properties were investigated. The precipitation condition was used to characterize the complexation degree between Ti (III) and tannin extracts. And the shrinkage temperature, tear strength, SEM, DSC, TG, FT-IR, and histological structure were used to characterize the changes in the physical and chemical properties of the combined tanned leather. Take-Away: The results showed that microwave irradiation can accelerate the complex reaction of Ti (III) with tannin extracts. At the room temperature, the mixture of tannin and titanous sulphate kept stable at pH 3-4. In addition, microwave could increase the shrinkage temperature, tear strength, thermal stability, and fibrage of Ti (III)-tannin tanned leather, and it would not change the combination mode of the skins with tanning agents as well as the hierarchical structure of collagen. Therefore, these results inferred that microwave could promote the reaction between Ti (III) and tannins and the combination of tannins with collagen, which may provide a theoretical basis for the application of microwave in Ti (III)-tannin combination tanning technology

A Novel Collagen Extraction Method Based on Microwave Irradiation

Content: Microwave was used as a thermal source to extract collagen acid from the cattle hide in the present work. The effects of microwave on collagen extraction yields were studied under different microwave temperatures, time and hide-liquid ratio. The optimal extraction process was obtained by an orthogonal experiment, and the composition, structure and properties of the extracted collagen were characterized by amino acid analysis, SDS-PAGE, FTIR, UV-Vis, CD, FL, and VP-DSC. The results showed that the extraction rate of collagen was positively correlated with temperature, time and hide-liquid ratio. Under the condition of 35 °C, 6 h and 1:30 of solid-liquid ratio, the extraction proportion of collagen extracted under microwave was the highest, reaching to 13.40 %. The extracted collagen was identified as type I collagen by Amino acid analysis, and the graphic pattern of SDS-PAGE, FTIR and UV-Vis showed that the extracted collagen was similar to the standard type I collagen. Also, the results suggest that the triple helical structure exists still in the extracted collagen. The transition from triple helix to random coil of the extracted collagen was 41 ℃. These results provide a scientific basis for microwave technology for the extraction of collagen. Take-Away: The results showed that the extraction rate of collagen was positively correlated with temperature, time and hide-liquid ratio. Under the condition of 35 °C, 6 h and 1:30 of solid-liquid ratio, the extraction proportion of collagen extracted under microwave was the highest, reaching to 13.40 %. The extracted collagen was identified as type I collagen by Amino acid analysis, and the graphic pattern of SDS-PAGE, FTIR and UV-Vis showed that the extracted collagen was similar to the standard type I collagen. Also, the results suggest that the triple helical structure exists still in the extracted collagen. The transition from triple helix to random coil of the extracted collagen was 41 ℃. These results provide a scientific basis for microwave technology for the extraction of collagen

Electrochemical Generation of Catalytically Active Edge Sites in C₂N‐Type Carbon Materials for Artificial Nitrogen Fixation

The electrochemical nitrogen reduction reaction (NRR) to ammonia (NH₃) is a potentially carbon‐neutral and decentralized supplement to the established Haber–Bosch process. Catalytic activation of the highly stable dinitrogen molecules remains a great challenge. Especially metal‐free nitrogen‐doped carbon catalysts do not often reach the desired selectivity and ammonia production rates due to their low concentration of NRR active sites and possible instability of heteroatoms under electrochemical potential, which can even contribute to false positive results. In this context, the electrochemical activation of nitrogen‐doped carbon electrocatalysts is an attractive, but not yet established method to create NRR catalytic sites. Herein, a metal‐free C₂N material (HAT‐700) is electrochemically etched prior to application in NRR to form active edge‐sites originating from the removal of terminal nitrile groups. Resulting activated metal‐free HAT‐700‐A shows remarkable catalytic activity in electrochemical nitrogen fixation with a maximum Faradaic efficiency of 11.4% and NH₃ yield of 5.86 µg mg⁻¹cat h⁻¹. Experimental results and theoretical calculations are combined, and it is proposed that carbon radicals formed during activation together with adjacent pyridinic nitrogen atoms play a crucial role in nitrogen adsorption and activation. The results demonstrate the possibility to create catalytically active sites on purpose by etching labile functional groups prior to NRR

Chrome tanning process and the leather properties under microwave irradiation

Content: In leather making processes, the thermal and non-thermal effect of microwave, especially non-thermal effect, strengthen the combination between collagen and chemicals. Although tanning under microwave makes the leather have better thermal stability, the tanning process and leather properties have not been studied in detail. For illustrating the influence of microwave on chrome tanning process, pickled skin was tanned for 6h as penetration procedure and then basified for another 4h as fixation procedure. The tanning under microwave heating (MW) was experimental sample and under water bath heating was control. UVVis, ICP-OES and pH meter were used to measure the changes of tanning effluent during tanning, and Shrinkage temperature meter, DSC, TG, FT-IR, SEM, XRD and XPS were applied to determine the differences between MW and WB in aspect of leather property and structure. The results indicated microwave accelerated chrome tanning agent penetration and had better promotion effect on chromium complex hydrolysis and olation. The leather tanned with microwave assisting had special effect on improve tanning effect which led better thermal stability and resistance of leather, but the collagen structure, including triple helix structure, stayed as WB and the combination mechanism between collagen and chromium was also same with conventional. In sum, microwave had positive effect on accelerating tanning rate and resulting in better leather without any negative effect on leather structure. Therefore, microwave would be a potential for achieving clean and sustainable chrome tanning by making tanning much faster and more efficiency. Take-Away: Microwave promotes chrome tanning agent penetration and combination Microwave has positive effect on tanning effect further as the leather tanned by microwave assisting has higher thermal stability. Although microwave promotes chrome tanning process, the collagen structure and tanning mechanism remained as normal

Chrome tanning process and the leather properties under microwave irradiation

Content: In leather making processes, the thermal and non-thermal effect of microwave, especially non-thermal effect, strengthen the combination between collagen and chemicals. Although tanning under microwave makes the leather have better thermal stability, the tanning process and leather properties have not been studied in detail. For illustrating the influence of microwave on chrome tanning process, pickled skin was tanned for 6h as penetration procedure and then basified for another 4h as fixation procedure. The tanning under microwave heating (MW) was experimental sample and under water bath heating was control. UVVis, ICP-OES and pH meter were used to measure the changes of tanning effluent during tanning, and Shrinkage temperature meter, DSC, TG, FT-IR, SEM, XRD and XPS were applied to determine the differences between MW and WB in aspect of leather property and structure. The results indicated microwave accelerated chrome tanning agent penetration and had better promotion effect on chromium complex hydrolysis and olation. The leather tanned with microwave assisting had special effect on improve tanning effect which led better thermal stability and resistance of leather, but the collagen structure, including triple helix structure, stayed as WB and the combination mechanism between collagen and chromium was also same with conventional. In sum, microwave had positive effect on accelerating tanning rate and resulting in better leather without any negative effect on leather structure. Therefore, microwave would be a potential for achieving clean and sustainable chrome tanning by making tanning much faster and more efficiency. Take-Away: Microwave promotes chrome tanning agent penetration and combination Microwave has positive effect on tanning effect further as the leather tanned by microwave assisting has higher thermal stability. Although microwave promotes chrome tanning process, the collagen structure and tanning mechanism remained as normal

A Novel Collagen Extraction Method Based on Microwave Irradiation

Content: Microwave was used as a thermal source to extract collagen acid from the cattle hide in the present work. The effects of microwave on collagen extraction yields were studied under different microwave temperatures, time and hide-liquid ratio. The optimal extraction process was obtained by an orthogonal experiment, and the composition, structure and properties of the extracted collagen were characterized by amino acid analysis, SDS-PAGE, FTIR, UV-Vis, CD, FL, and VP-DSC. The results showed that the extraction rate of collagen was positively correlated with temperature, time and hide-liquid ratio. Under the condition of 35 °C, 6 h and 1:30 of solid-liquid ratio, the extraction proportion of collagen extracted under microwave was the highest, reaching to 13.40 %. The extracted collagen was identified as type I collagen by Amino acid analysis, and the graphic pattern of SDS-PAGE, FTIR and UV-Vis showed that the extracted collagen was similar to the standard type I collagen. Also, the results suggest that the triple helical structure exists still in the extracted collagen. The transition from triple helix to random coil of the extracted collagen was 41 ℃. These results provide a scientific basis for microwave technology for the extraction of collagen. Take-Away: The results showed that the extraction rate of collagen was positively correlated with temperature, time and hide-liquid ratio. Under the condition of 35 °C, 6 h and 1:30 of solid-liquid ratio, the extraction proportion of collagen extracted under microwave was the highest, reaching to 13.40 %. The extracted collagen was identified as type I collagen by Amino acid analysis, and the graphic pattern of SDS-PAGE, FTIR and UV-Vis showed that the extracted collagen was similar to the standard type I collagen. Also, the results suggest that the triple helical structure exists still in the extracted collagen. The transition from triple helix to random coil of the extracted collagen was 41 ℃. These results provide a scientific basis for microwave technology for the extraction of collagen

Robust Extraction of 3D Line Segment Features from Unorganized Building Point Clouds

As one of the most common features, 3D line segments provide visual information in scene surfaces and play an important role in many applications. However, due to the huge, unstructured, and non-uniform characteristics of building point clouds, 3D line segment extraction is a complicated task. This paper presents a novel method for extraction of 3D line segment features from an unorganized building point cloud. Given the input point cloud, three steps were performed to extract 3D line segment features. Firstly, we performed data pre-processing, including subsampling, filtering and projection. Secondly, a projection-based method was proposed to divide the input point cloud into vertical and horizontal planes. Finally, for each 3D plane, all points belonging to it were projected onto the fitting plane, and the α-shape algorithm was exploited to extract the boundary points of each plane. The 3D line segment structures were extracted from the boundary points, followed by a 3D line segment merging procedure. Corresponding experiments demonstrate that the proposed method works well in both high-quality TLS and low-quality RGB-D point clouds. Moreover, the robustness in the presence of a high degree of noise is also demonstrated. A comparison with state-of-the-art techniques demonstrates that our method is considerably faster and scales significantly better than previous ones. To further verify the effectiveness of the line segments extracted by the proposed method, we also present a line-based registration framework, which employs the extracted 2D-projected line segments for coarse registration of building point clouds

Ti (III)-tannin combination tanning technology based on microwave irradiation

Content: Microwave is a fast, efficient and energy-saving thermal resource, hence an attempt has been made for applying this technology in the combination tanning using titanium (III) and tannin extracts. In this work, the microwave effects on the complex reaction of Ti (III) with tannin extracts and leather products properties were investigated. The precipitation condition was used to characterize the complexation degree between Ti (III) and tannin extracts. And the shrinkage temperature, tear strength, SEM, DSC, TG, FT-IR, and histological structure were used to characterize the changes in the physical and chemical properties of the combined tanned leather. Take-Away: The results showed that microwave irradiation can accelerate the complex reaction of Ti (III) with tannin extracts. At the room temperature, the mixture of tannin and titanous sulphate kept stable at pH 3-4. In addition, microwave could increase the shrinkage temperature, tear strength, thermal stability, and fibrage of Ti (III)-tannin tanned leather, and it would not change the combination mode of the skins with tanning agents as well as the hierarchical structure of collagen. Therefore, these results inferred that microwave could promote the reaction between Ti (III) and tannins and the combination of tannins with collagen, which may provide a theoretical basis for the application of microwave in Ti (III)-tannin combination tanning technology