Institutional Repository of GuangZhou Institute of Energy Conversion, CAS
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Developing a new ethylene glycol/H2O pretreatment system to achieve efficient enzymatic hydrolysis of sugarcane bagasse cellulose and recover highly active lignin: Countercurrent extraction
No full textImproving pretreatment efficiency is a critical premise in achieving efficient biomass conversion, and obtaining high-performance natural polymers is the guarantee of high-value conversion of biomass. In this study, a new pilot-scale continuous countercurrent pretreatment reaction unit about ethylene glycol-alkali solution was designed for pretreating sugarcane bagasse in order to achieve efficient separation of the three major components of lignocellulose when expanding the scale of pretreatment, reduce lignin deposition on the fiber surface, and obtain highly active lignin and excellent enzymatic hydrolysis efficiency of cellulose. X-ray diffractometer (XRD), X-ray photoelectron spectrometer (XPS), brunauer-emmett-teller (BET) and scanning electron microscope (SEM) methods are used to analyze the structural properties of sugarcane bagasse before and after pretreatment, and high-performance liquid chromatography (HPLC) is used to analyze the monosaccharide components in the enzymatic solution. In addition, the structural properties of the recovered lignin are analyzed by gel permeation chromatography (GPC), 31P NMR and 2D-HSQC-NMR methods. The results indicate that the system can gain a high cellulose recovery of 92.99% along with a lignin removal of 95.33%, and recovered lignin has low lignin carbohydrate complexes, low condensation, and rich in phenolic hydroxyl groups for 1.95 mmol/g. Meanwhile, the countercurrent pretreatment system can effectively reduce the deposition of lignin on the cellulose surface, which is evidently superior to the non-countercurrent pretreatment and facilitates the efficiency of enzymatic saccharification of substrate, achieving a high glucose yield of 99% as well as a total sugar yield of 91.11%. The method efficiently separates biomass in a green manner, and solid residues are easily hydrolyzed, showing potential for industrial-scale production
An alternative amino acid leaching of base metals from waste printed circuit boards using alkaline glutamate solutions: A comparative study with glycine
No full textOver the last decade, glycine has received significant attention as a green lixiviant, given its benign nature and selectivity. However, its application in leaching waste printed circuit boards faces limitations in production capacity. To address this challenge, the present study introduces alkaline glutamate (Glut) leaching as an alternative method. The glutamate leaching was found highly selective to Cu, Zn and Pb, and under the optimised conditions, 85.1 % Cu, 88.0 % Zn and 61.5 % Pb were extracted. Comparative analysis with glycine leaching revealed significant advantages of glutamate leaching. Glycine leaching with > 2 % solids resulted in limited Cu extraction and considerable Cu loss (30-65 %), due to the precipitation of oversaturated cupric glycinate. In contrast, 5 times higher solids content (10 %) could be accommodated in glutamate leaching. Furthermore, the Cu concentration in the leachate of alkaline glutamate leaching was found to be more than double that from glycine leaching (21.0 vs. 9.9 g/L)
Synergistic effect of carbon molecular sieve and alkali metal nitrate on promoting intermediate-temperature adsorption of CO2 over MgAl-layered double hydroxide
No full textThe development of intermediate-temperature adsorbents with high CO2 adsorption capacity is crucial for the tandem integration with CO2 hydrogenation catalyst, aimed at enhancing economy viability and minimizing energy consumption in Carbon capture, utilization and storage (CCUS). Although certain porous carbon materials (PCM) have been employed to enhance CO2 adsorption capability of layered double hydroxide (LDH), there remains an urgent necessity to identify more cost-effective and efficient PCM alternatives. Herein, alkali metal nitrates ((Li0.3Na0.18K0.52)NO3, hereafter referred to as LiNaK) modified layered double hydroxide (LDH)/carbon molecular sieve (CMS) composite (LiNaK-LDH/CMS) as promising adsorbents for CO2 capture was reported. The effects of CMS addition and nitrate loading, the calcination and adsorption temperature, as well as the cycling stability were investigated systematically. The results revealed that the CO2 capture capacity of the LiNaKmodified layered double oxide (LDO)/CMS composite (30 mol%LiNaK-LDO/CMS15%)-incorporating with 15 wt% CMS addition and 30 mol% nitrate loading-achieved a remarkable CO2 adsorption capacity of 1.32 mmol/g at 300 degrees C due to the synergetic interactions between CMS and nitrate; this represents nearly a sevenfold enhancement compared to initial LDO performance. Moreover, the 30 mol%LiNaK-LDO/CMS15% adsorbent also demonstrated commendable cyclic stability after ten adsorption/desorption cycles, retaining over 85 % of its initial adsorption capacity within half of adsorption time. Based on both obtained adsorption performance and characterization data from the adsorbents, a pre-adsorption enhancing CO2 intermediate-temperature adsorption mechanism over LiNaK-LDH/CMS composite through air calcination processes is proposed. This study significantly advances LDH-based adsorbent for future research into CO2 intermediate-temperature adsorption
Life cycle optimization oriented to sustainable waste management and circular economy: A review
No full textLife cycle optimization (LCO) is an effective decision-making method combining life cycle assessment and optimization, which is capable of adjusting system configurations to meet specified sustainability goals. This study analyzed the status quo of LCO studies related to sustainable waste management and the circular economy. Most studies have focused on simultaneously optimizing environmental and economic objectives, whereas few have considered social impacts. Greenhouse gas emissions is the most commonly used environmental indicator in optimization, followed by the endpoint single-score indicator. A static deterministic model is often employed to formulate an LCO problem, while uncertainty and dynamic models are less frequently applied but cause concerns. To deal with multi-objective optimization, the epsilon-constraint method and non-dominated sorting genetic algorithm are popular. Waste LCO has been mainly applied to macro system planning, such as integrated municipal solid waste management systems, biowaste supply chains, waste-to-energy systems, and waste-to- resource networks, aiming to determine optimal waste allocation, facility capacity/location, technology choice, etc. It is occasionally used in optimizing process structure, operating conditions, blending ratio of feedstocks, and product development. Future research should focus on exploring the integration of more environmental and social indicators into multi-objective optimization, modeling under uncertainty, dynamic LCO, process and product optimization, and addressing the lack of multi-scale studies
Analysis, risk assessment and treatment of aquatic micro/nanoplastics: A critical review
No full textAquatic micro/nanoplastics (M/NPs) as a global environmental pollutant, energetically prefers to the adsorption of heavy metals and organic matter in water, which is a serious threat to the ecological environment and people's health. At present, compared with hot research of M/NPs source, migration, transformation, reorientation and ecotoxicological effect, analysis and treatment of M/NPs in water environments is still in early stages. In this work, this review summarizes a panorama of the state-of-the-art progress related to the aquatic M/NPs analysis, including water collection, sample pretreatment and M/NPs identification. The construction and characteristics of each identification methods could be introduced, namely optical or electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric differential scanning calorimetry and pyrolysis gas chromatography-mass spectrometry. This is followed by a consideration of the risk assessment for aquatic M/NPs by employing different indicators. Apart from that, the review has clear clarification of M/NPs treatment methods based on its mechanism, such as coagulating sedimentation, filtering, adsorption, advanced oxidation process, disinfection process, traditional activated sludge process, membrane bioreactor and constructed wetland method. The removal performance, influence factors, limitations and future development directions of these treatment processes for M/NPs are also discussed and summarized. Last but not least, future opportunities and challenges for aquatic M/NPs analysis and treatment are presented. This review can not only serve as a scientific guidance to promote the progress of techniques and accelerate its large-scale application, but also provide new insights toward future research
Advances in thermochemical valorization of biomass towards carbon neutrality
No full textIn the context of carbon neutrality, the push for sustainable and low-carbon development in both economy and society have accelerated the large-scale utilization of biomass as a partial replacement for fossil fuels. As the only carbon-containing renewable resource, biomass valorization shows great potential in the production of valueadded products including carbon-negative biofuels, chemicals, and carbon materials. In this review, we highlight the key aspects of thermochemical upgrading, including the thermal deconstruction of biomass feedstock, selective production of high-value chemicals, and the preparation and application of carbon-based materials. Particularly, the application of sustainable and economical pretreatments is vital for promoting efficiency in the follow-up thermochemical transformation. The introduction of catalytic materials greatly contributes to the selective production of a series of building blocks and high-value chemicals. Furthermore, it is clear that the future application of porous biochar strongly depends on the modification methods. Last but not least, the challenges and future research directions for the large-scale utilization of biomass are proposed, where effective coupling of thermal deconstruction with further upgrading into a wide range of derivatives should be given significant emphasis. This review aims to provide strong support for the realization of carbon neutrality through high-value transformation of biomass resources
Advances in thermochemical valorization of biomass towards carbon neutrality
No full textIn the context of carbon neutrality, the push for sustainable and low-carbon development in both economy and society have accelerated the large-scale utilization of biomass as a partial replacement for fossil fuels. As the only carbon-containing renewable resource, biomass valorization shows great potential in the production of valueadded products including carbon-negative biofuels, chemicals, and carbon materials. In this review, we highlight the key aspects of thermochemical upgrading, including the thermal deconstruction of biomass feedstock, selective production of high-value chemicals, and the preparation and application of carbon-based materials. Particularly, the application of sustainable and economical pretreatments is vital for promoting efficiency in the follow-up thermochemical transformation. The introduction of catalytic materials greatly contributes to the selective production of a series of building blocks and high-value chemicals. Furthermore, it is clear that the future application of porous biochar strongly depends on the modification methods. Last but not least, the challenges and future research directions for the large-scale utilization of biomass are proposed, where effective coupling of thermal deconstruction with further upgrading into a wide range of derivatives should be given significant emphasis. This review aims to provide strong support for the realization of carbon neutrality through high-value transformation of biomass resources
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