Institutional Repository of GuangZhou Institute of Energy Conversion, CAS
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Ionic double-shell magnetic covalent organic framework for sharp and fast adsorption of critical metals
No full textThe recovery of critical metals (CMs) from waste streams has garnered increasing attention in recent years due to their increased demand, engineering applications, and vulnerability to supply disruptions. Herein, we synthesize two novel ionic materials, namely GIEC(704a) (magnetic covalent organic framework consisting of Fe3O4/TAGH-Dha) and GIEC(704b) (double-shell magnetic material formed of Fe3O4/TAGH-Dha/TpPa) using the solvothermal method for the recovery of CMs. The experimental data supported Langmuir's isotherm model, and the results showed that both GIEC(704a) and GIEC(704b) exhibited remarkable adsorption capacities (q(max)). GIEC(704a) exhibited adsorption capacities of 1531.8, 884.9, and 729.9 mg/g, while GIEC(704b) had 1681.5, 854.7, and 800 mg/g (Al3+, Fe3+ and Cu2+) capacities, respectively. Furthermore, GIEC(704a) and GIEC(704b) demonstrated approximately 80 % adsorption of REEs with high adsorption capacities of 53.6, 52.3, 41.2 mg/g and 55.3, 55.4, and 43.4 mg/g (Lanthanum, Yttrium, and Neodymium), respectively with excellent selectivity. The large surface areas of GIEC(704a) and GIEC(704b)-147.9 m(2)/g and 2143.1 m(2)/g, respectively-explain their excellent performance. The results of the kinetic study support the pseudo-second-order model with a high coefficient of (R-2 = 0.9999), and an efficiency of over 90 % was achieved within 5 min. The findings of the thermodynamic analysis indicated that the adsorption process was spontaneous and endothermic. Furthermore, the outstanding reusability of GIEC(704a) and GIEC(704b) confirmed their suitability for environmental chemical engineering and industrial applications
Aminated lignin improved enzymatic hydrolysis of cellulosic substrate treated by p-toluenesulfonic acid
No full textLignin can affect the enzymatic hydrolysis efficiency of lignocellulose. In this study, the lignin isolated from sugarcane bagasse (SCB) pretreated with p-toluenesulfonic acid (PL) was firstly aminated, and then the effects of PL and aminated PL (APL) on the bagasse enzymatic hydrolysis efficiency (EHE) were investigated. The results showed that the addition of PL and APL promoted the EHE, and EHE with APL (73.82 %) was higher than PL (51.39 %). To explore the reason, the data were further analyzed including cellulase adsorption capacity, enzyme activity, cellulase-lignin interaction, and molecular docking. It was found that APL adsorbed more cellulase (27.83 mg protein/g lignin) than PL (4.96 mg protein/g lignin), resulting from the greater interaction force and lower binding free energy between APL and cellulase. The addition of APL more remarkably enhanced the cellobiohydrolase and endoglucanase activities than PL due to more effectively inducing cellulase conformation optimization
Effect of pyrolysis temperature on migration characteristics of heavy metals during biomass pyrolysis
No full textIn this study, the distribution, morphology, and migration characteristics of heavy metals in the products obtained at different pyrolysis temperatures were studied. With an increase in the pyrolysis temperature, the heavy metals were more inclined to volatilize into bio-oil and syngas, and the volatilization ratio was Zn > Pb > Cr > Fe > Ni > Mn > Cu. At pyrolysis temperatures below 400 C-degrees, heavy metals were transformed from the migratory states (F1, F2, F3) to the residual state (F4). When the pyrolysis temperature exceeded 500 degrees C, heavy metals in migration states (F1, F2, F3) migrated to the bio-oil and syngas. The residual states (F4) of Fe, Cu, Ni, and Mn were stable. Although Zn and Pb in the residual state (F4) volatilized at high temperatures, the volatilization ratio was lower than that in the migratory state (F1, F2, and F3). At a pyrolysis temperature of 900(degrees)C, the potential risk factor (RI) of heavy metals decreased from 448.67 to 5.21, significantly reducing the environmental risk
Simultaneous regulation of nitrogen, sulfur and carbon using biochar during sewage sludge pyrolysis
No full textDue to the complex nature of sewage sludge (SS), how to control the emission of precursor pollutants during its pyrolysis remains a challenge. In this work, the evolution of N, S and C during SS pyrolysis was investigated and biochars were employed to regulate their distribution in the resulting products. The release of N-containing products followed a descending order of NH3>HCN > NO > NO2 and the biochar addition resulted in a reduction of 40.7-54.3 % for these volatiles. The nitrile-N and pyrrolic-N species decreased, while the quaternary-N in residue increased significantly. The emission of S-containing products showed a descending order of COS > SO2>CH3SH > H2S > CS2 and the co-pyrolysis with biochar showed a reduction of 40.6-65.7 % for these products. The relative contents of thiophene-S and sulfoxide-S species increased, while the content of sulfone-S decreased. Biochar incorporation also resulted in a reduction of 67.2 % and 47.4 % for CO and CO2, respectively. Both Raman and XPS analysis indicated an increase in the graphitization degree and a decrease in structural defects
Simultaneous regulation of nitrogen, sulfur and carbon using biochar during sewage sludge pyrolysis
No full textDue to the complex nature of sewage sludge (SS), how to control the emission of precursor pollutants during its pyrolysis remains a challenge. In this work, the evolution of N, S and C during SS pyrolysis was investigated and biochars were employed to regulate their distribution in the resulting products. The release of N-containing products followed a descending order of NH3>HCN > NO > NO2 and the biochar addition resulted in a reduction of 40.7-54.3 % for these volatiles. The nitrile-N and pyrrolic-N species decreased, while the quaternary-N in residue increased significantly. The emission of S-containing products showed a descending order of COS > SO2>CH3SH > H2S > CS2 and the co-pyrolysis with biochar showed a reduction of 40.6-65.7 % for these products. The relative contents of thiophene-S and sulfoxide-S species increased, while the content of sulfone-S decreased. Biochar incorporation also resulted in a reduction of 67.2 % and 47.4 % for CO and CO2, respectively. Both Raman and XPS analysis indicated an increase in the graphitization degree and a decrease in structural defects
Deep Reinforcement Learning-Based Joint Low-Carbon Optimization for User-Side Shared Energy Storage-Distribution Networks
No full textAs global energy demand rises and climate change poses an increasing threat, the development of sustainable, low-carbon energy solutions has become imperative. This study focuses on optimizing shared energy storage (SES) and distribution networks (DNs) using deep reinforcement learning (DRL) techniques to enhance operation and decision-making capability. An innovative dynamic carbon intensity calculation method is proposed, which more accurately calculates indirect carbon emissions of the power system through network topology in both spatial and temporal dimensions, thereby refining carbon responsibility allocation on the user side. Additionally, we integrate user-side SES and ladder-type carbon emission pricing into DN to create a low-carbon economic dispatch model. By framing the problem as a Markov decision process (MDP), we employ the DRL, specifically the deep deterministic policy gradient (DDPG) algorithm, enhanced with prioritized experience replay (PER) and orthogonal regularization (OR), to achieve both economic efficiency and environmental sustainability. The simulation results indicate that this method significantly reduces the operating costs and carbon emissions of DN. This study offers an innovative perspective on the synergistic optimization of SES with DN and provides a practical methodology for low-carbon economic dispatch in power systems
Analytical Solution for 2D Electro-Osmotic Consolidation of Unsaturated Soil With Non-linear Voltage Distribution
No full textExisting solutions for electro-osmotic consolidation assume a linear voltage distribution, which is inconsistent with the experimental findings. The present study introduces a novel two-dimensional electro-osmotic consolidation model for unsaturated soils, which considers the influence of non-linear voltage distribution. The closed-form solution is derived by employing the eigenfunction expansion method and the Laplace transform technique. The accuracy of the analytical solutions is validated through the implementation of finite element simulations. The findings from the parametric studies indicate that the excess pore water pressure (EPWP) observed in electro-osmotic consolidation is influenced by the distribution of voltage. The dissipation rate of EPWP is observed to be higher when subjected to non-linear voltage conditions compared to linear voltage conditions. Moreover, the impact of non-linear voltage distribution becomes more pronounced in unsaturated soil characterised by higher electro-osmosis conductivity and a lower ratio of kx/ky. In contrast, the excess pore air pressure (EPAP) remains unaffected by the voltage distribution
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