Institutional Repository of GuangZhou Institute of Energy Conversion, CAS
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Valorising lignocellulosic biomass to high-performance electrocatalysts via anaerobic digestion pretreatment
No full textAnaerobic digestion (AD) was initially evaluated as a potential preprocessing method for preparing biomass-based carbon electrocatalysts in this study. The AD pretreatment succeeded in the structural depolymerization and nitrogen enrichment of Hybrid Pennisetum, which provided favorable conditions to achieve efficient and homogeneous nitrogen introduction due to microorganism community enrichment and provided a porous structure by degradation of the biodegradable components. The resulted biochar exhibited improved physiochemical properties including higher specific surface areas, nitrogen content and graphitization degree than that obtained from pyrolyzing raw biomass. These improvements were positively correlated with the AD time and showed to have enhanced the performance in oxygen reduction reaction and practical microbial fuel cell applications. Amongst the investigated samples, the obtained biochar pretreated by AD for 15 days exhibited the most excellent performance with an onset potential of 0.17 V (VS. saturated calomel electrode) and the maximal power density of 543.2 mW cm-2 assembled in microbial fuel cells. This study suggested applying AD as a new biological pretreatment in the preparation of biomass-based electrocatalysts, and provided a unique pathway for fabricating high-performance biochar-based catalysts by structure optimization and N-containing active sites construction via gentle biological method, thereby providing a cost-effective method to fabricate metal-free catalysts for oxygen reduction reaction.
Anaerobic digestion pretreatment was conducted to assist electrocatalyst preparation.The biological pretreatment succeeded in carbohydrates decomposition and nitrogen enrichment.Pretreatment derived biochar significantly increased the ORR activity and microbial fuel cell performance
Synergistic Effect of Carbon Nanotubes, Zinc, and Copper Oxides on Rheological Properties of Fracturing Fluid: A Comparative Study
No full textNanomaterials play a beneficial role in enhancing the rheological behavior of fracturing (frac) fluid by reacting with intermolecular structures. The inclusion of these materials into the fluid improves its stability, increases the viscosity of polymers, and enhances its resistance to high temperature and pressure. In this investigation, multi-walled carbon nanotubes (CNTs), nano-zinc oxides (N-ZnO), and nano-copper oxides (N-CuO) have been utilized to ameliorate the rheological properties of water-based fracturing fluid. Different concentrations of these aforementioned nanomaterials were prepared to determine their effects on the rheological behavior of the fluid. The results revealed that the size of nanoparticles ranged from 10 to 500 nm, 300 nm, and 295 nm for CNTs, N-ZnO, and N-CuO, respectively. Moreover, employing CNTs exhibited a resistance of 550 cp at 25 degrees C and reached 360 cp at 50 degrees C with a CNT concentration of 0.5 g/L. In contrast, N-CuO and N-ZnO showed a resistance of 206 cp at 25 degrees C and significantly decreased to 17 cp and 16 cp with higher concentrations of 10 g/L and 1 g/L, respectively. Based on these findings, this study recommends utilizing CNTs to enhance fracking fluid's chemical and physical properties, which need to be highly viscous and stable under reservoir conditions
<i>In Situ</i> Ca- and Mg- Codoped Biochar Derived from Tobacco Stem for Phosphate Adsorption and Desorption
No full textPhosphorus is an important element for plant growth. The efficient use and recovery of phosphorus is crucial due to limited phosphate resource reserves. This study explored the potential application of an in situ Ca and Mg co-doped biochar derived from tobacco stem to reclaim and reuse phosphate from aqueous solutions. We performed various batch adsorption experiments and industrial analysis based on different parameters. The findings indicate that biochar prepared using the raw material particle size range of 0.85-2 mm and pyrolyzed at 800 degrees C presented good pore structure and specific surface area. Ca and Mg elements in biochar exhibited great influence on its phosphate adsorption property. The maximum phosphate adsorption capacity of the tobacco stem-based biochar was 54.66 mg/g, and the experimental data agreed with the Langmuir equation, suggesting monolayer adsorption. The adsorption process conformed to the pseudo-second-order kinetic equation, indicating that chemisorption was the dominant adsorption process and that the adsorption was controlled by intra-particle diffusion. Furthermore, phosphate adsorbed on tobacco stem-based in situ Ca and Mg co-doped biochar was released under acidic, alkaline, and neutral conditions. Therefore, in situ Ca and Mg co-doped biochar prepared from tobacco stems is a potential environmentally friendly and low-cost adsorbent for phosphorus recovery
Effect of Biochar in Modulating Anaerobic Digestion Performance and Microbial Structure Community of Different Inoculum Sources
No full textBiochar has attracted increasing attention as an additive for enhancing the performance of anaerobic digestion (AD), but the effect of biochar on microbial regulatory mechanisms in enhancing AD performance is unclear. To investigate how biochar modulates the process of AD, different inoculum sources including cellulose-peptone-swine inoculum (CPI) and swine manure inoculum (SMI) were designed to determine the effect of biochar on the performance and microbial communities of anaerobic digestion of the feedstock concentration from 1 to 6%. The results showed that the methane yields of CPI seeds were higher 20.3-38.7% than those of SMI seeds without a biochar addition, whereas the biochar addition reduced 5.3 and 23.1% of the corresponding methane yield of CPI and SMI, respectively. The biochar enhances the accumulation of volatile fatty acids (VFAs) and weakens the potential ammonia inhibition by adsorption, and it can improve the degradation rate of organic content of soluble COD for different inoculum sources. Microbial community analyses showed that the biochar addition could facilitate the growth of Bacteroidetes and Clostridiales, and it enriched the relative abundance of hydrogenotrophic methanogens Methanobrevibacter and Methanobacterium. Overall, although the modulation of biochar possessed different effects on the anaerobic digestion performance, it contributed to the stability and degradation efficiency of the digestion system. The recycling implication of biochar is critical to realizing a low-carbon and renewable treatment system for organic wastes
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