With the development of industry, the discharge of wastewater containing mercury ions posed a serious threat to human health. Using biomass waste as an adsorbent to treat wastewater containing mercury ions was a better way due to its positive impacts on the environment and resource saving. In this research, activated carbon (AC) was prepared from rice husk (RH) by the KOH chemical activation method. The characterization results of scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), Fourier transform infrared (FTIR), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) showed that rice husk-activated carbon (RHAC) had good pore structure and oxygen-containing functional groups. The influences of contact time, initial concentration of Hg(II), adsorbent dosage, pH, and ionic strength on mercury ion removal were investigated. The Langmuir model was most suitable for the adsorption isotherm of RHAC, and its maximum adsorption capacity for Hg(II) was 55.87 mg/g. RHAC still had a high removal capacity for Hg(II) after five regeneration cycles. RHAC had excellent removal efficiency for mercury ion wastewater. At the same time, RH could be used as a nonpolluting and outstanding characteristic adsorbent material.
Biorefinery technology contributes to promoting the realization of the Paris Agreement, China’s achievement of its carbon peak, and carbon neutralization. Photo-fermentation biohydrogen production, dark fermentation biohydrogen production, biomethane production, and bioethanol production are several promising biorefinery methods. In this study, corn stover was used as the raw material, and the gas, liquids, and kinetic characteristics; production yield; heat value, economy, and greenhouse gas emissions of the target products were investigated. The maximum yields of photo-fermentation biohydrogen production, dark fermentation biohydrogen production, biomethane production, and bioethanol production were 68.35 mL/g, 47.42 mL/g, 196.01 mL/g, and 2.70 g/L, respectively. The maximum heat value obtained by biomethane production was 6468.44 J/g. The maximum economy of 1.37 RMB/g was observed in photo-fermentation biohydrogen production. Biomethane production had the highest greenhouse gas emissions of 196.01 mL/g. The results provided a reference for the efficient utilization of biomass resources and the comprehensive evaluation of biorefinery technology.
In order to investigate the feasibility of treatment of dairy farm wastewater by constructed wetland and to provide the operation parameters for a full scale constructed wetlands to improve the quality of effluent water, A pilot test was conducted with a plug flow constructed wetland to treat dairy farm wastewater in Ji'nan city. The results show that, under influent loading rate 3m 3 ·d -1 , the average removal efficiency of chemical oxygen demand (COD), Total phosphorus (TP), total nitrogen (TN), and ammoniacal nitrogen(NH 4+ -N) in the plug flow constructed wetland were 66.98%, 57.49%, 57.16%, and 55.09%, respectively. Temperature has a positive effect on the removal rate. The study indicates that t purifying dairy farm wastewater by constructed wetland is the combined actions of physical chemistry, plants and microorganism.
China is a great agricultural country. Reasonable development and utilization of rural energy is related to Peasant's human production and life and improvement of rural eco-environment. Because lack of energy is serious in recent years. China strengthened study on biogas technology and got rich findings. But there is relatively backward in extended application of biogas technology. Therefore,this thesis adopted analytical hierarchy process to analyze on main factors which influenced extended application of rural biogas technology and made order about important level of influential factors of extended Application of biogas technology. Confirming main factors which influenced extended application of biogas technology. Laying the basis on making measure and program of extended application of biogas technology. Moreover, suggestions were put forward on this basis.
Water content plays a crucial role in seed development, particularly at the seed sowing stage, and it ensures good seed germination. A water seed drill was designed and developed to provide an optimum quantity of water that is required for the soil in the same furrow, right after seed placement. This soil moistening method not only improves the moisture level in the field, but it also saves a large amount of water by applying the needed water quantity in the line of sowing after seed placement. The water seed drill consisted of a wheat seed drill, a water application system, and a tank with 400 L capacity. The water seed drill yielded a 48% higher germination count than when wheat is planted through a conventional method. The data recorded also showed that the water seed drill raised the soil moisture to 24% from the existing 13% soil moisture content. The total operational cost of the water seed drill was 2.57-fold greater than the conventional seed drill, but the output cost of the water seed drill was 2.15 times (49,000 Rs/ha) more than that of the conventional seed drill.
The naturally lackadaisical kinetics of oxygen reduction reaction (ORR) in the cathode is one of the important factors that restrict the development of air-cathode microbial fuel cells (MFCs). In this work, the iron-nitrogen-carbon hierarchically nanostructured materials had been successfully fabricated by pyrolyzing glucose, iron chloride, and dicyandiamide with the aim of solving the issue. The obtained catalyst with an ultrathin nanostructure demonstrated an idiosyncratic electrocatalytic activity caused by the high content introduction of nitrogen and iron atoms, large surface area, which will offer sufficient active sites for improving the charge/mass transfer and reducing the diffusion resistance. Furthermore, with the increase of N dopant in the catalyst, better ORR catalytic activity could be achieved. Illustrating the N doping was beneficial to the ORR process. The high content of N, BET surface area caused by the N increasing could be responsible for the superior performance according to results of X-Ray photoelectron spectroscopy (XPS), Raman and Brunner-Emmet-Teller (BET) analysis. The ORR on the Fe–N3/C material follows 4e− pathway, and MFCs equipped with Fe–N3/C catalyst achieved a maximum power density (MPD) of 912 mW/m2, which was 1.1 times of the MPD generated by the commercial Pt/C (830 mW/m2). This research not only provided a feasible way for the fabrication of Pt-free catalyst towards oxygen reduction but also proposed potential cathode catalysts for the development of MFCs.
Keywords: one-pot pyrolysis route, Fe−N-Doped carbon nanosheets, microbial fuel cells, iron-nitrogen co-doping, carbon based catalyst, electrochemical performance, cathode materials
DOI: 10.25165/j.ijabe.20201306.5765
Citation: Sun Y, Zhang Z Z, Sun Y M, Yang G X. One-pot pyrolysis route to Fe−N-Doped carbon nanosheets with outstanding electrochemical performance as cathode materials for microbial fuel cell. Int J Agric & Biol Eng, 2020; 13(6): 207–214.
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