In this research, steel slag was used as a calcium source to synthesize a calcium-based CO2 sorbent (Ca-S) with high sorption capacity and cycling stability. The results showed that the sorption capacity of the prepared Ca-S can reach 14.54 mmol/g under the optimal synthesis and sorption conditions, reaching 81% of the theoretical sorption capacity of CaO. Moreover, the cyclic sorption performance of the synthesized Ca-S was compared with that of commercial Ca(OH)2, and it was found that the Ca-S still maintained a higher stability than commercial Ca(OH)2 after 30 cycles. In order to further improve the sorption performance of CO2, Ca-S was doped with Na2CO3/ K2CO3. When the Na2CO3 loading amount was 3 wt%, the sorption rate of the sorbent was improved, and the sorption capacity was increased to 16.18 mmol/g, reaching 91% of the theoretical sorption capacity of CaO. Finally, the anti-sintering mechanism of Ca-S and the promotion mechanism of Na2CO3 were discussed. The results show that the calcium-based CO2 sorbent prepared from steel slag will have broad application prospects.
Granular activated carbon is used in adsorption of low concentration ethanol in water, and the saturated carbon is desorbed by microwave irradiation under N2 condition for recovery of the ethanol and regeneration of the activated carbon. Through the study on microwave desorption of ethanol-loaded activated carbon under N2 condition, the following conclusions can be drawn. The highest value of the ethanol concentration appears quicker and higher when the microwave power is stronger. For example, the highest value appears before 80s when the microwave power is 320W; the ethanol-loaded activated carbon can be desorbed nearly completely after 120s when the microwave power is not weaker than 320W; the microwave power has an important effect on the outlet concentration curve of ethanol, and it is an important factor that affects the results of microwave desorption; After three processes of activated carbon adsorption and microwave desorption under N2 condition, the concentration of ethanol can come up to over than 94%～95% from 4%～8%. This paper sets forth the process and principle for microwave desorption of ethanol-loaded activated carbon under N2 condition.
Engineering survey often encountered some special complex terrain, for example, large-scale reservoirs, lakes, marshes and wetlands, and so on. Conventional measuring methods cannot accurately detect the data of these environments, because of their special terrain, and difficult to piling, to set up measurement instruments. This paper presents a new methodology formapping terrain and landscape of complex environment. And the mapping process of Heshun town wetland terrain by using this new and simple measuring method was introduced. This new measuring method could be useful for non-professionals to map the terrain and landscape of complex environment.
In response to the social goal of 'carbon peak and carbon neutral' in the 14th Five-Year Plan of China, this article used Enrofloxacin (ENR), a common antibiotic, as a model compound to study the method of efficiently degrading pharmaceutical sludge and simultaneously producing Formic Acid (FA), hydrogen storage energy, in a sub-supercritical system. The Ni/SnO2 bimetallic catalyst, which was prepared by the equal volume impregnation method, was used for the liquid phase catalysis. As shown by the results, when the reaction temperature was 330°C, and the addition amount of H2O2 was 0.38 mL, the degradation rate of antibiotics could reach 99% after the reaction proceeded for 6 h. In terms of the resource utilization, the yield of FA could reach up to 32.44%. The resource utilization efficiency with Ni/SnO2 catalyst in sub-/supercritical reaction was about 2.5 times higher than that without catalyst. The kinetic reaction model was established to explore the reaction rate of the antibiotic degradation process. In addition, the Ea and the frequency factor of the reaction were 6455 J/mol and 5.78, respectively. As shown by characterization, the prepared Ni/SnO2 bimetallic catalyst had good activity and has already passed repeated stability experiments. In short, this method has broad application prospects in antibiotic catalysis and resource degradation.
This paper may be of particular interest to the readers as it provides a new environmental risk assessment system for phosphogypsum tailing dams. In this paper, we studied the phosphogypsum tailing dams which include characteristics of the pollution source, environmental risk characteristics and evaluation requirements to identify the applicable environmental risk assessment methods. Two analytical methods, that is, the analytic hierarchy process (AHP) and fuzzy logic, were used to handle the complexity of the environmental and nonquantitative data. Using our assessment method, different risk factors can be ranked according to their contributions to the environmental risk, thereby allowing the calculation of their relative priorities during decision making. Thus, environmental decision-makers can use this approach to develop alternative management strategies for proposed, ongoing, and completed PG tailing dams.
A tubular resistance furnace was used as a reactor to simulate mercury and arsenic in smelter flue gases by heating mercury and arsenic compounds. The flue gas containing Hg(2+), Hg(0) and As was treated with ammonium sulphide. The experiment was conducted to investigate the effects of varying the concentration of ammonium sulphide, the pH value of ammonium sulphide, the temperature of ammonium sulphide, the presence of SO2 and the presence of sulphite ion on removal efficiency. The prepared adsorption products were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. The results showed that the optimal concentration of ammonium sulphide was 0.8 mol/L. The optimal pH value of ammonium sulphide was 10, and the optimal temperature of ammonium sulphide was 20°C.Under the optimum conditions, the removal efficiency of Hg(2+), Hg(0) and As could reach 99%, 88.8%, 98%, respectively. In addition, SO2 and sulphite ion could reduce the removal efficiency of mercury and arsenic from simulated flue gas.
In this study, MnO2 and pyrolusite were used as the catalysts to prepare modified activated carbon, that is, AC-Mn and AC-P, respectively, from coals by blending method and steam activation. The Brunauer–Emmett–Teller (BET) results indicated that the AC-P had higher surface areas and micropore volumes than the AC-Mn with the same blending ratio. The relative contents of basic functional groups (i.e., C = O, π-π*) on AC-P were slightly lower than those on AC-Mn, while both contained the same main metal species, namely, MnO. The desulfurization results showed that with 3 wt% of blending ratio, AC-Mn3 and AC-P3 had higher sulfur capacities at 220 and 205 mg/g, respectively, which were much higher than for the blank one (149.6 mg/g). Moreover, the AC-P had relatively higher sulfur capacity than the AC-Mn with the same contents of Mn, which might be attributed to the existence of other metals in pyrolusite. After the desulfurization process, MnO were gradually transferred into MnSO4, and the relative contents of basic functional groups decreased evidently for both AC-Mn3 and AC-P3. The results demonstrated that pyrolusite could be one good alternative to MnO2 to prepare modified activated carbon for desulfurization.Implications: MnO2 and pyrolusite were used as the additives to prepare modified activated carbon from coals by a blending method and by steam activation, that is, AC-Mn and AC-P, respectively. The AC-P had higher surface areas and micropore volumes than the AC-Mn with the same blending ratio. The AC-Mn and AC-P had higher sulfur capacities than a blank one. Moreover, the AC-P had relatively higher sulfur capacity than the AC-Mn with the same contents of Mn. The results demonstrated that pyrolusite could be one good alternative to MnO2 to prepare modified activated carbon for desulfurizatio.
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