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1.
The novel carbon dioxide(CO2) adsorbents with a high capture effciency were prepared through impregnating the as-synthesized MCM-41 with three kinds of amines,namely diethylenetriamine(DETA) ,triethylenetetramine(TETA) and 2-amino-2-methyl-1-propanol(AMP) .The resultant samples were characterized by small angle X-ray diffraction and low temperature N2 adsorption.The synthesis way not only saves the energy or extractor to remove the template but also is environmentally friendly due to the absence of the potential pollutants such as toluene.CO2 capture was investigated in a dynamic packed column.The sample impregnated by TETA showed the highest adsorption capacity,approximately 2.22 mmol/g at 60°C due to its highest amino-groups content among the three amines.The CO2 adsorption behavior was also investigated with the deactivation model,which showed an excellent prediction for the breakthrough curves.  相似文献   

2.
Carbon dioxide (CO2) adsorption on a standard metal-organic framework Mg2(dobdc) (Mg/DOBDC or Mg-MOF-74) and a tetraethylenepentamine (TEPA) modified Mgz(dobdc) (TEPA-Mg/DOBDC) were investigated and compared. The structural information, surface chemistry and thermal behavior of the adsorbent samples were characterized by X-ray powder diffraction (XRD), infrared spectroscopy (IR), thermogravimetric analysis (TGA) and nitrogen adsorption-desorption isotherm analysis. CO2 adsorption capacity was measured by dynamic adsorption experiments with N2-CO2 mixed gases at 60℃. Results showed that the CO2 adsorption capacity of Mg/DOBDC was significantly improved after amine modification, with an increase from 2.67 to 6.06 mmol CO2/g adsorbent. Moreover, CO2 adsorption on the TEPA-Mg/DOBDC adsorbent was promoted by water vapor, and the adsorption capacity was enhanced to 8.31 mmol CO2/g absorbent. The adsorption capacity of the TEPA-Mg/DOBDC adsorbent dropped only 3% after 5 consecutive adsorption]desorption cycles. Therefore, this kind of adsorbent can be considered as a promising material for the capture of CO2 from flue gas.  相似文献   

3.
Mesoporous carbon adsorbents, having high nitrogen content, were synthesized via nanocasting technique with melamine–formaldehyde resin as precursor and mesoporous silica as template. A series of adsorbents were prepared by varying the carbonization temperature from 400 to 700°C. Adsorbents were characterized thoroughly by nitrogen sorption, X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), thermogravimetric analysis(TGA), elemental(CHN) analysis, Fourier transform infrared(FTIR) spectroscopy and Boehm titration. Carbonization temperature controlled the properties of the synthesized adsorbents ranging from surface area to their nitrogen content, which play major role in their application as adsorbents for CO_2 capture.The nanostructure of these materials was confirmed by XRD and TEM. Their nitrogen content decreased with an increase in carbonization temperature while other properties like surface area, pore volume, thermal stability and surface basicity increased with the carbonization temperature. These materials were evaluated for CO_2 adsorption by fixed-bed column adsorption experiments. Adsorbent synthesized at 700°C was found to have the highest surface area and surface basicity along with maximum CO_2 adsorption capacity among the synthesized adsorbents. Breakthrough time and CO_2 equilibrium adsorption capacity were investigated from the breakthrough curves and were found to decrease with increase in adsorption temperature. Adsorption process for carbon adsorbent–CO_2 system was found to be reversible with stable adsorption capacity over four consecutive adsorption–desorption cycles. From three isotherm models used to analyze the equilibrium data, Temkin isotherm model presented a nearly perfect fit implying the heterogeneous adsorbent surface.  相似文献   

4.
The catalysts of iron-doped Mn-Ce/TiO 2(Fe-Mn-Ce/TiO 2) prepared by sol-gel method were investigated for low temperature selective catalytic reduction(SCR) of NO with NH 3.It was found that the NO conversion over Fe-Mn-Ce/TiO 2 was obviously improved after iron doping compared with that over Mn-Ce/TiO 2.Fe-Mn-Ce/TiO 2 with the molar ratio of Fe/Ti = 0.1 exhibited the highest activity.The results showed that 96.8% NO conversion was obtained over Fe(0.1)-Mn-Ce/TiO 2 at 180°C at a space velocity of 50,000 hr 1.Fe-Mn-Ce/TiO 2 exhibited much higher resistance to H 2 O and SO 2 than that of Mn-Ce/TiO 2.The properties of the catalysts were characterized using X-ray diffraction(XRD),N 2 adsorption,temperature programmed desorption(NH 3-TPD and NOx-TPD),and Xray photoelectron spectroscopy(XPS) techniques.BET,NH3-TPD and NOx-TPD results showed that the specific surface area and NH3 and NOx adsorption capacity of the catalysts increased with iron doping.It was known from XPS analysis that iron valence state on the surface of the catalysts were in Fe3+ state.The doping of iron enhanced the dispersion and oxidation state of Mn and Ce on the surface of the catalysts.The oxygen concentrations on the surface of the catalysts were found to increase after iron doping.Fe-Mn-Ce/TiO2 represented a promising catalyst for low temperature SCR of NO with NH3 in the presence of H2 O and SO2.  相似文献   

5.
Three organo-montmorillonites were prepared using surfactants, and their adsorption behaviors toward sulfamethoxazole(SMX) were investigated. The surfactants used were cetyltrimethyl ammonium bromide(CTMAB), 3-(N,N-dimethylhexadecylammonio) propane sulfonate(HDAPS) and 1,3-bis(hexadecyldimethylammonio)-propane dibromide(BHDAP). The properties of the organo-montmorillonites were characterized by X-ray diffraction, scanning electron microscopy and N2adsorption–desorption isotherm measurements. Results showed that the interlayer spacing of montmorillonite was increased and the surface area as well as the morphology were changed. Batch adsorption experiments showed that the surfactant loading amount had a great effect on the adsorption of SMX. The adsorption process was p H dependent and the maximum adsorption capacity was obtained at p H 3 for HDAPS-Mt, while CTMAB-Mt and BHDAP-Mt showed a high removal efficiency at 3–11. The adsorption capacity increased with the initial SMX concentration and contact time but decreased with increasing solution ionic strength.Kinetic data were best described by the pseudo second-order model. Equilibrium data were best represented by the Langmuir model, and the Freundlich constant(n) indicated a favorable adsorption process. The maximum adsorption capacity of SMX was 235.29 mg/g for CTMAB-Mt, 155.28 mg/g for HDAPS-Mt and 242.72 mg/g for BHDAP-Mt. Thermodynamic parameters were calculated to evaluate the spontaneity and endothermic or exothermic nature. The adsorption mechanism was found to be dominated by electrostatic interaction,while hydrophobic interaction played a secondary role.  相似文献   

6.
The objective of this research was to investigate CO_2adsorption capacity of tetraethylenepentamine-functionalized basic-modified calcined hydrotalcite(TEPA/b-c HT)sorbents at atmospheric pressure formed under varying TEPA loading levels,temperatures,sorbent weight to total gaseous flow rate(W/F)ratios and CO_2concentrations in the influent gas.The TEPA/b-c HT sorbents were characterized by means of X-ray diffraction(XRD),Fourier transform infrared spectrometry(FT–IR),thermal gravimetric analysis(TGA),Brunauer–Emmet–Teller(BET)analysis of nitrogen(N_2)adsorption/desorption and carbon–hydrogen–nitrogen(CHN)elemental analysis.Moreover,a full 2~4factorial design with three central points at a 95%confidence interval was used to screen important factor(s)on the CO_2adsorption capacity.It revealed that85.0%variation in the capacity came from the influence of four main factors and the15.0%one was from their interactions.A face-centered central composite design response surface method(FCCCD–RSM)was then employed to optimize the condition,the maximal capacity of 5.5–6.1 mmol/g was achieved when operating with a TEPA loading level of 39%–49%(W/W),temperature of 76–90°C,W/F ratio of 1.7–2.60(g·sec)/cm~3and CO_2concentration of 27%–41%(V/V).The model fitted sufficiently the experimental data with an error range of±1.5%.From cyclical adsorption/desorption and selectivity at the optimal condition,the 40%TEPA/b-c HT still expressed its effective performance after eight cycles.  相似文献   

7.
Adsorption and desorption of herbicide monosulfuron-ester in Chinese soils   总被引:1,自引:0,他引:1  
Monosulfuron-ester is a new, low rate, sulfonylurea herbicide that is being promoted for annual broadleaf and gramineal weed control; however, there is a lack of published information on its behavior in soils. The adsorption and desorption of monosulfuronester by seven type soils were measured using a batch equilibrium technique. The results showed that the Freundlich equation fitted its adsorption and desorption well, and the Freundlich constant values (Kf-ads) ranged from 0.88 to 5.66. Adsorption isotherms were nonlinear with 1/nf-ads values < 1. Soil pH, organic matter (OM), and clay content were the main factors influencing its adsorption and desorption. Adsorption and desorption were negatively correlated with pH 4.0–8.0 while positively correlated with OM and clay content. The adsorption of monosulfuron-ester was mainly a physical process, because its free energy (ΔG) in seven soils was less than 40 kJ/mol. Monosulfuron-ester adsorption by three soils increased with increasing CaCl2 concentration using CaCl2 as a background electrolyte. Monosulfuron-ester desorption was hysteretic in all tested soils.  相似文献   

8.
Adsorption and desorption are important processes that affect atrazine transport,transformation,and bioavailability in soils.In this study,the adsorption–desorption characteristics of atrazine in three soils(laterite,paddy soil and alluvial soil) were evaluated using the batch equilibrium method.The results showed that the kinetics of atrazine in soils was completed in two steps:a"fast" adsorption and a "slow" adsorption and could be well described by pseudo-second-order model.In addition,the adsorption equilibrium isotherms were nonlinear and were well fitted by Freundlich and Langmuir models.It was found that the adsorption data on laterite,and paddy soil were better fitted by the Freundlich model;as for alluvial soil,the Langmuir model described it better.The maximum atrazine sorption capacities ranked as follows:paddy soil alluvial soil laterite.Results of thermodynamic calculations indicated that atrazine adsorption on three tested soils was spontaneous and endothermic.The desorption data showed that negative hysteresis occurred.Furthermore,lower solution pH value was conducive to the adsorption of atrazine in soils.The atrazine adsorption in these three tested soils was controlled by physical adsorption,including partition and surface adsorption.At lower equilibrium concentration,the atrazine adsorption process in soils was dominated by surface adsorption;while with the increase of equilibrium concentration,partition was predominant.  相似文献   

9.
Water contamination by non-steroidal anti-inflammatory drugs, such as acetaminophen, is an emerging ecological concern. In this study, a new three-dimensional manganese dioxide-engrafted reduced graphene oxide (3D MnO2/rGO) hybrid aerogel was developed for acetaminophen sequestration. The synthesis involved firstly the self-assembly of GO aerogel, followed by thermal reduction and in-situ MnO2 growth by redox-reaction. The aerogel demonstrated interlinked planes with smooth surfaces deposited with MnO2 nanospheres and pores of 138.4 – 235.3 µm width. The influences of adsorbent dosage, initial pH, acetaminophen concentration, temperature and contact time were investigated. It was determined that the adsorption of acetaminophen occurred on uniform sorption sites in the aerogel, as suggested by the best fit of data to the Langmuir isotherm, yielding a maximum adsorption capacity of 252.87 mg/g. This highest adsorption performance of the 3D MnO2/rGO aerogel was attained at a dosage of 0.6 g/L, initial pH of 6.2 and temperature of 40°C. The process kinetics were in-line with the pseudo-first-order and pseudo-second-order kinetics at 10 and 20 – 500 mg/L concentrations, respectively. Thermodynamic assay showed the spontaneity and endothermicity features of the 3D MnO2/rGO-acetaminophen system. The acetaminophen adsorption mechanisms were mainly hydrogen bonding and pore entrapment. Moreover, the as-synthesised aerogel was effectively regenerated using acetone and re-utilised in four adsorption-desorption cycles. Overall, the results highly recommend the implementation of the 3D MnO2/rGO hybrid aerogel for purification of wastewater polluted by acetaminophen residue.  相似文献   

10.
The adsorption of Methyl Violet (MV) cationic dye from aqueous solution was carried out by using crosslinked poly (acrylic acid-co-acrylamide)/attapulgite (Poly(AA-co-AM)/ATP) composite as adsorbent. The factors influencing adsorption capacity of the composite such as pH, concentration of the dye, temperature, contact time, adsorbent dosage, ionic strength and surfactant were systematically investigated. The equilibrium data fitted very well to the Langmuir isotherm and the maximum adsorption capacity reached 1194 mg/g at 30°C. The thermodynamic parameters including G0, △H0 and △S 0 for the adsorption processes of MV on the composite were also calculated, and the negative △H0 and △G0 confirmed that the adsorption process was exothermic and spontaneous. The kinetic studies showed that the adsorption process was consistent with the pseudo second-order kinetic model and the desorption studies revealed that the regeneration of the composite adsorbent can be easily achieved.  相似文献   

11.
Sorbents for CO_2 capture have been prepared by wet impregnation of a commercial active carbon(Ketjen-black, Akzo Nobel) with two CO_2-philic compounds, polyethylenimine(PEI)and tetraethylenepentamine(TEPA), respectively. The effects of amine amount(from 10 to70 wt.%), CO_2 concentration in the feed, sorption temperature and gas hourly space velocity on the CO_2 capture performance have been investigated. The sorption capacity has been evaluated using the breakthrough method, with a fixed bed reactor equipped with on line gas chromatograph. The samples have been characterized by N_2 adsorption–desorption,scanning electron microscopy and energy dispersive X-ray(SEM/EDX). A promising CO_2 sorption capacity of 6.90 mmol/gsorbenthas been obtained with 70 wt.% of supported TEPA at 70℃ under a stream containing 80 vol% of CO_2. Sorption tests, carried out with simulated biogas compositions(CH_4/CO_2mixtures), have revealed an appreciable CO_2 separation selectivity; stable performance was maintained for 20 adsorption–desorption cycles.  相似文献   

12.
Mesoporous carbon adsorbents, having high nitrogen content, were synthesized via nanocasting technique with melamine–formaldehyde resin as precursor and mesoporous silica as template. A series of adsorbents were prepared by varying the carbonization temperature from 400 to 700°C. Adsorbents were characterized thoroughly by nitrogen sorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), elemental (CHN) analysis, Fourier transform infrared (FTIR) spectroscopy and Boehm titration. Carbonization temperature controlled the properties of the synthesized adsorbents ranging from surface area to their nitrogen content, which play major role in their application as adsorbents for CO2 capture. The nanostructure of these materials was confirmed by XRD and TEM. Their nitrogen content decreased with an increase in carbonization temperature while other properties like surface area, pore volume, thermal stability and surface basicity increased with the carbonization temperature. These materials were evaluated for CO2 adsorption by fixed-bed column adsorption experiments. Adsorbent synthesized at 700°C was found to have the highest surface area and surface basicity along with maximum CO2 adsorption capacity among the synthesized adsorbents. Breakthrough time and CO2 equilibrium adsorption capacity were investigated from the breakthrough curves and were found to decrease with increase in adsorption temperature. Adsorption process for carbon adsorbent–CO2 system was found to be reversible with stable adsorption capacity over four consecutive adsorption–desorption cycles. From three isotherm models used to analyze the equilibrium data, Temkin isotherm model presented a nearly perfect fit implying the heterogeneous adsorbent surface.  相似文献   

13.
利用高铝粉煤灰预脱硅液作为载体原料,通过使用胺基化合物对载体改性制备低温CO_2吸附剂.应用6 sigma中的工具,对制备工艺进行优化,得到理想的吸附剂,并对吸附剂样品进行表征.结果表明制备的CO_2吸附剂表现出良好的CO_2吸附性能.此类CO_2吸附剂具有吸附容量高(160 mg·g~(-1))、吸附速率快、对设备腐蚀低、成本低廉等特点,是一种极具工业应用潜力的CO_2吸附剂.  相似文献   

14.
Carbon-modified titanium dioxide(TiO2) was prepared by a sol-gel method using tetrabutyl titanate as precursor, with calcination at various temperatures, and tested for the photocatalytic oxidation(PCO) of gaseous NH3 under visible and UV light. The test results showed that no samples had visible light activity, while the TiO2 calcined at 400℃ had the best UV light activity among the series of catalysts, and was even much better than the commercial catalyst P25. The catalysts were then characterized by X-ray diffractometry, Brunauer-Emmett-Teller adsorption analysis, Raman spectroscopy, thermogravimetry/differential scanning calorimetry coupled with mass spectrometry, ultraviolet-visible diffuse reflectance spectra, photoluminescence spectroscopy and in situ diffuse reflectance infrared Fourier transform spectroscopy. It was shown that the carbon species residuals on the catalyst surfaces induced the visible light adsorption of the samples calcined in the low temperature range( 300℃). However, the surface acid sites played a determining role in the PCO of NH3 under visible and UV light over the series of catalysts. Although the samples calcined at low temperatures had very high SSA, good crystallinity, strong visible light absorption and also low PL emission intensity, they showed very low PCO activity due to their very low number of acid sites for NH3 adsorption and activation. The TiO2 sample calcined at 400℃ contained the highest number of acid sites among the series of catalysts, therefore showing the highest performance for the PCO of NH3 under UV light.  相似文献   

15.
树脂基固态胺吸附剂室温下对低浓度CO2的吸附性能研究   总被引:2,自引:1,他引:1  
以大孔甲基丙烯酸酯吸附树脂为载体,聚乙烯亚胺(PEI)为有机胺,采用液相浸渍法制备出固态胺吸附剂,并研究了其在室温下对低浓度CO2的吸附行为.同时,利用氮气吸附、热重分析和扫描电镜表征了材料的物理化学性质,并采用热重法和固定床吸附法考察了材料的CO2吸附性能.结果表明,大孔树脂担载50%PEI(质量分数)时吸附性能最佳,对纯CO2的最大吸附量为175 mg·g-1;CO2的吸附行为由扩散动力学与吸附热力学共同决定,低温有利于提高吸附容量;吸附剂对400 ppm~15%浓度的CO2都具有优异的动态吸附性能,其中对400 ppm CO2的吸附量达到86 mg·g-1,对15%CO2的吸附量达到150 mg·g-1;湿度对吸附起促进作用,相对湿度为10%时,对400 ppm CO2的吸附量提高至139mg·g-1;吸附剂具有优异的循环性能,具有直接空气捕集CO2的潜力.  相似文献   

16.
TiO_2 nanotube(Ti NT) electrodes anodized in fluorinated organic solutions were successfully prepared on Ti sheets. Field-emission scanning electron microscopy(FE-SEM) and X-ray diffraction(XRD) were performed to characterize the TiNT electrodes. The linear voltammetry results under irradiation showed that the TiNT electrode annealed at 450°C presented the highest photoelectrochemical activity. By combining photocatalytic with electrochemical process, a significantly synergetic effect on ammonia degradation was observed with Na_2SO_4 as supporting electrolyte at pH 10.7. Furthermore, the photoelectrocatalytic efficiency on the ammonia degradation was greatly enhanced in presence of chloride ions without the limitation of pH. The degradation rate was improved by 14.8 times reaching 4.98 × 10~(-2) min~(-1) at pH 10.7 and a faster degradation rate of 6.34 × 10~(-2) min~(-1)was obtained at pH 3.01. The in situ photoelectrocatalytic generated active chlorine was proposed to be responsible for the improved efficiency. On the other hand, an enhanced degradation of ammonia using TiNT electrode fabricated in fluorinated organic solution was also confirmed compared to TiNT electrode anodized in fluorinated water solution and TiO_2 film electrode fabricated by sol–gel method. Finally, the effect of chloride concentration was also discussed.  相似文献   

17.
In this work, the effects of different methods of activation on CO2 adsorption performance of activated carbon were studied. Activated carbons were prepared from biochar, obtained from fast pyrolysis of white wood, using three different activation methods of steam activation, CO2 activation and Potassium hydroxide (KOH) activation. CO2 adsorption behavior of the produced activated carbons was studied in a fixed-bed reactor set-up at atmospheric pressure, temperature range of 25–65°C and inlet CO2 concentration range of 10–30 mol% in He to determine the effects of the surface area, porosity and surface chemistry on adsorption capacity of the samples. Characterization of the micropore and mesopore texture was carried out using N2 and CO2 adsorption at 77 and 273 K, respectively. Central composite design was used to evaluate the combined effects of temperature and concentration of CO2 on the adsorption behavior of the adsorbents. The KOH activated carbon with a total micropore volume of 0.62 cm3/g and surface area of 1400 m2/g had the highest CO2 adsorption capacity of 1.8 mol/kg due to its microporous structure and high surface area under the optimized experimental conditions of 30 mol% CO2 and 25°C. The performance of the adsorbents in multi-cyclic adsorption process was also assessed and the adsorption capacity of KOH and CO2 activated carbons remained remarkably stable after 50 cycles with low temperature (160°C) regeneration.  相似文献   

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