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1.
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   

2.
The study evaluated the adsorption of two antibiotics by four engineered adsorbents (hypercrosslinked resin MN-202, macroporous resin XAD-4, activated carbon F-400, and multi-walled carbon nanotubes (MWCNT)) from aqueous solutions. The dynamic results demonstrated the dominant influence of pore size in adsorption. The adsorption amounts of antibiotics on XAD-4 were attributed to the hydrophobic effect, whereas steric hindrance or micropore-filling played a main role in the adsorption of antibiotics by F-400 because of its high microporosity. Aside from F-400, similar patterns of pH-dependent adsorption were observed, implying the importance of antibiotic molecular forms to the adsorption process for adsorbents. Increasing the ionic concentration with CaCl2 produced particular adsorption characteristics on MWCNT at pH 2.0 and F-400 at pH 8.0, which were attributed to the highly available contact surfaces and molecular sieving, respectively. Its hybrid characteristics incorporating a considerable portion of mesopores and micropores made hypercross linked MN-202 a superior antibiotic adsorbent with high adsorption capacity. Furthermore, the adsorption capacity of MWCNT on the basis of surface area was more advantageous than that of the other adsorbents because MWCNT has a much more compact molecular arrangement.  相似文献   

3.
Adsorption of the hydrophobic organic compounds (HOCs) trichloroethylene (TCE), 1,3-dichlorobenzene (DCB), 1,3-dinitrobenzene (DNB) and γ-hexachlorocyclohexane (HCH) on five different carbonaceous materials was compared. The adsorbents included three polymer-based activated carbons, one coal-based activated carbon (F400) and multiwalled carbon nanotubes (MWNT). The polymerbased activated carbons were prepared using KOH activation from waste polymers: polyvinyl chloride (PVC), polyethyleneterephthalate (PET) and tire rubber (TR). Compared with F400 and MWNT, activated carbons derived from PVC and PET exhibited fast adsorption kinetics and high adsorption capacity toward the HOCs, attributed to their extremely large hydrophobic surface area (2700 m2/g) and highly mesoporous structures. Adsorption of small-sized TCE was stronger on the tire-rubber-based carbon and F400 resulting from the pore-filling effect. In contrast, due to the molecular sieving effect, their adsorption on HCH was lower. MWNT exhibited the lowest adsorption capacity toward HOCs because of its low surface area and characteristic of aggregating in aqueous solution.  相似文献   

4.
The adsorption of six kinds of chlorophenols on pristine, hydroxylated and carboxylated single-walled carbon nanotubes(SWCNTs) has been investigated. Pseudo-first order and pseudo-second order models were used to describe the kinetic data. All adsorption isotherms were well fitted with Langmuir, Freundlich and Polanyi–Manes models, due to surface adsorption dominating the adsorption process. The close linear relationship between log Kowand log Kdsuggested that hydrophobicity played an important role in the adsorption. The SWCNTs' adsorption capacity for chlorophenols was weakened by addition of oxygen-containing functional groups on the surface, due to the loss of specific surface area, the increase of hydrophilicity and the reduction of π–π interaction. The best adsorption capacity of pristine SWCNTs, SWCNT-OH and SWCNT-COOH for six chlorophenols varied from 19 to 84 mg/g, from 19 to 65 mg/g and from 17 to 65 mg/g,respectively. The effect of pH on the adsorption of 2,6-dichlorophenol(2,6-DCP), was also studied. When p H is over the pK aof 2,6-dichlorophenol(2,6-DCP), its removal dropped sharply. When ionic strength increased(Na Cl or KCl concentration from 0 to 0.02 mmol/L),the adsorption capacity of 2,6-DCP on pristine SWCNTs decreased slightly. The comparison of chlorophenols adsorption by SWCNTs, MWCNTs and PAC was made, indicating that the adsorption rate of CNTs was much faster than that of PAC. The results provide useful information about the feasibility of SWCNTs as an adsorbent to remove chlorophenols from aqueous solutions.  相似文献   

5.
The study was attempted to produce activated carbons from palm oil mill effluent (POME) sludge. The adsorption capacity of the activated carbons produced was evaluated in aqueous solution of phenol. Two types of activation were followed, namely, thermal activation at 300, 500 and 800%, and physical activation at 150% (boiling treatment). A control (raw POME sludge) was used to compare the adsorption capacity of the activated carbons produced. The results indicated that the activation temperature of 800℃ showed maximum absorption capacity by the activated carbon (POME 800) in aqueous solution of phenol. Batch adsorption studies showed an equilibrium time of 6 h for the activated carbon of POME 800. It was observed that the adsorption capacity was higher at lower values ofpH (2--3) and higher value of initial concentration of phenol (200--300 mg/L), The equilibrium data were fitted by the Langmuir and Freundlich adsorption isotherms. The adsorption of phenol onto the activated carbon POME 800 was studied in terms of pseudo-first and second order kinetics to predict the rate constant and equilibrium capacity with the effect of initial phenol concentrations. The rate of adsorption was found to be better correlation for the pseudo-second order kinetics compared to the first order kinetics.  相似文献   

6.
In order to study the influences of functionalized groups onto the adsorption of tetracycline,we prepared a series of amino and amino–Fe~(3+)complex mesoporous silica adsorbents with diverse content of amino and Fe~(3+)groups(named N,N-SBA15 and Fe-N,N-SBA15).The resulting mesoporous silica adsorbents were fully characterized by X-ray powder diffraction(XRD),Fourier transform infrared spectrometer(FTIR)and N_2adsorption/desorption isotherms.Furthermore,the effects of functionalized groups on the removal of TC were investigated.The results showed that the periodic ordered structure of SBA-15 was maintained after modification of amino/Fe~(3+)groups.The functionalized amino groups decreased the adsorption capacity while the coordinated Fe~(3+)increased the adsorption capacity.The adsorption kinetics of TC fitted pseudo-second-order model well and the equilibrium was achieved quickly.The adsorption isotherms fitted the Langmuir model well and with the Fe~(3+)content increased from 3.93%to 8.26%,the Q_(max)of the adsorbents increased from 102 to 188 mmol/kg.The solution p H affected the adsorption of TC onto amino complex adsorbents slightly while influenced the adsorption onto Fe-amine complex adsorbents greatly.The adsorption of TC on SBA15 and N,N-SBA15 may be related to the formation of outer-sphere surface complexes,while the adsorption of TC onto Fe-N,N-SBA15 was mainly attributed to the inner-sphere surface complexes.This study could offer potential materials that have excellent adsorption behavior for environmental remediation and suggested useful information for the preparing other adsorbents in environmental applications.  相似文献   

7.
An activated semi-coke with industrial-scale size was prepared by high-pressure hydrothermal chemistry activation, HNO3 oxidation and calcination activation in proper order from Inner Mongolia Zhalainuoer semi-coke, which is rich in resource and cheap in sale.SO2 adsorption capacity on this activated semi-coke was assessed in the fixed bed in the temperature range of 60-170℃, space velocity range of 500-1300 h^-1, SO2 concentration of 1000-3000 ppmv, and N2 as balance. The surface area, elemental and proximate analysis for both raw semi-coke and activated semi-cokes were measured. The experimental results showed that the activated semi-coke has a high adsorption capacity for sulfur dioxide than the untreated semi-coke. This may be the result of increase of surface area on activated semi-coke and surface oxygen functional groups with basicity characteristics. Comparison to result of FTIR, it is known that group of-C-O-C-may be active center of SO2 catalytic adsorption on activated semi-coke.  相似文献   

8.
The effects of different outer diameters and surface oxygen contents on the adsorption of heavy metals onto six types of multi-walled carbon nanotubes (MWCNTs) were investigated in an aqueous solution and lead was chosen as a model metal ion. The results indicated that the percentage removal and adsorption capacity of lead remarkably increased with decreasing outer diameter due to larger specific surface area (SSA). The SSA-normalized maximum adsorption capacity (qm /SSA) and SSA-normalized adsorption coefficient (Kd /SSA) were strongly positively correlated with surface oxygen content, implying that lead adsorption onto MWCNTs significantly increases with the rise of oxygen content and decreases with decreasing SSA. The calculated thermodynamic parameters indicated that adsorption of lead on MWCNTs was endothermic and spontaneous. When the oxygen content of MWCNTs increased from 2.0% to 5.9%, the standard free energy (△ G0 ) became more negative, which implied that the oxygenated functional groups increased the adsorption affinity of MWCNTs for lead. Through calculation of enthalpy (△ H0 ), G0 and free energy of adsorption (Ea ), lead adsorption onto MWCNTs was recognized as a chemisorption process. The chemical interaction between lead and the phenolic groups of MWCNTs could be one of the main adsorption mechanisms due to highly positive correlations between the phenolic groups and K d /SSA or q m /SSA.  相似文献   

9.
A novel illite@carbon(I@C) nanocomposite adsorbent has been synthesized via a facile hydrothermal carbonization process(HTC) using glucose as carbonaceous source and illite as the carrier.The morphology,microstructure and surface properties of the prepared nanocomposite adsorbent were analyzed by FESEM,TGA,XRD,FT-IR and Zeta potential measurements.Batch experiments were carried out on the adsorption of Cr(Ⅵ) to determine the adsorption properties of the composite.The adsorption of Cr(Ⅵ) onto the I@C nanocomposite was well described by the pseudo-second-order kinetic model and Langmuir isotherm.Compared with the illite and carbon material(SC) separately,the prepared I@C nanocomposite adsorbent exhibited enhanced adsorption performance for Cr(Ⅵ) with a maximum adsorption capacity of 149.25 mg/g,which was higher than that of most reported adsorbents.In addition,the adsorption process was spontaneous and endothermic based on the adsorption thermodynamics study.The adsorption of Cr(Ⅵ) by I@C was highly p H-dependent and the optimum adsorption occurred at p H 2.0.The Zeta potential analysis results indicated that the electrostatic interactions between anionic Cr(Ⅵ) and the positively charged surface of the adsorbent might be critical to the adsorption mechanism.This study demonstrated that the I@C nanocomposite should be a promising candidate for a low-cost,environmental friendly and highly efficient adsorbent for the removal of toxic Cr(Ⅵ) from wastewater.  相似文献   

10.
Ordered mesoporous carbon(OMC) with high specific surface area and large pore volume was synthesized and tested for use as an adsorbent for volatile organic compound(VOC)disposal. Benzene, cyclohexane and hexane were selected as typical adsorbates due to their different molecular sizes and extensive utilization in industrial processes. In spite of their structural differences, high adsorption amounts were achieved for all three adsorbates, as the pore size of OMC is large enough for the access of these VOCs. In addition, the unusual bimodal-like pore size distribution gives the adsorbates a higher diffusion rate compared with conventional adsorbents such as activated carbon and carbon molecular sieve. Kinetic analysis suggests that the adsorption barriers mainly originated from the difficulty of VOC vapor molecules entering the pore channels of adsorbents. Therefore, its superior adsorption ability toward VOCs, together with a high diffusion rate, makes the ordered mesoporous carbon a promising potential adsorbent for VOC disposal.  相似文献   

11.
曾凡  廖筱锋  李勇  何莹  廖利  胡辉 《环境科学学报》2017,37(11):4269-4276
以市政污泥和玉米秸秆的混合物为原材料,KOH为活化剂,制备了秸秆污泥基活性炭(AC).实验考察了秸秆与污泥用量比例,以及活化剂用量对秸秆污泥基活性炭物化特性的影响.结果显示,m(污泥)∶m(秸秆)∶m(KOH)为3∶7∶2的条件下,制备的活性炭C372以微孔为主,微孔率达到0.59,比表面积达到369.271 m2·g-1.该活性炭的穿透硫容与饱和硫容均最高,分别为5.82 mg·g-1(以H2S计)和7.00 mg·g-1(以H2S计),活性炭表面内酯基的存在不利于其对硫化氢的吸附.SEM和BET表征分析显示,随着秸秆在污泥中比例的增加,活性炭比表面积增大,对H2S的吸附量提高.活性炭C372具有较好的再生性能,二次再生后其穿透硫容与饱和硫容均能恢复55%以上.  相似文献   

12.
提高污泥溶胞效率是强化污泥厌氧处理的关键.为加强污泥微波预处理溶胞效果,本研究分别考察了常压、半封闭条件下二氧化钛颗粒、碳质材料作为敏化剂与过氧化氢联合进行微波污泥预处理的效果.结果表明,碳质材料敏化剂对微波、过氧化氢-微波污泥预处理产生了负作用,降低了污泥的溶胞效果,而二氧化钛能有效增加污泥中营养物质的释放.当二氧化钛颗粒投加量为0.12 g·g~(-1)干污泥时,SCOD、PO_4~(3-)-P的浓度比单独微波处理分别增加了11.86%、61%;当二氧化钛颗粒投加量为0.24 g·g~(-1)干污泥时,NH_4~+-N释放比单独微波处理高出27.78%.微波辐射作用下投加二氧化钛颗粒产生了羟基自由基,强化了过氧化氢-微波对污泥细胞的氧化作用.  相似文献   

13.
基于铁锰泥的除砷颗粒吸附剂制备及其比较   总被引:1,自引:1,他引:0       下载免费PDF全文
曾辉平  于亚萍  吕赛赛  李冬  张杰 《环境科学》2019,40(11):5002-5008
地下水除铁除锰滤池反冲洗铁锰泥具有良好的除砷效果,但因其粉末形态不易固液分离,本文采用高温烘焙法和包埋法以铁锰泥为原料制备颗粒吸附剂,其中包埋法采用烘干和冻干两种干燥方法制粒.结果表明,3种颗粒吸附剂:高温烘焙颗粒吸附剂(GA)、包埋烘干吸附剂(H-GA)和包埋冻干吸附剂(D-GA),表面粗糙,比表面积分别为43. 830、110. 30和129. 18 m~2·g~(-1).吸附实验表明,H-GA和D-GA对砷的吸附远大于GA,GA、H-GA和D-GA最大吸附量分别为5. 05、14. 95和13. 45 mg·g~(-1). Langmuir模型能更好地拟合H-GA和D-GA对砷的吸附,Freundlich模型更好地拟合GA的吸附过程,准一级动力学和准二级动力学模型均能拟合3种吸附剂的动力学数据.酸性环境更有利于砷的吸附.包埋法制备的颗粒吸附剂H-GA和D-GA保留了铁锰泥原始结构,比表面积也远大于GA,因此吸附效果比GA好.两种干燥方式烘干和冻干对吸附没有明显影响.  相似文献   

14.
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   

15.
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   

16.
剩余污泥吸附剂的制备及其吸附性能研究   总被引:2,自引:3,他引:2  
利用城市污水处理厂剩余活性污泥,采用先干燥再浸渍于不同浓度活化剂,再于不同温度、时间下热解的流程,对有机剩余污泥进行改性吸附剂研究。采用正交设计以确定最佳制备条件,并对吸附剂的有机组成和比表面积等参数进行了测定。研究结果表明,有机污泥制备吸附剂的最佳条件是,污泥与活化剂质量比为5∶3,在550℃下恒温热解60min,所得改性污泥吸附剂具有最大比表面积;并利用制备的改性污泥对直接深棕M和酸性媒介棕RH染料进行吸附试验,动力学吸附速率符合Lagergren模型,吸附等温线与Freundlich和Langmuir模型有较好的拟合。同时与商品活性炭吸附性能进行对比,结果显示改性吸附剂吸附容量小于活性炭。  相似文献   

17.
为实现污水处理的深度脱氮除磷及蛋白质源污泥增量,进行了生物吸附/MBR/硫铁自养反硝化组合工艺处理城镇污水的试验研究.结果表明,生物吸附池可以快速富集进水中的大部分有机物,COD平均去除率为55.1%,剩余污泥采用厌氧发酵方式处理,用于生产优质碳源.通过组合工艺系统中的硝化、硫自养反硝化及铁屑除磷作用,出水氨氮、总氮和总磷分别达到1、5和0.4 mg·L~(-1)以下.优质碳源投加到MBR工艺段,碳源环境的改善使得污泥增长率从0.17 g VSS/g COD提高至0.49 g VSS/g COD,进水中总氮的同化比例从40%提高至59%.此外,污泥中蛋白质及氨基酸含量也显著增长,增长率分别为18.3%和19.7%.组合工艺在获得高排放标准水质的同时,实现了高蛋白质源污泥的增量,可为污泥资源化利用提供优质原料.  相似文献   

18.
利用热重分析法对城市污泥分别与煤或玉米秆混烧特性进行研究。结果表明:城市污泥燃烧过程存在挥发分析出和燃烧阶段及挥发分和固定碳燃尽阶段两个主要失重区间。城市污泥着火温度低,燃烧温度范围宽,失重速率低,燃尽性能特性指数Cb和综合燃烧特性指数SN性能均低于煤和玉米秆。掺混煤或玉米秆燃烧会改善城市污泥的燃尽特性和综合燃烧特性。采用积分法(Coats-Redfern方程)计算各阶段燃烧反应的动力学参数。混合试样中污泥含量增加,挥发分燃烧阶段活化能减小,固定碳燃烧阶段活化能增加。  相似文献   

19.
为了促进水葫芦和污泥的资源化利用,探究水葫芦/污泥生物炭粒的基本理化性质及其对水中Cr3+的吸附机制,以水葫芦、污泥为原料,在300~500℃热解温度下制得生物炭粒,通过产率分析、灰分分析、比表面积和孔径分析及SEM(扫描电镜)分析,同时利用吸附动力学模型和等温吸附模型对生物炭粒吸附水中Cr3+的内在机制进行研究,最后采用TCLP(毒性浸出法)测定了不同生物炭粒中重金属的浸出毒性.结果表明:随着热解温度从300℃升至500℃,生物炭粒的产率从14.93%降至11.75%,生物炭粒的灰分含量逐渐升高,比表面积增大.SEM结果显示,水葫芦与污泥质量比为1:10时,生物炭粒比表面积较大,孔隙结构明显.当水葫芦与污泥质量比为1:10、热解温度为500℃时生物炭粒对Cr3+的吸附量最大,为44.96 mg/g.热力学分析显示,生物炭粒对溶液中Cr3+的吸附以化学吸附为主,且为单层吸附.TCLP试验表明,水葫芦/污泥生物炭粒中各重金属(Cd、Zn、Cu、Pb、Ni、Cr)的浸出浓度均低于GB 5085.3-2007《危险废物鉴别标准浸出毒性鉴别》的限值.研究显示,添加水葫芦能改善生物炭粒的理化性质,使得生物炭粒对Cr3+的吸附量增大,以化学吸附为主,且为单层吸附,水葫芦/污泥生物炭粒浸出毒性较低,可为生物炭类环境功能材料的研制提供选材依据.   相似文献   

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