共查询到20条相似文献,搜索用时 15 毫秒
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《分离科学与技术》2012,47(18):2863-2877
Bio-inorganic chitosan based spherical shaped beads were prepared by dispersing rod-shaped FeOOH nanoparticles into a chitosan matrix for the removal of pure As(III) and As(V) from aqueous media, such as drinking water. A homogeneous mixture of chitosan and ferric nitrate, ferric chloride was prepared respectively with or without oxalic acid. The mixture was added dropwise in to a NaOH bath, where iron salts reacted with NaOH to form FeOOH particles. The scanning electron microscopy (SEM) showed that rod shaped FeOOH particles were distributed homogenously in the chitosan matrix. Diffuse reflective UV-vis (DRUV) spectra revealed that hydrated iron oxide formed a complex with functional groups in chitosan. Adsorption of As(III) and As(V) on different iron salt based bead was found to be pH dependent. The bead prepared from iron nitrate showed better performance for arsenic removal from aqueous solution over the bead that was prepared using iron chloride salt. The bead prepared using chitosan and iron-FeOOH is known as a chitosan-iron oxyhydroxide (CFOH) bead. The CFOH beads were found to be more efficient in removing As(III) from the solution compared to As(V). The adsorption of As(III) and As(V) from aqueous solution on CFOH beads was studied under equilibrium conditions in the concentration range of 1 mg/L to 50 mg/L in the presence of 0.05 M NaNO3 at pH 6.5 and 298 K temperature. The maximum adsorption capacity of the CFOH bead was found to be 5.4 mg/g for As(V) and 7.2 mg/g for As(III) using the Langmuir equation. The presence of sulphate, phosphate, and silicate in aqueous solution had no effects on adsorption of either As(III) or As(V) on CFOH beads but decreased significantly at pH> 8. 相似文献
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Pilot study of the removal of THMs, HAAs and DOC from drinking water by GAC adsorption 总被引:2,自引:0,他引:2
K.G. Babi K.M. Koumenides A.D. Nikolaou C.A. Makri F.K. Tzoumerkas T.D. Lekkas 《Desalination》2007,210(1-3):215-224
The objective of this pilot study was to evaluate the performance of a GAC postfilter-adsorber for the removal from the drinking water of Athens, Greece, of the two main groups of chlorination by-products, trihalomethanes (THMs) and haloacetic acids (HAAs), as well as of dissolved organic carbon (DOC). The analyses performed during the whole operation period (638 days) showed that the GAC breakthrough capacity for DOC was much higher than the capacity for total HAAs, which was higher than that for total THMs. The removal of THMs and the most part of the removal of HAAs and DOC should be attributed to adsorption by GAC, while that of a smaller part of HAAs and DOC may be attributed to biodegradation in the adsorber bed, where dechlorination, caused catalytically by the carbon surface, favoured microbial growth. Additionally, the GAC postfilter-adsorber showed a much higher adsorption efficiency than a GAC filter-adsorber, due to the smaller size of the carbon and the lower hydraulic loading rate. Also, observed desorption incidents of THMs (mainly) and HAAs, especially during the postfilteradsorber operation, were favoured by the same factors. Formation of THMs within the GAC bed was also indicated by the mass balance of total THMs during the whole cycle. 相似文献
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固体吸附式制冷因具有环保和节能两大优势,成为国内外竞相开发的热点,尤其是将其用于新型空调系统和太阳能应用产品方面的开发研究备受关注.但从实用化研究成果来看,还远不满足工业化条件,其主要原因之一是受吸附制冷工质对(吸附剂-制冷剂)的性能制约.目前,国内外关于吸附制冷工质对的研究报道比较多,所采用的吸附(工)质仍然以水、甲醇、乙醇和氨为主,对于吸附剂的研究进展比较快,已从当初单一组分吸附剂的选用发展到目前多组分、复合吸附剂的研制.研制性能优良的吸附剂被认为是推动固体吸附式制冷工业化的关键之一. 相似文献
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通过半动态实验,对MnOx/GAC(颗粒活性炭)催化臭氧氧化技术氧化硝基苯的降解效能与动力学规律进行了初步研究。结果表明MnOx/GAC催化臭氧氧化过程对硝基苯具有较高的催化活性,在相同的反应条件下,MnOx/GAC催化臭氧氧化技术对硝基苯的降解效率是单独臭氧氧化的2.4倍。催化剂对硝基苯有一定的吸附作用。MnOx/GAC催化剂的存在提高了臭氧的利用率。MnOx/GAC催化臭氧氧化过程存在着催化剂最佳投量,硝基苯初始浓度与反应速率常数有良好的线性相关性,水质本底对MnOx/GAC催化臭氧氧化效率也有影响。 相似文献
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以商业颗粒活性炭(GAC)为载体,乙酸锰为锰源,采用等体积浸渍法制备系列MnO_x/GAC复合材料。通过X-射线粉末衍射、透射电镜、拉曼光谱等对改性前后活性炭材料进行微观分析,并探讨锰负载量、反应温度、反应时间等对MnO_x/GAC复合材料处理苯酚模拟废水性能的影响。结果表明,MnO_x/GAC复合材料的活性物种主要以Mn_3O_4、Mn_2O_3和MnO_2为主,呈现均匀分散纳米晶态。在20 mL 1 500 mg·L~(-1)苯酚废水中加入1 g Mn质量分数为8%的MnO_x/GAC复合材料,反应温度50℃,反应时间240 min条件下,苯酚转化率99.88%,COD降解率97.80%,吸附动力学遵循准二级动力学模型。 相似文献
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《分离科学与技术》2012,47(14):3101-3116
Abstract In this study, the performance of GAC adsorption and biofiltration systems in treating biological treated sewage effluent (BTSE) was evaluated in terms of organic removal efficiency, organic fractions, and molecular weight distribution (MW) of organic matter (OM) removed. The GAC biofilter removed 23.5% and 61% of the hydrophobic fractions and hydrophilic fractions of OM in the BTSE respectively. MW distribution studies of GAC filter and GAC adsorption revealed the following: Hydrophobic fraction of the effluent showed a peak at 345 dalton after GAC biofiltration and 256 dalton after GAC adsorption, whereas, with hydrophilic fractions, peaks at 46,178 and 345 daltons were observed after GAC biofiltration and peaks at 46,178 and 256 daltons after GAC adsorption. Transphilic fraction showed the peaks at 12,783 dalton with GAC biofiltration, and 1,463 dalton with GAC adsorption. The performance of the GAC biofilter was successfully mathematically modelled. 相似文献
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Liang Shen Yu Liu Hai‐Lou Xu 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2010,85(6):814-820
BACKGROUND: This study investigated the treatment of ampicillin (AMP)‐loaded wastewater in airlift reactors where biofilms were developed on granular activated carbon (GAC). A series of batch experiments were thus carried out in order to differentiate potentials of adsorption and biodegradation which would jointly contribute to the AMP removal. RESULTS: Results showed that almost all influent AMP was removed in two reactors supplemented with 4 and 8 mg L?1 AMP, respectively. Batch experiments revealed that the percentage of the AMP removed through biodegradation increased along with the development of biofilms on GAC. For the mature biofilm‐covered GAC, adsorption accounted for about 60% of the observed AMP removal, whereas the other 40% could be attributed to biodegradation. Possible degraders of AMP were also identified, such as Acinetobacter sp., Flavobacterium sp., Pseudoxanthomonas sp., Delftia sp. and Sphingobium sp. CONCLUSION: The airlift biofilm reactor with GAC as carrier would be a feasible technology for treating AMP‐loaded wastewater due to the joint action of adsorption and biodegradation of AMP by the biofilm‐covered GAC. Copyright © 2010 Society of Chemical Industry 相似文献
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采用浓度为0.2g·ml-1的葡萄糖溶液对13X沸石/活性炭复合材料(AC/X)进行碳沉积,研究沉积次数对复合吸附剂(AC/X-G)孔结构、表面性质和CH4/N2吸附分离性能的影响。通过X射线衍射,77K下的N2吸附/脱附,扫描电镜,CO2-TPD以及红外光谱表征样品的晶型、孔结构和表面性质,在298K、100kPa下对其CH4和N2吸附等温线进行测定,并将吸附结果与文献中碳材料和13X沸石的吸附性能进行比较。结果表明:随着沉积次数的增加,AC/X-G吸附剂中X型沸石的相对含量降低,微孔比表面积和微孔体积减少。AC/X-G的表面被碳膜覆盖,碱量降低,但出现强碱位和含氧基团C-O键。AC/X-G的CH4和N2吸附量下降,但吸附分离系数提高,沉积3次的样品AC/X-G-3的CH4/N2吸附分离系数达到3.0,表面的含氧基团有利于提高复合材料的CH4/N2吸附分离性能。 相似文献
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以单层分散理论为指导,研究了氯化钙在大球硅胶上的单层分散、氨吸附及吸附稳定性。结果表明,对于焙烧分散法,氯化钙/大球硅胶的适宜焙烧温度为500℃;对于微波分散法,适宜的微波辐射时间是20 min。焙烧样品的单层分散阈值为0.2~0.3 g/g,微波样品的单层分散阈值为0.3~0.4 g/g。将吸附量较大的样品进行比较,在35℃下,担载量为0.4 g/g的焙烧样品氨吸附量为0.35 g/g;担载量0.5 g/g的微波样品氨吸附量为0.41 g/g。微波样品的氨吸附量大于焙烧样品。吸附-脱附循环实验表明,2种分散法所得复合吸附剂同样具有较好的吸附稳定性。 相似文献
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Blaž Likozar David Senica Aleksander Pavko 《American Institute of Chemical Engineers》2012,58(1):99-106
Isolation step of vancomycin, a glycopeptide antibiotic, is usually done from fermentation broth filtrate, while its adsorption directly from the whole broth could rationalize the process. The equilibrium and kinetics of vancomycin adsorption from broth supernatant, diluted and whole broth on polymeric adsorbent was studied in this work. Experimental equilibrium data was correlated with Sips, Langmuir, Freundlich, and linear adsorption isotherms. Agreement between measured and regressed data for the first three mentioned models did not vary much and was relatively high. The maximum adsorbed amount for supernatant was higher than for fermentation broths because mycelium particles blocked adsorbent surface. Liquid film mass transfer studies showed that external mass transfer resistance could have been neglected. Diffusion of vancomycin inside adsorbent particles was acknowledged using a nonstructural, homogenous surface diffusion and bidisperse pore models. Model simulations indicated that kinetics of the process could be improved by using smaller adsorbent particles. © 2011 American Institute of Chemical Engineers AIChE J, 2012 相似文献
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A hydrodynamic model including only one parameter (λO) for the prediction of both axial dispersion and external mass transfer in fixed-bed adsorbers at low Reynolds numbers (creeping flow regime) has been developed. The theoretical analysis is based on the application of the (two-dimensional) uniform dispersion model originally proposed by Bischoff and Levenspiel [1962a. Fluid dispersion—generalization and comparison of mathematical models—I. Generalization of models. Chemical Engineering Science 17, 245-255] to the representative capillary of a tube bundle model for describing the flow and mixing behaviour in packed beds. The combination of this model with the relationship between longitudinal and radial dispersion leads to the definition of the sole hydrodynamic parameter λO (one-parameter hydrodynamic model). Furthermore, the detailed investigation reveals that the one-parameter concept may be utilized for the application of the (one-dimensional) axial dispersed plug flow model as well. The functional dependence of the parameter λO on the flow conditions is elaborated from axial dispersion measurements. Both the new (one-parameter) hydrodynamic model and the classical model including axial dispersion and external mass transfer coefficients (two-parameter model) are utilized to simulate the breakthrough curves for the adsorption of naphthalene onto silica gel. This simulation study reveals that only the one-parameter hydrodynamic model is able to predict the adsorber dynamics over a large range of flow rates. 相似文献
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通过研磨将多壁碳纳米管分别与质量分数为30%、40%和50%的无水氯化镁复合,制备了3种不同配比的复合吸附剂MWCNT/MgCl2。采用数字化扫描电子显微镜(SEM)观察复合吸附剂表面材质的结构样貌,通过Hot Disk热常数分析仪测得复合吸附剂的热导率,使用恒温恒湿箱选取具有代表性的温湿度,测试复合吸附剂在不同工况下的水蒸气吸附性能,并采用准二级动力学模型对25℃、50% RH工况下的实验数据进行拟合,应用Autosorb-IQ全自动气体分析仪测试了三种样品在25℃下的等温吸湿曲线。实验结果表明,相同温湿度工况下,随着氯化镁含量增加,复合吸附剂的吸附量提高,25℃、50% RH下氯化镁含量为30%、40%和50%的复合吸附剂M1、M2和M3的吸附量分别为0.62、0.79和0.94 g/g;恒定湿度为50% RH,温度变化为15~35℃时,复合吸附剂吸附量受温度和饱和水蒸气分压力的双重影响,表现为先增加后减小;温度固定为25℃,相对湿度从50% RH增加到80% RH时,复合吸附剂吸附量均大大提升;复合吸附剂在35℃、25% RH中高温、低湿条件下仍表现出较好的吸附能力;在相对压力P/P0为0.3时,M1、M2和M3的吸附量分别为0.24、0.25和0.30 g/g,随着吸附压力的增加,复合吸附剂的吸附量也不断提升,最大吸附量分别达到3.54、3.75和4.42 g/g。复合吸附剂MWCNT/MgCl2的制备研究,为吸附剂的性能研究提供了基础,对太阳能吸附式空气取水的研究具有潜在意义。 相似文献
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P. Mondal B. Mohanty C. B. Majumder N. Bhandari 《American Institute of Chemical Engineers》2009,55(7):1860-1871
A study on kinetics and equilibrium is presented on the adsorption of arsenic species from simulated groundwater containing arsenic (As(III):As(V)::1:1), Fe and Mn in concentrations of 0.188 mg/L, 2.8 mg/L and 0.6 mg/L, respectively, by iron impregnated granular activated charcoal (GAC‐Fe). Also presented is the interaction effect of As, Fe and Mn on the removal of arsenic species from water, which simulates contaminated groundwater. Among conventional models, pseudo second‐order kinetic model and Freundlich isotherm were adequate to explain the kinetics and equilibrium of adsorption process, respectively. However, in comparison to conventional isotherm empirical polynomial isotherm provided a more accurate prediction on equilibrium specific uptakes of arsenic species. Effects of initial concentrations of As, Fe and Mn on the removal of total arsenic (As(T)), As(V) & As(III) have been correlated within the error limit of ?0.2 to +5.64%. © 2009 American Institute of Chemical Engineers AIChE J, 2009 相似文献
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Ping Li 《Chemical engineering science》2004,59(18):3837-3847
The adsorption behavior of expanded beds is more complex than that of fixed beds, since the adsorbent particle size, local bed voidage and liquid axial dispersion will vary axially with expanded height. Models applicable to fixed beds maybe not adequately describe the hydrodynamic and adsorption behavior in expanded beds. In this paper, a 3-zone model is developed, in which the model equations are written for the bottom zone, middle zone, and top zone of the column, respectively, and the model parameters, such as the adsorbent particle diameter, bed voidage and liquid axial dispersion coefficient, are zonal values. In-bed breakthrough curves are predicted by the 3-zone model, and tested against literature data for lysozyme adsorption on Streamline SP in an expanded bed.Model parametric sensitivity is analyzed. The effects of film mass transfer resistance, liquid axial dispersion and adsorbent axial dispersion on the breakthrough curves are weaker than that of protein intraparticle diffusion resistance for stable expanded beds. Adsorbent particle size axial distribution and bed voidage axial variation significantly affect in-bed breakthrough curves, therefore, model parameters should not be assigned uniform values over the whole column; instead the model should account for the adsorbent particle size axial distribution and bed voidage axial variation. 相似文献