39 resultados para Freundlich

em Chinese Academy of Sciences Institutional Repositories Grid Portal


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通过静态吸附实验,研究了五氯苯酚在武汉东湖底质颗粒物上的吸附行为,并考察了pH值、颗粒物浓度、盐度和腐殖酸对吸附行为的影响.结果表明,25℃时五氯苯酚在该颗粒物上的吸附行为可用Freundlich吸附等温式描述,在pH值3.0~10.0范围内,五氯苯酚在颗粒物上的平衡吸附量先减小后又缓慢增加;颗粒物浓度在0.1~2.0g.L-1之间变化时,东湖底质颗粒物对五氯苯酚的吸附具有浓度效应;腐殖酸和盐度在一定范围内对五氯苯酚在颗粒物上吸附行为的影响为先促进其平衡吸附量增加,然后这种促进作用趋于缓和.

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随着长江三峡工程的建设 ,上游来水的流速在此减缓 ,随江水而下的大量泥沙在此沉淀 ,将使坝下 (长江中下游 )水中的悬移质浓度降低、粒径改变 ,从而改变水环境容量。利用长江宜昌江段的周年悬移质样及水样 ,研究了悬移质对重金属 (铜、锌、铅、镉及铬 )的吸附特征。结果表明 ,悬移质对上述金属的吸附可用Freundlich型及Langmuir型等温式较好进行拟合 ;当较高浓度的金属污染物排入江水后 ,在吸附及沉淀的共同作用下 ,浓度明显降低 ;单位悬移质的吸附量随悬移质浓度降低而上升 ,但总吸附量降低 ,从而

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In this paper, the adsorption equilibrium and kinetic behaviors of pentachlorophenol (PCP) on suspended particulate matter (SPM) in Donghu Lake water were investigated. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms and their constants were evaluated. The results indicated that the adsorption of PCP on Donghu Lake SPM followed the Freundlich isotherm. Furthermore, the first order Lagergren rate equation and the pseudo-second order rate equation were used to describe the kinetic behaviors of PCP adsorption on Donghu Lake SPM, the rate constants were determined, and the kinetic process of the adsorption of PCP on Donghu Lake SPM followed the second order kinetic model.

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本论文分为两部分:1. 综述部分(第一章和第二章),介绍了我国包头地区稀土工业区钍污染概况,对稀土工业生产造成的放射性生态环境污染进行了分析和归纳;评述了土壤和沉积物中放射性核素污染生态物理化学研究和进展;说明了本研究课题的背景、意义和技术路线。2. 实验部分(第三章至第六章),包括以下几方面内容:土壤样品和高铁矿渣样品中钍的分析方法的建立;对土壤和矿渣样品中钍的形态进行定量分析,考察了土壤性质对土壤中钍形态分布的影响;模拟自然环境,研究钍在土壤-植物系统之间的迁移积累和钍形态的植物可利用性;土壤样品对钍的吸附-解吸行为及其影响因素。 我国包头稀土工业在稀土矿浮选和稀土精矿湿法冶炼过程中产生了大量含放射性钍的废渣、废水和粉尘,对当地生态环境造成严重的破坏和放射性污染。 采用合适内标,ICP-MS法对样品中钍分析,考察了基体干扰、记忆效应和质谱干扰,比较了不同的样品消解方法对钍测定的影响,并用标准土壤样品和标准加入法对方法的准确性进行了评价。分别采用Tessier、BCR和Martínez-Aguirre形态萃取方法对土壤和样品中钍的形态进行分析,通过对总量的回收率和萃取剂选择性比较,选择了Martínez-Aguirre连续萃取法定量样品中钍的形态,并对其进行了优化和评价。考察了土壤性质影响着钍的形态分布。 通过盆栽实验,考察了小麦对根际土壤中钍形态分布以及的在不同生长期对钍的吸收影响。利用相应的材料人工模拟了土壤中钍的形态,对模拟的钍各形态的植物可利用性和植物吸收贡献指数进行评估分析。利用不同的磷酸盐对土壤进行培养处理,考察了磷酸盐的加入对土壤中钍的生物可利用性影响。 实验了土壤样品对钍的吸附-解吸过程,通过吸附容量、分配系数和吸附百分比等参数考察土壤对钍吸附能力,并考察了被土壤吸附钍的解吸行为。通过吸附机理的分析,土壤对钍的吸附作用主要是通过Th(IV)的表面水解吸附模式进行。根据实验结果,土壤样品对溶液中钍的吸附热力学可以用Freundlich方程式来描述,吸附的动力学过程可用Elovich方程描述,并对吸附方式和吸附过程进行论述。实验发现,吸附-解吸条件、土壤性质、外源稀土元素和施肥等对土壤吸附钍有一定影响。

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钴离子在γ-Al_2O_3上的吸附等温线符合Langmuir等温式,而钼的吸附等温线符合Freundlich等温式。在等孔体积法制备催化剂时,低PH下由于Al_2O_3吸附钼较多而对钴的吸附较少导致钴、钼在颗粒中分布不均;在高PH值下,由于钼的吸附量锐减,可用共浸法得到钴、钼分布均匀的催化剂。K_2CO_3在均匀型CoMo/Al_2O_3催化剂上的吸附等温线符合Langmuir等温式,虽然吸附量较大,但在浸渍液中今是足够时,等孔体积法也能得到均匀分布的结果。Co/Al_2O_3氧化态催化剂中存在和Al_2O_3表面作用的Co_3O_4及表面Co~(2+)离子;Co~(2+)/Al_2O_3中,K~+的存在减弱了Al_2O_3表面上的Co~(2+)和表面的作用,有是于Co~(2+)的还原和硫化。Mo/Al_2O_3催化剂中Mo以+6价的形式存在于Al_2O_3表面上,Al~(3+)对表面上Mo的极化作用Mo~(6+)在低温易于被部分还原,Mo-o-Al键作用较强,使Mo的完全还原又比MoO_3困难;K~+的存在减弱了MoK/Al_2O_3氧化态催化剂中的Mo-o-Al键强度,有助于Mo的深度还原和硫化。Co, Mo水溶液等孔体积共浸制备的氧化态CoMo/Al_2O_3催化剂中,存在CoMoO_4,并有利于Co, Mo硫化为Co_9S_8和MoS_2;CoMoK/Al_2O_3氧化态催化剂中,K~+的存在破坏了催化剂中CoMoO_4结构,被置换出的Co~(2+)和Al_2O_3表面发生一定作用使Co的硫化程度降低;当K_2CO_3在催化剂中含量小于15wt%时,Mo的硫化随K~+含量增加而增大,但当K_2CO_3在催化剂中含量高于15wt%,Mo的硫化程度随K~+含量增加而微有减少。CoMoK/Al_2O_3, CoMo/Al_2O_3, MoK/Al_2O_3, Mo/Al_2O_3, CoK/Al_2O_3, Co/Al_2O_3催化剂在H_2S/H_2的TPS过程中,H_2S 对活性组份起硫化和还原作用,H_2仅仅是还原了反应中生成的单质S。

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人工合成麝香作为一种替代型香料被广泛应用于日用化工行业,由于其持续不断地输入环境,其中一些典型化合物如加乐麝香和麝香酮等,在水、土壤和大气环境中的浓度日益增加,并且在动物体和人体组织中产生了蓄积作用,其效应相当于持久性有机污染物,为此,人工合成麝香作为一种新型污染物,其生态行为及生态效应已经越来越受到关注。本文研究了人工合成麝香(加乐麝香和麝香酮)和典型重金属镉(Cd)单一、复合污染对小麦种子发芽的急性毒性效应以及加乐麝香对重金属镉在棕壤中吸附解吸行为的影响,为合理评价人工合成麝香和Cd污染土壤的生态风险提供理论依据。 研究结果表明:人工合成麝香(麝香酮、加乐麝香)-镉复合污染对小麦根长和芽长伸长都有极显著的抑制作用。麝香酮和镉单一、复合污染条件下,根长和芽长抑制率与麝香酮浓度之间存在显著的剂量-效应关系。此外,加乐麝香和低浓度的镉(2 mg•kg-1)复合污染对小麦根长和芽长有协作效应。实验结果还表明根长和芽长是指示麝香酮、加乐麝香和Cd单一、复合污染最为敏感的指标。然而,麝香酮与加乐麝香对小麦种子发芽和根长、芽长伸长具有不同的毒性效应。 加乐麝香对Cd在土壤中吸附解吸行为的影响的研究结果表明,无论加乐麝香存在与否,Freundlich方程是描述镉等温吸附行为最好的方程。低浓度的加乐麝香抑制棕壤对镉的吸附,而高浓度的加乐麝香促进Cd在棕壤中的吸附。土壤对镉的解吸容量随加乐麝香浓度的增加先增加,然后又迅速减少。在加乐麝香与镉共存体系中,双常数方程是拟合Cd在棕壤中吸附解吸动力学过程的最优方程。加乐麝香浓度对吸附速率随时间的变化的影响不显著。

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染料废水成分复杂,色度高,是主要的环境污染源之一。应用微生物对染料废水脱色具有处理费用低和操作管理方便等优势,具有较好的发展前景。 本文采用筛选到一株短刺小克银汉霉(Cuuninghamella echinulata) KM3及一株红酵母(Rhodotorula sp.)YR-1分别对偶氮染料刚果红废水和酸性红废水进行了脱色研究,同时利用KM3及YR-1组成的复合菌种脱色体系对酸性红废水进行了脱色实验,为染料脱色真菌的应用奠定了基础。 KM3形成的菌丝球对多种染料具有较好脱色效果。KM3最适菌丝球形成条件:pH6-7、装液量90ml、孢子悬液浓度105个/ml (接种5ml)、摇床转速120rpm、培养温度30℃、培养时间72h;成球机理为凝聚型发育。KM3菌丝球对刚果红最佳脱色条件为:染料溶液初始pH值7.0,温度为33℃,摇床转速为120rpm。在刚果红50~200mg/l 浓度范围内, KM3菌丝球对刚果红吸附脱色动力学可用拟二级动力学方程描述。菌丝球对刚果红的吸附行为符合Langmuir和Freundlich 等温方程模型,Langmuir方程能更好的描述菌丝球对刚果红的吸附行为。丙酮对刚果红的解吸率最高,其解吸动力学过程符合二级动力学方程。将KM3应用在真菌生物滤床反应器中,在非灭菌和灭菌情况下接种孢子悬液后处理刚果红废水的过程中,均需长时间挂膜,处理效果一般。反应器中投加菌丝球后处理刚果红废水在3小时内达到92%以上的脱色效果。 YR-1对酸性红脱色机制属于降解脱色。YR-1对酸性红的最佳脱色培养条件为:初始pH 5.0、接种量5%、温度30℃;最佳碳源是葡萄糖,其次是蔗糖;最佳氮源是酵母膏或蛋白胨。在替换分批脱色实验和连续补料脱色实验中,脱色率一直保持在75%以上,显示YR-1在上述脱色体系中均具有良好适应性。 在三种复合菌种对酸性红的脱色体系中,体系Ⅲ(菌丝球与海藻酸钠固定化的酵母细胞混合培养)的脱色效果可达98%以上。对该体系而言,3种粒径固定化酵母小球(Ø1.1mm、1.8mm、3.1mm)中Ø1.8mm、3.1mm小球脱色率较为理想,而酵母细胞初始密度对脱色效果的影响不大。 KM3、YR-1分别具有处理刚果红废水和酸性红废水的应用前景,而KM3与YR-1联合应用对酸性红的脱色效果更好。

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环境突发污染事故给人民生活、经济发展和生态环境造成重大影响,研究污染物泄漏造成河流突发污染事故的应急处理方法十分必要。本论文选取苯酚、苯胺和亚甲基蓝等典型污染物为实验对象,采用吸附容量大、密度与水接近的活性炭纤维(ACF)为吸附剂。在自制的河流模型中,研究了ACF以苯酚、苯胺和亚甲基蓝为典型污染物的吸附过程,考察了吸附剂投加量、污染物浓度、吸附剂比表面积、吸附剂投加方式、水流速度与水质等对吸附速率与吸附效果的影响。实验结果表明,ACF能以较快的速率吸附苯酚、苯胺和亚甲基蓝,吸附率都在95%以上; ACF投加量是影响吸附速率最重要的因素,当一次性投加ACF质量之比为 1:2:4时,吸附速率常数之比近似为1:2:4;污染物浓度对吸附速率的影响显著,浓度较低时吸附速率较高。苯酚初始浓度为7mg·L-1时,经过86分钟的吸附,处理后的浓度可以达到地表水Ⅴ类水中挥发酚的限值要求(0.1mg·L-1);在吸附11分钟左右追加适量的ACF,能够明显提高吸附速率;河水流速和河流中的天然有机物、浊度、河水硬度对ACF吸附都不产生显著影响,这说明ACF作为河流突发污染事故应急处理的吸附剂,有广泛的适应性。在实际河水中,ACF对苯酚的吸附过程与在模拟河水中相似,吸附效果显著。实验结果还表明,ACF对苯酚的吸附是放热反应,符合Freundlich模型和Langmuir模型。事故应急处理后,应该及时将吸附了污染物的ACF打捞上来,有利于进行后续处理。 Emergency environmental pollution accidents pose significant impacts on our living, economic development and ecological environment. The study on the approach of emergency control for the contingency caused by leakage of pollutants in rivers is very necessary. In the experiment, phenol, aniline and methylene blue were selected as representative pollutant and activated carbon fiber (ACF) was selected as adsorbent, which has strong adsorption capacity and similar density to water. In the self-made river model, the effects of ACF dosage, pollutant concentration, ACF surface area, ACF adding ways, water flow rate and water quality on adsorption courses were investigated. The experimental results showed that ACF could adsorb pollutant quickly and effectively. The ACF dosage was the most important factor that affected adsorption rate .When the ACF dosage rate was 1:2:4, the constants of adsorption rate was approximately 1:2:4. The effect of pollutant concentrations on the adsorption rate was notable. Faster adsorption rates were achieved at low pollutant concentrations. Phenol concentration reached the limits of volatile phenol in Category Ⅴ surface water (0.1 mg·L-1) after 86 minutes of adsorption with initial phenol concentration of 7 mg·L-1. After 11 minutes of adsorption, certain amount of ACF was added and the adsorption rate was improved significantly. River flow rate and water quality have little effect on the adsorption rate. The adsorption results obtained in actual river water were comparable with that in simulating river water. The results also showed that, ACF on the absorption of phenol is exothermic reaction, witch matched with the Freundlich model and the Langmuir model. After emergency treatment, the ACF absorbed pollutants should be promptly salvaged for follow-up treatment.

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The present paper reports the biosorption of uranium onto chemically modified yeast cells, Rhodotorula glutinis, in order to study the role played by various functional groups in the cell wall. Esterification of the carboxyl groups and methylation of the amino groups present in the cells were carried out by methanol and formaldehyde treatment, respectively. The uranium sorption capacity increased 31% for the methanol-treated biomass and 11% for the formaldehyde-treated biomass at an initial uranium concentration of 140 mg/L The enhancement of uranium sorption capacity was investigated by Fourier transform infrared (FTIR) spectroscopy analysis, with amino and carboxyl groups were determined to be the important functional groups involved in uranium binding. The biosorption isotherms of uranium onto the raw and chemically modified biomass were also investigated with varying uranium concentrations. Langmuir and Freundlich models were well able to explain the sorption equilibrium data with satisfactory correlation coefficients higher than 0.9. (C) 2010 Elsevier Ltd. All rights reserved.

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采用1次平衡法对Cd2+、Pb2+在小麦根际和非根际土壤中的吸附-解吸行为进行比较研究.结果表明,根际土对Cd2+和Pb2+的吸附能力高于非根际土,2类土壤对Cd2+的吸附等温线与Freundlich方程有较好的拟合性,Pb2+的等温吸附过程可由Langmuir方程与Freundlich方程来描述.双常数方程是描述根际、非根际土Cd2+和Pb2+吸附动力学行为的最优模型,其次为Elovich方程,最差模型是一级动力学方程.Cd2+、Pb2+的解吸存在滞后现象,相比于非根际土,根际土吸附态Cd2+、Pb2+的解吸率更低,Cd2+、Pb2+的解吸量与其初始吸附量之间的关系符合2次幂方程.2类土壤Cd2+、Pb2+的解吸速率随重金属初始浓度的增加而增加,随解吸时间的延长而不断降低.描述根际和非根际土Cd2+、Pb2+的解吸动力学过程的最优模型均为双常数方程,其次为Elovich方程,一级动力学方程拟合效果不佳.

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研究了板栗壳吸附Cu2+的平衡、动力学和热力学特征并对吸附工艺进行设计.采用Langmuir和Freundlich等温线对静态吸附平衡数据进行了拟合,同时采用准一级动力学和准二级动力学模型对静态吸附动力学数据进行了拟合,并计算了吸附过程的热力学参数自由能变(ΔGo)、焓变(ΔHo)和熵变(ΔSo).结果表明,平衡实验数据符合Langmuir等温吸附模型,分离因子RL值在0~1之间,为有利吸附;动力学实验数据符合准二级动力学方程,平衡吸附量随Cu2+起始浓度增大而增大;ΔHo和ΔSo分别为12.206kJ·mol-1和21.534J·mol-·1K-1,ΔGo为负值,表明板栗壳吸附Cu2+为放热过程,可以自发进行,吸附过程增加了固液界面的混乱度.基于Langmuir等温吸附模型推导出的板栗壳用量计算公式可用于预测将一定体积一定起始浓度Cu2+溶液经过吸附降至所需浓度的板栗壳用量.

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采用一次平衡法,对3种不同污染负荷土壤Cd2+和Pb2+的吸附-解吸行为进行了比较.结果表明,低污染负荷土壤对Cd2+和Pb2+的吸附能力高于高污染负荷土壤.3种土壤对Cd2+的吸附等温线与Freundlich方程有较好的拟合性,Pb2+的等温吸附过程可用Langmuir方程与Freundlich方程来描述.双常数方程是描述这3种不同污染负荷土壤中Cd2+和Pb2+吸附动力学行为的最优模型,其次为Elovich方程,最差模型是一级动力学方程.Pb2+的解吸滞后现象较Cd2+明显.高污染负荷土壤的吸附态Cd2+、Pb2+解吸率高于低污染负荷土壤,Cd2+、Pb2+解吸量与其初始吸附量之间的关系符合二次幂方程.3种土壤Cd2+、Pb2+的解吸速率随重金属初始浓度的增加而增加,随解吸时间的延长而降低.

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The surface properties, porosities, and adsorption capacities of activated carbons (AC) are modified by the oxidation treatment using concentrated H2SO4 at temperatures 150-270 degreesC. The modified AC was characterized by N-2 adsorption, base titration, FTIR, and the adsorption of iodine, chlorophenol, methylene blue, and dibenzothiophene. The treatment of AC with concentrated H2SO4 at 250 degreesC greatly increases the mesoporous volume from 0.243 mL/g to 0.452 mL/g, specific surface areas from 393 m(2)/g to 745 m(2)/g, and acidic surface oxygen complexes from 0.071 meq/g to 1.986 meq/g as compared with the unmodified AC. The base titration results indicate that the amount of acidic surface oxygen groups on the modified AC increases with increasing the treatment temperatures and carboxyls and phenols are the most abundant carbon-oxygen functional groups. The carboxyl groups, COO- species, and hydroxyl groups are detected mainly for the sample treated at 250 degreesC. The mesoporous properties of the AC modified by concentrated H2SO4 were further tested by the adsorption of methylene blue and dibenzothiophene. The AC modified by concentrated H2SO4 at 250 degreesC has much higher adsorption capacities for large molecules (e.g., methylene blue and dibenzothiophene) than the unmodified AC but less adsorption capacities for small molecules (e.g., iodine). The adsorption results from aqueous solutions have been interpreted using Freundlich adsorption models.

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为探索真菌对染料的脱色特性,利用分离得到的短刺小克银汉霉对偶氮染料刚果红进行了脱色研究.短刺小克银汉霉菌丝球能在3h内使刚果红脱色率达到96%以上.在通气脱色体系中研究了短刺小克银汉霉菌丝球在不同pH值、脱色温度、摇床转速、盐度等条件下对刚果红脱色效果的影响.研究结果表明,短刺小克银汉霉菌丝球在温度为33℃,pH6.5,摇床转速120r/min的条件下对刚果红具有最大脱色率,染料溶液中盐浓度对脱色率有一定影响,但影响不大.在刚果红50~200mg/L质量浓度范围内,小克银汉霉菌丝球对刚果红吸附脱色动力学符合拟二级动力学方程(R2>0.999).菌丝球对刚果红的吸附等温线可用Langmuir和Freundlich等温方程模型表达,其中Langmuir方程能更好地描述菌丝球对染料的吸附行为(R2>0.999).

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采用络合溶胶-凝胶法制备了钛酸锶钡溶胶,将其浸渍在硅胶G上,经高温煅烧后,制得固载于硅胶G上的纳米钛酸锶钡,以X射线衍射(XRD)、扫描电镜(SEM)和傅里叶变换红外光谱(FTIR)进行了表征。以火焰原子吸收为检测手段,系统地研究了负载型纳米钛酸锶钡对水中Cd2+的吸附行为。结果表明,纳米钛酸锶钡能够牢固地负载于硅胶G表面。当介质的pH值为4~7时,该吸附剂对水中的Cd2+具有很强的吸附能力,其吸附行为符合Freundlich吸附等温模型和HO准二级动力学方程式,并分别计算了吸附过程的焓变(ΔΗ),自由能变(ΔG)和熵变(ΔS)等热力学参数,表明该吸附过程是自发的吸热物理过程。被吸附的Cd2+可用1 mol.L-1的硝酸完全洗脱回收。将其应用于水中痕量Cd2+的吸附,建立了负载型纳米钛酸锶钡吸附富集,火焰原子吸收法测定水中痕量Cd2+的新方法。用于自来水和地表水中镉的测定,结果满意。