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1.
坡缕石粘土对Cu2+的吸附热力学 总被引：1，自引：0，他引：1
将坡缕石粘土分离提纯后作为吸附剂,通过对水中Cu2+的静态吸附实验,考察了时间及介质pH值对吸附效果的影响,并对吸附平衡和吸附热力学特征进行了探讨。结果表明:在实验条件下坡缕石粘土对水中的Cu2+离子具有较强的吸附作用,吸附平衡时间约为60 min,pH值对吸附效果有显著的影响,吸附量随pH值的升高而增加,当平衡溶液pH>7时吸附率超过99%;吸附平衡与Langmuir方程的符合程度优于D-R方程和Freundlich方程,由Langmuir方程拟合饱和吸附量为33.0～34.0 mg/g,由D-R方程得平均吸附能Es为13 kJ/mol,吸附过程为离子交换反应;吸附过程吸热,吸附焓为16.97 kJ/mol,吸附Gibbs函数在-27～-24 kJ/mol之间,吸附熵大于零,吸附过程可自发进行。 相似文献
2.
利用粉碎分级的天然锰钾矿去除水溶液中Hg^2 的实验研究表明：反应平衡时间约为20小时；pH值对其吸附率影响很大，在中性（氯化物在偏碱性）条件下吸附率较高；溶液中阳离子的存在会产生竞争吸附而降低对Hg^2 的吸附量，2价金属离子较1价金属离子对Hg^2 竞争干扰明显；溶液中Cl^-的存在能明显降低对Hg^2 的吸附量。对等温吸附曲线的回归分析得出在浓度为5～350mg/L段能很好地符合Langmuir单吸附位吸附曲线，并计算出在该实验条件下其最大理论吸附量为27.6mg/g。解吸实验结果表明，在无其他电解质参与的条件下解吸量较少，受多种电解质干扰时其解吸率不超过20%。 相似文献
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研究了水滑石(LDH)及其焙烧产物(LDO)吸附脱除水溶液中活性深蓝ST-2GLN的性能。考察了pH值、吸附剂投加量、时间等因素对吸附的影响。结果表明:LDH及LDO对活性深蓝ST-2GLN染料具有良好的脱除效果,室温下,1 g/L的LDH和0.5 g/L的LDO对浓度为100 mg/L的染料的脱色率分别达到96.11%和98.58%。pH值是影响吸附能力的关键因素,吸附剂对溶液pH值有一定缓冲作用。LDH及LDO对活性深蓝ST-2GLN吸附结果均符合Langmuir吸附等温式。饱和吸附后的LDH用高温热解法再生,再生产物吸附性能良好,随再生次数增多,脱色率下降。 相似文献
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陆架边缘海是“河口—陆架”体系重要的碳汇,黏土矿物作为主要载体将有机质与金属元素吸附于表面或层间,通常表现为粒度、有机质和金属元素含量之间高度正相关。本文通过分析南黄海中部沉积物粒度、总有机碳、主微量元素,探讨三者之间分布特征和相互关系,进一步开展金属元素、有机质与黏土矿物吸附模拟实验,结果表明,酸性条件（pH=4）下适量的金属离子（Zn2+、Ni2+、Pb2+）明显促进伊利石对腐殖酸（有机质主要组成部分）吸附,腐殖酸吸附量达到20.06 mg/g,其中金属离子加入使腐殖酸吸附量提高6.25%;同时碱性条件（pH=8）下金属离子也能够促进伊利石对腐殖酸吸附,腐殖酸吸附量达到15.7 mg/g,金属离子加入使腐殖酸吸附量提高38.9%。金属离子的阳离子键桥作用促进伊利石吸附腐殖酸,且酸性环境下腐殖酸的吸附量高于碱性环境。证实了陆架边缘海背下金属元素的参与对黏土矿物吸附腐殖酸具有明显促进作用,有利于在全球碳循环过程形成边缘海“碳库”,同时海洋酸化可能造成海洋溶解有机质降低和重金属离子浓度升高,对陆架边缘海海洋生态系统平衡构成威胁。 相似文献
7.
土壤重金属元素地球化学行为是目前国内外研究的热点。研究显示重金属元素地球化学行为与土壤理化性质有密切关系。本文选择河北平原农田为研究区,采集了325个根系土样品,测定了Pb、Hg有效态含量,并探讨了影响其地球化学行为的主要因素。研究表明:(1)Pb、Hg水溶态和离子交换态与土壤p H值呈显著负相关关系,土壤酸化使Pb、Hg有效性增加,直接导致农作物中Pb、Hg含量增加,保持土壤p H值在弱酸性至弱碱性范围,防止土壤酸化,可以降低重金属危害。(2)土壤中有机质含量与Pb、Hg全量呈显著的正相关性,但与水溶态和离子交换态呈负相关。所以土壤中有机质的增加可以降低Pb、Hg元素水溶态和离子交换态含量。(3)随着土壤黏粒的增加,Pb、Hg水溶态和离子交换态含量降低,说明黏粒可以吸附一定量的重金属离子,与重金属元素Pb、Hg地球化学行为存在一定关系。土壤p H值、有机质、黏粒是控制重金属元素Pb、Hg地球化学行为的重要因素。 相似文献
8.
土壤样品分别采于山西省大同、太原和临汾3个地区。实验分成吸附解吸实验和运移实验2个部分。其中吸附实验分成砂粒土壤和粘粒土壤2个粒级分别进行。结果表明：3种土壤对Hg的吸附量随着加入Hg离子溶液浓度的增加而增加。用4种吸附模式来拟合3种土样对Hg的吸附可以得出,Freundlich模式和Langmuir模式能较好地拟合3种土壤对Hg吸附的实验数据。3种土壤对Hg都有一定的吸持固定作用。解吸率由大到小依次为大同土壤〉临汾土壤〉太原土壤。当Hg^2＋的浓度为300mg/L时,Hg在大同土壤中的穿透速率最快,在太原土壤中穿透速率最慢。从而得出Hg^2＋在壤质砂土中运移速度最快、在粉壤土中运移速度最慢的结论。 相似文献
9.
The adsorption behaviors of Cr(VI) on laterite from Guizhou Province were studied in this paper, and the adsorption mechanism
was discussed as well. Results showed that different mineral compositions in the laterite would cause differences in the capacity
of laterite to absorb Cr(VI). Gibbsite, iron oxide minerals and non-crystalloids are the main contributors to enhancing the
capacity of laterite to absorb Cr(VI). The pH of the solution is an important factor affecting the adsorption of Cr(VI) on
laterite. Acidic environment (pH=2–5) is favorable to the adsorption of Cr(VI). The amount of adsorbed Cr(VI) decreases with
increasing pH of the solution. With increasing initial concentrations of Cr(VI), the amount of adsorbed Cr(VI) increases first,
and then decreases. The optimal adsorption concentration of Cr(VI) on laterite is 250 μg/mL. The adsorption of Cr(VI) on laterite
is a rapid process, about 80% Cr(VI) will be adsorbed within 2 hours. And the adsorption of Cr(VI) on kaolinite is a slow
process. 相似文献
10.
用合成的13X沸石对废水中氨基酸(赖氨酸)进行静态吸附实验,研究了pH、温度、吸附时间、沸石用量等对吸附率的影响,结果表明,室温下沸石对赖氨酸的吸附平衡时间为30min,pH=pKa1=2.2时,赖氨酸在沸石上的吸附效果最好,吸附率大于82%,饱和吸附量达51.73mg.g-1。吸附等温线近似呈直线型,表明离子交换机制是沸石吸附氨基酸的主要方式。对已饱和吸附的沸石用饱和氯化钠溶液进行再生实验,赖氨酸的解吸率大于95%,沸石可重复使用。实验研究表明可用13X分子筛处理含氨基酸废水,为实际处理含氨基酸废水提供了可行性依据。 相似文献
11.
Adsorption kinetics and intraparticulate diffusivities of Hg, As and Pb ions on unmodified and thiolated coconut fiber 总被引：9，自引：9，他引：0
J. C. Igwe M.Sc. D.CHE M.Eng. Ph.D. A. A. Abia M.Sc. Ph.D. C. A. Ibeh B.Sc. 《International Journal of Environmental Science and Technology》2008,5(1):83-92
As, Hg and Pb are examples of heavy metals which are present in different types of industrial effluents responsible for environmental pollution. Their removal is traditionally made by chemical precipitation, ion-exchange and so on. However, this is expensive and not completely feasible to reduce their concentrations to the levels as low as required by the environmental legislation. Biosorption is a process in which solids of natural origin are employed for binding the heavy metal. It is a promising alternative method to treat industrial effluents, mainly because of its low cost and high metal binding capacity. The kinetics was studied for biosorption experiments using coconut fiber for As (III), Hg (II) and Pb (II) ions adsorption. The specific surface area and surface charge density of the coconut fiber are 1.186×1025 (m2/g) and 5.39 ×1024 (meq/m2), respectively. The maximum adsorption capacity was found to be the highest for Pb (II) followed by Hg (II) and As (III). The modification of the adsorbent by thiolation affected the adsorption capacity. Equilibrium sorption was reached for the metal ions at about 60 min. The equilibrium constant and free energy of the adsorption at 30 °C were calculated. The mechanism of sorption was found to obey the particle-diffusion model. The kinetic studies showed that the sorption rates could be described by both pseudo first-order and pseudo second-order models. The pseudo second-order model showed a better fit with a rate constant value of 1.16 × 10?4/min. for all three metal ions. Therefore, the results of this study show that coconut fiber, both modified and unmodified, is an efficient adsorbent for the removal of toxic and valuable metals from industrial effluents. 相似文献
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Pb and Co removal from paint industries effluent using wood ash 总被引：2，自引：2，他引：0
M. Malakootian Ph.D. A. Almasi Ph.D. H. Hossaini 《International Journal of Environmental Science and Technology》2008,5(2):217-222
The release of heavy metals into the environment is a worldwide major concern. Different studies have demonstrated that natural agents have a high removal capacity for divalent heavy metal ions. Wood ash is a natural adsorbent and, in comparison with others, has a very low price. In this study, the removal of heavy metals (Pb and Co) from Binalood paint industry (Kerman, Iran) effluent was investigated in batch condition. Pb and Co measurement in samples were done with atomic absorption equipment and test methods were adapted from standard methods for the examination of water and wastewater. The effect of pH and the amount of adsorbent was determined and different adsorption isotherms were also obtained. This study shows that the adsorption process follows the adsorption Langmuir isotherm. The amount of wood ash has a great role in the adsorption rate and adsorption rate increased as wood ash increased. In the study, the reactions reached equilibrium in 3 h contact time. The maximum Pb removal efficiency was 96.1 % at pH 2 with a contact time of 3 h and 100 g/L wood ash and the maximum Co removal efficiency was 99 % at pH 2 with a contact time of 3 h and 100 g/L wood ash. According to the results, wood ash is recommended as a low cost and available adsorbent to remove Pb and Co from municipal and industrial wastewaters. 相似文献
13.
M. Ghasemi N. Ghasemi G. Zahedi S. R. W. Alwi M. Goodarzi H. Javadian 《International Journal of Environmental Science and Technology》2014,11(7):1835-1844
In this study, the adsorption behavior of Ni(II) in an aqueous solution system using natural adsorbent Peganum harmala-L was measured via batch mode. The prepared sorbent was characterized by scanning electron microscope, Fourier transform infrared spectroscopy, N2 adsorption–desorption and pHzpc. Adsorption experiments were carried out by varying several conditions such as contact time, metal ion concentration and pH to assess kinetic and equilibrium parameters. The equilibrium data were analyzed based on the Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherms. Kinetic data were analyzed using the pseudo-first-order, pseudo-second-order and intra-particular diffusion models. Experimental data showed that at contact time 60 min, metal ion concentration 50 mg/L and pH 6, a maximum amount of Ni(II) ions can be removed. The experimental data were best described by the Langmuir isotherm model as is evident from the high R 2 value of 0.988. The adsorption capacity (q m) obtained was 68.02 mg/g at an initial pH of 6 and a temperature of 25 °C. Kinetic studies of the adsorption showed that equilibrium was reached within 60 min of contact and the adsorption process followed the pseudo-first-order model. The obtained results show that P. harmala-L can be used as an effective and a natural low-cost adsorbent for the removal of Ni(II) from aqueous solutions. 相似文献
14.
Evaluating the effectiveness of a hybrid sorbent resin in removing fluoride from water 总被引：1，自引：1，他引：0
M. Rahmani Boldaji A. H. Mahvi S. Dobaradaran S. S. Hosseini B.Sc. 《International Journal of Environmental Science and Technology》2009,6(4):629-632
In some regions of the world, the concentration of fluoride in groundwater is high. To reduce the amount of fluoride to acceptable drinking water standard, it is highly recommended to treat the water. Fluoride adsorption in aqueous solution by a hybrid resin was studied in this research because of its functional groups likeness with goethite. Kinetic data showed that F adsorption was rapid in the beginning and maximum uptake occurred in within 10 min and equilibrium reached within 100 min. The experimental results showed that fluoride adsorption was influenced by pH of solution and optimum operating pH was in the range of 3 to 5.5. Langmuir model was applicable to the present study and F ions were exchanged with hydroxide ions in nano-scaled structure on the surface of sorbent. This adsorbent with 61 % efficiency is suitable for the regions where F concentration is less than 4 mg/L. 相似文献
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Adsorption behaviors of Cd^2＋ on Fe2O3/MnO2 and the effects of coexisting ions under alkaline conditions 总被引：2，自引：0，他引：2
This study describes the adsorption features of cadmium on Fe2O3 and MnO2 in alkaline saline conditions. The adsorption reached equilibrium in 6 hours under alkaline conditions. The absorption of cadmium on Fe2O3 and MnO2 was consistent with Freundlich absorption isotherms, and the corresponding adsorption capacities were 16.3 and 16.7 mg·g-1, respectively. Moreover, the adsorption quantity of cadmium on Fe2O3 and MnO2 rose with increasing pH from acidic to neutral, and reached the maximum at pH= 9. The coexisting chlorides reduced the adsorption capacity of Fe2O3 and MnO2. The influence intensities of different cations follow the order of CaCl2>>KCl>NaCl. However, the influence of sodium salts on the capacities of Fe2O3 and MnO2 to adsorb cadmium appeared more complicated: the relatively low concentrations of sodium salts could reduce the adsorption capacity; with increasing concentrations of sodium salts, e.g. NaCl and NaNO3. The adsorption capacity decreased continually. Moreover, due to the competition adsorption and precipitation effects, the adsorption capabilities of Na2CO3, NaH2PO4 and Na2HSO4 could also be reduced and cadmium concentrations in the solution were reduced as well. 相似文献
16.
M. Nameni M.Sc. M. R. Alavi Moghadam M. Arami 《International Journal of Environmental Science and Technology》2008,5(2):161-168
In this research, adsorption of chromium (VI) ions on wheat bran has been studied through using batch adsorption techniques. The main objectives of this study are to 1) investigate the chromium adsorption from aqueous solution by wheat bran, 2) study the influence of contact time, pH, adsorbent dose and initial chromium concentration on adsorption process performance and 3) determine appropriate adsorption isotherm and kinetics parameters of chromium (VI) adsorption on wheat bran. The results of this study showed that adsorption of chromium by wheat bran reached to equilibrium after 60 min and after that a little change of chromium removal efficiency was observed. Higher chromium adsorption was observed at lower pHs, and maximum chromium removal (87.8 %) obtained at pH of 2. The adsorption of chromium by wheat bran decreased at the higher initial chromium concentration and lower adsorbent doses. The obtained results showed that the adsorption of chromium (VI) by wheat bran follows Langmuir isotherm equation with a correlation coefficient equal to 0.997. In addition, the kinetics of the adsorption process follows the pseudo second-order kinetics model with a rate constant value of 0.131 g/mg.min The results indicate that wheat bran can be employed as a low cost alternative to commercial adsorbents in the removal of chromium (VI) from water and wastewater. 相似文献
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以氧化还原共沉淀的方法将铁锰复合氧化物负载于坡缕石黏土表面,制备负载型吸附剂,由静态吸附实验研究了吸附剂对磷的吸附性能,探讨了吸附的动力学特征、热力学参数和吸附机理。结果显示,吸附剂对磷的吸附受溶液初始pH值、吸附时间及温度的影响,在中性条件下吸附平衡时间为90 min,pseudo-second-order吸附动力学方程能较好描述吸附过程,吸附表观活化能为11.76 k J/mol;吸附等温线与Freundlich方程的拟合结果略优于Langmuir方程,由Langmuir方程得到最大吸附量为26~31 mg/g。吸附焓变为9.29 k J/mol,吸附熵变为正值,自由能变为-4.3~-5.8 k J/mol,吸附作用有多层不均匀吸附的性质,同时包含物理作用和化学作用,但不属强的化学键作用。 相似文献
19.
水悬浮体系中凹凸棒石与Cu2+作用机理 总被引：12，自引：0，他引：12
研究矿物吸附重金属性能和机理,对正确认识矿物吸附性质、环境矿物材料应用研究以及重金属环境化学行为具有重要理论和实际意义。凹凸棒石是重要粘土矿物之一,也是重要的环境矿物材料,其吸附净化功能潜在应用受到广泛关注。在制备凹凸棒石纯样基础上,进行了凹凸棒石吸附Cu^2 单因素实验,吸附前后溶液pH值变化观测和吸附Cu^2 后凹凸棒石表面结构高分辨透射电镜调查。结果表明,从表面来看,凹凸棒石对Cu^2 的吸附性能主要受振荡速度、吸附时间、初始溶液pH值、吸附剂用量等因素影响,但实际上,凹凸棒石对Cu^2 的吸附作用主要是凹凸棒石诱导的Cu^2 水解沉淀作用以及凹凸棒石(带负电荷)与氢氧化铜(带正电荷)正负电荷胶体颗粒的互相作用,这有别于严格意义的矿物界面吸附作用。产生这种作用的机制在于凹凸棒石属于天然纳米矿物材料,具有较高的表面化学活性,凹凸棒石一水悬浮体系中凹凸棒石表面水解呈现出碱性,结果导致吸附平衡水溶液pH值较初始水溶液有较大程度的升高,达到Cu^2 水解基本完全的pH条件. 相似文献
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中国和世界上许多国家（地区） 都面临着饮用水氟含量超标的问题,因此研究氟的环境地球化学行为以及探索除氟
技术和原理至关重要。本实验采用廉价的非金属矿物羟基磷灰石作为吸附材料,研究羟基磷灰石吸附溶解态F-的地球化学
行为和机制,考察反应时间、pH、初始F-浓度等环境参数对吸附反应的影响。实验结果发现羟基磷灰石对F-的吸附反应需
进行到48 h以上时才接近反应平衡。在实验条件下（pH≥4）,F-的吸附量随pH升高而降低,羟基磷灰石对F-的吸附受pH
调控。同时还发现羟基磷灰石在pH=6条件下对F-的吸附等温线既满足Langmuir等温模式（R2=0.89） 同时也满足Freundlich
等温模式（R2=0.99）,并推导出该条件的理论最大吸附量为21.6×10-3。本研究还进一步采用了先进的XRD、SEM、
HR-TEM、19F NMR手段,系统地表征了反应前后吸附产物的形态和成分变化,发现在高F-浓度条件下,F-在羟基磷灰石表
面的吸附机制不再是单层的表面配位。核磁共振的结果表明F-可部分取代羟基磷灰石结构中的隧道羟基而形成含氟羟基磷
灰石。研究结果表明羟基磷灰石是一种相当具有潜力的除氟材料,值得进一步开发。 相似文献