共查询到19条相似文献，搜索用时 375 毫秒
1.
土壤对可溶性油的吸附作用及其影响因素分析 总被引：21，自引：0，他引：21
在沈(阳) 抚(顺) 灌区土-水-作物系统石油污染调查的基础上, 根据土壤非饱和带的结构和组成, 选择代表性的土壤剖面分别采集表土和底土, 分析土样的主要物理和化学性质, 系统测定不同土样对可溶性油吸附的动力学曲线和吸附等温线, 并分析了有机质、粘粒含量和含盐量对吸附作用的影响.结果表明, 土壤对可溶性油的吸附平衡时间为20~24h, 而且不同土样的吸附等温线均为直线型理想吸附.另外, 通过试验发现, 当水相中可溶性油低于一定浓度时, 不但不产生吸附, 反而使土壤中的残留油分释放出来. 相似文献
2.
为揭示可溶盐对黄土触变性的影响程度及作用规律,以宁夏同心黄土为研究对象,以干密度、含水率、含盐量为因素,设计正交试验方案进行了黄土的触变性研究。结果表明：黄土的触变性参数随干密度和含盐量的增大而增大、随含水率的增大而减小、并且随龄期的增长而增大;各因素影响的主次顺序为含水率、干密度和含盐量。在正交试验结果分析的基础上,以含盐量为因素进行了单因素试验,发现触变性参数与含盐量呈对数关系,且有很好的相关性,可溶盐对黄土触变性的影响明显,是影响黄土触变性的重要因素之一。研究结论对黄土地基设计、施工和处理有重要的指导意义。 相似文献
3.
铬是一种重金属痕量元素,人体通过食物链摄入过量的铬会在人体内富集,随之产生中毒反应。研究Cr(III)的浓度、反应时间、反应温度、pH值等因素对Cr(III)在黄土上吸附特性的影响,结果表明黄土对Cr(III)的吸附非常迅速,并且吸附量非常大,等温吸附模型Freundlich和Dubinin-Radushkevich(D-R)模型都能很好地解释Cr(III)在黄土上的吸附过程。热动力学分析表明,吸附是一个自发的过程,升温可促进吸附作用的进行。随着温度的不断升高,Cr(III)的吸附量逐渐增大。溶液的pH值是影响Cr(III)吸附效果的一个重要因素,当pH>6时,Cr(III)几乎完全被去除。利用X光衍射图谱和红外光谱分析,探讨黄土与Cr(III)的结合机制,黄土中的高岭土、石英等黏土矿物以及有机质成分对吸附过程起重要作用。 相似文献
4.
为揭示冲积与湖积成因土壤镉的吸附特征,以安徽省当涂县冲积成因的江心洲和冲积、湖积成因的大陇乡根际土壤为研究对象,开展土壤镉的等温吸附实验和吸附动力学实验.等温吸附实验结果表明,冲积土壤镉的吸附量（S）、等温吸附常数（K）和固液分配系数（Kd）均较湖积土壤明显偏大,显示冲积土壤对镉的吸附能力较湖积土壤强;吸附动力学实验表明,冲积土壤的最大吸附量、平衡吸附量均较湖积土壤大,吸附速率也明显偏大,尤其在吸附实验早期更为显著;等温吸附常数K和平衡吸附速率Vb与土壤理化性质的分析表明,土壤pH是造成研究区土壤镉吸附能力差异的主要原因,其次为物理性粘粒含量;土壤pH是影响研究区冲积土壤镉吸附能力的主要因素;湖积土壤镉的吸附能力受土壤pH、有机质含量、Cd含量、物理性粘粒含量等因素的综合影响.研究对于揭示Cd在水土系统的迁移转化规律以及土壤Cd的污染防治具有重要的指导意义. 相似文献
5.
《吉林大学学报(地球科学版)》2015,(Z1)
页岩气是赋存于泥页岩中的自生自储天然气,其赋存形式具有多样性,包括游离态、吸附态和少量的溶解态。其中吸附态是页岩气的主要赋存方式,占到页岩气总含量20%~85%。页岩吸附气含气量是计算页岩气资源量的关键性参数,是评价泥页岩是否具有开采价值的重要标准。国内外学者针对不同地区不同类型泥页岩做了大量的等温吸附实验,然而等温吸附实验只能开展恒定温度下的页岩吸附实验,不能研究任意温度下页岩气吸附能力。笔者选取渝东南地区4口井8个龙马溪组泥页岩样品开展气体(CH4、N2、CO2)吸附实验、有机碳含量分析、X-衍射岩矿分析、SEM扫描电镜实验,研究页岩吸附甲烷能力的主要控制因素。在高过成熟阶段,丰富的有机质发育大量的微孔隙,使得页岩对气体的吸附能力增加;在地下页岩储层含水条件下,黏土矿物主要吸附水,而有机质由于具有亲油气性,使得页岩气绝大部分吸附在页岩有机质表面,且有机质吸附甲烷等量吸附热远大于黏土矿物,因此页岩吸附甲烷最重要的内部控制因素是有机碳含量。甲烷等温吸附实验表明,随温度升高页岩吸附量显著降低,随压力增加,页岩吸附量增加,当压力达到一定值时,页岩吸附量不再随压力的增加而增加,最大甲烷吸附量随温度具有线性降低的趋势,且兰氏压力的对数与温度的倒数有很好的线性关系。基于兰氏方程,以甲烷等温吸附实验数据为基础,利用多元线性回归的方法,建立兰氏体积与w(TOC)、温度的关系及兰氏压力与温度的关系,带入兰氏方程,建立温度压力耦合控制下的扩展兰氏方程,进而计算地层温度压力条件下页岩储层吸附甲烷能力。结果表明:随深度增加,在温度压力耦合控制下,泥页岩吸附甲烷能力先增加后降低,800~1350m达到最大吸附能力;浅层压力对页岩吸附甲烷能力起主要作用,随深度的增加温度对页岩吸附甲烷能力控制作用增强;随w(TOC)增大,富有机质页岩吸附甲烷能力增加,达到最大吸附能力时的深度也随之增加。当页岩有机碳含量为1%时,页岩最大甲烷吸附量为1.6m3/t,当页岩有机碳含量为3%时,页岩最大甲烷吸附量为2.5m3/t,每增加2%的w(TOC)页岩最大吸附能力大约增加1 m3/t。 相似文献
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7.
采用辽宁某矿山的硼废水,研究了轻烧白云石对废水中硼的吸附及其影响因素,硼在矿物表面的吸附状态以及吸附作用机理,确定了实验最佳条件。在20mL反应体系中,反应温度为25℃,溶液pH为9.5～10.5,白云石(热处理温度750℃,粒径200～300目)矿样用量为2.0g,反应3h后,除硼率可达90%以上。pH9.2时,矿物对硼的吸附作用甚微;9.2pH12(轻烧白云石的零电荷点)时,溶液中的B(OH)4-被吸附到矿物表面,吸附机制为外层络合模式,此过程中OH-浓度是硼吸附量的重要控制因素;pH12时,矿物表面带负电,无静电吸附作用。通过XPS及红外光谱分析,硼以硼氧四面体的络合结构形式吸附于矿样表面。 相似文献
8.
我国部分地区土壤污染形势严峻,主要表现为Cu等重金属元素严重超标。污水灌溉以及含Cu饲料过量使用等不合理的农业生产方式是导致Cu在耕地中富集的主要因素,严重威胁粮食安全和人类健康。以河北保定典型污灌区为研究区,通过静态吸附批量实验探究土壤吸附Cu的动力学和热力学特性。吸附动力学模型和等温吸附经验模型中得到的参数一致表明,表层土壤S1对Cu的吸附能力强于底部土壤S2。S1的有机质含量高于S2,提供了更多的表面吸附点位,这可能是导致土壤S1对Cu的吸附能力更强的原因之一。离子强度对土壤Cu吸附率的影响较小。溶液pH和溶解性有机物(DOM)含量对土壤Cu吸附率的影响明显,pH值与吸附量呈正相关,DOM浓度与吸附量呈负相关。由于土壤对pH有很强的缓冲能力,短时间的酸雨可能不会导致Cu的迁移。施用有机肥时,有机肥浸出液中高浓度的DOM可能会与Cu形成水溶性Cu-DOM络合物,促进Cu在土壤中的迁移,导致浅层地下水污染。 相似文献
9.
包气带土壤组成对三氯乙烯的吸附影响研究 总被引：1，自引：0，他引：1
有机质和矿物质是包气带土壤中的主要吸附介质,其吸附特性直接影响有机污染物在环境中的迁移、转化等过程。分别采用分析纯石英砂和典型粘土矿物高岭石模拟土壤的原生矿物和粘土矿物,利用批实验的方法研究土壤中各组成部分对三氯乙烯(TCE)的吸附行为。土壤有机质的吸附行为通过全土样和矿物质的对比得出。结果表明,粘土矿物是吸附氯代烃的主要矿物质,原生矿物对氯代烃的吸附量很小;土壤有机质含量和土壤吸附量之间有很好的正相关性;土壤有机碳含量与土壤粘土矿物含量的比值是影响吸附行为的另一重要因素,比值越小,Koc值越大,土壤对TCE的亲和力就越强。由于自然界中的土壤有机质大都与矿物质形成有机质-粘土矿物结合体,据此推测有机质-矿物质结合体会影响有机质的组成和形态,从而对其吸附行为有重要作用。 相似文献
10.
为了研究土壤中有机质-矿质复合体结合形式对有机污染物吸附的影响, 利用批实验的方法, 对比研究有机质-矿质复合体与无机矿物和腐殖酸简单的混合物对三氯乙烯的吸附.结果表明, 与腐殖酸相比, 高岭石和石英砂吸附三氯乙烯量很小.模拟有机质-矿质复合体吸附三氯乙烯是线性吸附, Koc值随腐殖酸含量的增加而减小, 并且比纯腐殖酸样品的Koc值小.有机质与矿质的相互作用影响了有机质的吸附性能.对有机质在复合体中的形态变化进行了分析, 提出了有机质-矿质复合体模型, 并对实验结果进行了合理的解释. 相似文献
11.
Mu. Naushad Z. A. AL-Othman M. Islam 《International Journal of Environmental Science and Technology》2013,10(3):567-578
A new organic–inorganic composite cation exchanger polyaniline Sn(IV) silicate has been synthesized. The physicochemical properties of this ion exchanger were determined using different analytical techniques including fourier transform infrared spectroscopy, simultaneous thermogravimetry–differential thermogravimetry analyses, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy and elemental analysis studies. Ion exchange capacity and effect of heating temperature on ion exchange capacity were also carried out on this ion exchange material. Adsorption properties for different metal ions have been investigated and the results revealed that polyaniline Sn(IV) silicate had the highest adsorption capacity for Cd2+ ion. It’s selectivity was tested by achieving some important binary separations. Dependence of adsorption on contact time, temperature, pH of the solution and exchanger dose had been studied to achieve the optimum conditions. Adsorption kinetic study showed that the adsorption process followed the first order kinetics. Adsorption data were fitted to linearly transformed Langmuir isotherm with R 2 (correlation coefficient) >0.99. The maximum removal of Cd2+ was found at pH 9. The adsorption was fast and the equilibrium established within 40 min. Thermodynamic parameters viz- entropy change, enthalpy change and Gibb’s free energy change were also calculated. 相似文献
12.
Adsorption behavior of Cr (VI) in vadose zone, which is silty clay and clayey soil, was studied through kinetics experiments, isothermal adsorption experiments under various conditions, including different ph, temperature and organic contents. The results from kinetics experiments showed that the sorption progress of Cr (VI) has clear features in different stages, and adsorption equilibrium showed at 30 min, the adsorption rate of silty clay and clayey soil were 60%. The isothermal adsorption curve of Cr (VI) fitted closely with Freundlich equation model. When pH is 3-5 a plateau were seen, thereafter with increase in pH the adsorption rate of Cr (VI) dropped sharply and the minimum achieved at pH 10, the adsorption rate were only 35%. Adsorption rate of Cr (VI) increased gradually with the increase of temperature, the temperature of vadose zone is 14.7 ℃, according to the experimental results, the adsorption rate of Cr (VI) is about 40%. The use of organics represents an important contribution to the sorption of Cr (VI), sorption rate up to 100% when 30% of organic content. These studies will provide basis for manager to minimize the impacts, and provide basic data for pollution prevention and remediation of vadose zone. 相似文献
13.
M. Aliabadi M.Sc. K. Morshedzadeh B.Sc. H. Soheyli B. Sc. 《International Journal of Environmental Science and Technology》2006,3(3):321-325
The batch removal of Cr(VI) from aqueous solution using lignocellulosic solid wastes such as sawdust and pine leaves under different experimental conditions was investigated in this study. The influence of pH, temperature, contact time, initial concentration of Cr(VI) and particle size on the chromium removal was investigated. Adsorption of Cr(VI) is highly pH-dependent and the results indicate that the optimum pH for the removal is 2. The capacity of chromium adsorption at equilibrium by these natural wastes increased with absorbent concentration. Temperature in the range of 20–60 °C showed a restricted effect on the adsorption capacity of pine leaves, but had a considerable effect on the adsorption capacity of sawdust. The capacity of chromium adsorption at the equilibrium increased with the decrease in particle sizes. The suitability of adsorbents was tested with Langmuir and Freundlich isotherms and their constants were evaluated. Results indicated that the Freundlich model gave a better fit to the experimental data in comparison with the Langmuir equation. The study showed that lignocellulosic solid wastes such as sawdust and pine leaves can be used as effective adsorbents for removal of Cr(VI) from wastewater. 相似文献
14.
廖敏 《中国地球化学学报》2004,23(4)
Adsorption isotherms of 2,4-dinitrophenol and 2,4-dichlorophenol on hexadecyltrimethylammonium (HDTMA) bromide modified red soil under different ionic strength, divalent cation Cu 2 or different pH conditions were studied. All the adsorption isotherms were well fitted to the Freundlich equation. The adsorption capacities of 2,4-dinitrophenol or 2,4-dichlorophenol were dramatically enhanced by HDTMA treatment of red soil. The increase of ionic strength and the addition of divalent heavy metal cation Cu 2 significantly enhanced the adsorption of 2,4-dinitrophenol or 2,4-dichlorophenol on the HDTMA-modified red soil. Adsorption capacities of HDTMA-modified red soil for 2,4-dinitrophenol and 2,4-dichlorophenol gradually increased with decreasing pH in the aqueous phase. 相似文献
15.
采用批实验方法,研究了北京平原典型沉积物对NH+4 N的吸附规律。结果表明颗粒越细的沉积物,达到吸附反应平衡所需的时间越长,对NH+4 N的吸附量也越大;NH+4 N初始浓度在0~50 mg/L范围内,Henry、Langmuir、Freundlich吸附等温模式均能较好地描述北京平原典型沉积物对NH+4 N的吸附特性。沉积物对NH+4 N的吸附量随初始浓度的增加而增加;沉积物的颗粒越细,Henry吸附系数K越大,单位质量沉积物的饱和吸附量也越大;沉积物中TOC含量对沉积物的NH+4 N吸附行为有一定的控制作用,永定河、潮白河沉积物TOC值与Henry吸附系数K的相关系数R2分别为050,076;沉积物对NH+4 N的饱和吸附量随着土水比的增加而减少,通过乘幂的方式拟合不同土水比下的饱和吸附量,得出了北京平原包气带沉积物对NH+4 N的饱和吸附量;相同岩性条件下,特别是细颗粒沉积物中,潮白河沉积物对NH+4 N的吸附能力较永定河沉积物强,而同一流域内,中、下游沉积物的吸附能力较上游强。 相似文献
16.
Adsorption of 2,4-dinitrophenol and 2,4-dichlorophenol on Cationic Surfactant modified red soil 总被引：2，自引：0，他引：2
廖敏 《中国地球化学学报》2004,23(4):301-308
Adsorption isotherms of 2,4-dinitrophenol and 2,4-diehlorophenol on hexadeeyhrimethylammonium (HDTMA) bromide modified red soil under different ionic strength, divalent cation Cu2 or different pH conditions were studied. All the adsorption isotherms were well fitted to the Freundlich equation. The adsorption capacities of 2,4-dinitrophenol or 2,4-dichlorophenol were dramatically enhanced by HDTMA treatment of red soil. The increase of ionic strength and the addition of divalent heavy metal cation Cu^2 significantly enhanced the adsorption of 2,4-dinitrophenol or 2,4-dichlorophenol on the HDTMA-modified red soil. Adsorption capacities of HDTMA-modified red soil for 2,4-dinitrophenol and 2,4-dichlorophenol gradually increased with decreasing pH in the aqueous phase. 相似文献
17.
《Applied Geochemistry》2001,16(7-8):793-802
The adsorption of As(V) onto α-Al2O3 was investigated at 25, 50 and 70°C using batch adsorption experiments. Results indicate that As is strongly adsorbed at low pH and gets progressively released to the fluid with increasing pH above 7. At any pH, increasing temperature favors aqueous species of As over surface species. Surface complexation constants were determined at the experimental temperatures by fitting the adsorption data. Adsorption reactions were then converted to semi-isocolumbic reactions, i.e. reactions with balanced like-charged aqueous species. Intrinsic adsorption constants of semi-isocolumbic reactions change linearly when plotted against inverse temperature, suggesting that the heat capacity of these reactions remains constant over the temperature range considered. This permitted thermodynamic parameters of intrinsic surface complexation constants to be determined. Changes in surface complexation constants result in a change in the surface speciation with increasing temperature. This change is similar to the one observed for aqueous species, i.e. increasing temperature favors less negatively charged species below a pH of 9 and more negatively charged species above a pH of 10. Comparison with the stability of As surface complexes with Fe suggests that surface complexes with Al are more stable. 相似文献
18.
C. M. Zvinowanda J. O. Okonkwo Ph.D. P. N. Shabalala B.Tech. N. M. Agyei Ph.D. 《International Journal of Environmental Science and Technology》2009,6(3):425-434
The objective of this study was to investigate the possibility of using maize tassel as an alternative adsorbent for the removal of chromium (VI) and cadmium (II) ions from aqueous solutions. The effect of pH, solution temperature, contact time, initial metal ion concentration and adsorbent dose on the adsorption of chromium (VI) and cadmium (II) by tassel was investigated using batch methods. Adsorption for both chromium (VI) and cadmium (II) was found to be highly pH dependent compared to the other parameters investigated. Obtained results gave an adsorption capacity of 79.1 % for chromium (VI) at pH 2, exposure time of 1h at 25 °C. Maximum capacity of cadmium of 88 % was obtained in the pH range of 5-6 at 25 °C after exposure time of 1 h. The adsorption capacities of tassel for both chromium (VI) and cadmium (II) were found to be comparable to those of other commercial adsorbents currently in use for the removal of heavy metals from aqueous wastes. These results have demonstrated the immense potential of maize tassel as an alternative adsorbent for toxic metal ions remediation in polluted water and wastewater. 相似文献
19.
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