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1.
以17年不同施肥处理土壤胡敏酸为材料,研究了不同性质胡敏酸与钙饱和蒙脱石的
吸附特征。结果表明,钙饱和蒙脱石对土不同施肥处理胡敏酸的吸附曲线可用单表面Langmuir方程、双表面Langmuir方程以及Freundlich方程来描述。由单表面Langmuir方程计算的有机肥处理（厩肥、秸秆）胡敏酸的吸附量和吸附强度大于无肥、化肥处理。温度升高各处理胡敏酸吸附量增加,但吸附强度下降。双表面Langmuir揭示,蒙脱石对胡敏酸的吸附呈现高低两种能位的吸附。高能点位的吸附以化学吸附为主,是吸热反应,低能点位的吸附以物理吸附为主,是放热反应。有机肥处理和无肥、化肥处理相比,高能点位吸附相对减弱,低能点位吸附相对增强。 相似文献
2.
Water vapor adsorption isotherms were measured for soil samples taken from five subsequent 10 cm layers of limed and unlimed Cambic Arenosol under forest. Applying the numerical approximation of adsorption isotherms with an exponential isotherm equation and a local BET model, the surface areas, average adsorption energies and adsorption energies distribution functions were calculated. The values of average adsorption energies increased slightly with the depth of the layer, however no marked differences were observed between the average energies for the equivalent layers of both limed and unlimed profiles. For unlimed profiles the energy distribution functions possessed two maxima, the smaller maximum, however, disappeared in limed profile. 相似文献
3.
Gel permeation chromatography was used for monitoring the changes in humic molecular weight distribution after contact with kaolin clay and activated carbon. The high molecular weight fractions excluded from Sephadex G-50 were less removed by carbon indicating the exclusion effect of pores, but were preferentially adsorbed by clay. The aliphatic portion of humic acids is effectively removed by carbon as suggested by the decrease in E4: E6 ratio. The Freundlich and the Langmuir isotherms showed curvilinearity which was resolved into two straight lines. The sorption effect in humic molecular weight distribution suggests the necessity of batch adsorption test with respect to the treated humic material. 相似文献
4.
白浆土是吉林省和黑龙江省东部地区的主要农田土壤之一,研究白浆土对腐殖酸的吸附作用,可为探究白浆土的固碳潜力提供理论依据。采用批量平衡法,分析不同有机碳含量的白浆土及其组分(包括去有机质土壤、粉粒、黏粒)对腐殖酸的吸附动力学和等温吸附特性。结果表明:随吸附时间的延长,白浆土及其各组分对腐殖酸的吸附量逐渐增加;整个吸附动力学过程可划分为快速(0～30 min)和慢速(30～480 min)反应阶段,伪二级动力学方程的拟合效果优于Elovich、双常数和伪一级动力学方程。白浆土及其各组分对腐殖酸的吸附量随腐殖酸初始浓度的增加逐渐增大,Langmuir方程的拟合效果通常优于Freundlich方程和Temkin方程。随白浆土有机碳含量的增加,其对腐殖酸的最大吸附量分别为26.9,24.1,15.6 mg/g。而白浆土不同组分相比,最大吸附量的顺序依次为黏粒>去有机质土壤>粉粒,黏粒对腐殖酸的吸附量分别是原土的2.15～3.88倍,去有机质土壤的1.61～2.21倍,粉粒土壤的7.90～8.65倍。有机碳含量低的白浆土对腐殖酸具有更强的吸附能力,黏粒含量高的白浆土对腐殖酸的吸附潜力更大。 相似文献
5.
改性高岭土对废水中磷的吸附性能及机理研究 总被引：5，自引：1，他引：4
采用盐酸和煅烧2种方法对苏州高岭土进行了改性,分析其对模拟含磷废水中磷的吸附效果,并初步探讨了其作用机制,继而进行了等温吸附和吸附动力学试验研究。结果显示,酸、热改性均不同程度地提高了高岭土对模拟废水中磷的吸附净化能力,尤以9%酸改性和500℃煅烧效果最为明显。在处理25 ml浓度为20 mg/L的模拟含磷废水中,高岭土投加量为2%(重量比)时,经9%酸改性高岭土对磷去除率达81.8%,较天然高岭土提高了44.6%。在处理50 ml浓度为20 mg/L的模拟含磷废水时,经500℃煅烧改性高岭土对磷的去除率高达99.5%,残留溶液中磷浓度仅为0.10 mg/L,达到我国相应排放标准。酸改性可通过改变高岭土的吸附活性点位来提高其对磷的吸附净化性能,而煅烧通过活化高岭石中的铝而提高其对磷的吸附净化性能。天然、9%酸改性及500℃煅烧高岭土磷吸附等温线均符合Freundilch和Langmuir方程,皆达极显著水平(P<0.01)。天然、9%酸改性及500℃煅烧高岭土对磷的动力学吸附特征一致,皆与准二级方程拟合最佳,达极显著水平(P<0.01)。500℃煅烧高岭土对磷的饱和吸附量最大,在净化含磷废水中具有良好的应用前景。 相似文献
6.
Mieczyslaw Hajnos Grzegorz Jozefaciuk Zofia Soko&#x;owska Andreas Greiffenhagen Gerd Wessolek 《植物养料与土壤学杂志》2003,166(5):625-634
In this paper, we tried to find interrelations between water retention properties, surface characteristics, and structural features of sandy soils rich in organic matter. Raw humic, epihumic, and endohumic horizons of four acidic sandy forest soils were selected for this study. Specific areas and water adsorption energies were estimated from water vapor adsorption isotherms, micropore (nanometer range) parameters from desorption isotherms, mesopore (micrometer range) parameters from mercury intrusion porosimetry, and macropore (millimeter range) parameters from water retention curves measured using combined suction plate and pressure chamber methods. In the studied soils, pore volumes in all pore ranges were proportional to soil organic matter content. Thin column wicking technique was used to determine migration velocity vs. time dependence in the samples beds for a range of liquids of various surface tensions. From these dependencies the surface free energy and its components were estimated that were used for calculation of water contact angles and forces of interparticle interaction via a water meniscus. The dominant interactions in the studied soils were dispersive Lifshitz‐Van der Waals forces. In the two upper horizons polar acid‐base interactions were absent, however in the deepest horizons, high input of polar interactions occurred, due practically to electron‐donor component of the surface free energy. The electron‐acceptor contribution was low. The wettability of the soils was low in upper horizons as indicated by high water contact angles. 相似文献
7.
Adsorption and desorption of triasulfuron by soil 总被引：10，自引：0，他引：10
Pusino A Fiori MG Braschi I Gessa C 《Journal of agricultural and food chemistry》2003,51(18):5350-5354
The adsorption and desorption of the herbicide triasulfuron [2-(2-chloroethoxy)-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl]benzenesulfonamide] by three soils, soil organic matter (H(+) and Ca(2+)-saturated), and an amorphous iron oxide were studied. Adsorption isotherms conformed to the Freundlich equation. It was found that pH is the main factor influencing the adsorption in all of the systems. Indeed, the adsorption on soils was negatively correlated with pH. The highest level of adsorption was measured on soils with low pH and high organic carbon content. Moreover, it was found that humic acid is more effective in the adsorption compared with calcium humate (the pH values of the suspensions being 3.5 and 6, respectively). Experiments on amorphous iron oxide confirmed the pH dependence. Desorption was hysteretic on soils having high organic carbon content. 相似文献
8.
The adsorption isotherm of nicotine on humic acid - surface was found to be multiphase according to the applied concentrations of nicotine. Each phase was characterized by its own change in free energy and represented a mechanism of interaction. At low concentrations, the isotherm showed a H-curve of high affinity between both reactants as a result of protonation of the pyrrolidine nitrogen atom of nicotine, the second phase was that of flat adsorption in which the nitrogen atoms of nicotine acted as electron donor. The third phase was that of the rearrangement of the nicotine from flat to side adsorption on the humic surface, after which the phase of multilayer formation followed. The adsorption on the surface of the humic acid-clay complex showed no distinct phases but an isotherm looks like the L-type, although it could not verify Langmuir's equation. Probably the isotherm was the resultant of two mechanisms one due to the adsorption of the humic acid part and the other due to the clay part in the complex. Comparison of the constants of Freundlich's equation showed that the capacity of the adsorption humic surface was greater than that of the complex. 相似文献
9.
Robert Mayer 《植物养料与土壤学杂志》1978,141(1):11-28
Adsorption isotherms as regulators controlling heavy metal transport in soils The adsorption and desorption of Pb2+ and Cd2+ from equilibrium solutions with heavy metal contents up to 5000 μg/1 were determined in bulk experiments for soil samples from an acid Braunerde developed in loess loam, taken from the humic surface layer of the mineral soil (0–10 cm) and from the subsoil fairly free from organic matter (30–40 cm). Pb and Cd in solutions were determined by flameless atomic absorption spectroscopy. Pb was more strongly retained in the solid phase than Cd, and higher amounts of heavy metals were retained in the humic surface soil than in the subsoil free of organic matter. In the case of Pb adsorption/desorption showed slight hysteresis in the subsoil. The quantity/intensity (Q/I) relationships found in the experiments could be described by the Freundlich equation. The Q/I-relationships were substituted in the general transport equation. With a simulation model the transport of Pb and Cd through the soil with vertical water flow was calculated by the use of the Continuous Simulation Programming Language (CSMP). Two different cases were considered: a small, continuous increase in the heavy metal input of the soil surface, and a high, instantaneous peak input. Simulation of the transport and distribution mechanisms induced by the inputs over a period of 10 years showed strong retention of lead in the surface layer and consequently a strong damping of the concentration peak in the soil solution. In contrast, cadmium is distributed more quickly over the whole profile, yet the concentration peak in the solution phase is, too, damped considerably in the surface layer by temporary retention in the solid phase. The results of the simulation runs are in accordance with the situation in real soils where often strong accumulation of Pb is found in the top soil, while Cd is accumulated only slightly. 相似文献
10.
H. Filiz Ayyildiz Mustafa Topkafa FatmaNur Arslan Fatih Durmaz Semahat Kucukkolbasi Ismail Tarhan Huseyin Kara 《Water, air, and soil pollution》2012,223(7):3817-3830
This work assesses the use of immobilized humic acid (ImHA) onto aminopropyl silica (APS) as a sorbent for the removal and preconcentration of trace amounts of cobalt ions by on-line solid phase extraction (SPE) technique in the column system prepared in our laboratory. Different parameters, such as the effect of the pH, concentration, and flow rate, were studied and throughput was observed by a UV detector. All SPE steps were monitored by breakthrough curves used to visualize distribution of cobalt concentration between mobile and solid phase. The solutions collected from stripping steps were analyzed in atomic absorption spectrometer (AAS) and the amount of sorbed ions was calculated. Sorption characteristics were evaluated by using common adsorption isotherms and Scatchard plot analysis. From the obtained results, it was seen that sorption mechanism of cobalt ions were fitted to Langmuir model on a large scale and thought to be localized. Mean free energy (E?=?40.82?kJ?mol?1) calculated from D-R isotherm showed that chemical interactions are more effective than physical interactions. This investigation reveals a new, simple, environmentally friendly, and cost-effective method for removal and preconcentration of cobalt ions from aqueous solutions by a new aminopropyl silica-immobilized humic acid material. 相似文献
11.
采用镉离子选择电极研究了镉在胡敏酸上的吸附特征。实验结果表明 ,胡敏酸对镉的等温吸附规律与介质pH有关。当pH为 3 0 0和 3 50时符合Freundlich方程 ,当pH在 4 0 0～ 6 50之间更好地符合Langmuir方程 ;在pH为 3 0 0～ 6 50之间 ,吸附量与pH成显著正相关。温度升高吸附量降低 ,吸附热与反应介质的pH有关 ,pH升高 ,吸附反应放热增加 ;胡敏酸对镉的吸附作用力随介质pH改变发生较大变化 ,当pH为6 50时主要为配位基交换作用。胡敏酸对镉的吸附含有部分不释放氢的静电吸附 ,其吸附反应动力学用Elovich方程拟合效果较好 相似文献
12.
根瘤菌存在下土壤胶体和矿物对镉的吸附 总被引：8，自引：2，他引：6
Experiments were conducted to study the adsorption of Cd on two soil collids(red soil and yellowbrown soil) and three variable-charge minerals (goethite,noncrystalline Fe oxide and kaolin) in the absence and presence of rhizobia.The tested strain Rhizobium fredii C6,tolerant to 0.8 mmol L^-1 Cd,was selected from 30 rhizobial strains.Results showed that the isotherms for the adsorption of Cd by examined soil colloids and minerals in the presence of rhizobia could be described by Langmuir equation.Within the range of the numbers of rhizobial cells studied,the amount of Cd adsorbed by each system increased with increasing rhizobial cells,Greater increases for the adsorption of Cd were found in red soil and kaolin systems.Rhizobia influence on the adsorption of Cd by examined soil colloids and minerals was different from that on the adsorption of Cu.The presence of rhizobia increased the adsorption affinity of soil colloids and minerals for Cd,particularly for the goethite and kaolin systems.The discrepancies in the influence of rhizobia on the adsorbability and affinity of selected soil colloids and minerals for Cd suggesed the different interactions of rhizobia with various soil components.It is assumed that bacterial biomass plays an important role in controlling the mobility and bioavailability of Cd in soils with kaolinite and goethite as the major colloidal compnents,such as in variable-charge soil. 相似文献
13.
Influence of pH and organic substance on the adsorption of As(V) on geologic materials 总被引：1，自引：0，他引：1
The adsorption of As(V) on alumina, hematite, kaolin and quartz has been measured as a function of pH (2 to 10), and As concentrations (10?4 to 10 ?8 M; in the alumina and kaolin systems only). The effects of sulfate (0 to 80 mg L?1) and fulvic acid (0 to 25 mg L?1) were studied. The charge of the solid surface and the As speciation in solution (determined by pH) were the most important chemical parameters affecting the sorption behavior. At pH below PZC of the solid, there was a qualitative correlation between the adsorption and the anion exchange capacity of the solid. For hematite at low pH (below 5) there was a reduction of the adsorption possibly related to the formation of positively charged species. The presence of sulfate or fulvic acid reduced the adsorption. 相似文献
14.
采用吸附等温线的试验方法,研究了平衡溶液中磷浓度、反应时间及介质pH对不同处理的2种褐煤腐殖酸吸附磷的影响及其规律性。结果表明:在试验pH范围内,pH的升高减缓了吸附反应进行的速度,对于未经硝酸处理的样品S1,在pH为4.7时,吸附量和分配系数有一最大值,而样品S2,随着pH的升高,吸附量和分配系数一直减小;经硝酸处理后,样品对磷的吸附能力降低,一定条件下其单位吸附量仅为处理前的5.33%。适宜的固液比例可提高2个不同处理供试样品对磷的单位吸附量,其等温吸附规律可用Langmuir方程来加以描述;其吸附动力学用Elovich方程描述最佳。 相似文献
15.
Adsorption on a soil matrix of the insecticidal protein from Bacillus thuringiensis ( Bt) transgenic plants affects their accumulation and release and, hence, bioavailability in soil. Cry1Ab protein isolated from Bt transgenic rice was used to evaluate the adsorption and desorption on bentone, kaolin, and humic acids (HAs). The adsorption equilibrium of Cry1Ab protein was reached within 1-2 h for bentone and kaolin and within 4-8 h for HAs. The adsorption isotherms were better described by linear expressions ( R (2) >/= 0.973) rather than by the Freundlich model. No saturation was observed, even at the maximum concentration used (3.71 microg mL (-1)). The adsorbed protein was not easily desorbed at the used protein concentrations (0.18-3.71 microg mL (-1)); more than 50-70%, 70-80%, and 90% of the adsorbed protein remained on HAs, kaolin, and bentone, respectively, after washing with water. Adsorption and desorption of the Cry1Ab protein were further studied using five soils, and the isotherms were also well-described by linear equations ( p < 0.05). Adsorption of the Cry1Ab protein on soils was positively related to the soil organic matter content. 相似文献
16.
为筛选稳定、高效、环境友好的重金属污染修复材料,利用批吸附试验研究了不同温度下褐煤、腐植酸、活性炭对镉(Cd~(2+))的吸附特征,采用非线性χ~2检验辅助决定系数判断等温线模型拟合度,用红外光谱对材料功能团进行了识别。结果表明,Temkin模型能最好拟合3种材料对Cd~(2+)的等温吸附过程,Langmuir和Freundlich模型也能较好拟合但与温度有关。吸附热力学参数表明,3种材料对Cd~(2+)的吸附为优惠发生的物理吸附,并且是自发的吸热过程,3种材料与Cd~(2+)之间均有较强的作用力。在温度294.55~313.15 K时腐植酸、褐煤和活性炭对Cd~(2+)的最大吸附量分别为36.14~44.09、29.63~38.20 mg·g~(-1)和21.04~30.34 mg·g~(-1),吸附量随温度升高而升高,吸附自由能随着温度升高而降低,说明升温吸附更容易发生。准二级动力学拟合数据最好,表明3种材料对Cd~(2+)的吸附存在着化学过程。褐煤基活性炭和褐煤基腐植酸具有丰富的孔隙结构。红外光谱图表明腐植酸和褐煤较大的吸附量与其含氧功能团种类较多以及在波数2 360 cm~(-1)和2 342 cm~(-1)附近吸收峰有关。因此,褐煤基3种材料对Cd~(2+)的吸附是自发的吸热过程,腐植酸对Cd~(2+)的最大吸附量和吸附能力最大,用Temkin等温方程和准二级动力学曲线能最适宜描述褐煤基材料对Cd~(2+)的吸附特征。 相似文献
17.
P Leone M Nègre M Gennari V Boero R Celis J Cornejo 《Journal of agricultural and food chemistry》2002,50(2):291-298
Adsorption of imazapyr (IMZ), imazethapyr (IMZT), and imazaquin (IMZQ) was studied on two smectite-humic acid and two smectite-ferrihydrite binary systems prepared by treating a Wyoming smectite with a humic acid extracted from soil (4 and 8% w/w of the smectite) and with just-precipitated synthetic ferrihydrite (8 and 16% w/w of the smectite). Adsorption of the three herbicides on the smectite was not measurable at pH >4.5, presumably because of negative charges on the surface of the smectite. Adsorption on the smectite-humic acid systems was also not measurable, presumably because of negative charges on the surface, despite the high affinity of the three herbicides for humic acid, the adsorption order of which was IMZ < IMZT < IMZQ. Adsorption decreased in the order IMZ < IMZT < IMZQ on the smectite-ferrihydrite systems and IMZQ < IMZT < IMZ on ferrihydrite, although here the differences were small. These results show that even though pure smectite cannot adsorb herbicides, it modifies the adsorption capacity of ferrihydrite. The mutual interaction of active phases such as humic acid, ferrihydrite, and smectite alters the characteristics of the resulting surface and hence the adsorption process. Investigations of herbicide adsorption have been seen to produce more reliable results if conducted on polyphasic systems rather than on single soil components. 相似文献
18.
The adsorption of ionic Cd has been investigated on three humic acids isolated from podzol, rendzina and brown Mediterranean soils of Tuscany. The adsorption isotherms have been determined at 5 and 25°C. Cadmium adsorption was described by the Langmuir adsorption equation. Langmuir parameters were related to the functional groups content of humic acids and decreased in the following order: rendzina>brown Mediterranean soil>podzol. Adsorption was independent on temperature and increased with pH. Desorption experiments with 0.1 N NH4OAc and 0.25 M Cu (OAc)2 proved that Cd is adsorbed on humic acid about 50% in an exchangeable form and 50% in coordination complexes. 相似文献
19.
20.
Chendong Shuang Mengqiao Wang Penghui Li Aimin Li Qing Zhou Fei Pan Weiwei Zhou 《Journal of Soils and Sediments》2014,14(2):312-319