不同条件下菲和萘在塿土上的吸附特征研究

以平衡吸附法研究了菲和萘在塿土上的吸附行为,考察了初始浓度、温度、pH、离子强度和CaCO3对塿土吸附菲和萘的影响,Henry方程、Freundlich方程和deBoer-Zwikker极化方程被用来拟和吸附等温线。结果表明,菲和萘在塿土上的吸附等温线为非线性,Freundlich方程最符合其吸附行为。菲和萘在塿土上的吸附量随温度升高而降低,其吸附是一个放热过程;吸附自由能小于零,表明吸附过程是自发的;熵变值也小于零,说明焓变是吸附过程的驱动力。随着pH增加,塿土对菲和萘的吸附量下降;而随着离子强度增加,塿土对菲和萘的吸附量增加。CaCO对菲和萘的吸附等温线也为非线性,其对塿土吸附菲和萘具有较大的贡献。     

几种土壤在单一Zn及Cd Cu共存条件下对Zn的吸附

研究了Zn2+在单一及与Cd2+、Cu2+共存条件下在塿土、黄绵土、黑垆土、黄褐土、砂土5种土壤中的吸附特征,并探讨了其吸附机制。结果表明,在20℃、30℃下,Zn2+在各供试土样中吸附等温线总体上均呈I或III型等温线形式,总体上黑垆土、塿土对Zn2+吸附最强,而砂土的吸附总是最差;塿土、黄绵土和黄褐土中Zn2+吸附的温度效应呈现升温正效应特征,砂土中则总体上表现出随温度上升呈下降趋势,黑垆土中Zn2+吸附的温度效应则与重金属处理有关。Freundlich模型是描述Zn2+吸附等温线最佳模型。Cd2+、Cu2+的共存对Zn2+的吸附均具有显著的拮抗作用,但对Zn2+吸附规律的影响不同。机理分析表明,Zn2+在土壤中的吸附主要以化学吸附为主,Cu2+由于其与Zn2+相似的化学吸附特点而竞争Zn2+化学吸附点位,但Cd2+吸附主要竞争以电性引力形式吸附的Zn2+,因而Cu2+对Zn2+吸附的影响较大,而Cd2+影响较小。     

塿土对阴-非离子表面活性剂的吸附特征研究

以平衡吸附法研究了塿土对阴离子表面活性剂（SDS）、非离子表面活性剂（TritonX-100、Tween80和Brij35）的吸附特征,考察了pH、阴-非离子表面活性剂混合对塿土吸附表面活性剂的影响。结果表明,非离子表面活性剂在塿土上吸附等温线均呈L型,且均符合Freundlich和Langmuir方程;塿土对SDS的吸附等温线呈LS型,可用Freundlich方程来描述;塿土对4种表面活性剂吸附量的大小顺序为Tween80〉SDS〉Brij35〉TritonX-100。当阴-非离子表面活性剂一起进入土壤中,SDS-Brij35之间的相互影响不大;TritonX-100与SDS相互作用较大,无论二者以何种方式混合都会使TritonX-100在塿土上的吸附量增加,SDS的吸附量下降;SDS与Tween80之间的相互作用最大,混合后吸附量均下降,但Tween80吸附量降低的幅度最大。pH对非离子表面活性剂的吸附影响不大,而随着pH的增加,塿土对SDS的吸附百分率明显下降;在pH为8.0时,塿土对非离子表面活性剂的吸附百分率达到80以上。因此在选择合适的表面活性剂进行有机污染土壤修复和治理时,考虑土壤的特性和表面活性剂的结构是非常重要的。     

CTMAB对塿土表面的修饰机制

以平衡吸附法研究了十六烷基三甲基溴化铵(CTMAB)对塿土耕层·粘化层表面的修饰机制,结果表明,CTMAB在两层次土样上吸附等温线20℃时均呈直线型,40℃时均转变为H型等温线形式·在修饰比例0%～100%CEC区间,土壤表面对CTMAB的亲和力随温度的升高均增加,其吸附具有熵增控制自发性反应的热力学特征,两个温度下,土层吸附CTMAB亲和力之比与土层CEC之比相近;在修饰比例100%～200%CEC区间,土壤表面对CTMAB的亲和力随温度的升高均呈现下降的趋势,呈现放热熵减反应特征,20℃时土层吸附CTMAB亲和力之比与土层CEC之比相近,而40℃时则与土层性质无关。CTMAB在两层次土样上解吸等温线均呈直线型。CTMAB对塿土表面的修饰在100%CEC修饰比例前以离子交换为主,100%后以疏水键结合为主,CTMAB在塿土表面易于吸附但难于解吸,解吸的CTMAB主要是以疏水键形式结合在土壤表面上。     

Cu^2＋、Zn^2＋复合条件下Cd^2＋在陕西5种土壤中的吸附

通过平衡吸附的方法,研究了Cd2＋在单一及与Cu2＋、Zn2＋复合条件下,在陕西塿土、黄绵土、黑垆土、黄褐土、砂土5种土壤中的吸附特征,并通过多重相关分析探讨了其吸附机制。结果表明,在20、30℃条件下,Cd2＋在各供试土样中吸附等温线总体上呈H或L型等温线形式,黑垆土对Cd2＋总是吸附最强,而砂土的吸附总是最弱;Cd2＋吸附的温度效应呈现升温负效应特征,塿土土样中,Cu2＋的共存对其温度效应影响较大,而在其他4种土样中Zn2＋的共存具有较大影响;Cu2＋、Zn2＋的共存均降低了Cd2＋的吸附量,具有显著的拮抗作用;Freundlich模型是描述Cd2＋吸附等温线最佳模型。相关分析结果表明,Cd2＋在土壤中的吸附主要以电性引力吸附为主,Cu2＋的共存主要和其与土壤有机质之间的络和吸附等化学吸附作用有关,因此其对Cd2＋以化学竞争性吸附的影响相对较弱,而Zn2＋共存吸附与Cd2＋吸附机制类似,因此表现出Zn2＋共存对Cd2＋吸附影响较大的特点。     

腐殖酸对农田土壤磷素吸附行为的影响研究

土壤有机腐殖酸类物质具有巨大的比表面积和表面活化基团,在土壤污染物和养分的吸附、利用和转化过程中起着重要作用。该研究选取5种中国典型农区土壤,采用增加和减少有机腐殖酸类物质含量的方法,设置不同含量梯度,利用振荡平衡法来定量研究不同腐殖酸含量对磷素吸附特性的影响,并对其利用Freundlich、Langumuir和Temkin方程来进行定量化拟合分析研究,试图定量探讨有机腐殖酸类物质对磷素吸附行为的影响。研究结果表明:Freundlich、Langumuir和Temkin这3种方程均可对磷素吸附特征进行拟合,但拟合相关性以Freundlich最好,对于不同土壤而言,对磷素吸附拟合方程的适应性,以Freundlich方程对黑土和红土最好,塿土和黑垆土次之,潮土最差。加入腐殖酸明显地减少土壤对磷素的吸附量和吸附速率。腐殖酸对于土壤磷素有一定的活化激发作用,无论是增加还是减少腐殖酸时,黑土和红土对磷素的最大吸附量变化比例不是很大,而塿土和黑垆土变化最大,可以减少50%～60%左右,而潮土次之。腐殖酸可作为土壤P素增效剂,改善肥料物理性状,提高其稳定性和有效性,尤其是在黄土高原石灰性土更为有效。     

Langmuir,Temkin和Freundlich方程应用于土壤吸附锌的比较

本文分别用Langmuir,Temkin和Freundlich方程拟合土壤吸附锌的等温线。结果表明,吸附数据能很好地符合Freunblich方程,而Langmuir和Temkin方程拟合程度较差。作者从吸附热角度证明了土壤表面不均匀性是造成这种差别的最主要因子。土壤吸附锌过程中吸附热与吸附量的关系满足Freundlich方程模型中关于能量的假设。所以Freundlich方程能比较真实地反映土壤吸附锌的本质,可用予锌吸附机制的探讨。     

干旱区绿洲灌漠土对铜的吸附解吸特性研究

土壤对重金属的吸附解吸是影响土壤系统中重金属的移动性和归宿的主要过程.本文使用序批实验方法、单步提取方法、连续提取方法等研究了干旱区绿洲灌漠土Cu的吸附解吸特性.结果表明,灌漠土对Cu的吸附等温线可很好地用Freundlich等温方程拟合,灌漠土的Cu吸附可能受土壤理化综合因素影响,而不仅是某个土壤理化指标所控制;二次...     

金霉素在不同耕作土壤中的吸附－解吸行为

用批平衡吸附试验研究了金霉素在河南封丘潮土、南京黄棕壤、常熟水稻土和江西鹰潭红壤4种土壤中的吸附行为。结果表明,金霉素的土壤吸附-解吸行为均可用Freundlich模型和Langmuir模型进行良好的线性拟合。其Kf值差异较大,分别为潮土1135Lkg-1,黄棕壤1250Lkg-1,水稻土2618Lkg-1和红壤4315Lkg-1,显示金霉素在4种土壤中的吸附行为存在较大的差异。此外,金霉素在4种土壤上的解吸过程存在明显的滞后现象。研究还表明4种土壤中金霉素的吸附参数Kf值与土壤pH呈显著负相关。     

阿特拉津对绿麦隆吸附-解吸作用的影响

采用批平衡实验,研究绿麦隆在单一及复合污染体系中的吸附-解吸行为。结果表明,无论是单一体系还是复合体系,吸附等温线均可用Freundlich模型进行良好的拟合。随着阿特拉津浓度的增加,土壤对绿麦隆的吸附作用降低,表明绿麦隆和阿特拉津之间存在竞争吸附,这可能与土壤的有机质类型和绿麦隆、阿特拉津的性质、结构有关。解吸实验表明,随着阿特拉津的浓度增加,绿麦隆的解吸作用增加。吸附过程的拟合指数n值大于解吸过程的对应值,即绿麦隆在不同体系中的解吸作用均存在一定的滞后性。应用Freundlich解吸等温线参数对吸附-解吸等温线的滞后作用进行量化,CT、（CT＋0.5AT）、（CT＋1AT）和（CT＋2AT）处理解吸等温线的滞后系数ω分别为165.200,146.132,94.534和85.945,即随阿特拉津浓度增加,绿麦隆解吸等温线的滞后性降低。     

Adsorption and Desorption of Boron as Influenced by Soil Properties in Temperate Soils of Lesser Himalayas

Boron (B) adsorption increased with increasing concentration. Langmuir adsorption isotherm was curvilinear. The maximum value of adsorption maxima (b1) was observed Sagipora soil and maximum bonding energy (k) constant was in Anantnag soil. The Langmuir isotherm best explains the adsorption trend at low adsorbent concentrations. A significant correlation among b1, clay, and cation exchange capacity was observed. Linear affiliation was observed in all the soils at all concentration, indicating that B adsorption data conform to the Freundlich equation. Soils with greater affinity for B adsorption, like Sagipora, tended to desorb less B. Boron desorption was positively and significantly correlated with sand content and negatively with clay content and cation exchange capacity. The maximum value of 50.76 mg g^?1 for desorption maxima (Dm) was observed in Sagipora soil, and mobility constant (Kd) was maximum in Khag soil (0.412 ml kg^?1).     

Zinc Adsorption by Mineral Soils of Finland

Abstract

Zinc adsorption by 10 (pH 4.0–6.5) cultivated mineral soils from Finland was studied in batch experiments. Additions of Zn ranged up to 600 mg kg^?1 of soil and the corresponding equilibrium concentrations were 0.1–13 mg 1^?1. In each soil, Zn adsorption conformed to the Freundlich isotherm. Despite a relatively low initial Zn adsorption by the acidic soils, each of the soils proved to have a high potential to adsorb Zn, but the capacity was highly pH dependent. In addition to the conventional Freundlich adsorption isotherms, calculated separately for each soil, extended Freundlich-type isotherms that also incorporate soil pH and other soil characteristics were used to describe Zn adsorption of several soils simultaneously in one equation. The pH-dependent Freundlich adsorption isotherm proved to serve as a practical tool to assess Zn adsorption by soils varying in pH and other characteristics.     

有机修饰塿土对苯胺的吸附

以十六烷基三甲基溴化铵(CTMAB)单一修饰和CTMAB+十二烷基磺酸钠(SDS)混合修饰塿土耕层和粘化层土样,从吸附实验和热力学角度研究修饰土样对苯胺的吸附特征和机理。结果表明,供试土样对苯胺吸附均呈现100CB>50CB>120CS>CK的高低顺序,耕层修饰后对苯胺的平衡吸附量增大了4.5￣8.57倍,粘化层土样增大了6.0￣18.33倍;温度为40℃时耕层未修饰土样对苯胺的吸附量高于粘化层未修饰土样,20℃时则低于粘化层原土土样,而修饰土样则均呈现粘化层修饰土样对苯胺的吸附高于塿土耕层修饰土样的结果;耕层土样随温度升高苯胺平衡吸附量升高,而粘化层土样则表现出降温有利于苯胺吸附的现象,修饰剂对土样的修饰对苯胺的吸附具有"感温钝化"效应;Henry模型适用于描述苯胺的吸附;修饰土样对苯胺的吸附自由能变均为ΔG<0,属于自发反应,粘化层各土样对苯胺吸附为放热熵减过程,吸附自发性由焓减控制,耕层各土样对苯胺吸附为吸热熵增过程,其吸附自发过程为熵增控制过程;疏水吸附是修饰土样对苯胺吸附的主要机理,但修饰剂对于土壤表面的修饰是不均匀修饰,粘化层土样以物理吸附机制为主,耕层土样则存在化学吸附的机制。     

有机修饰改性土对镉离子的吸附及温度效应

主要研究了以不同比例十六烷基三甲基溴化铵(CTMAB)单一修饰和十六烷基三甲基溴化铵 十二烷基磺酸钠(CTMAB SDS)混合修饰的土耕层、黏化层土样对重金属镉离子的吸附。结果表明:吸附量顺序分别为耕层原土(GCK) >CTMAB5 0 %修饰改性土(5 0GCB) >CTMAB10 0 % SDS2 0 %修饰改性土(12 0GCS) >CTMAB10 0 %修饰改性土(10 0GCB)和粘化层原土(NCK) >CTMAB5 0 %修饰改性土(5 0NCB) >CTMAB10 0 %修饰改性土(10 0NCB) >CTMAB10 0 % SDS2 0 %修饰改性土(12 0NCS)的顺序,表明以表面修饰剂修饰土表面,确实存在着使得镉离子吸附能力减弱的趋势,但并未使修饰改性土完全丧失对于镉离子的吸附能力;吸附等温线可以用Langmuir方程描述;热力学参数的研究表明Cd2 吸附反应是熵增控制的自发性过程,但在探讨吸附自发性和最大吸附量关系时应考虑土壤本身的容量性质。机理研究认为,表面修饰剂对土壤表面的修饰改性是不均匀的,阳离子交换吸附和疏水键键合两种机制的竞争性吸附是修饰改性土壤依然具有对镉离子吸附作用的原因。土耕层各改性土样对Cd2 吸附的温度效应明显高于粘化层土样,证实了耕层对镉离子的化学吸附作用强于粘化层的结果     

咪鲜胺及其三种主要代谢物在六种水稻土中的吸附

用批量平衡法研究了咪鲜胺及其三种主要代谢物BTS44595、BTS44596和BTS45186在六种水稻土中的吸附。结果表明：水稻土以物理吸附作用来吸附咪鲜胺及其代谢物，吸附平衡时间为7—14h，吸附过程可用Freundlich吸附等温式描述。水稻土对咪鲜胺吸附能力均比其代谢物要强，三种代谢物之间的吸附量差异性不是很大。咪鲜胺在水稻土中的吸附与土壤有机质含量、阳离子交换量和粘粒含量成显著正相关，而BTS44595、BTS44596和BTS45186在水稻土中的吸附主要受土壤pH值的控制。这说明咪鲜胺在降解代谢后改变了它在土壤中的吸附行为与吸附机理，对此应予以足够的关注。     

Molybdenum Determination in Mehlich‐1 and Mehlich‐3 Soil Test Extracts and Molybdenum Adsorption in Brazilian Soils

Abstract

The extractant Mehlich‐1 is routinely used in Brazil for determination of soil nutrients, whereas Mehlich‐3 has been suggested as a promising extractor for soil fertility evaluation. Both were used for extraction of molybdenum (Mo) in Brazilian soils with Mo dosage by the KI+H₂O₂ method. The Langmuir and Freundlich isotherms were used to study soil Mo adsorption. Mehlich‐1 extracted more Mo than Mehlich‐3 in soils with high contents of organic matter, clay, and iron (Fe) oxides. Mehlich‐3 and Mehlich‐1 extractions correlated positively and significantly with amorphous Fe oxides, crystalline Fe oxides, and organic matter. Molybdenum recovering rates correlated to crystalline Fe oxides and clay contents but not to organic matter, pH, and Mo adsorption capacity. Amorphous and crystalline Fe oxides, clay, and organic matter were responsible for most of the Mo adsorption. The Langmuir isotherm described better the Mo adsorption to soil amorphous Fe oxides and organic matter than the Freundlich isotherm.     

Effect of Soil Properties on Boron Adsorption and Release in Arid and Semi-Arid Benchmark Soils

The adsorption isotherms indicated that the adsorption of boron (B) increased with its increasing concentration in the equilibrium solution. The Langmuir adsorption isotherm was curvilinear and it was significant when the curves were resolved into two linear parts. The maximum value of adsorption maxima (b1) was observed to be 7.968 mg B kg^?1 in Garhi baghi soil and the bonding energy (k) constant was maximum at 0.509 L mg^?1 in Jodhpur ramana soil. The Langmuir isotherm best explains the adsorption phenomenon at low concentrations of the adsorbent, which of course was different for different soils. There was significant correlation between b1 and clay (r = 0.905**), organic matter contents (r = 0.734*), and cation exchange capacity (CEC; r = 0.995**) of soils. A linear relationship was observed in all the soils at all concentration ranges between 0 and 100 mg B L^?1, indicating that boron adsorption data conform to the Freundlich equation. Soils that have a higher affinity for boron adsorption, like Garhi baghi, tended to desorb less amount of boron, that is, 43.54%, whereas Ballowal saunkhari desorbed 48.00%, Jodhpur ramana 48.42%, and Naura soil 58.88% of the adsorbed boron. Boron desorption by these soils is positively and significantly correlated with the sand content (r = 0.714**) and negatively with clay content (r = ?0.502*) and CEC (r = ?0.623**). The maximum value of 37.59 mg kg^?1 for desorption maxima (Dm) was observed in Garhi baghi soil and also a constant related to B mobility (Kd) was found to be maximum in Garhi baghi (0.222 L kg^?1) soil Note: *P<0.05; ^**P<0.01.     

Adsorption of Cadmium by Indian Soils

Adsorption behaviour of cadmium (Cd) in soils is an important process which exerts a major influence on its uptake by plant roots. Thirteen soils from various parts of India (tropical region), their pH ranging from 4.2 to 8.4, were subjected to Cd treatment at various concentrations (1 to 100 μg ml-1) and equilibrated at room temperature (25 ± 1 °C). The Cd adsorbed by each soil was calculated as the difference between the amount of Cd present in the solution initially and that remaining after equilibration. Results indicated that the adsorption capacity of the soils for Cd increased with an increase in the pH or alkalinity of the soils. The rate of adsorption was, however, found to decrease with increased pH. All the 13 soils used in this study followed linear and Freundlich adsorption isotherms with highly significant positive correlations (r). The neutral and alkaline soils also followed the Langmuir adsorption isotherm, the adsorption maxima being lowest for the neutral soil and highest for the alkaline soil. The adsorption data, in general, indicated that Cd was in a fixed form at higher pH levels. The results are generally similar to those of the temperate regions; however, Cd adsorption capacity of tropical vertisols was comparatively higher than those of temperate vertisols.