土壤对氟离子吸附与解吸的动态土柱法研究

用饱水动态土柱法对氟离子的吸附与解吸特征及其反应动力学特征进行了初步探讨。结果表明，氟离子的吸附与解吸特征可分别用Ｌａｎｇｍｉｕｒ模型和Ｆｒｅｎｄｌｉｃｈ模型来表征，而氟的吸附与解吸反应动力学均可用Ｅｌｏｖｉｃｈ方程来述。吸附与解吸过程是一个由反应速率控制的不可逆过程。     

铅在高岭石表面的解吸动力学

经过酸性条件下（pH=3.1)Pb(Ⅱ）高岭石表面解吸动力学的研究，发现解吸反应与吸附反应动力学相似，也是一个二阶段的过程，即初始的快速解吸之后伴随着一个缓慢的释放过程。在快速解吸阶段，7min内解吸量即已达到41％。吸附铅没有完全解吸，有近38％残留在高岭石表面，即解吸和吸附过程不是完全可逆的。解吸过程可以用扩展Elovich方程、Elovich方程、双常数方程和一级扩散方程较好地似合。     

煤基质中甲烷扩散动力学特性研究

甲烷在煤基质中的质量传递过程可用费克第一定律或费克第二定律来模拟。本文通过等温吸附-解吸实验的动力学数据,以费克第二定律为理论基础,对煤基质球形单元模型建立了试验求取扩散特性的方法。晋城煤样等温吸附及解吸实验的数据处理结果表明,吸附-解吸速率均随压力及煤样气含量的增加而增加;吸附速率与解吸速率随压力的变化曲线基本相同。      

方解石负载羟基磷灰石复合材料去除水中铀离子的PRB活性介质研究

铀污染地下水分布于世界多国,其危害备受关注。本文基于溶胶-凝胶法制备方解石负载羟基磷灰石复合材料(CLHC),通过静态与动态对比试验,探讨了PRB活性介质对水中铀离子的吸附机理和去除效果。试验结果表明,制备的CLHC表面被羟基磷灰石覆盖,对铀离子具有较强的吸附能力。当U的初浓度为5.0 mg/L、试验周期为2 h、溶液pH值为4、CLHC用量为0.5 g/L时,CLHC可以吸附水中所有的铀离子。CLHC对铀离子的吸附过程可以用Langmuir等温吸附模型、粒子内扩散吸附动力学模型和准二级吸附动力学模型较好地进行描述。石英砂负载羟基磷灰石与CLHC相比,后者具有更强的吸附能力,而且具有更长的使用寿命。CLHC在吸附铀的过程中没有价态变化,其对铀离子的吸附主要为离子交换的化学吸附。本研究的成果可为可渗透反应墙被应用于铀污染地下水修复提供试验依据。     

铁（氢）氧化物悬液中磷酸盐的吸附-解吸特性研究

铁（氢）氧化物对P的吸持和释放在一定程度上决定着P的生物有效性和水体富营养化。以两种环境中常见晶质铁氧化物（针铁矿和赤铁矿）为对照,采用X射线衍射（XRD）、透射电镜（TEM）、热重分析（TGA）和孔径分析以及动力学和吸附-解吸热力学平衡等技术方法,研究了弱晶质水铁矿对P吸附-解吸特性,并探讨了相关机制。实验表明,三种矿物对P的吸附分为起始的快速反应和随后的慢速反应,它们均符合准一级动力学过程,反应中OH释放明显滞后于P吸附,P吸附经历了从外围到内囤配位、单齿到多齿配位过渡的过程,与晶质氧化铁比,水铁矿吸附容量和OH释放量更大、慢速吸附反应更快、存在缓慢扩散反应阶段,吸附容量依次是：水铁矿（436μmol／m^2）〉针铁矿（262μmol／m^2）〉赤铁矿（228μmol／m^2）,针铁矿和赤铁矿吸附P符合L（Langmuir）模型,而水铁矿更符合F（Fremldlictl）模型。中性盐介质（KCl）中在最大吸附量时P的解吸率依次为：水铁矿（85％）〈针铁矿（10％）〈赤铁矿（125％）,柠檬酸通过配体解吸和诱导溶解两种机制促进P的解吸,最大吸附量时解吸率依次是：针铁矿（25％）〈水铁矿（32％）〈赤铁矿（50％）。     

天然黄铁矿对阳离子有机染料RhB吸附特性研究

以黄铁矿作为吸附剂研究罗丹明B(Rhodamine B,RhB)的吸附特性,用X射线衍射仪(XRD)、扫描电子显微镜(SEM)对黄铁矿进行了表征。考察了接触时间、溶液pH值、离子强度、温度等对黄铁矿吸附RhB的影响。结果表明,在吸附平衡时间120 min、pH值4.0时,吸附量达到最大值21.3 mg/g。升高温度,黄铁矿对RhB的吸附量逐渐增大。而离子强度对吸附几乎没有影响。实验数据与Langmuir吸附模型拟合良好,整个吸附动力学模型符合准二级吸附动力学模型。热力学研究证实了该吸附过程是自发进行的。通过对吸附反应结束后的黄铁矿进行煅烧处理,去除表面吸附的RhB,结果表明煅烧一次的黄铁矿仍然可以吸附废水中约50%的RhB,具有重复利用的价值。     

碳羟磷灰石吸附水溶液中镉离子的动力学研究

碳羟基磷灰石(CHap)对水溶液中镉离子的吸附过程是一个复杂的非均相固液反应过程，从动力学角度来看，大致可分为两个阶段：初期阶段反应速度快，动力学过程复杂；后期阶段反应速度较慢，并符合一级反应动力学方程。实验表明：反应速率常数k1与温度T之间的关系符合阿累尼乌斯公式，吸附的活化能为Ea=6．075J／mol，吸附的频率因子A=220s^-1。同时，k1与镉离子初始浓度呈负相关性，与介质pH值、CHap用量呈正相关性．     

氟铝交互作用对茶园土壤氟吸附动力学特征的影响

在氟的不同初始浓度及不同水土比情况下,茶园土壤对氟的吸附平衡时间均在25min左右,但对动力学方程拟合效果有一定差异,除了初始浓度为4.0mg/L(水土比10∶1)、20.0mg/L(水土比40∶1)、100.0mg/L(水土比40∶1和20∶1)处理氟的吸附动力学不能用一级动力学方程或二级动力学方程描述外,其余处理均可以用双常数方程、Elovich方程、一级动力学方程、二级动力学方程和抛物线方程这5个动力学方程描述。在铝存在下,不同氟铝比对氟的吸附动力学过程有明显影响,表现为吸附速率下降,吸附平衡时间延长,50min左右达吸附平衡。动力学方程拟合效果虽然有一定差异,但均可以用这5个动力学方程描述。在有无铝存在下,茶园土壤氟的吸附动力学特征用双常数方程和Elovich方程描述的效果更好。     

江汉平原旱地和水田土壤镉的吸附与解吸特征及影响因素

为揭示旱地和水田土壤镉的吸附解吸特征,以江汉平原黄豆地、棉花地以及水稻田土壤为研究对象,开展土壤镉的吸附动力学实验、等温吸附?解吸实验以及有机质的影响实验.结果表明:江汉平原土壤对镉的吸附是一个较为复杂的吸附动力学过程且以化学吸附为主,研究区土壤镉的初始吸附速率总体上表现为水田土壤大于旱地土壤;旱地土壤对Cd2+具有较...     

粉煤灰-粉质粘土对氟离子的吸附作用

不同土层对氟离子的吸附能力不同,在吸附能力较弱的土层建设贮灰场,会导致周边地下水中氟离子质量浓度较高,污染地下水。吉林市来发屯灰场运行多年来,地下水中氟离子质量浓度与背景环境未见明显差异,本文通过对来发屯灰场粉煤灰-粉质粘土和灰场外土层的比较分析,探究吸附机理,结果表明：粉煤灰-粉质粘土对氟离子有较强的吸附能力,能有效防止其对地下水的污染。     

Geochemical process of fluorine in soil

Fluorine is in the dynamic balance of two geochemical processes, enrichment and leaching, reflecting the adsorption and desorption of fluoride by clay minerals, respectively. The two geochemical processes of fluorine in soil are influenced by factors including geochemical characteristics of soil and clay minerals, pH and sanity of soil solutions, climate, grazing and agriculture activities. Main factors controlling enrichment and leaching process of fluorine in soil can be found with interaction consideration.     

高氟土壤的氟动力学吸附试验研究

通过室内水土试验,研究山东高密高氟地区的土壤对氟的动力学吸附特性,并用典型的低氟土试验进行对比。从化学动力学的角度讨论高氟土壤对氟的吸附行为。高氟土壤对氟的吸附有其特殊性;高氟土壤对氟的吸附分为快、慢两个阶段;羟基是影响氟吸附的重要因素。     

Adsorption of oxyanions by spent western oil shale: II. selenite

The adsorption and desorption behavior of selenite by processed Green River Formation oil shales were examined. The selenite adsorption data could be quantitatively described by both the Freundlich and Langmuir isotherms. However, greaterR ² values were obtained for the Freundlich isotherms. Furthermore, selenite adsorption was not a function of the extraction process. The adsorption of selenite by the processed oil shales was irreversible. Upon dilution of the equilibrium systems, additional selenite removal from solution occurred. A thermochemical analysis of the adsorption and desorption equilibrium solutions indicated that the solutions were undersaturated with respect to a number of metal selenite solids. This indicates that precipitation processes are not influencing selenite behavior. However, not all selenite minerals were examined in the evaluation because of the lack of thermochemical data. An insufficient equilibration period for the adsorption study or the alteration of processed oil shale solids as a result of hydration reactions may also have hastened the additional removal of selenite during the desorption studies.     

Adsorption of roxarsone by iron (hydr)oxide-modified multiwalled carbon nanotubes from aqueous solution and its mechanisms

The adsorption of roxarsone by iron (hydr)oxide-modified multiwalled carbon nanotubes (MWCNTs) from aqueous solution and its mechanism were investigated. The amount of roxarsone adsorbed by modified MWCNTs is higher than MWCNTs at the same condition. The results show that the sorption isotherms are nonlinear, and can be well fitted according to the Freundlich and Polanyi–Manes models. The adsorption kinetics could be well described by pseudo-second-order model. Thermodynamic analysis shows that the adsorption of roxarsone on the adsorbents is an exothermic and spontaneous process. Desorption process had no obvious desorption hysteresis phenomenon. The FT-IR and XPS analysis confirmed the loading of iron ions on the MWCNTs, and revealed the involvement of carboxyl groups and iron ions on the adsorption of roxarsone.     

苏州城市河道底泥对磷酸盐的吸附与释放特征

为了探讨苏州古城区河道底泥对磷酸盐的吸附-释放特征,文中分别从改变上覆水的pH值、底泥吸附-释放动力学和等温吸附实验三个方面进行了研究。结果表明:(1)随着上覆水pH值的增大,苏州河道底泥对磷的吸附量逐渐减小;(2)底泥对磷的吸附过程是一个复合动力学过程,通常包括快吸附和慢吸附两个过程。底泥对磷的快速吸附在2h内快速进行,之后为慢吸附过程,到6h左右,基本达到一种动态吸附平衡;底泥对磷释放的动力学过程也包括快释放和慢释放过程。底泥释放磷在1·5h内快速进行,之后进入慢释放过程,磷酸盐含量基本稳定,达到释放平衡;(3)底泥具有较大的吸附磷的能力。随着上覆水的磷酸盐浓度增高,底泥吸附磷酸盐的量也增加。上覆水与底泥的比值越大,底泥对磷的吸附率越小。     

An Experimental Study on the Conductivity Changes in Coal during Methane Adsorption-Desorption and their Influencing Factors

During the processes of methane adsorption and desorption, the internal structure of coal changes, accordingly leading to changes in electrical conductivity. In this paper, using low rank coal seams of the Yan’an Formation in the Dafosi field as the research subject, the relationship between coal resistivity, methane adsorption quantity, and equilibrium pressure is analyzed through proximate analysis, mercury injection tests, low temperature liquid nitrogen adsorption tests, and coal resistivity measurements during methane adsorption and desorption. The results show that during the process of pressure rise and methane adsorption, the conductivity of coal increases, resulting from heat release from methane adsorption, coal matrix swelling and adsorbed water molecules replaced by methane, but the resistivity reduction gradually decreases. The relationship between coal resistivity and methane adsorption quantity and equilibrium pressure can be described by a quadratic function. During the processes of depressurization and desorption, the resistivity of coal rebounds slightly, due to decalescence of methane desorption, coal matrix shrinkage and water-gas displacement, and the relationship coincides with a linear function. Methane adsorption leads to irreversible changes in coal internal structure and enhances the coal conductivity, and resistivity cannot be restored to the initial level even after methane desorption. The resistivity and reduction rate of durain are higher than those of vitrain, with relatively greater homogeneous pore throat structure and fewer charged particles in the double electric layer. In addition, moisture can enhance the conductivity of coal and makes it change more complexly during methane adsorption and desorption.     

污灌土壤对铅的吸附和解吸特性

为了解污灌土壤对铅的吸附-解吸机制,进行不同条件下的吸附-解吸试验。结果表明：污灌土壤对铅的吸附量随铅初始浓度的增大,呈现先强烈吸附再缓和的过程。Langmuir模式对污灌土壤等温吸附铅的拟合效果最好,其饱和吸附量为7.84 mg/g。亚砷酸盐的存在会阻碍污灌土壤对Pb²⁺的吸附,亚砷酸盐加入前后污灌土壤对铅的吸附率从99.9％～100％下降到97.8％～99.0％。加亚砷酸盐条件下污灌土壤对铅的等温吸附模式以Freundlich模式的拟合效果最好。污灌土壤对吸附态铅的解吸量随解吸振荡时间的延长而不断增加,且解吸率随时间增加总体趋于降低。Elovich方程和幂函数方程均能很好地拟合污灌土壤对铅的解吸动力学过程,尤其是Elovich方程的拟合效果最为显著。     

Adsorption and desorption characteristics of ammonium in eight loams irrigated with reclaimed wastewater from intensive hogpen

There are many reports of NO₃ ^? violating safety standards in the neighboring areas of concentrated animal feeding operations (CAFOs), which have become the bottleneck of the CAFOs development. The high concentration of ammonium nitrogen (NH₄ ⁺-N), which transforms into nitrate nitrogen (NO₃ ^?-N) through nitrification, and then leaches into the groundwater, is a potential threat to the environment. Adsorption and desorption characteristics of ammonium can reduce the amount of NH₄ ⁺-N in soils, which effectively prevents or slows down the nitrate leaching. Researches on the adsorption and desorption of ammonium mainly focus on the simple NH₄ ⁺ solution. Researches on the adsorption and desorption from hogpen wastewater are few, which is a complex system coexisting with many ions. In this paper, ammonium was selected as the object of pollutant, a batch of equilibration experiments was conducted to evaluate the adsorption–desorption and its kinetics in eight loams, typically found in Northern China, irrigated with original wastewater (OW) and reclaimed wastewater (RW) from intensive hogpen and a simple one consisting of clean water (CW). This study showed that the Freundlich and Langmuir model described the ammonium adsorption properties very well in multi-ion coexistensive system of hogpen wastewater; the ammonium adsorbed amount in the corresponding matrices followed by OW < RW < CW tendency, although the adsorption model parameters had great diversity. The adsorbed amount increased as the adsorption time went on and then approached to a stable state. CW had the shortest reaction time to reach equilibrium, whereas OW had the longest. The normal adsorption kinetics equation could not depict the adsorption behavior of loams but characterized by the ExpAssoc equation well. The study could provide references for the wastewater treatment and recycling, and rural water pollution controlling.     

石油类污染物在土壤中的吸附/解吸机理研究及展望

石油类污染物在土壤中的吸附与解吸研究是目前土壤学及环境科学研究的重要领域,石油类污染物在土壤中的吸附/解吸影响因素、机理及研究方法已有大量研究,但由于吸附/解吸传统研究方法受各种参数的限制,对影响因素、吸附模式、机理的研究难以进一步深入,多种影响因素之间的相互作用也是一个重要的研究方向;石油类污染物的吸附模式随着吸附方式的不同而适用于不同土壤的吸附,而用SPE技术可以从分子水平来认识吸附/解吸的本质。同时本文提出了石油类污染物在土壤中吸附/解吸机理研究中存在的问题,并展望未来的发展趋势。     

Adsorption kinetic control of As(III &; V) mobilization and sequestration by Mangrove sediment

Elevated concentrations of arsenic in the sediment and pore water in the Sundarban wetlands pose an environmental risk. Adsorption and desorption are hypothesized to be the major processes controlling arsenic retention in surface sediment under oxic/suboxic condition. This study aims to investigate sorption kinetics of As(III & V) and its feedback to arsenic mobilization in the mangrove sediment. It ranges from sand to silty clay loam and shows the adsorption of As(III & V) following the Langmuir relation. Estimates of the maximum adsorption capacity are 59.11 ± 13.26 μg g⁻¹ for As(III) and 58.45 ± 8.75 μg g⁻¹ at 30°C for As(V) in the pH range 4 to 8 and salinity 15–30 psu. Extent of adsorption decreases with increasing pH from 4 to 8 and desorption is the rate-limiting step in the reaction of arsenic with sediment. Arsenic in the sediment could be from a Himalayan supply and co-deposited organic matter drives its release from the sediment. Arsenic concentration in the sediment is well below its maximum absorption capacity, suggesting the release of sorbed arsenic in pore water by the microbial oxidation of organic matter in the sediment with less feedback of adsorption.