镉在黑土和棕壤中吸附行为比较研究

比较研究了重金属镉在黑土和棕壤中的吸附热力学和动力学行为.结果表明,在实验设定的浓度范围内,黑土和棕壤对Cd²⁺吸附量随溶液中Cd²⁺浓度的增加而增加.黑土对Cd²⁺的吸附固定能力明显强于棕壤.在平衡液浓度为20 mg·kg^-1时,黑土对Cd²⁺的吸附量为1 485.2 mg·kg^-1、棕壤为700.6 mg·kg^-1.两种土壤对Cd²⁺的吸附等温线与Langmuir、Freundlich和Henry方程均有较好的拟合性,而Temkin方程不适合用来描述Cd²⁺在两种土壤中的等温吸附.根据Langmuir的拟合结果,Cd²⁺在黑土和棕壤中的最大吸附量分别可达5 939.3和2 790 mg·kg^-1.黑土较高的吸附能力与其高的有机质含量和粘粒含量有关.黑土和棕壤中Cd²⁺的吸附是一个快速反应过程,2 min内能达到平衡吸附量的90%,15～30 min左右达到吸附平衡.一级动力学方程是拟合Cd²⁺在黑土和棕壤中吸附动力学过程的最优方程,其次为Elovich方程和双常数方程.随着初始浓度的增加,Cd²⁺在土壤中的吸附速率也不断增大.随着吸附量的增大和反应时间的延长,吸附速率不断下降.在较低的初始浓度下,Cd²⁺在黑土中的下降趋势要快于棕壤.     

不同污染负荷土壤中镉和铅的吸附－解吸行为

采用一次平衡法,对3种不同污染负荷土壤Cd2 和Pb2 的吸附-解吸行为进行了比较.结果表明,低污染负荷土壤对Cd2 和Pb2 的吸附能力高于高污染负荷土壤.3种土壤对Cd2 的吸附等温线与Freundlich方程有较好的拟合性,Pb2 的等温吸附过程可用Langmuir方程与Freundlich方程来描述.双常数方程是描述这3种不同污染负荷土壤中Cd2 和Pb2 吸附动力学行为的最优模型,其次为Elovich方程,最差模型是一级动力学方程.Pb2 的解吸滞后现象较Cd2 明显.高污染负荷土壤的吸附态Cd2 、Pb2 解吸率高于低污染负荷土壤,Cd2 、Pb2 解吸量与其初始吸附量之间的关系符合二次幂方程.3种土壤Cd2 、Pb2 的解吸速率随重金属初始浓度的增加而增加,随解吸时间的延长而降低.     

三江平原典型湿地及其开垦后土壤中总硫变化的初步研究

以三江平原3种主要沼泽类型--小叶章(Calamagrostis angustifolia)沼泽、乌拉苔草(Carex meyeriana)沼泽、毛果苔草(Carex lasiocarpa)沼泽以及不同开垦年限的耕地为研究对象,对其土壤中总硫含量进行分析,3种沼泽中总硫量的顺序为小叶章沼泽(622．4mg·kg^-1)<乌拉苔草沼泽(820．5mg·kg^-1)、毛果苔草沼泽(1022．4mg·kg^-1),挠力河、鸭绿河、别拉洪河及浓江流域土壤中总硫量的顺序为挠力河(925．0mg·kg^-1)>鸭绿河(841．8mg·kg^-1)>浓江(636．5mg·kg^-1)>别拉洪河(520．8mg·kg^-1)沼泽湿地及耕地土壤总硫量在层次上具有明显的规律性,即由表土层向下,含量逐渐降低,1980～2000年开垦的耕地土壤中总硫含量平均值为180．5mg·kg^-1,而未开垦湿地中的总硫含量平均值为735．8mg·kg^-1。耕地中的总硫量显著低于湿地中的总硫量,并且开垦年限越长,土壤中的总硫量越低,表明湿地开垦导致土壤总硫明显流失。     

碳酸钙对土壤镉吸附及解吸的影响

采用等温吸附法,并以1mol/L KNO3进行解吸试验,研究CaCO3对3种土壤镉吸附和解吸的影响。结果表明,3种土壤的原状土样对镉吸附总趋势为：栗钙土＞棕壤＞淋溶褐土,均符合Langmuir方程、Frenudlich方程和Temink方程,其中以Freumdlich方程最佳。镉的专性吸附量表现为栗钙土＞淋溶褐土＞棕壤。添加CaCO3使3种土壤中镉的吸附量增加,增加幅度棕壤为4％－11％,淋溶褐土2％－11％,栗钙土2％－8％。外界加入的镉浓度越高,增加幅度越大。Freundlich方程（lgX=lgK lgC/n）拟合的参数结果表明：加入CaCO3后,K和n值均下降;Langmuir方程中镉最大吸附值增加,吸附平均常数减小。可以推测,CaCO3的存在之所以能够使土壤体系吸附镉能力增加,除CaCO3本身的吸附作用增加,吸附平衡常数减小。可以推测,CaCO3的存在之所以能够使土壤体系吸附镉能力增加,除CaCO3本身的吸附作用外,还可能影响反应体系的平衡系数。加入CaCO3,土壤对镉的专性吸附明显增加,尤其以棕壤专性吸附的镉最多,淋溶褐土其次,而栗钙土增加较少,栗钙土去除CaCO3后,镉的吸附减少了2.0%-26.0%,土壤专性吸附的镉减少4.0%-38.2%。3种土壤镉的解吸能力表现为：棕壤＞淋溶褐土＞栗钙土。添加CaCO3,土壤镉的解吸量下降。去除CaCO3后,栗钙土匐解吸量明显增加。     

氧化还原条件对湿地土壤磷吸附与解吸特性的影响

采用室内模拟试验研究了氧化还原条件对盘锦天然湿地土壤磷吸附与解吸特性的影响,并对磷的吸附与解吸过程进行拟合。结果表明,氧化或还原条件下Langmuir模型和Freundlich模型均能较好地拟合磷的等温吸附曲线,且Langmuir方程的拟合效果好于Freundlich方程。淹水还原条件下,湿地土壤对磷的最大吸附量和解吸率比淹水前分别降低了9.5%和16.3%;吸附解吸平衡浓度升高,平均增加158.8%。淹水后土壤活性铁含量明显升高,淹水前后活性铁变化与吸附解吸平衡浓度变化之间的相关性达到了显著水平,与土壤中磷的最大吸附量和解吸率变化的相关性不显著,表明活性铁含量的变化是淹水还原条件下影响土壤磷吸附解吸平衡浓度变化的主要因素。     

溶解性有机碳在红壤水稻土中的吸附及其影响因素

吸附作用是影响土壤中溶解性有机碳(DOC)迁移转化及生物有效性的重要反应过程,研究DOC在土壤中的吸附行为,对正确阐明土壤有机碳的循环和转化特征以及进行污染风险评估有重要意义.采用平衡法研究了红壤水稻土对DOC的吸附特征,并分析土壤有机质、粘粒含量及pH值与DOC吸附量之间的关系.结果表明,供试土壤对DOC的吸附等温线符合Freundlich和Linear方程.不同土壤对DOC的吸附能力有明显差异.在相同浓度下,DOC吸附量以第四纪红色粘土发育的低肥力水稻土最大,第三纪红砂岩风化物发育的低肥力水稻土次之,两种高肥力水稻土最小.土壤对DOC的吸附过程分为快、慢两个阶段,0-0.25 h内DOC的吸附速率最大,随着时间的推移,吸附速率渐小,2-4 h后基本达到吸附平衡.描述供试土壤对DOC吸附动力学过程的最优模型为一级扩散方程,其次为Elovich方程和抛物扩散方程.粘粒含量和有机质是影响土壤DOC吸附量的重要因素,随着粘粒含量的增加,有机质含量的降低,DOC的吸附量增大.     

铅离子的生物吸附动力学及吸附热力学研究

目的：研究非活性深红酵母（Rhodotorula rubra）对重金属离子Pb^2＋的生物吸附热力学和动力学特性。方法：采用恒温摇床振荡吸附的实验方法,研究Pb^2＋生物吸附的动力学和热力学,并以适当的数学模型对实验数据进行拟合;对吸附前后的酵母进行红外光谱及X射线光电子能谱分析。结果：在20℃～45℃温度范围内,吸附5min时即达到了饱和吸附量的80%以上,2h左右达到平衡;深红酵母对Pb^2＋的生物吸附过程适宜用Elovich方程来描述;由二级动力学方程计算的生物吸附活化能为21.56kJ/mol;生物吸附平衡可用Langmuir等温式、Freundlich等温式及Dubinin-Radushkevich等温式来描述,拟合相关系数均接近0.99;Langmuir方程计算所得ΔH^0为13.93kJ/mol。结论：深红酵母对Pb^2＋的生物吸附是非均相的扩散过程,由快速吸附和慢速吸附两个阶段组成,以物理吸附为主,并伴随有化学吸附。     

红螺菌对Cu2+的吸附研究

研究了4株红螺菌(R-01,R-02,R-03,R-04)对Cu^2 的生物吸附行为。结果表明,3株红螺菌(R-01,R-02,R-04)对20mg／L的Cu^2 有较高的吸附率,其中R-04达99．1％。进一步研究了R-04菌体的最佳吸附条件,在pH2、浓度为80mg／L Cu^2 、35℃、微光厌氧下吸附45min,吸附率、吸附量分别达94％,48．08mg／g。在一定的浓度范围内红螺菌对Cu^2 的吸附符合Langmuir吸附模型和Freundlich吸附模型,但符合Langmuir吸附模型的程度更优。     

黑曲霉发酵菌渣对臧红T的吸附研究

将糖化酶发酵生产过程中产生的黑曲霉菌渣作为一种复合吸附剂进行了染料吸附研究,以挖掘其吸附潜力。首先对菌渣的理化性质进行了分析,然后以臧红T为模型染料,考察了几种因素(接触时间、溶液温度、吸附剂量、初始浓度和盐离子)对吸附的影响,并将所得数据用等温吸附方程、动力学方程和热力学方程进行了模型拟和。结果表明,吸附可在2 h内达到平衡,吸附过程符合准二级动力学模型,属于化学吸附,膜扩散模型比内扩散模型更适合解释吸附行为;温度对吸附有促进作用,吸附过程是一个自发的吸热反应;通过Langmuir方程可计算出最大单分子层吸附容量为166.67 mg/g,但Freundlich能更好的描述吸附行为,说明菌渣表面存在多个不同的吸附位点。此外,菌渣投加量和钠离子浓度均可影响吸附效果,染料去除率最高可达91%。     

磷对土壤中砷吸附的影响

在黄壤、红壤和褐土中进行As的等温吸附实验表明,在不添加P的情况下,3种土壤对As的吸附能力随土壤pH的升高而降低,随土壤粘粒含量的降低而减弱,3种土壤吸附能力为黄壤>红壤>褐土,As在土壤中的吸附受P存在的影响,60mg·kg^-1的P可以降低黄壤和红壤对As最大吸附量．吸附质中P：As的比例不同,P对土壤吸附As的影响差异很大：吸附质中P：As=1：2时,土壤对As的吸附能力均强于P：As=1：1和P：As=2：1,后两者差异不显著,表明土壤中的吸附点位对As和P的亲和性具有一定的差异,Languir方程能很好地拟合所测得的土壤平衡溶液中As浓度。     

Effects of methamidophos and glyphosate on copper sorption-desorption behavior in soils

A batch-equilibration technique was employed to study the impact of two organo-phosphorus pesticides methamidophos (MDP) and glyphosate (GPS) on copper (Cu2+) sorption-desorption for phaeozem and burozem collected from Northeastern China. The addition of the two pesticides decreased Cu2+ sorption, increased Cu2+ desorption and prolonged the equilibrium time of Cu2+ sorption-desorption. But GPS appeared to exert a stronger influence on Cu2+ sorption-desorption due to its stronger complexion with Cu2+. When MDP was added, Cu2+ sorption-desorption was linearly correlated with MDP treatment concentrations. But in the presence of GPS, Cu2+ sorption first underwent a rapid decrease period, and then slowly tended towards a steady period. The reverse pattern could be found for Cu2+ desorption in the presence of GPS. Without pesticides and with the existence of MDP, Cu2+ sorption-desorption kinetics was well conformed to two-constant equation and Elovich equation. But that was not the case for Cu2+ desorption kin     

Effects of methamidophos and glyphosate on copper sorption-desorption behavior in soils

A batch-equilibration technique was employed to study the impact of two organophosphorus pesticides methamidophos (MDP) and glyphosate (GPS) on copper (Cu2+) sorptiondesorption for phaeozem and burozem collected from Northeastern China. The addition of the two pesticides decreased Cu2+ sorption, increased Cu2+ desorption and prolonged the equilibrium time of Cu2+ sorption-desorption. But GPS appeared to exert a stronger influence on Cu2+ sorption-desorption due to its stronger complexion with Cu2+. When MDP was added, Cu2+ sorption-desorption was linearly correlated with MDP treatment concentrations. But in the presence of GPS, Cu2+ sorption first underwent a rapid decrease period, and then slowly tended towards a steady period. The reverse pattern could be found for Cu2+ desorption in the presence of GPS.Without pesticides and with the existence of MDP, Cu2+ sorption-desorption kinetics was well conformed to two-constant equation and Elovich equation. But that was not the case for Cu2+ desorption kinetics in the presence of GPS although its sorption could be also described by these two equations.     

Effects of methamidophos and glyphosate on copper sorption-desorption behavior in soils

A batch-equilibration technique was employed to study the impact of two organophosphorus pesticides methamidophos (MDP) and glyphosate (GPS) on copper (Cu²⁺) sorptiondesorption for phaeozem and burozem collected from Northeastern China. The addition of the two pesticides decreased Cu²⁺ sorption, increased Cu²⁺ desorption and prolonged the equilibrium time of Cu²⁺ sorption-desorption. But GPS appeared to exert a stronger influence on Cu²⁺ sorption-desorption due to its stronger complexion with Cu²⁺. When MDP was added, Cu²⁺ sorption-desorption was linearly correlated with MDP treatment concentrations. But in the presence of GPS, Cu²⁺ sorption first underwent a rapid decrease period, and then slowly tended towards a steady period. The reverse pattern could be found for Cu²⁺ desorption in the presence of GPS. Without pesticides and with the existence of MDP, Cu²⁺ sorption-desorption kinetics was well conformed to two-constant equation and Elovich equation. But that was not the case for Cu²⁺ desorption kinetics in the presence of GPS although its sorption could be also described by these two equations.     

不同水分管理下稻田土壤CH4和N2O排放与微生物菌群的关系

采用MPN计数法对黑土(海伦)和草甸棕壤(沈阳)稻田生长季4种微生物菌群数量进行了测定,同时采用封闭式箱法对CH4和N2O通量进行观测,以深入了解稻田生物源温室气体排放的微生物学过程,两地试验田均采用长期淹灌与间歇灌溉两种不同水分管理,对实验结果多元回归分析,结果表明,海伦与沈阳两地稻田两种水分管理条件下CH4通量季节变化与产甲烷菌数季节变化存在极显著正相关关系沈阳稻田生长季CH4通量季节变化与甲烷氧化菌数季节变化具有显著正相关性,间歇灌溉条件下黑土稻田N2O通量与反硝化菌数呈显著性正相关关系,两种水分管理条件下沈阳稻田N2O通量与硝化菌数具有显著正相关关系,间歇灌溉条件下沈阳稻田N2O通量与反硝化菌数呈显著性正相关关系。     

甲胺磷、乙草胺和铜单一与复合污染对蚯蚓的毒性效应研究

以赤子爱胜蚓(Eisenia foetida)为例,通过滤纸急性毒性试验法研究了东北黑土区普遍存在的3种农用化学品甲胺磷、乙草胺和Cu对蚯蚓的单一与复合毒性效应．单一实验结果表明,三者对蚯蚓均有毒性,它们的毒性顺序为乙草胺＞甲胺磷＞Cu,半致死浓度分别为：0．307、0．708和118．70mg.kg^-1;同时通过观察可知,乙草胺与Cu以皮肤渗入蚯蚓体的毒性效应较甲胺磷明显．复合毒性实验结果表明,低浓度Cu与高浓度Cu对甲胺磷的毒性均有增强作用;低浓度Cu对乙草胺的毒性有削弱作用,但高浓度Cu对乙草胺的毒性有增强作用．可见,三者对土壤生态系统生态安全性和土壤健康质量存在潜在危害,同时这几种污染物的共存进一步加大了潜在危害性,且复合毒性效应与各组浓度组合密切相关．     

Poliovirus adsorption by 34 minerals and soils

The adsorption of radiolabeled infectious poliovirus type 2 by 34 well-defined soils and mineral substrates was analyzed in a synthetic freshwater medium containing 1 mM CaCl(2) and 1.25 mM NaHCO(3) at pH 7. In a model system, adsorption of poliovirus by Ottawa sand was rapid and reached equilibrium within 1 h at 4 degrees C. Near saturation, the adsorption could be described by the Langmuir equation; the apparent surface saturation was 2.5 x 10(6) plaque-forming units of poliovirus per mg of Ottawa sand. At low surface coverage, adsorption was described by the Freundlich equation. The soils and minerals used ranged from acidic to basic and from high in organic content to organic free. The available negative surface charge on each substrate was measured by the adsorption of a cationic polyelectrolyte, polydiallyldimethylammonium chloride. Most of the substrates adsorbed more than 95% of the virus. In general, soils, in comparison with minerals, were weak adsorbents. Among the soils, muck and Genesee silt loam were the poorest adsorbents; among the minerals, montmorillonite, glauconite, and bituminous shale were the least effective. The most effective adsorbents were magnetite sand and hematite, which are predominantly oxides of iron. Correlation coefficients for substrate properties and virus adsorption revealed that the elemental composition of the adsorbents had little effect on poliovirus uptake. Substrate surface area and pH, by themselves, were not significantly correlated with poliovirus uptake. A strong negative correlation was found between poliovirus adsorption and both the contents of organic matter and the available negative surface charge on the substrates as determined by their capacities for adsorbing the cationic polyelectrolyte, polydiallyldimethylammonium chloride.     

Synthesis of tentacle-type magnetic beads as immobilized metal-chelate affinity support for cytochrome c adsorption

Magnetic poly(2-hydroxyethylmethacrylate) (mPHEMA) beads with an average diameter of 100-140 microm were produced by suspension polymerization in the presence of magnetite particles (i.e. Fe3O4). Specific surface area and average pore size of the magnetic beads was found to be 50 m2/g and 819 nm, respectively. Ester groups in the mPHEMA structure were converted to imine groups by reacting with poly(ethyleneimine) (PEI) in the presence of NaH. Amino (-NH2) content of PEI-attached mPHEMA beads was determined as 102 mg PEI/g. Then, Cu2+ ions were chelated on the magnetic beads in the range of 20-793 micromol Cu2+/g. Cytochrome c (cyt c) adsorption was performed on the metal chelating beads from aqueous solutions containing different amounts of cyt c at different pHs, Cu2+ loadings and temperatures. Cyt c adsorption on the mPHEMA/PEI beads was 4.6 mg/g. Cu2+ chelation increased the cyt c adsorption significantly (40.1 mg/g). Adsorption capacity increased with Cu2+ loading and then reached a saturation value. Cyt c adsorption decreased with increasing temperature. Cyt c molecules could be reversibly adsorbed and eluted ten times with the magnetic adsorbents without noticeable loss in their cyt c adsorption capacity. The applicability of two kinetic models including pseudo-first order and pseudo-second order model was estimated on the basis of comparative analysis of the corresponding rate parameters, equilibrium capacity and correlation coefficients. Results suggest that chemisorption processes could be the rate-limiting step in the adsorption process. In the last part of this article, cyt c adsorption experiments were performed in a magnetically stabilized fluidized bed (MSFB) system at optimum conditions determined from the batch experiments. The adsorption capacity decreased significantly from 46.8 to 15.4 mg/g polymer with the increase of the flow-rate from 0.5 to 4.0 ml/min. The resulting magnetic chelator beads possessed excellent long-term storage stability.     

Removal of Zn2+ and Cu2+ by a sequencing batch reactor (SBR) system

Both resting (living) and autoclaved (dead) bio-sludges showed almost the same Cu2+ and Zn2+ adsorption capacities with synthetic industrial estate wastewater (SIEWW). The resting bio-sludge showed not only Cu2+ and Zn2+ adsorption abilities but also organic matter adsorption ability. But, the organic matter (COD and BOD5) adsorption ability of bio-sludge with SIEWW containing 60 mg/L Cu2+ was about half of that with SIEWW containing 60 mg/L Zn2+. The adsorbed Cu2+ and Zn2+ were easily eluted (70-75%) from bio-sludge with 0.1 N HNO3 and 0.1 M EDTA solutions. Bio-sludge from a wastewater treatment plant could be used as an adsorbent for metal ions (Cu2+ and Zn2+). Cu2+ and Zn2+ could repress the SBR system efficiency but its efficiency could be increased with the increase of mixed liquor suspended solids (MLSS), and Cu2+ had more effect than Zn2+ to repress the system efficiency. The SBR system showed very low removal efficiencies of the pollutants with industrial estate wastewater (IEWW), but its pollutant removal efficiencies with IEWW could be increased with the addition of glucose. The Zn2+, Cu2+, BOD5, COD and TKN removal efficiencies of the system with IEWW containing 1.27 g/L glucose, 10 mg/L Cu2+ and 10 mg/L Zn2+ under MLSS of 4500 mg/L were 92.61 +/- 0.28%, 83.77 +/- 0.93%, 98 +/- 0%, 92 +/- 0% and 78.1 +/- 0.1%, respectively.     

Enhanced and selective adsorption of Pb2+ and Cu2+ by EDTAD-modified biomass of baker's yeast

Enhanced and selective removal of Pb2+ and Cu2+ in the presence of high concentration of K+, Na+, Ca2+ and Mg2+ were achieved by adsorption on biomass of baker's yeast modified with ethylenediaminetetraacetic dianhydride (EDTAD). The modified biomass was found to have high adsorption capacities and fast rates for Pb2+ and Cu2+, and it also displayed consistently high levels of metal uptake over the pH range from 2.7 to 6.0. From Langmuir isotherm, the adsorption capacities for Pb2+ and Cu2+ were found to be 192.3 and 65.0 mg g(-1), respectively, which are about 10 and 14 times higher than that of the unmodified biomass. Competitive biosorption experiments showed that the co-ions of K+, Na+, Ca2+ and Mg2+ had little effects on the uptake of Pb2+ and Cu2+ even at the concentration of 1.0 mol L(-1). The adsorbed Pb2+ and Cu2+ on the modified biomass could be effectively desorbed in an EDTA solution, and the regenerated biomass could be reused repeatedly with little loss of the adsorption capacity.