木粉/壳聚糖接枝丙烯酸-丙烯酰胺吸附树脂对二元重金属离子溶液中Pb^2＋的吸附

采用自制木粉/壳聚糖接枝丙烯酸-丙烯酰胺吸附树脂R1、R2、R3对二元金属离子Cu2＋/Pb2＋和Zn2＋/Pb2＋溶液中的吸附性能进行了较系统考察。Pb2＋离子溶液中存在竞争离子Cu2＋、Zn2＋时,随竞争离子浓度增加,3种吸附树脂R1、R2、R3对Pb2＋的吸附量明显下降,而竞争离子吸附量显著增加。二元溶液中各金属离子浓度相同时,3种树脂对竞争离子Cu2＋、Zn2＋的吸附量大于对Pb2＋的吸附量;各溶液中分别加入NaCl及NaNO3、尿素后,对Pb2＋离子的吸附量下降迅速。随吸附树脂用量增加,竞争离子Cu2＋、Zn2＋的吸附量逐渐减小,Pb2＋的吸附量在吸附树脂用量0.10 g/L（Zn2＋/Pb2＋溶液）或0.15 g/L（Cu2＋/Pb2＋溶液）时出现最大值。溶液pH值对树脂吸附性能有显著影响。3.0     

胺化木质素对水中Cu（Ⅱ）、Cd（Ⅱ）的吸附

以胺化木质素作吸附剂对水中Cu2＋、Cd2＋的去除进行了研究，主要考察了吸附时间、溶液pH值、温度和金属离子初始浓度对吸附去除率的影响，并研究了其吸附等温线和动力学。结果表明，胺化木质素能有效去除水溶液中的Cu2＋、Cd2＋，且对Cd2＋的吸附能力大于Cu2＋吸附动力学符合准二级动力学方程，吸附等温线均可以很好地用Langmuir方程描述。     

赭石对模拟重金属废水的吸附效果研究

采用模拟重金属废水的正交试验设计，进行赭石对模拟重金属废水的吸附效果研究，探讨pH、赭石加入量和振荡时间等影响因素对吸附效果的影响。结果表明，在一定pH、赭石加入量和振荡时间条件下，赭石对6种重金属（Pb、Cd、Mn、Zn、Cr和Ni）均有较好吸附效果，对Pb、Cd、Mn、Zn和Cr的最大吸附率可达100%，对Ni的吸附率达8963%。处理后废水中重金属达到污水排放标准。各影响因素对Mn、Zn和Cr吸附效率的影响大小表现为：pH＞赭石加入量＞振荡时间，Ni和Cd表现为：赭石加入量＞pH＞振荡时间，Pb表现为：pH＞振荡时间＞赭石加入量。赭石对废水中重金属吸附的最佳条件为赭石加入量40 g/L，pH 10～10.5，振荡时间2 h。     

液/固体系中硅藻土对Pb2+和Cd2+的吸附机制

为了提高硅藻土在重金属废水处理上的应用水平,采用静态吸附实验考察了液/固体系中硅藻土对Pb2＋、Cd2＋的吸附影响因素、吸附等温线和吸附动力学属性。结果表明,随着投加量的减少,离子初始浓度的提高,pH值的增大,吸附作用时间的延长,硅藻土对Pb2＋、Cd2＋吸附量不断上升;硅藻土对Pb2＋、Cd2＋的等温吸附都符合Langmuir模型,硅藻土对Pb2＋、Cd2＋最大吸附量分别为10.428 mg/g和7.916 mg/g,硅藻土对Pb2＋具有更好的吸附能力;Pb2＋具有较低的水合自由能,更容易脱去水膜与硅藻土孔道内的活性基团发生吸附作用;双常数扩散方程可以很好地描述硅藻土对Pb2＋、Cd2＋的吸附动力学属性,硅藻土对Cd2＋有较快的吸附速率。     

木粉/壳聚糖接枝丙烯酸-丙烯酰胺吸附树脂对二元重金属离子溶液中Pb2+的吸附

采用自制木粉/壳聚糖接枝丙烯酸-丙烯酰胺吸附树脂R1、R2、R3对二元金属离子Cu2 +/pb2和Zn2+/pb2+溶液中的吸附性能进行了较系统考察.pb2+离子溶液中存在竞争离子Cu2+、Zn2+时,随竞争离子浓度增加,3种吸附树脂R1、R2、R3对pb2+的吸附量明显下降,而竞争离子吸附量显著增加.二元溶液中各金属离子浓度相同时,3种树脂对竞争离子Cu2+、Zn2+的吸附量大于对pb2+的吸附量;各溶液中分别加入NaCl及NaNO3、尿素后,对pb2+离子的吸附量下降迅速.随吸附树脂用量增加,竞争离子Cu2+、Zn2+的吸附量逐渐减小,pb2+的吸附量在吸附树脂用量0.10 g/L(Zn2 +/pb2+溶液)或0.15 g/L(Cu2+/pb2+溶液)时出现最大值.溶液pH值对树脂吸附性能有显著影响.3.0＜pH＜5.O时,3种树脂对竞争离子和pb2+的吸附量快速增大;5＜ pH ＜9时,树脂对竞争离子和pb2+的吸附量基本不变;9＜pH＜ll时,树脂对pb2+的吸附量减小,而对竞争离子的吸附量或增大或减小.     

皂化改性橘子皮生物吸附剂对重金属离子的吸附

以生物废料橘子皮(OP)为原料,经乙醇、氢氧化钠处理,得到改性橘子皮生物吸附剂SOP,将其用于对重金属离子Cu2+、Pb2+、Cd2+、Zn2+和Ni2+的吸附。研究了溶液pH、吸附时间和重金属离子初始浓度对SOP吸附性能的影响。结果表明,重金属离子在生物吸附剂上的吸附速率快,符合准二级动力学方程。SOP对重金属离子的吸附等温线符合Lang-muir模型,根据Langmuir模型计算SOP对Cu2+、Pb2+、Cd2+、Zn2+和Ni2+的饱和吸附量分别为56.82、152.4、66.27、33.90和23.02 mg/g,均高于改性前。常见阳离子的存在对重金属离子吸附的影响较小,改性后的橘子皮生物吸附剂可以再生重复使用4次以上,是性能良好的重金属离子吸附剂。     

不同硅铝比的ZSM-5型沸石分子筛吸附水中Cu2＋离子的研究

考察了3种不同硅铝比的ZSM-5沸石分子筛（25H、38H和50H，25、38和50为硅铝比）对水中Cu2＋的吸附过程及其影响因素。结果表明，3种材料均能有效吸附去除水中Cu2＋离子，动力学符合假二阶动力学模型，吸附等温线符合Langmuir吸附等温式。3种材料吸附速率及吸附容量顺序为：25H〉50H〉38H，其中，25H最大吸附容量达到12．83mg／g。投加量由0．8g／L增加至2．0g／L，材料对Cu2＋吸附去除率由87．0％增加至97．5％。考察水中常见阳离子对吸附的干扰作用，结果表明，干扰离子的影响顺序为：Pb2＋〉K＋〉Na＋〉Mg2＋；随着干扰离子浓度的增大，材料对Cu2＋的去除率显著下降。硅铝比及晶粒形貌均对沸石分子筛吸附Cu2＋有较大影响，小的孔径不利于Cu2＋的吸附，低硅铝比有利于Cu2＋在分子筛上的吸附。     

膨润土对Pb2+、Cu2+、Cr3+的吸附动力学及等温线研究

研究所用膨润土的主要成分为SiO2和Al2O3,属于Ca基膨润土,BET表面积为50.83 m2/g.在恒温及恒定pH条件下,用静态吸附法研究了膨润土对Pb2 、Cu2 、Cr3 的吸附特性,结果表明其较好地符合Lagergten二级吸附速率方程,对这3种离子的吸附速率为Pb2 ＞Cu2 ＞Cr3 .利用3种等温线方程对吸附过程进行拟合,发现利用Langmuir吸附等温方程计算的值与膨润土吸附Pb2 、Cu2 、Cr3 试验数据最为吻合.膨润土对3种金属离子的平衡吸附量为Cr3 ＞Cu2 ＞Pb2 .     

改性白菜叶渣对重金属Zn2＋吸附性能

为了研究白菜叶渣对锌离子的吸附作用，采用静态吸附的方法，以酸碱处理后的废弃白菜渣为原材料，获得加人量（X1）、浓度（X2）、时间（X3）、pH（X4）和温度（X5）各单因素对Zn2＋的最佳吸附点，再通过二次回归正交旋转组合设计对白菜渣吸附Zn2＋的条件进行优化，并讨论了吸附过程中吸附等温线与动力曲线的相关特征。结果表明，当加入量0．2g、浓度2mg／L、吸附时间5h、pH为4以及温度20％时，吸附达到最大95．08％，验证所测最大吸附率93．89％，与预测值基本相符。对比实验说明白菜渣对Zn2吸附效果要优于活性炭。25℃和35℃时的等温线的拟合结果表明，白菜渣对Zn2＋是物理化学共同吸附的复杂过程。     

橘子皮皂化交联改性及其对重金属离子的吸附

以生物废料橘子皮(OP)为原料,经乙醇、NaOH和CaCl2处理,得到皂化交联改性橘子皮(SCOP)生物吸附剂,将其用于对重金属离子Cu2+、pb2+、Cd2+、Zn2+和Ni2+的吸附,并研究了溶液pH、吸附时间和重金属离子初始浓度对SCOP吸附性能的影响.结果表明,重金属离子在改性橘子皮上的吸附速率快,符合准二级动力学方程；改性橘子皮对Cu2+、pb2+、Zn2+和Ni2+的吸附等温线符合Langmuir方程,对Cd2+的吸附等温线符合Freundlich方程,根据Langmuir方程计算对Cu2+、pb2+、Cd2+、Zn2+和Ni2+的饱和吸附量分别为72.73、209.80、85.84、56.18、33.80mg/g,均高于改性前.改性后的橘子皮生物吸附剂可以再生重复使用4次以上,是性能良好的重金属离子吸附剂.     

Evaluation of pectin binding of heavy metal ions in aqueous solutions

Evaluation of adsorption performance of several industrially manufactured pectins towards some toxic heavy metals was carried out. Adsorption isotherms for divalent cations in simulant aqueous solutions were measured and corresponding distribution coefficients were calculated. The following selectivity sequences we found for pectins: Pb2+ > Cu2+ > Co2+ > Ni2+ > Zn2+ > Cd2+. It was shown that a beet pectin exhibits a high affinity for Pb2+ and Cu2+ ions, an apple pectin for Co2+ ion and a citrus pectin for Ni2+ ion. The binding properties of all pectins towards Zn2+ and Cd2+ ions are extremely poor. The quantitative data on adsorption performance of pectins suggest their applicability as food additives or remedies for efficient removal of Pb2+, Cu2+, Co2+, and Ni2+ ions from different biological systems, including human and animal organisms.     

4A沸石对复合污染水体中Pb2+、Cu2+和Cd2+的去除

采用静态吸附法以4A沸石为吸附剂研究其对复合污染水体中Pb2+、Cu2+和Cd2+的竞争吸附特性,并探讨了影响吸附的环境因素。实验表明,在室温条件下,溶液pH5～6,4A沸石15 mg对10 mL复合污染溶液(Pb2+、Cu2+和Cd2+浓度分别为100 mg/L)吸附20 min时,对溶液中3种重金属的吸附去除率均可达99.8%以上。反应过程中4A沸石对3种重金属的吸附速率大小为Pb2+>Cu2+>Cd2+。复合污染水体中4A沸石对Pb2+、Cu2+和Cd2+的吸附符合Langmuir和Fre-undlich等温吸附方程,相关系数分别为0.9981、0.9901、0.9916和0.9638、0.9194、0.9689。经计算,4A沸石对Pb2+、Cu2+和Cd2+的饱和吸附量分别为129.9 mg/g、107.5 mg/g和99.0 mg/g。4A沸石吸附重金属离子达到吸附平衡的时间较短,对溶液pH值的适应性较好。吸附后的4A沸石可以再生利用,对铅离子洗脱重复利用性较铜离子和镉离子强。     

浮游球衣菌对Pb2+、Cu2+、Zn2+、Cd2+的吸附性能研究

研究了浮游球衣菌（Sphaerotilus natans）在不同吸附条件下对溶液中Pb^2＋、Cu^2＋、Zn^2＋、Cd^2＋的吸附规律。结果表明,Sphaerotilus natans对这4种重金属离子均有一定的吸附作用,并在20min内达到吸附平衡,pH对吸附过程影响较大,pH为5.5时Sphaerotilus natans对这4种金属离子的吸附效果最好,Sphaerotilus natans对它们的吸附选择性为Pb^2＋〉Cu^2＋〉Zn^2＋〉Cd^2＋,Pb^2＋、Cu^2＋能部分置换出已被菌体吸附的Zn^2＋、Cd^2＋。HCI和EDTA溶液可有效地将金属离子从菌体上解吸下来,解吸后的菌体可重复使用。     

麦秆黄原酸酯对水中Cu(II)的吸附

采用农业废弃物麦秆为原料制备黄原酸酯,通过傅立叶变换红外光谱FT-IR、扫描电子显微镜SEM等技术对麦秆黄原酸酯物理化学性质进行表征,并对水中Cu2+进行吸附特性研究,考察了不同条件对Cu2+吸附效果的影响,并将其应用于跌水式吸附法对含重金属沼液进行处理,为麦秆黄原酸酯应用于实际污水处理提供理论参考。结果表明,麦秆黄原酸酯对Cu2+的吸附行为符合伪二级动力学吸附模型与Langmuir等温吸附方程,298 K时,Cu2+的饱和吸附量为28.33 mg/g,溶出率为4.97%,对Cu2+的固持能力较强;黄原酸酯跌水吸附法对于含量为50 mg/L以下的Cu2+废水去除率达到80%以上,对实际沼液中Pb、Zn、Cd、Cu的去除率为44.42%~90.16%,去除顺序为Cd>Pb>Cu>Zn。     

The solid-solution partitioning of heavy metals (Cu,Zn, Cd,Pb) in upland soils of England and Wales

Ninety-eight surface soils were sampled from the uplands of England and Wales, and analysed for loss-on-ignition (LOI), and total and dissolved base cations, Al, Fe, and trace heavy metals (Cu, Zn, Cd, Pb). The samples covered wide ranges of pH (3.4-8.3) and LOI (9-98%). Soil metal contents measured by extraction with 0.43 mol l-1 HNO3 and 0.1 mol l-1 EDTA were very similar, and generally lower than values obtained by extraction with a mixture of concentrated nitric and perchloric acids. Total heavy metal concentrations in soil solution depend positively upon soil metal content and [DOC], and negatively upon pH and LOI, values of r2 ranging from 0.39 (Cu) to 0.81 (Pb). Stronger correlations (r2=0.76-0.95) were obtained by multiple regression analysis involving free metal ion (Cu2+, Zn2+, Cd2+, Pb2+) concentrations calculated with the equilibrium speciation model WHAM/Model VI. The free metal ion concentrations depend positively upon MHNO3 and negatively upon pH and LOI. The data were also analysed by using WHAM/Model VI to describe solid-solution interactions as well as solution speciation; this involved calibrating each soil sample by adjusting the content of "active" humic matter to match the observed soil pH. The calibrated model provided fair predictions of total heavy metal concentrations in soil solution, and predicted free metal ion concentrations were in reasonable agreement with the values obtained from solution-only speciation calculations.     

Predictions of binary sorption isotherms for the sorption of heavy metals by pine bark using single isotherm data

The adsorption of three heavy metal ions by pine bark was studied. The study was divided into two parts; single component adsorption of the metals Cu2+, Cd2+ and Ni2+ and bisolute adsorption of the three binary systems Cu2+-Cd2+, Cu2+-Ni2+ and Cd2+-Ni2+. Extended Langmuir model, extended Freundlich model. Sips model and ideal adsorption solution theory (IAST) models were used to predict the equilibrium uptake for Cu2+, Cd2+ and Ni2+ in the binary diluted solutions using the single adsorption constants. The experimental data of single isotherm adsorption process were found to follow Langmuir isotherm model with less accuracy than Freundlich and Sips models. Whereas, the predictions of bisolute adsorption isotherms of the mentioned three systems, Cu2+-Cd2+, Cu2+-Ni2+ and Cd2+-Ni2+, showed good agreement with experimental data when using Extended-Langmuir, Extended-Freundlich and IAST. However, the only good fit of the Sips model was with the Cu2+-Cd2+ system.     

Simultaneous heavy metal removal mechanism by dead macrophytes

The use of dead, dried aquatic plants, for water removal of metals derived from industrial activities as a simple biosorbent material has been increasing in the last years. The mechanism of simultaneous metal removal (Cd2+, Ni2+, Cu2+, Zn2+ and Pb2+) by 3 macrophytes biomass (Spirodela intermedia, Lemna minor and Pistia stratiotes) was investigated. L. minor biomass presented the highest mean removal percentage and P. stratiotes the lowest for all metals tested. Pb2+ and Cd2+ were more efficiently removed by the three of them. The simultaneous metal sorption data were analysed according to Langmuir and Freundlich isotherms. Data fitted the Langmuir model only for Ni and Cd, but Freundlich isotherm for all metals tested, as it was expected. The K(F) values showed that Pb was the metal more efficiently removed from water solution. The adsorption process for the three species studied followed first order kinetics. The mechanism involved in biosorption resulted ion exchange between monovalent metals as counter ions present in the macrophytes biomass and heavy metal ions and protons taken up from water. No significant differences were observed in the metal exchange amounts while using multi-metal or individual metal solutions.     

Adsorption mechanism of Zn2+, Ni2+, Cd2+, and Cu2+ ions by carbon-based adsorbents: interpretation of the adsorption isotherms via physical modelling

Environmental Science and Pollution Research - A theoretical physicochemical and thermodynamic investigation of the adsorption of heavy metals Zn2+, Cd2+, Ni2+, and Cu2+on carbon-based adsorbents...     

Correlations between cadmium and mineral nutrients in absorption and accumulation in various genotypes of rice under cadmium stress

The absorption and accumulation of Cd2+, Fe3+, Zn2+, Mn2+, Cu2+ and Mg2+ in the roots and leaves of 20 rice cultivars (Oryza sativa L.) with different genotypes under cadmium (Cd) stress were investigated with pot experiments. The results showed that there existed significant differences among the rice cultivars in the contents of six mineral elements in both roots and leaves at both heading and ripening periods. The statistical analysis showed that, for their contents in roots, significant and positive correlations between Cd2+ and Fe3+, Cd2+ and Zn2+, Cd2+ and Mn2+, Cd2+ and Cu2+ existed, but no significant correlation between Cd2+ and Mg2+, at the two periods. In the leaves, Cd also showed significant and positive correlations with Fe3+, Zn2+ and Cu2+ at the both periods, but a significant and negative correlation with Mn2+ and no significant correlation with Mg2+ at heading, a significant and positive correlation with Mg2+ and no significant correlation with Mn2+ at ripening. These results suggested that there were cooperative absorption between Cd2+ and Fe3+, Mn2+, Cu2+, Mn2+ in rice plants. Genotypic differences in Cd uptake and translocation among the rice cultivars suggested that paddy field of some rice cultivars may be irrigated with partially treated sewage water.