生物吸附剂-虾壳吸附镉(II)的实验研究

本文采用廉价的生物吸附剂-虾壳来吸附水中的Cd2+,研究溶液的pH值、初始Cd2+ 离子浓度、虾皮不同粒度、外加盐等因素对Cd2+ 的吸附特性的影响.探讨了经过一定浓度酸处理的虾壳对Cd2+ 的吸附情况.得到了最佳的pH值,得出了适宜的吸附等温线经验方程.     

黄孢展齿革菌菌丝球同时吸附铅镉离子的动力学

采用间歇法，利用黄孢展齿革菌菌丝球吸附溶液中的Pb^2 和Cd^2 ，研究Pb^2 和Cd^2 共存体系中吸附初速率随初始浓度的变化规律。实验结果表明，少量Cd^2 的存在促进其对Pb^2 的吸附，并提高吸附初速率，但随着Cd^2 初始浓度的增加，促进作用逐渐减弱并转为抑制作用；Cd^2 的吸附初速率随着Pb^2 初始浓度增大而减小；Pb^2 和Cd^2 的吸附初速率都随自身初始浓度的增加而增大。     

CMC-Na/DETA-B62型蛇笼树脂对金属离子的吸附性能

本文研究了自合成的蛇笼型螯合树脂-二乙烯三胺交联甘油环氧树脂/羰甲基纤维素体系对Cd^2 ,Pb^2 ,Fe^2 的吸附量，吸附动力学，等温吸附过程等静态吸附性能，同时研究了pH值等因素对吸附性能的影响。实验结果表明，该树脂对Cd^2 具有较强的吸附选择性，能在Cd^2 ,Pb^2 ,Fe^2 3种离子共存时选择吸附Cd^2 ，其选择性系数分别为Kcd^2 /pb^2 =3.77,Kcd^2 /Fe^2 =9.61。该树脂对上述3种离子的吸附量可分别达4.00,1.06,0.42mmol/g。该类树脂可用于含重金属离子污水的处理和金属离子的分离等方面。     

不同海藻吸附重金属镉离子的研究

本文采用6种分别属于褐藻门、绿藻门、红藻门的海边常见大型海藻对重金属镉离子进行吸附比较实验，镉离子浓度较低时，其吸附容量排列顺序为：海黍子＞海带＞孔石莼＞节荚藻＞刺松藻＞内枝藻，海黍子的吸附量高达181mg/g，超出文献报道值，对3种吸附容量较高的海藻进行了较详细的研究，研究溶液的pH值、初始Cd^2 离子浓度等因素对Ca^2 的吸附特性的影响，对吸附机理进行了初步的探讨，发现镉离子与海藻中的钙离子发生离子交换作用，交换率占总吸附量的33－34％，得出了适宜的吸附等温线方程。     

pH值对海藻吸附镍离子的影响研究

采用3种大型海藻－裙带菜，海黍子，马尾藻对重金属镍离子进行吸附，研究了溶液的pH值对Ni^2 吸附特性的影响，得到最佳pH值，发现了相同浓度，不同pH值的溶液吸附镍离子后pH值的变化规律及不同浓度。相同pH值的溶液吸附镍离子后pH值得变化规律，为进一步探讨海藻吸附重金属的吸附机理提供了依据。     

巯基树脂对重金属离子的吸附性能

研究了自合成的巯基树脂对重金属离子Pb^2 、Cu^2 、Cd^2 ．Ni^2 、Co^2 的吸附容量、吸附动力学、等温吸附过程等静态吸附性能，同时研究了影响吸附的因素和吸附机理．结果表明，该树脂对软酸型重金属离子吸附容量高．pH=5．0-5．7，低温有利于吸附，树脂对各重金属离子等温吸附在实验浓度范围内均符合Langmuir和Freundnch方程．吸附机理研究表明，巯基与重金属离子发生了离子交换和配位反应，化学吸附起支配作用。     

壳聚糖分离-原子吸收光谱法测定水中铜、锌、钴、镍、铅和镉

研究了天然高分子吸附剂-壳聚糖对Cu^2 、Zn^2 、Co^2 、Ni^2 、Pb^2 和Cd^2 6种离子的吸附行为以及在不同pH值、干扰离子存在时对壳聚糖吸附6种离子的影响,建立了壳聚糖柱同时分离六种离子,火焰原子吸收法测定含量的分析方法,并应用于自来水和电镀废水中6种金属离子分离和测定。     

D301R树脂吸附-解吸钼的行为研究

对D301R型阴离子交换树脂吸附-解吸钼的条件进行了研究，采用静态法试验了pH值、钼的浓度等因素对该树脂吸附钼的影响；采用动态法讨论了该树脂对钼的饱和吸附量、解吸剂及其浓度对解吸钼的影响。结果表明在pH2．5，钼的浓度为20g/L时吸附效果最好，树脂对钼的饱和吸附量为1020mg／g，而采用150g/L NaOH溶液解吸钼效果最佳。     

巯基壳聚糖富集火焰原子吸收光谱法测定天然水体中Pb2+和Cd2+ 的研究

利用自己研制的巯基壳聚糖对Pb^2 和Cd^2 具有良好的吸附效果这一特性，建立了巯基壳聚糖分离富集原子吸收光谱法测定天然水体中Pb^2 和Cd^2 的新方法，研究了最佳吸附和脱附条件，该法对Pb^2 和Cd^2 的准确检测下限可达到1.00μg/L和0.050μg/L。回收率分别达到96.5%和97.6%。该法灵敏度高，选择性好，用于实际水样的测定取得了满意的。     

乙二胺硅胶复合材料对Zn2+的吸附特性

以γ-氯丙基三氯硅烷为偶联剂,将乙二胺偶合接枝在硅胶表面,合成对锌离子具有吸附作用的乙二胺硅胶复合材料（EDA/SiO2）,考察了Zn2+溶液pH值、初始浓度、吸附温度和吸附时间等因素对复合材料吸附性能的影响。 结果表明,在研究的溶液浓度及温度范围内,Zn2+溶液pH值对EDA/SiO2的吸附量影响显著,吸附的最佳pH值范围在3.0~5.5;Zn2+的吸附平衡数据符合Langmuir吸附模型,热力学数据显示,EDA/SiO2对Zn2+的吸附行为为一吸热且自发进行的过程,升高温度有利于吸附,并对此吸附行为作了解释;吸附动力学数据可用拟二级吸附动力学方程描述,得到的吸附速率常数与溶液初始浓度有关。     

Determination of trace cadmium in waters by flame atomic absorption spectrophotometry after preconcentration with 1-nitroso-2-naphthol-3,6-disulfonic acid on Ambersorb 572

A procedure for the determination of trace amount of cadmium after adsorption of its 1-nitroso-2-naphthol-3,6-disulfonic acid chelate on Ambersorb 572 has been proposed. This chelate is adsorbed on the adsorbent in the pH range 3-8 from large volumes of aqueous solution of water samples with a preconcentration factor of 200. After being sorbed, cadmium was eluted by 5 mL of 2.0 mol L(-1) nitric acid solution and determined directly by flame atomic absorption spectrophotometery (FAAS). The detection limit (3sigma) of cadmium was 0.32 microg L(-1). The precision of the proposed procedure, calculated as the relative standard deviation of recovery in sample solution (100 mL) containing 5 microg of cadmium was satisfactory (1.9%). The adsorption of cadmium onto adsorbent can formally be described by a Langmuir equation with a maximum adsorption capacity of 19.6 mg g(-1) and a binding constant of 6.5 x 10(-3) L mg(-1). Various parameters, such as the effect of pH and the interference of a number of metal ions on the determination of cadmium, have been studied in detail to optimize the conditions for the preconcentration and determination of cadmium in water samples. This procedure was applied to the determination of cadmium in tap and river water samples.     

内蒙风化煤对镉离子溶液的吸附行为

本文利用内蒙风化煤[1,3]作吸附剂对镉离子溶液中的镉的吸附性能、特征和机理进行探索,以利内蒙风化煤的深度开发利用。1　实验内蒙风化煤(腐植酸含量高达41 3%)。空气中风干研细后,过80目筛。用3ＣｄＳＯ4·8Ｈ2Ｏ和Ｈ2ＳＯ4配制含Ｃｄ(Ⅱ)酸性溶液[4],镉含量采用ＡＡ 670原子吸收分光光度法(日本岛津)测定。吸附实验采用静态分析方法。准确称取一定量的风化煤放入干燥的250ｍｌ锥形瓶中,加入25ｍｌ一定浓度的含镉溶液,在室温下连续振荡2ｈ,静置0 5ｈ,过滤,分析滤液中的镉含量。取6ｇ内蒙风化煤于250ｍｌ磨口锥形瓶中,移入25ｍｌ1000ｍ…     

Preliminary Research on Cd^2＋ Removal from Wastewater by Sphaerotilus Natans

Influencing factors, such as the biomass concentration, pH value, temperature and time of adsorption on the removal of Cd^2＋ were investigated when Sphaerotilus natans was used as a biosorbent. The results show that Sphaerotilus natans has a significant effect on the adsorption of Cd^2＋. The process of adsorption will reach the equilibrium in 20 min. Temperature has no significant effect on the adsorption. The removal rate of Cd^2＋. can approach to 90% under the conditions of pH 5.5, the biomass mass concentration O. 6 g/L and the initial mass concentration of cadmium ≤20 mg/L. The maximum specific uptake is 1.9 mmol/g dry biomass . The adsorption was fitted with the Freundlich isotherm adsorption equation when the concentration of Cd^2＋ is in a range of 0--100 mg/L. HCl and EDTA can desorb Cd^2＋ from biomass effectively.     

Adsorption and oxidation of aromatic amines by metal hexacyanoferrates(II)

Interaction of aniline, p-toluidine and p-chloroaniline with nickel, cadmium and manganese hexacyanoferrates(II) has been studied. Nickel and cadmium hexacyanoferrates(II) showed maximum adsorption at neutral pH, whereas, manganese hexacyanoferrate(II) reacts with aniline, p-toluidine and p-chloroaniline forming the colored oligomers on its surface. The adsorption data obtained at neutral pH is fitted in Langmuir adsorption isotherm. The adsorption behavior of the studied aromatic amines followed the order: p-toluidine>aniline>p-chloroaniline, which is related to the basicities of the amines. Results of the present study suggest the importance of metal hexacyanoferrates(II) and metal ions in stabilization of aromatic amines during the processes of prebiotic condensation reactions.     

Kinetic, equilibrium and thermodynamic studies of cadmium (II) adsorption by modified agricultural wastes

Agricultural wastes have great potential for the removal of heavy metal ions from aqueous solution. The contamination of water by toxic heavy metals is a worldwide environmental problem. Unlike organic pollutants, the majority of which are susceptible to biological degradation, heavy metals do not degrade into harmless end products. Discharges containing cadmium, in particular, are strictly controlled because of the highly toxic nature of this element and its tendency to accumulate in the tissues of living organisms. This work aims to develop inexpensive, highly available, effective metal ion adsorbents from natural wastes as alternatives to existing commercial adsorbents. In particular, Tamrix articulata wastes were modified chemically by esterification with maleic acid to yield a carboxyl-rich adsorbent. The adsorption behavior of treated Tamrix articulata wastes toward cadmium ions in aqueous solutions in a batch system has been studied as a function of equilibration time, adsorbent dose, temperature and pH. Results showed that the maximum adsorption capacity was 195.5 mg/g in a pH 4 solution at 30 °C with a contact time of 120 min, an initial concentration of 400 mg/L and an adsorbent dose of 0.3 g/L. The kinetic data were analyzed using pseudo-first-order and pseudo-second-order kinetic models. It was shown that the adsorption of cadmium could be described by a pseudo-second-order equation. The experimental data were also analyzed using the Langmuir and Freundlich models of adsorption. Thermodynamic parameters such as ΔG°, ΔH° and ΔS° have been evaluated and it has been found that the sorption process was spontaneous and exothermic in nature. From all of our data, we conclude that the treated Tamrix articulata wastes investigated in this study showed good potential for cadmium removal from aqueous solutions.     

Modeling the adsorption of Cd(II) onto kaolinite and Muloorina illite in the presence of citric acid

The adsorption of cadmium onto kaolinite and Muloorina illite in the presence of citric acid has been measured as a function of pH and cadmium concentration at 25 degrees C. When citric acid is present in the systems cadmium adsorption is slightly enhanced below pH 5, but significantly suppressed between pH 5 and 8, for both substrates. At higher citric acid concentrations very little cadmium adsorbs onto kaolinite from pH 5 to 8. Above pH 8 adsorption of Cd(II) onto illite is enhanced in the presence of citric acid, especially at lower concentrations, but this does not occur for kaolinite. Adsorption and potentiometric titration data were fitted by simple extended constant-capacitance surface complexation models for the two substrates. Enhancement of adsorption at lower pH values was ascribed to the ternary reaction [X(-)--K(+)](0)+Cd(2+)+L(3-)+2H(+) right arrow over left arrow (0)+K(+) involving outer-sphere complexation with permanently charged X(-) sites on the "silica" faces of both clay minerals. The models suggested that suppression of adsorption in the intermediate pH range was due to the formation of a strong CdL(-) solution complex which adsorbed neither on the permanently charged sites nor on the surface hydroxyl groups at the edges of the clay crystals. At higher pH values the dominant solution complex, CdLOH(2-), apparently adsorbed as an outer-sphere complex at surface hydroxyl groups on illite, SOH+2Cd(2+)+L(3-) right arrow over left arrow [SOCd(+)--CdOHL(2-)](-)+2H(+), but not on kaolinite. This difference in behavior results from the presence of =FeOH groups on the illite surface which can form surface complexes with CdLOH(2-), while the =AlOH groups on the kaolinite surface cannot.     

Adsorption of cadmium from aqueous solutions on manganese dioxide

Journal of Radioanalytical and Nuclear Chemistry - The adsorption of cadmium on manganese dioxide has been investigated from different media in relation to shaking time, pH, composition and...     

Adsorption of univalent and bivalent metal nitrates on hydrous lead dioxide Adsorption behaviour of potassium, cupric, zinc, cadmium and nitrate ions

The individual adsorption behaviour of potassium, cupric, zinc, cadmium and nitrate ions on hydrous lead dioxide (HLD) was investigated. HLD was found to be an amphoteric ion-exchanger with an equi-adsorption point in the vicinity of pH 4.6. For bivalent metal ions, the amount of adsorption increased with pH (at pH > 3) and there was almost 100% adsorption at pH > 6. Both the adsorption capacity and the adsorption affinity on HLD were in the order copper(II) > zinc(II) > cadmium(II).     

Adsorption of Cu(II), Zn(II), Ni(II), Pb(II), and Cd(II) from aqueous solution on Amberlite IR-120 synthetic resin

The adsorption of copper(II), zinc(II), nickel(II), lead(II), and cadmium(II) on Amberlite IR-120 synthetic sulfonated resin has been studied at different pH and temperatures by batch process. The effects of parameters such as amount of resin, resin contact time, pH, and temperature on the ion exchange separation have been investigated. For the determination of the adsorption behavior of the resin, the adsorption isotherms of metal ions have also been studied. The concentrations of metal ions have been measured by batch techniques and with AAS analysis. Adsorption analysis results obtained at various concentrations showed that the adsorption pattern on the resin followed Freundlich isotherms. Here we report the method that is applied for the sorption/separation of some toxic metals from their solutions.