Biosorption of cadmium(Ⅱ) and lead(Ⅱ) ions from aqueous solutions onto dried activated sludge

The removal of heavy-metal ions from aqueous solutions by using dried activated sludge has been investigated in batch systems. Effect of solution pH, initial metal ion concentration, and temperature were determined. The results of the kinetic studies showed that the uptake processes of the two metal ions（Cd（Ⅱ） and Pb（Ⅱ）） followed the pseudo-second-order rate expression. The equilibrium data fitted very well to both the Langmuir and Freundlich adsorption models. The FT-IR analysis showed that the main mechanism of Cd（Ⅱ） and Pb（Ⅱ） biosorption onto dried activated sludge was their binding with amide I group.     

Biosorption of cadmium(II) and lead(II) ions from aqueous solutions onto dried activated sludge

Introduction Toxic metal compounds are frequently used in industrial processes and are widely distributed in the environment. Due to their extended persistence in biological systems and tendency to bioaccumulate as they move up the food chain, they repres…     

Biosorption of cadmium(Ⅱ) and lead(Ⅱ) ions from aqueous solutions onto dried activated sludge

The removal of heavy-metal ions from aqueous solutions by using dried activated sludge has been investigated in batch systems. Effect of solution pH, initial metal ion concentration, and temperature were determined. The results of the kinetic studies showed that the uptake processes of the two metal ions(Cd(Ⅱ) and Pb(Ⅱ)) followed the pseudo-second-order rate expression. The equilibrium data fitted very well to both the Langmuir and Freundlich adsorption models. The FT-IR analysis showed that the main mechanism of Cd(Ⅱ) and Pb(Ⅱ) biosorption onto dried activated sludge was their binding with amide I group.     

Adsorption and desorption of lanthanum at sulfide mineral surface

Batch adsorption experiment with four sulfide minerals - Chalcocite galena, pyrite and sphalerite - were used to study for the adsorption and desorp-tion behavior of La (III) in the presence of EDTA, a model humic matter. Linear adsorption was found in all cases.The presence of soluble organic complexing ligand should reduce the mobility of La (III) in porous media and its transport to groundwater in the percolating soil solution. Binding mechanism is proposed to account for this preferential binding behavior.     

Adsorption and desorption of Cu(Ⅱ) and Pb(Ⅱ) in paddy soils cultivated for various years in the subtropical China

The adsorption and desorption of Cu(Ⅱ) and Pb(Ⅱ) on upland red soil,and paddy soils which were originated from the upland soil and cultivated for 8,15,35 and 85 years,were investigated using the batch method.The study showed that the organic matter content and cation exchange capacity (CEC) of the soils are important factors controlling the adsorption and desorption of Cu(Ⅱ) and Pb(Ⅱ).The 15-Year paddy soil had the highest adsorption capacity for Pb(Ⅱ),followed by the 35-Year paddy soil.Both the 35-Year paddy soil and 15-Year paddy soil adsorbed more Cu(Ⅱ) than the upland soil and other paddy soils.The 15-Year paddy soils exhibited the highest desorption percentage for both Cu(Ⅱ) and Pb(Ⅱ).These results are consistent with the trend for the CEC of the soils tested.The high soil CEC contributes not only to the adsorption of Cu(Ⅱ) and Pb(Ⅱ) but also to the electrostatic adsorption of the two heavy metals by the soils.Lower desorption percentages for Cu(Ⅱ) (36.7% to 42.2%) and Pb(Ⅱ) (50.4% to 57.9%) were observed for the 85-Year paddy soil.The highest content of organic matter in the soil was responsible for the low desorption percentages for the two metals because the formation of the complexes between the organic matter and the metals could increase the stability of the heavy metals in the soils.     

Loss of ozone on sulfate and sulfide doped-ice surfaces

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Adsorption of acetanilide herbicides on soil and its components Ⅱ. Adsorption and catalytic hydrolysis of diethatyl-ethyl on saturated Na~+-, K~+-, Ca~(2+)-, and Mg~(2+)- montmorillonite

1　Ｍａｔｅｒｉａｌｓａｎｄｍｅｔｈｏｄｓ1.1　ＣｌａｙａｎｄｃｈｅｍｉｃａｌｓＴｈｅｃｌａｙｕｓｅｄｗａｓａｍｏｎｔｍｏｒｉｌｌｏｎｉｔｅＳｗｙ2ｆｒｏｍＣｒｏｏｋＣｏｕｎｔｙ,Ｗｙｏｍｉｎｇ,ａｎｄｗａｓｐｕｒｃｈａｓｅｄｆｒｏｍｔｈｅＳｏｕｒｃｅＣｌａｙＭｉｎｅｒａｌｓＲｅｐｏｓｉｔｏｒｙａｔＵｎｉｖｅｒｓｉｔｙｏｆＭｉｓｓｏｕｒｉ,Ｃｏｌｕｍｂｉａ,ＭＯ.Ｔｈｅ<2μｍｆｒａｃｔｉｏｎｗａｓｏｂｔａｉｎｅｄｂｙｓｅｄｉｍｅｎｔａｔｉｏｎ.Ｎａ+,Ｋ+,Ｍｇ2+ａｎｄＣａ2+ｓａｔｕｒａｔｅｄｃｌａｙｓｗｅ…     

Underestimation of phosphorus fraction change in the supernatant after phosphorus adsorption onto iron oxides and iron oxide–natural organic matter complexes

The phosphorus(P) fraction distribution and formation mechanism in the supernatant after P adsorption onto iron oxides and iron oxide-humic acid(HA) complexes were analyzed using the ultrafiltration method in this study.With an initial P concentration of 20 mg/L(I =0.01 mol/L and pH = 7),it was shown that the colloid(1 kDa-0.45 μm) component of P accounted for 10.6%,11.6%,6.5%,and 4.0%of remaining total P concentration in the supernatant after P adsorption onto ferrihydrite(FH),goethite(GE),ferrihydrite-humic acid complex(FH-HA),goethite-humic acid complex(GE-HA),respectively.The 1 kDa component of P was still the predominant fraction in the supernatant,and underestimated colloidal P accounted for 2.2%,55.1%,45.5%,and 38.7%of P adsorption onto the solid surface of FH,FH-HA,GE and GE-HA,respectively.Thus,the colloid P could not be neglected.Notably,it could be interpreted that Fe~(3+) hydrolysis from the adsorbents followed by the formation of colloidal hydrous ferric oxide aggregates was the main mechanism for the formation of the colloid P in the supernatant.And colloidal adsorbent particles co-existing in the supernatant were another important reason for it.Additionally,dissolve organic matter dissolved from iron oxide-HA complexes could occupy large adsorption sites of colloidal iron causing less colloid P in the supernatant.Ultimately,we believe that the findings can provide a new way to deeply interpret the geochemical cycling of P,even when considering other contaminants such as organic pollutants,heavy metal ions,and arsenate at the sediment/soil-water interface in the real environment.     

Effects of Ca2+ ions antagonistic to Al3+ ions poisoningin root growth , cell division and nucleolusin root tip cells of Allium cepa

The effects of different aluminium chloride concentrations together with varying calciumchloride concentrations on root growth, cell division and nucleoli in root tip cells of Allium cepa werestudied. The concentrations used for aluminium chloride were 10^-4, 10^-3 and 10^-2 mol/L ; and for calcium chloride were 10^-5 , 10^-4 , 10^-3 and 10^-2 mol/L, respectively. The results showed that after thetreatments with 10^-2 to 10^-3 mol/L Al³⁺ , root growth was severely inhibited , a large nurnber of thecells with c-mitosis were induced and the nucleolar material was extruded from the nucleus into the cytoplasm. However , the treatments with 10^-2 to 10^-3 mol/L of Al³⁺ together with 10^-2)to 10^-5 mol/LCa²⁺ suggested that Ca²⁺ gave the obviously protective effects against Al³⁺ poisoning in root growth.cell division and nucleoli of the root tip cells in A. cepa. The possible mechanism of these protective effects of Ca²⁺) is also briefly discussed.     

Photooxidation of hydrochlorofluocarbons and hydrofluorocarbons initiated by OH radicals

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Reaction mechanism of 3-chlorophenol with OH, H in aqueous solution

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Fluoride distribution and the effect of some ions along Alexandria coastal Mediterranean seawater of Egypt

The coastal seawater of Mediterranean of Alexandria receives large amount of discharged waters containing industrial wastes, sewage, and agricultural and domestic drainage. Fluoride and some parameters were( chemical and physical) determined. The data gave indication that the content and the amount of the discharged water largely affect the chemical composition of the coastal water. Stepwise regression analysis was highly significant and the model was very fruitful, where the observed and calculated values were mostly concordant. This may indicated that there was a relation between fluoride content in cosslal seawater and its content in the discharged water.     

Fluoride distibution and the effect of some ions along Alexandria coastal Mediterranean seawater of Egypt

The coastal seawater of Mediterranean of Alexandria receives large amount of discharged waters containing industrial wastes, sewage, and agricultural and domestic drainage. Fluoride and some parameters were(chemical and physical) determined. The data gave indication that the content and the amount of the discharged water largely affect the chemical composition of the coastal water. Stepwise regression analysis was highly significant and the model was very fruitful, where the observed and calculated values were mostly concordant. This may indicated that there was a relation between fluoride content in coastal seawater and its content in the discharged water.     

Oxidation of Cr(Ⅲ) on birnessite surfaces: The effect of goethite and kaolinite

Oxidation of Cr(Ⅲ) by manganese oxides may pose a potential threat to environments due to the formation of toxic Cr(Ⅵ) species. At present, it was still unclear whether the extent of Cr(Ⅲ) oxidation and fate of Cr(Ⅵ) would be changed when manganese oxides co-exist with other minerals, the case commonly occurring in soils. This study investigated the influence of goethite and kaolinite on Cr(Ⅲ) oxidation by birnessite under acidic p H condition(p H 3.5)and background electrolyte of 0.01 mol/L Na Cl. Goethite was found not to affect Cr(Ⅲ)oxidation, which was interpreted as the result of overwhelming adsorption of cationic Cr(Ⅲ) onto the negatively-charged birnessite(point of zero charge(PZC) 3.0) rather than the positively-charged goethite(PZC = 8.8). However, more Cr(Ⅵ) would be retained by the surface with the increase in addition of goethite because of its strong ability on adsorption of Cr(Ⅵ) at low p H. Moreover, either Cr(Ⅲ) oxidation or distribution of the generated Cr(Ⅵ)between the solid and solution phases was not affected by kaolinite(PZC 3.0), indicating its low affinity for Cr species. Reactions occurring in the present mixed systems were suggested, which could be partly representative of those in the soils and further indicates that the mobility and risk of Cr(Ⅵ) would be decreased if goethite was present.     

Adsorption characteristics and mechanism of Cr （Ⅵ） on chitoan-yttrium porous microsphere

以壳聚糖和Y2（OH）5NO3为原料通过乳液交联法制备了壳聚糖-钇（Ch—Y）复合微球,通过扫描电镜、透射电镜、X射线衍射、红外光谱等方法对其表面形貌、结构进行了表征.探讨了溶液的pH值、反应时间、投加量、离子初始浓度对其吸附性能的影响.研究结果表明,壳聚糖-钇（Ch—Y）复合微球在pH值为3的酸性环境中对Cr（Ⅵ）保持了较高的吸附能力,吸附容量为52.39mg·g-1,其吸附行为符合Langmuir吸附等温模型;通过吸附机理的研究,发现壳聚糖-钇（Ch—Y）对Cr（Ⅵ）吸附是化学吸附静电吸附协同氧化Cr（Ⅵ）离子作用来实现的.     

Reaciton mechanism of 3—chloroiphenol with OH,H in aqueous solution

The reaction mechanism of 3-chlorophenol with OH, H in aqueous solution was studied by transient technology.The 3-chlorophenol aqueous solutions have been saturated with air or N2 previously.Under alkaline condition,the reaction of OH radical with 3-chlorophenol produces 3-chlorinated phenoxyl radical ,with the absorption peaks at 400 nm and 417nm.Under neutral condition,the reaction of OH radical with 3-chlorophenol produces OH-adduct with the maximal absorption at about 340 nm.And in acid solution,the reaction of H with 3-chlorophenol produces H-adduct with the maximal absorption at about 320nm.3-chlorophenol is compared with 4-and 2-chlorophenols from the free radical pathways.The results show that the positions of chlorine on the aromatic ring strongly influence the dehalogenation and degradation process.     

Comparative equilibrium studies of sorption of Pb(Ⅱ) ions by sodium and calcium alginate

The absorption of Pb(Ⅱ) ions from aqueous solution by different alginate compounds was studied in a batch sorption system.Water soluble sodium alginate and insoluble calcium alginate beads were investigated.The lead-binding capacity of both alginate compounds was highest within the pH range 6-8.The binding capacities and rates of Pb(lI) ions by alginate compounds were evaluated.The Langmuir,Freundlich,and Bruneaur,Emmet and Teller (BET) sorption models were applied to describe the isotherms and isotherm ...     

Performance and mechanism of Cr(Ⅵ) removal by zero-valent iron loaded onto expanded graphite

Zero-valent iron(ZⅥ) was loaded on expanded graphite(EG) to produce a composite material(EG-ZⅥ) for efficient removal of hexavalent chromium(Cr(Ⅵ)). EG and EG-ZⅥ were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM),Fourier-transform infrared(FTIR) spectroscopy and Brunauer–Emmett–Teller(BET) analysis. EG-ZⅥ had a high specific surface area and contained sub-micron sized particles of zero-valent iron. Batch experiments were employed to evaluate the Cr(Ⅵ) removal performance. The results showed that the Cr(Ⅵ) removal rate was 98.80% for EG-ZⅥ,which was higher than that for both EG(10.00%) and ZⅥ(29.80%). Furthermore, the removal rate of Cr(Ⅵ) by EG-ZⅥ showed little dependence on solution p H within a p H range of 1–9.Even at pH 11, a Cr(Ⅵ) removal rate of 62.44% was obtained after reaction for 1 hr. EG-ZⅥ could enhance the removal of Cr(Ⅵ) via chemical reduction and physical adsorption,respectively. X-ray photoelectron spectroscopy(XPS) was used to analyze the mechanisms of Cr(Ⅵ) removal, which indicated that the ZⅥ loaded on the surface was oxidized, and the removed Cr(Ⅵ) was immobilized via the formation of Cr(III) hydroxide and Cr(III)–Fe(III)hydroxide/oxyhydroxide on the surface of EG-ZⅥ.     

Insight into the adsorption of tetracycline onto amino and amino–Fe functionalized mesoporous silica: Effect of functionalized groups

In order to study the influences of functionalized groups onto the adsorption of tetracycline (TC), we prepared a series of amino and amino–Fe^3 + complex mesoporous silica adsorbents with diverse content of amino and Fe^3 + groups (named N,N-SBA15 and Fe-N,N-SBA15). The resulting mesoporous silica adsorbents were fully characterized by X-ray powder diffraction, Fourier transform infrared spectrometer and N₂ adsorption/desorption isotherms. Furthermore, the effects of functionalized groups on the removal of TC were investigated. The results showed that the periodic ordered structure of SBA-15 was maintained after modification of amino/Fe^3 + groups. The functionalized amino groups decreased the adsorption capacity while the coordinated Fe^3 + increased the adsorption capacity. The adsorption kinetics of TC fitted pseudo-second-order model well and the equilibrium was achieved quickly. The adsorption isotherms fitted the Langmuir model well and with the Fe^3 + content increased from 3.93% to 8.26%, the Q_max of the adsorbents increased from 102 to 188 mmol/kg. The solution pH affected the adsorption of TC onto amino complex adsorbents slightly while influenced the adsorption onto Fe-amine complex adsorbents greatly. The adsorption of TC on SBA15 and N,N-SBA15 may be related to the formation of outer-sphere surface complexes, while the adsorption of TC onto Fe-N,N-SBA15 was mainly attributed to the inner-sphere surface complexes. This study could offer potential materials that have excellent adsorption behavior for environmental remediation and suggested useful information for the preparing other adsorbents in environmental applications.