The surface reaction on liquid-solid interface of “amino acid-Cu(II)−MnO2” system in seawater

The results obtained from the Cu(II)%-pH curve of the system in the presence of added amino acid indicated that the added amino acids of higher concentration can inhibit the Cu(II)-σ-MnO₂ ion exchange and that their inhibiting effects decrease in the following sequence when the initial amino acid concentrations are 20.00 ppm: histidine > cystine > glutamic acid > proline > alanine > glycine. The determination of amino acid in solution performed with an amino acid analyser showed that added amino acids react chemically on the surface of the σ-MnO₂ According to thermodynamic equilibria relations in the system, amino acids can be changed to amines because of their decarboxylation on the surface of the σ-MnO₂. Considering (1) the effect-inhibiting factor of amine F_A(β, K_a, pH) representing the complex potential of amine with Cu(II) in solution and (2) the acidic constant of −NH ₃ ⁺ group in the amine molecule representing the ability of cation exchange of the amine with σ-MnO₂, the inhibiting seqence of added amino acid of 20.00 ppm (Eq.(1)) is reasonable. Thus added amino acids do inhibit Cu(II)-σ-MnO₂ ion exchange because (1) the amino acid and/ or amine, which is the decarboxylate of the corresponding amino acid, complex with Cu(II) in solution and compete with σ-MnO₂ for Cu(II); (2) the cation exchange of the amino acid and/or amine reduce the exchange site on the surface of the σ-MnO₂. The results obtained from the isotherms indicated that the theory of interfacial stepwise ion exchange can be extended to the Cu(II) σ-MnO₂ ion exchange system in the presence of added amino acid.     

The intrinsic acidity constants and specific surface area of marine solid particles

This paper deals with the infrared spectra of “amino acid-clay, calcium carbonate and γ-AlOOH” and “Cu(II)-clay-amino acid” model systems, and shows that the model of the ternary surface complex is M-OHLCu (L=amino acid) for marine solid particle-Cu (II)-amino acid. Study of the formation mechanism of the ternary surface complex shows that the specific surface area, and especially the intrinsic acidity constant, determine whether the ternary surface complex is easily formed, and that factor,F _TSC, quantifies the relationship between the promoting effect of organics on M_t-marine solid particle ion exchange and the intrinsic acidity constant and specific surface area.     

Fourier-transform infrared spectroscopic studies on the interaction among marine trace metal ions,solid particles and organics

IR spectra of Cu (II)-marine solid particle systems show that Cu(II)-marine solid particle ion exchange causes a stepwise change in the surface H-bonding hydroxyl groups on illite, montmorillonite, CaCO₃, γ-AlOOH and goethite, but that this does not affect the surface free hydroxyl groups on illite, montmorillonite and CaCO₃, and framework hydroxyl group on goethite and on γ-AlOOH. Over the range of Cu (II) exchange amounts in the present experiment, four stepwise changes were discovered for the surface H-bonding hydroxyl group on illite, while two stepwise changes were observed on the other marine solids. The interfacial stepwise ion exchange theory was first demonstrated by the above experimental evidence.     

Study on the isotherms of the interaction between suspended particles and Cu (II) in the Huanghe River

The isotherms of the interaction between the suspended particles and Cu²⁺, and the effects of lysine and asparaginic acid on the isotherms in the Huanghe (Yellow) River were studied by applying the theory and method of interfacial stepwise ion/coordination particle exchange. We obtained a new stepped river isotherm, formed by two curves joined together with a “plateau” in the middle. The adsorption equilibrium constantsK ₁ andK ₂ were calculated by using the isothermal equation of surface stepwise ion exchange. Amino acid in small amount promotes exchange adsorption of the suspended particles with Cu²⁺. The degree of promotive action relates to the isoelectric point of amino acid. The promotive effect of lysine is bigger than that of asparaginic acid. Project 29361001 supported by NSFC.     

STUDY ON THE ISOTHERMS OF THE INTERACTION BETWEEN SUSPENDED PARTICLES AND Cu (Ⅱ) IN THE HUANGHE RIVER

ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｖａｒｉｏｕｓｐｈｙｓｉｃａｌａｎｄｃｈｅｍｉｃａｌｒｅａｃｔｉｏｎｓｔｈａｔｏｃｃｕｒｂｅｔｗｅｅｎｔｈｅｓｕｓｐｅｎｄｅｄｐａｒｔｉｃｌｅｓ,ｓｅｄｉｍｅｎｔｓ,ｅｔｃ.ａｎｄｈｅａｖｙｍｅｔａｌｓｉｎａｎａｔｕｒａｌａｑｕａｔｉｃｓｙｓｔｅｍｐｌａｙｅｘｔｒｅｍｅｌｙｉｍｐｏｒｔａｎｔｐａｒｔｓｉｎｃｏｎｔｒｏｌｌｉｎｇｔｈｅｄｉｓｔｒｉｂｕｔｉｏｎｐａｔｔｅｒｎ,ｍｉｇｒａｔｉｏｎａｎｄｔｒａｎｓｆｏｒｍａｔｉｏｎｏｆｈｅａｖｙｍｅｔａｌｓｔｈｅｒｅ.Ｓｉｎｃｅ…     

THE INTRINSIC ACIDITY CONSTANTS AND SPECIFIC SURFACE AREA OF MARINE SOLID PARTICLESII. THE RELATIONSHIP BETWEEN THE INTRINSIC ACIDITY CONSTANT AND THE TERNARY SURFACE COMPLEX

This paper deals with the infrared spectra of " amino acid- clay , calcium carbonate and y-AlOOH" and " Cu (II )-clay-amino acid" model systems, and shows that the model of the ternary surface complex is M-OHLCu (L = amino acid) for marine solid particle-Cu (II)-amino acid. Study of the formation mechanism of the ternary surface complex shows that the specific surface area , and especially the intrinsic acidity constant, determine whether the ternary surface complex is easily formed, and that factor, FTSC,quantifies the relationship between the promoting effect of organics on Mt-marine solid particle ion exchange and the intrinsic acidity constant and specific surface area.     

Effect of organics (fulvic acid and amino acids) on the interaction between Cu(II) and clays in sea water II. Isotherms and isotherm equations

In the present paper, determination of isotherms of the exchange reaction between Cu(II) and clays is presented, verifying again the “cation exchange—surface precipitation” isotherm worked out formerly in our laboratory. A modified BET equation was applied to treating the experimental data and describing the new isotherm. In addition, the mechanism of the effects of organics are further discussed and verified. Based on the isotherm equations and the estimates of the average area occupied by a single molecule on the surface, we put forward a new hypothesis which differs from the current one of “organic film”. Projects sponsored by the Science Fund of the Chinese Academy of Sciences.     

Interfacial stepwise ion/coordination particle exchange isotherm and isotherm equation on suspended marine particles

This article deals with a new type of isotherm discovered in sea water systems. The characteristics of this type of isotherm are the non-linear exponential relationship in the low concentration region and the isotherm composed of two or three “S” curves with one or two plateaus in the middle. This isotherm cannot be expressed by the isotherm equation used in marine chemistry at present.[⁷] Besides, there has been no report in literature about this type of isotherm in so far as the reaction of minor elements on hydrous oxides is concerned. In order to explain theoretically this type of isotherm, this article suggests the use of the theory of interfacial stepwise ion/coordination particle exchange (for simplicity, ion exchange is used herein-after) of suspended particles to deduce a corresponding isotherm equation. Proceeding from the isotherm of this article, we made theoretical analyses of these two characteristics as well as experiments in verification thereof. Twenty-four systems of experiments on this new type of isotherm and isotherm equation were designed and conducted. Experiment results agree with the theory reported here. Project supported by the Science Fund of the Chinese Academy of Sciences.     

Plateau typeE(%)- pH curves of interfacial exchange between liquid and solid in seawater

A study on the curves of the exchange ratioE(%)- pH on the liquid-solid interface of the systems Zn (II) with clay minerals, (Kaolinite, illite and montmorillonite), Zn (II) with hydrous ferric oxides (amorphous ferric oxide, geothite and hematite), Zn (II) with hydrous manganese oxide (γ-MnOOH, manganite and δ-MnO₂) etc. in seawater resulted in the discovery of new plateau type exchange ratioE(%)-pH curves not yet reported in literature. The two factors that decide the growth, decline and the change of the “plateau type” curve are: (1) the inherent characteristics of systems, which can be explained by the exchange constants (i=1, 2, 3, etc.) of interfacial stepwise ion/coordination particle exchange between liquid and solid; and (2) . The theory of interfacial stepwise ion/coordination particle exchange in seawater was applied to explain the experimental results of the above study and a general formula was derived for the plateau type exchange ratioE(%)-pH curves. The theoretically simulated and calculated curves coincided well with the experimental results. This paper provides new and powerful experimental basis to support the theory of interfacial stepwise ion/coordination particle exchange in seawater. The project was supported by the National Natural Science Foundation of China.     

Effect of organics (amino acids and fulvic acid) on the interaction between Cu(II) and clays in sea water

By the study of the effects of pH on the exchange ratio (%) of Cu(II) with clay(illite) in the presence of different concentrations of amino acids and fulvic acid, a new model of the mechanism of the effect of organics has been presented in this paper. Projects sponsored by the Natural Science Fund of the Chinese Academy of Sciences.     

Physical and interfacial chemistry of Huanghe estuary

Summarized results of studies on the physical and interfacial chemistry of the Huanghe estuary are presented as follows: 1. The relationship between the exchange ratio (%) and pH for the Cu (II)-Sedi.ments of the Huanghe Estuary and that of the Cu (II)-illite system were observed to be very similar. 2. A stepwise ion/coordination particle exchange isotherm of trace metal in Huanghe estuary sediment was derived. 3. The ion/coordination particle exchange between trace metal and Huanghe Estuary sediment is analogous to the interfacial chemical characteristic of illite.     

A new type of isotherm for zinc liquid-solid partitioning on δ−MnO2, γ−MnOOH and manganite in seawater

This article deals with the interaction of zinc with δ−MnO₂, γ−MnOOH and manganite existing in natural water systems. The mechanism of the reaction has been studied in detail. From the fact that the “ratio of ion exchange(%)-pH” graph is an “S shaped” curve, it is possible to deduce that the chemical reaction is of the nature of cation exchange. And since the pH range of ion exchange=4, it is possible to further deduce that the reaction can be explained by the mechanism of monovalence cation exchange. The main result of this article is the discovery of a new type of isotherm which has not been mentioned in previous literature here and abroad. This isotherm cannot be represented by any presently available adsorption isotherm equations in marine chemistry. The characteristics of this new type of isotherm are as follows: the isotherm has two “knees” and three “plateaus”, the heights of these three “plateaus” are in the ratio 1:2:3. In order to explain theoretically our new isotherm, this article suggests the application of the principle of interfacial stepwise ion exchange for liquid-solid distribution of minor elements on suspended particulate matter. The corresponding isotherm equation was derived from this theory. The results obtained in this article will be of theoretical guiding significance in the study of the marine geochemistry of zinc. Projects supported by the Science Fund of the Chinese Academy of Sciences.     

Measurement of Labile Cu, Pb and Their Complexation Capacity in Yueqing Bay in Zhejiang Province, China

1　INTRODUCTIONRecently ,thepollutionoftracemetalinseawaterhasbecomeincreasinglyevident.Researchershavefo cusedattentiontotracemetalpresentinvariousexistenceforms ,especiallyorganiccomplexingphases.Theexistencestatesandtransportmechanismofbaytracemetalswerethesubjectofstudybysomere searchers(Gu ,1 991 ;Florence ,1 998;Guo ,1 998;Wells,1 991 ,1 998a ,b ;Wellsetal.,1 998) .Whetherinfreshwaterorseawater,colloidsareclearlydominantfactorsaffectingtheexistencestatesandtransportmechanismoftrac…     

Photochemical oxidation of benzothiophene in seawater

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Determination of Trace Copper （Ⅱ） in Water Samples by Kinetic-spectrophotometry

A new kinetic-spectrophotometric method is proposed for the determination of copper （ Ⅱ ）. The method is based on the catalytic effect of copper （ Ⅱ ） on the oxidation of weak acid brilliant blue dye （RAWL） by hydrogen peroxide. The copper （ Ⅱ ） can be determined spectrophotometrically by measuring the decrease of absorbance of RAWL at λ = 626 nm using the fix-time method. The optimum reaction conditions are as follows： pH 7.20, buffer solution NaOH-KH2PO4, RAWL （200 mgL-1） 5.00 mL, H2O2 （30%） 0.50 mL, reaction temperature 80 ？？ and reaction time 20 min. The linear range of this method is between 0 μg L^-1 and 12 μg L^-1 and the limit of detection is 0.011 μg L-1, the relative standard deviation （RSD） in five replicate determinations for 2 and 8 μg L-1 copper （ Ⅱ ） are 3.2% and 2.3%, respectively. Twenty ions do not interfere in the determination of copper （ Ⅱ ）. The method has been applied satisfactorily to the determination of copper （ Ⅱ ） in freshwater samples （tap water and Yellow River water from Lijin, Shandong, China） and seawater samples （from the South China Sea）, the recovery rates are 98.0%, 102.5% and 96.0%, respectively.     

Biosorption of Cd (Ⅱ) and Pb (Ⅱ) Ions by Aqueous Solutions of Novel Alkalophillic Streptomyces VITSVK5 spp. Biomass

Discharge of heavy metals from metal processing industries is known to have adverse effects on the environment. Biosorption of heavy metals by metabolically inactive biomass of microbial organisms is an innovative and alternative technology for removal of these pollutants from aqueous solution. The search of marine actinobacteria with potential heavy metal biosorption ability resulted in the identification of a novel alkalophilic Streptomyces VITSVK5 species. The biosorption property of Streptomyces VITSVK5 spp. was investigated by absorbing heavy metals Cadmium (Cd) and Lead (Pb). Physiochemical characteristics and trace metal concentration analysis of the backwater showed the concentrations of different metals were lead 13±2.1 μg L⁻¹, cadmium 3.1±0.3μg L⁻¹, zinc 8.4±2.6μg L⁻¹ and copper 0.3±0.1μg L⁻¹, whereas mercury was well below the detection limit. The effect of pH and biomass dosage on removal efficiency of heavy metal ions was also investigated. The optimum pH for maximal biosorption was 4.0 for Cd (II) and 5.0 for Pb (II) with 41% and 84% biosorption respectively. The biosorbent dosage was optimized as 3 g L-1 for both the trace metals. Fourier transform infrared absorption spectrum results indicated the chemical interactions of hydrogen atoms in carboxyl (-COOH), hydroxyl (-CHOH) and amine (-NH₂) groups of biomass with the metal ions. This could be mainly involved in the biosorption of Cd (II) and Pb (II) onto Streptomyces VITSVK5 spp. The results of our study revealed Streptomyces metabolites could be used to develop a biosorbent for adsorbing metal ions from aqueous environments.     

Application of transition metal isotope tracers in global change research

High-precision isotope composition determinations using multicollector, magnetic-sector inductively coupled plasma mass spectrometry (MC-ICPMS) have recently revealed that some transition metal isotopes such as those of Mo, Fe, Cu, Zn etc. can be used as biogeochemical tracers in global change research.The Mo isotope system may be useful in paleoredox investigations indicating that δ^97 ^95Mo in seawater may co-vary with changes in the relative proportions of anoxic and oxic sedimentation in the ocean, and that this variation may be recorded in δ^97 ^95Mo of anoxic sediments. The Mo continental flux into the oceans and the global Mo isotope budget can be estimated from δ^97 ^95M0 values. The Fe isotope composition in seawater is an important issue because Fe plays a controlling role in biological productivity in the oceans and its abundance in seawater may have substantial effect on climate changes. Iron isotope fractionations could result from bio- and abio-processes and have about 0.1% variation ( δ^56 ^54Fe), so Fe isotopes considered alone cannot be used to distinguish the products of abiotic and biotic Fe processing in geological records. Cu and Zn isotopes are also used as biogeochemical tracers, but the researches are relatively less. This review mainly focuses on the methods for preparation, purification and determination of new isotope tracer samples, and on isotope applications in marine environmental changes.     

Embeddable reference electrode for reinforced concrete

Laboratory and field tests on our newly developed embeddable reference electrode for reinforced concrete show it can be embedded into reinforced concrete structures and be used for measuring the potentials of the rebar or other metal elements in the outer structural part exposed to seawater. Its potential varies little with the change of Cl⁻ concentration of the electrolyte and is stable over a time range of 260 days. The electrode can be used for monitoring corrosion and cathodic protection of reinforced concrete structures in seawater. Contribution No. 1605 from the Institute of Oceanology, Academia Sinica.     

PLATEAU TYPE E(%)-pH CURVES OF INTERFACIAL EXCHANGE BETWEEN LIQUID AND SOLID IN SEAWATER

A study on the curves of the exchange ratio E(%)-pH on the liquid-solid interface of the systems Zn(II) with clay minerals (Kaolinite , illite and montmorillonite), Zn(II) with hydrous ferric oxides (amorphous ferric oxide, goethite and hematite). Zn(II) with hydrous manganese oxide (y-MnOOH, manganite and 5-MnO2) etc . in seawater resulted in the discovery of new plateau type exchange ratio ?%)-pH curves not yet reported in literature. The two factors that decide the growth , decline and the change of the " plateau type " curve are : (1) the inherent characteristics of systems , which can be explained by the exchange constants i(i=1 ,2 , 3 . etc .) of interfacial stepwise ion / coordination particle exchange between liquid and solid ; and (2)The theory of interfacial stepwise ion/coordination(the amount of solid exchange reagent)particle exchange in seawater was applied to explain the experimental results of the above study and a general formula was derived for the plateau type exchange ratio E(%)-pH c     

Concentrations and distribution of trace metals of PM<Subscript>10</Subscript> and TSP particles collected in the qingdao area

Aerosol samples of PM₁₀ (particulate matter with aerodynamic diameters less than 10μm) and TSP (total suspended particles) were simultaneously collected from April 2001 to March 2002 at the top of Mount Baguan on the downtown campus of Ocean University of China, Qingdao, China. The concentrations of Al, Fe, Mn, Cu, Pb and Zn were determined by means of inductively coupled plasma atomic emission spectrometry (ICP-AES). The monthly variability of the mass concentrations of aerosol particles and the concentrations of trace metals are presented and discussed. The distribution pattern of these metals in PM₁₀ and TSP is also discussed. During the observation period, the mass concentration of PM₁₀ at this site ranged from 13.80 to 306.42 μgm⁻³, while that of TSP ranged from 31.02 to 568.82μgm⁻³. Both PM₁₀ and TSP reached their highest concentrations in springtime, while the lowest values occurred in summertime. The concentrations of crustal metals followed the same variation pattern, while those of anthropogenic metals did not. A closer examination led to the conclusion that anthropogenic metals are mainly from local sources. The average concentration ratios of anthropogenic metals in PM₁₀ to TSP were higher than the average mass ratio of PM₁₀ to TSP, suggesting that there was a higher proportion of anthropogenic metals on smaller particles although there were a few exceptions. For crustal metals, however, the metal concentration ratios were close to the particle mass ratio, indicating that the distribution of crustal metals was much more homogeneous on aerosol particles with different sizes. The correlation analysis indicated that Al, Fe and Mn were originated from similar sources and were mainly controlled by the particle mass, while Cu, Pb and Zn were predominated by local anthropogenic sources, with Pb and Zn having similar origins.