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Remote sensing of the Earth has demonstrated that photosynthesis is traceable as the vegetation red edge (VRE), which is a steep rise in the reflection spectrum of vegetation, and as solar-induced fluorescence. This study examines the detectability of biological fluorescence from two types of photosynthetic pigments, chlorophylls (Chls) and bacteriochlorophylls (BChls), on Earthlike planets with oxygen-rich/poor and anoxic atmospheres around the Sun and M dwarfs. Atmospheric absorption, such as H2O, CH4, O2, and O3, and the VRE obscure the fluorescence emissions from Chls and BChls. We find that the BChl-based fluorescence for wavelengths of 1000–1100 nm, assuming the spectrum of BChl b–bearing purple bacteria, could provide a suitable biosignature, but only in the absence of water cloud coverage or other strong absorbers near 1000 nm. The Chl fluorescence is weaker for several reasons, e.g., spectral blending with the VRE. The apparent reflectance excess is greatly increased in both the Chl and BChl cases around TRAPPIST-1, due to the fluorescence and stellar absorption lines. This could be a promising feature for detecting the fluorescence around ultracool red dwarfs using follow-up ground-based observations at high spectral resolution; however, this would require a long time around Sunlike stars, even for a LUVOIR-like space mission. Moreover, the simultaneous detection of fluorescence and the VRE is the key to identifying traces of photosynthesis, because absorption, reflectance, and fluorescence are physically connected. For further validation of the fluorescence detection, the nonlinear response of biological fluorescence as a function of light intensity could be considered.

Novel reaction pathways with the neutral radical-molecule reaction to form cytosine, a nucleobase of DNA and RNA, which can proceed in the interstellar environment, were discovered by automated reaction pathway calculations based on transition state theory. We suggested the barrierless and exothermic formation of cytosine in two steps. First, the reaction between O radical and ethynamine forms a key precursor species, NH2CCHO. Then, this radical reacts with CN and HNCH to form cytosine. This study would contribute to elucidating possible reactions on nucleobases under lower temperatures, and further tests are effective by astronomical modeling/observations and laboratory experiments.

In a certain period of Earth's history, chlorophylls with Mg as their central metal would have been selected as the major photosynthetic pigments, reflecting the radiation in habitats. Assuming evolution in different light and material environments, different photosynthetic pigments would occur. This study is the first attempt to evaluate the physical and chemical properties of model photosynthetic pigments and their potential to function in a variety of light environments using quantum chemistry calculations. Specifically, bacteriochlorophyll b (Bchl b), phthalocyanine (Pht) and meso-dibenzoporphycene (mDBPc) were selected as template molecules, while Be, Mg, Ca, Ni, Zn, Sr, Pd, Cd, Ba, Pt, Hg, Pb and H2 were examined as the central metals in each molecule in various solvents. The results showed that the light absorption by each of these compounds varied over a range of 100 nm depending on the central metal and the surrounding solvent, and Pb produced the largest red shift in the absorption bands of all three photosynthetic pigments. The Pht molecules showed similar redox properties to the chlorophylls, suggesting that these derivatives could be substituted for the special pairs in reaction centers, while the mDBPc molecules appear to be more suitable as accessory pigments due to their extraordinarily broad absorption ranges of approximately 500 nm depending on the conditions.

Surface functionalized mesoporous silicates, MCM-41s, having 3-(2-pyridylmethylideneimino)propyl group (PI-MCM-41) or 3-(2-quinolylmethylideneimino)propyl group (QI-MCM-41) were prepared via Schiff base reaction, and the adsorption behavior of metal ions onto the modified MCM-41s was investigated. The function groups on the modified MCM-41 surface were confirmed by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and elemental analysis. The metal ions examined, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, and Pb2+, were quantitatively adsorbed on the PI-MCM-41 and QI-MCM-41, except for Mn2+. In the complexation with these metal ions, it was suggested that imine-N and heterocyclic-N atoms act as donor atoms. In addition, it was considered that the hydrophobicity derived from the organo-functional groups modified on MCM-41 contributed to improving the adsorption ability.

Anti-bear podoplanin (bPDPN) monoclonal antibodies (mAbs), including PMab-247 and PMab-241, have been previously established. Although PMab-247 has shown positive immunostaining for lymphatic endothelial cells (LECs), type I alveolar cells of the lung, and podocytes of the kidney, PMab-241 stains LECs but does not react with lung type I alveolar cells. PDPN possesses three platelet aggregation-stimulating (PLAG) domains (PLAG1, PLAG2, and PLAG3) and the PLAG-like domain (PLD). The binding epitope of PMab-247 was previously determined to include bPDPN residues Asp76, Arg78, Glu80, and Arg82. Among these, Glu80 and Arg82 are included in PLD of bPDPN. The purpose of this study is to determine the binding epitope of PMab-241 and to clarify the difference between these two anti-bPDPN mAbs. Analysis of bPDPN deletion mutants revealed that the N-terminus of the PMab-241 epitope exists between amino acids (aa) 75 and 80 of bPDPN. In addition, analysis of bPDPN point mutants demonstrated that the critical epitope of PMab-241 includes Thr75, Asp76, and Arg78 of bPDPN. The binding epitopes of PMab-241 and PMab-247 seem to overlap, but this slight difference may be sufficient to provide the specificity of PMab-241 to discriminate LECs from type I alveolar cells of the lung.

Antibody–drug conjugates (ADCs), which consist of a monoclonal antibody (mAb), a linker, and a payload, can deliver a drug to cancer tissues. We previously produced an anti-dog podoplanin (dPDPN) mAb, PMab-38, which reacts with dPDPN-expressing canine melanomas and squamous cell carcinomas (SCCs), but not with dPDPN-expressing canine type I alveolar cells or lymphatic endothelial cells, indicating that PMab-38 possesses cancer specificity. In this study, we developed an ADC, P38B-DM1, using the mouse–canine chimeric anti-dPDPN antibody, P38B as the antibody, a peptide linker, and emtansine as the payload using the chemical conjugation by affinity peptide (CCAP) method. We investigated its cytotoxicity against dPDPN-overexpressed Chinese hamster ovary (CHO/dPDPN) cells in vitro and its antitumor activity using a mouse xenograft model of CHO/dPDPN cells. P38B-DM1 showed cytotoxicity to CHO/dPDPN cells in a dose-dependent manner in vitro. Furthermore, P38B-DM1 exhibited higher antitumor activity than P38B in the mouse xenograft model. These results suggest that P38B-DM1, developed using the CCAP method, is useful for antibody therapy against dPDPN-expressing canine SCCs and melanomas.

CD19 is a type I transmembrane glycoprotein belonging to the immunoglobulin superfamily. It is expressed in normal and neoplastic B cells, and it modulates the threshold of B cell activation for amplifying B cell receptor signaling. Blinatumomab (a CD3-CD19-bispecific T cell-engaging antibody) and tisagenlecleucel (genetically modified T cells that express a CD19 chimeric antigen receptor [CART-19]) provide significant benefits for patients with CD19-positive relapsed or refractory B cell malignancies. In this study, we first employed the Cell-Based Immunization and Screening (CBIS) method to produce anti-CD19 monoclonal antibodies using CD19-overexpressing cells for both immunization and screening. One established clone-C19Mab-1-proved to be useful in flow cytometry assays against lymphoma cell lines, such as BALL-1, P30/OHK, and Raji. Second, the extracellular domain of CD19 was immunized into mice, and enzyme-linked immunosorbent assays were performed for the first screening. One established clone-C19Mab-3-was determined to be useful for Western blotting and immunohistochemical analysis. Due to their complementary utility, a combination of C19Mab-1 (established using CBIS) and C19Mab-3 (established using conventional method) could be useful for the pathological analysis of CD19.

C-C motif chemokine receptor 8 (CCR8) is a G protein-coupled receptor predominantly expressed in regulatory T (Treg) and T helper 2 cells. The evidence that CCR8 expression in Treg is increased in cancers, CCR8 increases migration activity of Treg, and CCR8 induces the anti-apoptotic activity in T cell leukemia and lymphoma suggests that CCR8 is associated with cancer development. Thus, developing a specific monoclonal antibody (mAb) for CCR8 is useful for diagnostic and therapeutic purposes and the anti-CCR8 mAb becomes a remarkable experimental tool for basic research. We previously developed an anti-mouse CCR8 (mCCR8) mAb called C

This study was undertaken to investigate the extraction of In3+ and Ga3+ by 7-(4-ethyl-1-methyloctyl)-8-hydroxy-quinoline (Kelex100), which has been found to be a slow extraction process. H...

Sensitive and specific monoclonal antibodies (mAbs) targeting podoplanin (PDPN) are needed for immunohistochemical analyses as a marker for lymphatic endothelial cells. We recently have developed anti-PDPN mAbs against many species, including human, mouse, rat, rabbit, dog, cat, bovine, pig, Tasmanian devil, alpaca, tiger, whale, goat, horse, and bear. However, anti-sheep PDPN (sPDPN) has not yet been established. In this study, we used the Cell-Based Immunization and Screening method for the development of anti-sPDPN mAbs. RAP14 tag was added to N-terminus of sPDPN, and anti-RAP14 tag mAb (PMab-2) was used to detect the expression level of sPDPN in flow cytometry and western blot. We immunized mice with sPDPN-overexpressing Chinese hamster ovary (CHO)-K1 (CHO/sPDPN) cells and screened mAbs against sPDPN using flow cytometry. One of the mAbs, PMab-256 (IgG1, kappa), specifically detected CHO/sPDPN cells by flow cytometry and western blot. Furthermore, PMab-256 stained type I alveolar cells of lung, renal glomerulus and Bowman's capsule, and lymphatic endothelial cells of lung and colon. Our findings suggest the potential usefulness of PMab-256 for the functional analyses of sPDPN.

Glycine, the simplest amino acid, has been intensively searched for in molecular clouds, and the comprehensive clarification of the formation path of interstellar glycine is now imperative. Among all the possible glycine formation pathways, we focused on the radical pathways revealed by Garrod (2013). In the present study, we have precisely investigated all the chemical reaction steps related to the glycine formation processes based on state-of-the-art density functional theory (DFT) calculations. We found that two reaction pathways require small activation barriers (ΔE‡ ≤ 7.75 kJ mol–1), which demonstrates the possibility of glycine formation even at low temperatures in interstellar space if the radical species are generated. The origin of carbon and nitrogen in the glycine backbone and their combination patterns are further discussed in relation to the formation mechanisms. According to the clarification of the atomic correspondence between glycine and its potential parental molecules, it is shown that the nitrogen and two carbons in the glycine can originate in three common interstellar molecules, methanol, hydrogen cyanide, and ammonia, and that the source molecules of glycine can be described by any of their combinations. The glycine formation processes can be categorized into six patterns. Finally, we discussed two other glycine formation pathways expected from the present DFT calculation results.

As a possible formation mechanism of glycine in astrophysical environments, a reaction path via aminoacetonitrile and hydantoin (2,4-imidazolidinedione), which have been detected in an interstellar cloud and meteorites, respectively, were analyzed using the density functional theory. The formation of hydantoin from aminoacetonitrile via the Bucherer-Bergs reaction and the hydrolysis of hydantoin were investigated. The results showed that the catalytic water molecules significantly lower the reaction barriers for the formation of hydantoin. Although the highest barrier is still too high that the pathway is inactive in an interstellar medium, this reaction would proceed during the heating of the meteorite parent body.

In photosynthetic organisms, light energy is converted into chemical energy through the light absorption and excitation energy transfer (EET) processes. These processes start in light-harvesting complexes, which contain special photosynthetic pigments. The exploration of unique mechanisms in light-harvesting complexes is directly related to studies, such as artificial photosynthesis or biosignatures in astrobiology. We examined, through ab initio calculations, the light absorption and EET processes using cluster models of light-harvesting complexes in purple bacteria (LH2). We evaluated absorption spectra and energy transfer rates using the LH2 monomer and dimer models to reproduce experimental results. After the calibration tests, a LH2 aggregation model, composed of 7 or 19 LH2s aligned in triangle lattice, was examined. We found that the light absorption is red shifted and the energy transfer becomes faster as the system size increases. We also found that EET is accelerated by exchanging the central pigments to lower energy excited pigments. As an astrobiological application, we calculated light absorptions efficiencies of the LH2 in different photoenvironments.

For detecting life from reflection spectra on extrasolar planets, trace of photosynthesis is one of the indicators. However, it is not yet clear what kind of radiation environments is acceptable for photosynthesis. Light absorption in photosystems on the Earth occurs using limited photosynthetic pigments such as chlorophylls (Chls) and bacteriochlorophylls (BChls). Efficiencies of light absorption for the pigments were evaluated by calculating the specific molecular absorption spectra at the high accuracy-quantum mechanical level. We used realistic stellar radiation spectra such as F, G, K and M-type stars to investigate the efficiencies. We found that the efficiencies are increased with the temperature of stars, from M to F star. Photosynthetic pigments have two types of absorption bands, the Qy and Soret. In higher temperature stars like F star, contributions from the Soret region of the pigments are dominant for the efficiency. On the other hand, in lower temperature stars like M stars, the Qy band is crucial. Therefore, differences on the absorption intensity and the wavelength between the Qy and Soret band are the most important to characterize the photosynthetic pigments. Among photosynthetic pigments, Chls tend to be efficient in higher temperature stars, while BChls are efficient for M stars. Blueward of the 4000 Å break, the efficiencies of BChls are smaller than Chls in the higher temperature stars.

Rational design of protein surface is important for creating higher order protein structures, but it is still challenging. In this study, we designed in silico the several binding interfaces on protein surfaces that allow a de novo protein–protein interaction to be formed. We used a computer simulation technique to find appropriate amino acid arrangements for the binding interface. The protein–protein interaction can be made by forming an intermolecular four-helix bundle structure, which is often found in naturally occurring protein subunit interfaces. As a model protein, we used a helical protein, YciF. Molecular dynamics simulation showed that a new protein–protein interaction is formed depending on the number of hydrophobic and charged amino acid residues present in the binding surfaces. However, too many hydrophobic amino acid residues present in the interface negatively affected on the binding. Finally, we found an appropriate arrangement of hydrophobic and charged amino acid residues that induces a ...

BACKGROUND A number of inorganic fertilizers have been used as a slow-release fertilizer for plants but control of release rates of nutrient ions can be difficult. We have prepared a novel slow-release inorganic fertilizer consisting of zeolite NaP1/hydroxyapatite nanocomposite containing the following nutrient ions: 17.4 mg g-1 of ammonium ion, 54.6 mg g-1 of potassium ion and 24.1 mg g-1 of phosphate ion. The release behavior of nutrient ions were evaluated in distilled water. RESULTS Zeolite NaP1 was synthesized from coal fly ash by alkaline hydrothermal treatment. The zeolite surfaces were then covered with hydroxyapatite needle-like crystals of about 200 nm diameter by a hydrothermal treatment of the calcium-exchanged zeolite NaP1 in a mixed solution of potassium and ammonium phosphates at 40°C for 8 h. The release behavior of the nanocomposite was evaluated by measuring the release into distilled water of nutrient ions over the long term. Phosphate ions were slowly released by the dissolution of HA in water, ammonium and potassium ions by cation exchange with calcium co-dissolved with phosphate. CONCLUSION The zeolite NaP1/hydroxyapatite nanocomposite obtained is very useful as an inorganic fertilizer which can release nutrient ions over a long time. © 2013 Society of Chemical Industry

Oxidized di(2-ethylhexyl)dithiophoshate (Phoslex DT-8) in n-hexane is shown to extract Sc(III) greater than 97% in the pH range of 1.01–4.46, while ZrO(II) is not extracted under the same conditions. Phoslex DT-8 was oxidized by blowing air in it, and the percent extraction of Sc(III) increased along with the duration of air-oxidation. The present extraction system can be used to separate Sc(III) from ZrO(II), Ti(III), Y(III) and Al(III) in a single batchwise extraction.

Nano-sized boehmites with different crystallinity were synthesized at the temperature range of 25 to 200°C in order to produce phosphate absorbents with high capacity. The physicochemical property of boehmites was depended on the synthesis temperature: the particle size was increased and the surface area showed the maximum for the boehmite at 50°C. The phosphate sorptions into boehmites were analyzed at room temperature in the phosphoric acid solutions as a model of wastewater at the concentration of 0.1 to 3.0 mmol l−1 and the pH of 3 to 7. The boehmite synthesized at 50°C exhibited the highest amount of phosphate sorption (1.73 mmol g−1 at pH 3.3) compared with Al-bearing materials. The reaction mechanism during phosphate sorption was described by the anion exchange reaction between phosphate ions in sodium phosphate solution and hydroxide ions on boehmite surfaces. Therefore, the variation in the amount of phosphate sorption on the different boehmite samples depends strongly on the surface area in the ...

Hydrophobic zeolite was synthesized, modified and characterized for its suitability as a permeable reactive barrier (PRB) material for treatment of hydrocarbons in groundwater. Batch sorption tests were performed along with a number of standard characterization techniques. High and low ionic strength and pH tests were also conducted to determine their impact on hydrocarbon uptake. Further ion exchange tests were conducted to determine the potential for the zeolite to act as both a hydrocarbon capture material and nutrient a delivery system for bioremediation. The zeolite was coated with octadecyltrichlorosilane (C18) to change its surface properties. The results of the surface characterization tests showed that the underlying zeolite structure was largely unaffected by the coating. TGA measurements showed a reactive carbon content of 1-2%. Hydrocarbon (o-xylene and naphthalene) sorption isotherms results compared well with the behaviour of similar materials investigated by other researchers. Ionic strength and pH had little effect on hydrocarbon sorption and the treated zeolite had an ion exchange capacity of 0.3 mequiv./g, indicating it could be utilised as a nutrient source in PRBs. Recycle tests indicated that the zeolite could be used cleaned and reused at least three times without significant reduction in treatment effectiveness.

Zeolite A whose surface was evenly covered with tiny scaly calcium deficient hydroxyapatite (Ca-def HA) nanocrystals was prepared through the ion exchange reaction of ammonium and calcium ions as a novel encapsulation material for the long-term immobilization of radioactive Sr-90. The maximum capacity for Sr ion uptake in the zeolite A/Ca-def HA nanocomposite was determined to be 0.40 mmol g−1, which was comparable to the value for zeolite A alone; this was because of the loose arrangement of Ca-def HA nanocrystals on the surfaces. The nanocomposite obtained was heated at 800 to 1200°C to improve the solution stability of adsorbed Sr ions. The low crystalline Ca-def HA became tricalcium phosphate (TCP) after heating at over 850°C. A phase change from zeolite A to an amorphous phase was observed at 850°C and to feldspar at 1000°C. The elution of Sr ions from the nanocomposites heated was compared to those from the heated zeolite A, under alkaline conditions (pH 10.2) similar to those found in geological layers deeper than 300 m. The elution amounts of Sr ions from the nanocomposites decreased with heating temperatures over 950°C compared with those of zeolite A, due to the complete coverage of TCP crystals. These results indicate that calcium phosphate nano-layers on the zeolite A surfaces play an important role for the long-term encapsulation of Sr ions in the nanocomposites.

Highly crystalline Ca-Al layered double hydroxides (LDH) covered with needle-like hydroxyapatite (HA) nanocrystals was prepared from Ca-Al-Cl LDH by an alkaline treatment at 40°C using a Na 3 PO 4 solution at pH 9.0. The HA nanocrystals had lengths of 100-200 nm, widths of 30 nm, and were grown on the surface of hexagonal LDH plate crystals. A 80-nm-thick nanolayer was observed between the HA and LDH, and was found to contain calcium and phosphate, but no aluminum or chloride. This layer was initially formed by the anion exchange reaction of phosphate ions in solution with chloride ions in the LDH crystals. The LDH structure was retained during this reaction. The elution of calcium ions from the LDH basal layers initiated the precipitation of the HA crystals on the surface. The stability of LDH in hydrochloric acid (pH 3) was dramatically improved by the presence of the nanolayers. The LDH-HA nanocomposites are acid-resistant and have potential in areas such as the sustainable removal of harmful anions and cations and as drug delivery carriers.

MCM-41 is a synthetic, mesoporous silicate material, which currently has limited use as an industrial catalyst. This material is considered to have good potential for adsorption/separation applications due to its regular hexagonal structure, uniform pore distribution, large surface area and large pore volume. In order to enhance the adsorption of metal ions on MCM-41, a metal ion chelating agent, acetylacetone is added and the capacity of the adsorbent for three divalent metal cations in aqueous solutions; Cu(II), Ni(II) and Co(II) determined. Adsorption isotherms for these metal ions are presented, along with adsorption selectivity with respect to pH. Metal ion adsorption results are compared with published data for solvent extraction systems utilising pure acetylacetone and acetylacetone in benzene. It was found that the MCM-41/acetylacetone system produced equal or better metals removal in comparison to solvent extraction methods for some of the metal species tested. Further, the pH of maximum adsorption is shifted in the MCM-41 system compared with the solvent extraction case, thus presenting the possibility of processing under different conditions.

A simple, sensitive and selective method for the simultaneous determination of nitrite and nitrate in water samples has been developed. The method is based on ion-exchange separation, online photochemical reaction, and luminol chemiluminescence detection. The separation of nitrite and nitrate was achieved using an anion-exchange column with a 20 mM borate buffer (pH 10.0). After the separation, these ions were converted to peroxynitrite by online UV irradiation using a low-pressure mercury lamp and then mixed with a luminol solution prepared with carbonate buffer (pH 10.0). The calibration graphs of the nitrite and nitrate were linear in the range from 2.0 × 10−9 to 2.5 × 10−6 M and 2.0 × 10−8 to 2.5 × 10−5 M, respectively. Since the sensitivity of nitrite was about 10 times higher than that of nitrate, the simultaneous determination of nitrite and nitrate in the water samples could be efficiently achieved. This method was successfully applied to various water samples – river water, pond water, rain water, commercial mineral water, and tap water – with only filtration and dilution steps.

Heteroaromatic compounds, such as 2,5-dimethylthiophene, 2,5-dimethylpyrrole, and 2,5-dimethylfuran, were found to act as reducing agents for the tris(2,2'-bipyridine)ruthenium(III), Ru(bpy)3(3+), chemiluminescent reaction. In order to characterize the chemiluminescent reaction of Ru(bpy)3(3+) with heteroaromatic compounds, we have investigated various mono-, di-, and tri-heteroaromatic compounds. The pi-electron density and stability of aromatic rings influence the chemiluminescent efficiency of the reaction. Above all, 2,5-dimethylthiophene produced strong chemiluminescence under acidic conditions. In addition, we confirmed that the rate of the chemiluminescent reaction of Ru(bpy)3(3+) with 2,5-dimethylthiophene is very fast.

—In this study mesoporous silicates MCM-41 and SBA-15 were investigated for their potential as metal ion-selective adsorbents. The greatest advantage of these materials is their large surface area, uniform pore size and controlled surface chemistry, and hence their potential for adsorption processes. The studies of the adsorption of transition metal ions onto MCM-41 examined the comparative adsorption behavior of Zn(II) and Cu(II), using acetylacetone (Hacac) as a chelating agent. The results showed that the MCM-41/Hacac system has potential as an ion-selective adsorbent material. However, due to the relatively small pore size and potential instability of MCM-41 when immersed in water for long time periods, a second mesoporous silicate, SBA-15, has been investigated. The SBA-15 was coated with octadecyltrichlorosilane (C18), and then loaded with a chelating agent (Cyanex 272) and assessed for its potential as an adsorbent material. The surface-modified SBA-15 has been found to have high metal ion selectivity and extractability, and hence good potential as an alternative to established solvent extraction systems.

Korean natural zeolite with feldspar and illite as impurities was purified by air classification to improve the ammonium adsorption capacities. The treated zeolite was classified into 5 fractions with different amounts of zeolite minerals and impurities. Ammonium adsorptions on the air-classified samples in ammonium chloride solution were compared with that of unclassified zeolite. The highest capacity for ammonium adsorption was obtained for the air-classified sample operated at 12000 rpm with the largest amount of zeolite and the smallest amount of feldspar. The maximum adsorption capacity was 0.93 mmol/g, which was 1.2 times the unclassified sample.

The extraction and separation of the divalent metals was studied by using ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6) including the extractant of 2-pyridinealdoxime (2-PA) . The divalent metals used here are Cd2+ and Pb2+ for the toxic and Ni2+ and Zn2+ for the valuable metals in industry. These metal ions in potassium nitrate of 0.10 mol dm-3 concentration were examined to be extractable. It was observed that Cd2+ was extracted into ionic liquid phase better than Pb2+ and Zn2+ in the pH range of 5.15-9.83 and its extractability was reached to >99% in the pH of 7.93-9.83. The extraction equilibrium of Cd2+ with 2-PA into BMIM-PF6 was found to be Cdcit (w) -+3HL (o) _??_CdL2HL (o) +2H++cit3-, whose mechanism is the same way as that into chloroform (CHCl3) . The mutual separation of Cd2+, Pb2+, Ni2+, and Zn2+ can be achieved by using the different pH values of the aqueous phase in 2-PA/BMIM-PF6 extraction system. From these results, it can be stated that the 2-PA/BMIM-PF6 extraction system is useful to extract and separate the divalent metal ions examined in this work.

The hydrotalcite-type compounds were prepared to examine the possibility for use at elevated temperature. The combinations of di- and tri-valent metals were Ni2+-Al3+, Ni2+-Fe3+, and Co2+-Al3+ The ion exchange property was examined on chloride ion, nitrate ion, and chromate ion. The temperature examined was RT - 200 °C. Among the combination of metal ions, Ni2+-A13+ combination was most stable and Ni2+ content over 0.84 in mole ratio gave a sturdy granular lump and chemically stable during the ion exchange reaction. The ion exchange reaction at the elevated temperature was examined for the sample with Ni2+ content around 0.84. Almost no NO3-as well as Cl- ion was exchanged on the sample treated with 0.1 mol dm-3 NaOH. As for CrO42- ion, the exchange ratio was about 93 % at room temperature and almost 100 % at 120 - 200 °C. The dissolution of Ni2+ and Al3+ from the host exchanger was hardly observed below 120 °C, fairly stable at 150 °C, a small amount of dissolved Al3+ being observed.

A noble photometric method using a transparent polymer beads consisting of gelatinous poly (sodium acrylate) as an adsorbent was newly developed. Seven different cationic dyes were arbitrarily chosen as a colored species to establish the optimum conditions. It was confirmed that Beer's law held between the absorbance of polymer beads and the concentration of cationic dye when 40 cm3 of sample solution was equilibrated with 2.0 cm3 of polymer gel by shaking for 60 min.

The ammonium ion exchange behaviors on three natural zeolites (clinoptilolites) with different particle sizes were investigated for ammonium removal from wastewaters. In particular, the effects of reaction time, and ammonium concentration were examined in ammonium chloride solutions. The reaction rate for ammonium ion exchange on clinoptilolites depended on the particle size, and the ammonium exchange capacities of clinoptilolites have no effect on particle sizes. The ammonium ions in solutions were exchanged with dominantly Na+ ions on clinoptilolites.

The Steric effect of two di-Schiff base ligands having phenylene skeleton as extractant on ion-pair extraction of divalent metal cations into nitorbenzene with picrate anion was investigated. In these extraction systems, all of the extraction except for nickel was equilibrated within 1 h, and ratio of metal: ligand: picrate in the extracted species was 1: 2: 2 or 1: 3: 2. In the extraction of nickel, 2 or 10 hours needed to be equilibrated and the Steric effect of ligands resulted in the change of the extracted species. Namely, a difference between the favorable extracted species for kinetics and equilibrium appeared by the steric effect. Consequently, nickel was extracted quantitatively and the highly selectivity for nickel was obtained.

In this study surface modified SBA‐15, coated with octadecyltrichlorosilane (C18), is considered as an alternative adsorbent for metal ions in water. The SBA‐C18 was loaded with Bis(2,4,4-trimethylpentyl) phosphinic acid (cyanex 272) as the metal ion extractant. The adsorption characteristics of phosphinic acid loaded SBA‐C18 were evaluated for Cu(II) and Zn(II) ions in aqueous solution. Adsorption tests indicated that a contact time of 1 hour was sufficient for adsorption equilibrium to occur. The pH1/2 values of Zn(II) and Cu(II) onto SBA‐C18, were found to be similar to published data for levextrel ion exchange resins and around 1 pH unit lower than published solvent extraction data for cyanex 272 in xylene.

This investigation examines metal ion adsorption on mesoporous silicate, MCM‐41, synthesized from sodium silicate solution and cethyltrimethylammonium bromide (CTAB). MCM‐41 has potential as an adsorbent material, with a regular hexagonal pore structure, large specific surface area, and large pore volume. The MCM‐41 synthesized for this investigation is characterized using powder X‐ray diffraction and nitrogen adsorption and desorption isotherms data. The adsorption behavior for cadmium(II) and lead(II) onto MCM‐41 was studied by contacting the mesoporous silicate with an aqueous solution of metal salts and acetylacetone. Both Cd2+ and Pb2+ were found to quantitatively adsorb onto MCM‐41. The results of this study suggest that MCM‐41 may have applications in the recovery of toxic metals from waste waters.

Mesoporous molecular sieves are promising as adsorbents for purification of biological molecules, such as amino acids, due to their tuneable mesopore sizes and high surface area. In this study, the adsorption of the basic amino acid, lysine, onto MCM-41, a siliceous mesoporous molecular sieve, has been investigated under a range of solution conditions. It was found to adsorb according to a Langmuir-type isotherm with a maximum capacity at pH 6 of 0.21 mmol/g. The extent of adsorption depends strongly on the pH and ionic strength of the adsorbate solution, due to a combination of ion exchange and electrostatic interactions governing the adsorption process. © 2005 Elsevier B.V. All rights reserved.