Fabrication and Properties of Adsorptive Ceramic Membrane Made from Kaolin with Addition of Dolomite for Removal of Metal Ions in a Multielement Aqueous System.

The exorbitant presence of heavy metals has emerged as one of the most serious ecological issues facing the world. The treatment processes currently employed are not effective for removing all of the contaminants completely. Therefore, it is necessary for better operational technology to be developed.

Adsorption of Chromium (III) and Chromium (VI) Ions from Aqueous Solution Using Chitosan-Clay Composite Materials.

In this work, biopolymer chitosan and natural clay were used to obtain composite materials. The overall aim of this study was to improve the properties (porosity, thermal stability and density) of pure chitosan beads by the addition of clay and to obtain a chitosan-based composite material for the adsorption of heavy metals from an aqueous solution, using Mongolian resources, and to study the adsorption mechanism. The natural clay was pre-treated with acid and heat to remove the impurities.

Contribution Factors of the First Kind Calculated for the Marcus Electron-Transfer Rate and Their Applications.

In this study, we applied the concept of the "contribution factor of the first kind (CFFK)" to the original electron-transfer (ET) rate theory proposed by Marcus. Mathematical derivations provided simple and convenient formulas for estimating the relative contributions of ten physical and chemical parameters involved in the Marcus ET rate formula: (1) the maximum strength of the electronic coupling energy between two molecules, (2) the exponential decay rate of the electronic coupling energy versus the distance between both molecules, (3) the distance between both molecules, (4) the equilibrium distance between both molecules, (5) the Gibbs free energy, (6) reorganization free energy in the prefactor of the Marcus ET rate equation, (7) reorganization free energy in the denominator of the exponential term, (8) reorganization free energy in the argument of the exponential term, (9) Boltzmann constant times absolute temperature in the prefactor of the rate equation, and (10) Boltzmann constant times absolute temperature in the denominator of the exponential term. We applied our theories to (i) ET reactions at bacterial photosynthesis reaction centers, PSI and PSII, and soluble ferredoxins (Fd); (ii) intraprotein ET reactions for designed azurin mutants; and (iii) ET reactions in flavodoxin (Fld).

Enhanced uranium separation by charge enabling γ-MnO with oxygen vacancies.

Numerous efforts have been devoted to understanding the electron transfer process of uranium (UO) on adsorbent materials, whereas the potential oxygen vacancies (OVs) in metal oxides have long been overlooked. Once these interactions are taken into account, the emerging molecular orbital effects undoubtedly affect the adsorption process. Here, we synthesized CC/γ-MnO by growing MnO on carbon cloth (CC), followed by the creation of oxygen vacancies (OVs) through electrochemical methods to form CC/γ-MnO-OVs.

Preparation and Characterization of Low-Cost Ceramic Membrane Coated with Chitosan: Application to the Ultrafine Filtration of Cr(VI).

In this work, low-cost ceramic membranes (CMs) were prepared from ultrafine starting powders such as kaolin, clay, and starch by a dry compaction method. The ceramic membranes were sintered at different temperatures and times and were characterized by XRD, XRF, TG-DTA, SEM-EDS, N-BET, water absorption, compressive strength, and pure water flux. The optimal membrane, sintered at 1000 °C for 3 h, possessed water absorption of 27.

Adsorption of an Anionic Surfactant (Sodium Dodecyl Sulfate) from an Aqueous Solution by Modified Cellulose with Quaternary Ammonium.

In this study, a method of removing an anionic surfactant sodium dodecyl sulfate (SDS) from an aqueous solution by cellulose modified with quaternary ammonium cation was discussed. Cellulose, as the adsorbent, was obtained from medical cotton balls, and the quaternary ammonium cation (synthesized from dodecyl dimethyl tertiary amine and epichlorohydrin) was grafted onto the sixth hydroxyl group of D-glucose in the cellulose by the Williamson reaction under alkaline conditions. The modified cellulose was characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS); and the zeta potential of the material was also measured after confirmation of the synthesis of quaternary ammonium salts by nuclear magnetic resonance (NMR).

Adsorption of REEs from Aqueous Solution by EDTA-Chitosan Modified with Zeolite Imidazole Framework (ZIF-8).

Chitosan (CS) modified with ethylenediamine tetraacetic acid (EDTA) was further modified with the zeolite imidazole framework (ZIF-8) by in situ growth method and was employed as adsorbent for the removal of rare-earth elements (REEs). The material (EDTA-CS@ZIF-8) and ZIF-8 and CS were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), and nitrogen adsorption/desorption experiments (N- Brunauer-Emmet-Teller (BET)). The effects of adsorbent dosage, temperature, the pH of the aqueous solution, contact time on the adsorption of REEs (La(III), Eu(III), and Yb(III)) by EDTA-CS@ZIF-8 were studied.

Experimental and Theoretical Studies on the Adsorption Mechanisms of Uranium (VI) Ions on Chitosan.

An experiment on the adsorption of uranium (VI) by chitosan was conducted to investigate the efficiency of chitosan as an adsorbent for U(VI). The adsorption potential of U(VI) by chitosan was investigated with ICP-MS by varying the experimental conditions such as the pH in order to obtain the optimum conditions. Adsorption dependence on the pH was confirmed, and the highest uptake of U(VI) was observed at pH 5.

Experimental and Theoretical Studies on the Adsorption and Desorption Mechanisms of Chromate Ions on Cross-Linked Chitosan.

In this work, chitosan bead materials were modified by cross-linking with epichlorohydrin (EP) and glutaraldehyde (GA) for the removal of heavy metals in wastewater. Using these cross-linked chitosan materials, the dependence of adsorption of chromate anions on pH was investigated experimentally and theoretically. The experimental results show that the adsorption process of the chromate (Cr) ions greatly depends on the pH of the solution, with the chitosan modified by cross-linking being an efficient adsorbent for chromate.

Stable Isotope Analysis of Hydrogen and Oxygen in a Traditional Japanese Alcoholic Beverage, Sake, from Niigata Prefecture in Japan and Other Countries.

Stable hydrogen and oxygen isotopic compositions (δD and δO values, respectively) were analyzed for "sake," a traditional Japanese alcohol beverage, to assess these values for the identification of its geographic origin. We collected sake (Junmai-shu; made of only rice, water, and koji) and its source water (i.e.

Behavior and distribution of heavy metals including rare Earth elements, thorium, and uranium in sludge from industry water treatment plant and recovery method of metals by biosurfactants application.

In order to investigate the behavior, distribution, and characteristics of heavy metals including rare earth elements (REEs), thorium (Th), and uranium (U) in sludge, the total and fractional concentrations of these elements in sludge collected from an industry water treatment plant were determined and compared with those in natural soil. In addition, the removal/recovery process of heavy metals (Pb, Cr, and Ni) from the polluted sludge was studied with biosurfactant (saponin and sophorolipid) elution by batch and column experiments to evaluate the efficiency of biosurfactant for the removal of heavy metals. Consequently, the following matters have been largely clarified.

Biosorption of Lanthanides from Aqueous Solutions Using Pretreated Buccinum tenuissimum Shell Biomass.

Biosorption experiment from aqueous solutions containing known amount of rare earth elements (REEs) using pre-treated Buccinum tenuissimum shell was explored to evaluate the efficiency of shell biomass as sorbent for REEs. In this work, four kinds of sieved shell samples: (a) "Ground original sample", (b) "Heat-treatment (480°C, 6 hours) sample", (c) "Heat-treatment (950°C, 6 hours) sample" and (d) "Heat-treatment (950°C, 6 hours) and water added sample" were used. Furthermore, to confirm the characteristics of the shell biomass, the crystal structure, the surface morphology, and the specific surface area of these shell samples were determined.

Biosorption of uranium and rare Earth elements using biomass of algae.

In order to investigate the behavior of rare earth elements (REEs) and uranium (U) in marine organism, the concentrations of REEs and U in some brown algae samples taken on the coast of Niigata Prefecture were determined. In addition, laboratory model experiment to uptake these elements using living and dried algae (Undaria pinnatifida and Sargassum hemiphyllum) was also carried out to survey the uptake and bioaccumulation mechanism of REEs and U in algae. Consequently, the following matters have been mainly clarified.