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Adsorption of arsenate on hydrous iron oxide is an important process controlling geochemical cycling of arsenic in environment as well as the fate of arsenic-bearing mining wastes. The widely accepted view on the mechanism of adsorption is that arsenate is adsorbed via bidentate binuclear inner-sphere complexation. In this study, we characterized the arsenate-hydrous iron oxide sorption solids synthesized at pH=3-8 using Fourier transformed infrared spectroscopy （FTIR） and X-ray diffraction （XRD）. It has been determined that poorly crystalline ferric arsenate developed on the surface of iron oxide when arsenate was sorbed at acidic pH, while at alkaline pH the adsorption of arsenate was via bidentate complexation.

Yolk-shell Fe3O4@N-doped carbon nanochains, intended for application as a novel microwave-absorption material, have been constructed by a three-step method. Magnetic-field-induced distillation-precipitation polymerization was used to synthesize nanochains with a one-dimensional （1D） structure. Then, a polypyrrole shell was uniformly applied to the surface of the nanochains through oxidant-directed vapor-phase polymerization, and finally the pyrolysis process was completed. The obtained products were characterized by X-ray diffraction （XRD）, X-ray photoelectron spectra （XPS）, and thermogravimetric analyses （TGA） to confirm the compositions. The morphology and microstructure were observed using an optical microscope, scanning electron microscope （SEM）, and transmission electron microscope （TEM）. The N2 absorption-desorption isotherms indicate a Brunauer-Emmett-Teller （BET） specific surface area of 74 m^2/g and a pore width of 5-30 nm. Investigations of the microwave absorption performance indicate that paraffin-based composites loaded with 20wt.% yolk-shell Fe3O4@N-doped carbon nanochains possess a minimum reflection loss of -63.09 dB （11.91 GHz） and an effective absorption bandwidth of 5.34 GHz at a matching layer thickness of 3.1 mm. In addition, by tailoring the layer thicknesses, the effective absorption frequency bands can be made to cover most of the C, X, and Ku bands. By offering the advantages of stronger absorption, broad absorption bandwidth, low loading, thin layers, and intrinsic light weight, yolk-shell Fe3O4@N-doped carbon nanochains will be excellent candidates for practical application to microwave absorption. An analysis of the microwave absorption mechanism reveals that the excellent microwave absorption performance can be explained by the quarter-wavelength cancellation theory, good impedance matching, intense conductive loss, multiple reflections and scatterings, dielectric loss, magnetic loss, and microwave plasma loss.

Understanding the processes of protein adsorption/desorption on nanopartieles＇ surfaces is important for the development of new nanotechnology involving biomaterials; however, an atomistic resolution picture for these processes and for the simultaneous protein conformational change is missing. Here, we report the adsorption of protein GB 1 on a polystyrene nanoparticle surface using atomistic molecular dynamic simulations. Enabled by metadynamics, we explored the relevant phase space and identified three protein states, each involving both the adsorbed and desorbed modes. We also studied the change of the secondary and tertiary structures of GB 1 during adsorption and the dominant interactions between the protein and surface in different adsorption stages. The results we obtained from simulation were found to be more adequate and complete than the previous one. We believe the model presented in this paper, in comparison with the previous ones, is a better theoretical model to understand and explain the experimental results.

First-principles calculanons were performed to investigate the mechamsm of Hg0 adsorpnon and oxidation on CeO2（111）. Surface oxygen acnvated by the reducnon of Ce to Ce a vlta to Hg~ adsorption and oxidation processes. Hg0 was fully oxidized by the surface lattice oxygen on CeO2（111）, without using any other oxidizing agents. HCI could dissociate and react with the Hg adatom on CeO2（111） to form adsorbed Hg CI or CI-Hg-Cl groups, which promoted the desorption of oxidized Hg and prevented CeO2 catalyst deactivation. In contrast, O-H and H-O-H groups formed during HC1 adsorption consumed the active surface oxygen and prohibited Hg oxidation. The consumed surface oxygen was replenished by adding O2 into the flue gas. We proposed that oxidized Hg desorption and maintenance of sufficient active surface oxygen were the rate-determining steps of Hg0 removal on CeO2-based catalysts. We believe that our thorough understanding and new insights into the mechanism of the Hg0 removal process will help provide guidelines for developing novel CeO2-based catalysts and enhance the Hg removal efficiency.

The contents of total phenolics and extractable condensed tannins in the leaves, twigs and stem bark of Canarium album were determined. The structural heterogeneity of condensed tannins from stem bark was characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry （MALDI-TOF MS） and nuclear magnetic resonance （NMR） analyses The results show the predominance of signals representative of procyanidins and prodelphinidins. In addition, epicatechin and epigallocatechin polymers with galloylated procyanidin or prodelphinidin were also observed. The tannins were screened for their potential antioxidant activities using l,l-diphenyl-2-picrylhydrazyl （DPPH） and ferric reducing/antioxidant power （FRAP） model systems. Tannins extracted from leaves, twigs and stem bark all showed a very good DPPH radical scavenging activity and ferric reducing power.

The adsorbing effect of calcined layered double hydroxide （CLDH） for chloride ions in simulated concrete pore （SCP） solutions was investigated with the potentiodynamic polarization method, impedance measurement, ion selective electrode analysis and XRD. CLDH could effectively adsorb Cl^- and increase pH value in SCP solutions containing NaCl. The chloride to hydroxyl ions ratio （[C1^-]/[OH^-]） of the solution greatly decreased by CLDH treatment. In CLDH treated SCP solution with CI-, the pitting potential of carbon steel notably increased, and the surface impedance was much higher, indicating strengthened passivation. The process of CLDH adsorbing chloride ions from SCP solutions was accompanied with the reconstruction of the layered structure.

The key aim of this study is to evaluate the adsorption of heavy oil from aqueous solutions with different oil contents over mesoporous silicate materials having different surfactant template contents. The mesoporous silicate materials have been synthesized from tetraethylorthosilicate as a silica precursor and cetyltrimethylammonium bromide as a template using the sol-gel technique. Four samples were prepared by (1) totally removing the template using the calcination process, (2) partially removing the template via ethanol extraction, (3) partially removing the template via water extraction, and (4) keeping the template as synthesized, respectively. These four samples have been characterized using X-ray diffraction, nitrogen adsorption, thermal gravimetric analysis and Fourier transformed infrared. The effect of the degree of template removal of these mesoporous materials for the oil removal has been investigated. The oil removal is inversely proportional to the surfactant content in the mesoporous material, being highest for the calcined sample but lowest for the as-synthesized sample. The kinetic of oil adsorption over the calcined material has been also studied and the data obtained fit well a second-order model.

Commercial activated carbons were modified by a series of chemical or physical treatments using H202, NH3, and heating under N2 flow without notably changing their pore structures. The resultant carbons were characterized by N2 adsorption and Bohem titration and then used to remove Ponceau 4R, methyl orange and brilliant blue from aqueous solutions. Surface chemistry was found to play a signifi- cantly different role in removing these three compounds. The removal of anionic Ponceau 4R increases with increasing carbon surface ba- sicity due to the predominant dispersive interaction mechanism. In contrast, surface chemistry has little effect on the removal of anionic methyl orange, which can be explained by two parallel mechanisms involving electrostatic and dispersive interactions due to the basic amine group in a dye molecule. The influence of surface chemistry on the removal of amphoteric brilliant blue dye can also be ignored due to a weak interaction between the carbons and dye molecules, which is resulted from strong cohesive energy from electrostatic forces inside amphoteric dye molecules.

Radiotracer techniques were employed to characterize 65Zn adsorption and desorption in root-cell-wall of hyperaccumulating ecotype （HE） and non-hyperaccumulating ecotype （NHE） species of Sedum alfredii Hance. The results indicated that at the end of a 30 min short time radioisotope loading period, comparable amounts of 65Zn were accumulated in the roots of the two ecotypes Sedum alfredii, whereas 2.1-fold more 65Zn remains in NHE root after 45-min desorption. At the end of 60 min uptake period, no difference of 65Zn accumulation was observed in undesorbed root-cell-wall of Sedum alfredii. However, 3.0-fold more 65Zn accumulated in desorbed root-cell-wall ofNHE. Zn^2＋ binding in root-cell-wall preparations of NHE was greater than that in HE under high Zn^2＋ concentration. All these results suggested that root-cell-wall of the two ecotypes Sedum alfredii had the same ability to adsorb Zn2＋, whereas the desorption characteristics were different, and with most of 65Zn binding on root of HE being available for loading into the xylem, as a result, more 65Zn was translocated to the shoot.

The adsorption behavior and mechanism of D ll 3 resin for Dy（lII） was investigated by using the method of resin adsorption. Experimental results show that the optimum medium pH of adsorption of D 113 resin for Dy^3- is pH=6.00 in the HAc-NaAc medium. The static adsorption capacity of D113 resin for Dy3. is 292.7 mg·g^-1. The optimum eluant is 0.5 mol,L-~ HC1. The adsorption rate constant is k298=6.8× 10-6s^-1. The apparent activation energy of D113 resin for Dy（Ⅲ） is 14.79 kJ·mol^-1. The adsorption behavior of D113 resin for Dy（Ⅲ） obeys the Freundlich isotherm. The adsorption parameters of thermodynamic are AH=14.48 kJ·mol^-1,△S=54.69 J·mol^-1,K^-1, △G= 1.82 kJ·mol^-1.The adsorption mechanism of Dll3 resin for Dy^3- was confirmed by chemical analysis and IR spectra.