Adsorptive Properties of Dyes to Cellulosic Sheet and Discoloration of Dye Solution by UV-ray Irradiation

The adsorptive properties and selectivity of dyes and water molecules to cellulosic sheet, dependence of adsorptive properties of dyes on the concentration of dye solution, and discoloration of the dye solution due to the UV-ray irradiation were determined for 18 kinds of commercial dyes. The results are as follows： 1） the adsorptive properties of dyes to cellulose sheet differed greatly, but did not depend on the dye types such as acidic, basic and so on; 2） adsorptive properties of dyes to cellulosic sheet de- pended on the concentration of dye solution and were classified into 4 types： concentration-independent, increasing or decreasing with dye concentration, and having a maximum. This classification was irrelevant to the dye types; 3） the irradiation of UV-ray did not cause significant discoloration of dye solution itself, which suggested that wood components as well as dye molecules influence the discoloration of wood.

Characteristics and mechanism of Ni^(2+)and Cd^(2+)adsorption by recovered perlite from agar extraction residue

Ni^(2+)and Cd^(2+)in wastewater accumulated through the ecological chain and could jeopardize human health.Adsorption of Ni^(2+)and Cd^(2+)from wastewater using recovered perlite was an important way to solve the problem of resource utilization of solid waste from agar production.Our previous study confirmed that recovered perlite from agar extraction residue had better pore size and specific surface area than commercial perlite.However,the adsorption efficiency and adsorption mechanism of recovered perlite were the main factors limiting its adsorption application.The adsorption process of Ni^(2+)and Cd^(2+)by recovered perlite in aqueous solution was described by the pseudo-second-order kinetic equation,and the relevant adsorption mechanism was mainly chemisorption.Compared with commercial perlite,the adsorption removal rate of Ni^(2+)and Cd^(2+)by enzymatic recovered perlite could reach 92.9%and 89.2%,respectively,and were improved by 12.63%and 13.03%.Langmuir isothermal adsorption model could better describe the isothermal adsorption process of recovered perlite on heavy metal Ni^(2+)and Cd^(2+),and the relevant adsorption mechanism was mainly monolayer adsorption.The X-ray photoelectron spectroscopy(XPS)results indicated that the decrease of Si—O Si^(2+)hydroxyl coordination bond and the increase of C—Si bond might make the binding effect of recovered perlite with heavy metals stronger.The competitive adsorption of Ni^(2+)and Cd^(2+)by recovered perlite was still dominated by chemisorption and monolayer adsorption.This study was expected to provide a theoretical basis and technical support for the removal of Ni^(2+)and Cd^(2+)from wastewater using recovered perlite from seaweed residue.

Theoretical studies of adsorption property on Ir_4/MgO and Ir_4/γ-Al_2O_3

The adsorption properties of atomic and molecular species on Ir4/MgO and Ir4/γ-Al2O3 have been systematically studied by means of planewave density functional theory（DFT）calculations using the periodic boundary conditions.The binding energies of these species were ordered as follows：H2O〈C2H4〈H〈OH〈S〈N〈O〈C.The adsorption energies of adatoms on Ir4/MgO were larger than those on Ir4/γ-Al2O3 except hydrogen atom,but were in reverse for the molecules calculated.In addition,the difference of adsorption energies on MgO and γ-Al2O3 supports has been elucidated by analyzing the electronic properties.A detailed investigation on state density clarifies the nature of the magnitude of adsorption energy.These calculated results are consistent well with the available experimental and theoretical results.

Synthesis and Adsorption Property of Dihydroxyl Azacrown Ether-Grafted Chitosan

A novel dihydroxyl azacrown ether chitosan was synthesized by reacting dihydroxyl azacrown ether with epoxy activated chitosan. The adsorption property of the azacrown ether chitosan for Pb2+, Cr3+, and Ag+, were determined. The experimental results showed that the dihydroxyl azacrown ether grafted chitosan has high adsorption capacity and high selectivity for some metal ions.

ADSORPTIVE STRIPPING VOLTAMMETRIC PROPERTIES OF DBPPH AT MERCURY ELECTRODE

Cyclic voltammetry shows that DBPPH has a pair of cathodic and anodic peaks at Hg electrode.Epc=-1.49 V and Fpa=-1.43 V(vs.Ag/AgCl).The cathodic peak shows adsorptive characteristics.The adsorbed species is DBPPH neutral molecule. The method for measuring trace amount of DBPPH by adsorptive stripping voltammetry is established.

Thermal decomposition of magnesium ammonium phosphate and adsorption properties of its pyrolysis products toward ammonia nitrogen

High-purity magnesium ammonium phosphate （MAP） was precipitated by controlling pH value of the reaction system of 9.0-9.5. The thermal decomposition behavior of MAP and the adsorption properties of its pyrolysis products toward ammonia-nitrogen were also studied by XRD, SEM, TGA-DTA and FT-IR methods. The results indicated that high-purity MAP was obtained at pH value of 9.0-9.5. Upon heating to 100-120℃ for 120 min, MAP was thermally decomposed, losing water and ammonia concomitantly with a reduction in grain size and crystallinity. The capacity of pyrolysis products for ammonia nitrogen adsorption reached 72.5 mg/g, with a removal rate of up to 95% from an 800 mg/L solution. The characteristic diffraction peaks corresponding to MAP mainly appeared in their XRD patterns after adsorption of ammonia nitrogen. The pyrolysis products of MAP at 100-120 ℃ could be recycling-used as the chemical treatment regents of ammonia nitrogen in the practical application.

Synthesis of Li^+ adsorbent(H_2TiO_3) and its adsorption properties

H2TiO3 was obtained from the acid-modified adsorbent precursor Li2TiO3,which was synthesized by a solid-phase reaction between TiO2 and Li2CO3.The extraction ratio of Li＋ from Li2TiO3 was 98.86%,almost with no Ti4＋ extracted.The effects of lithium titanium ratio,calcining temperature and time were investigated on the synthesis of Li2TiO3.Li2TiO3,H2TiO3 and the adsorbed Li＋ adsorbent were characterized by XRD and SEM.The lithium adsorption properties were investigated by the adsorption kinetics and adsorption isotherm.The results indicate that H2TiO3 has an excellent adsorptive capacity for Li＋.Two simplified kinetic models including the pseudo-first-order and pseudo-second-order equations were selected to follow the adsorption processes.The rate constants of adsorption for these kinetic models were calculated.The results show that the adsorption process can be described by the pseudo-second-order equation,and the process is proved to be a chemical adsorption.The adsorption process that H2TiO3 adsorbs Li＋ in LiCl solution well fits the Langmuir equation with monolayer adsorption.

Preparation, characterization, and catalytic performance of high efficient CeO_2-MnO_x-Al_2O_3 catalysts for NO elimination

A series of CeO2‐MnOx‐Al2O3 mixed oxide catalysts （Ce：Mn：Al mole ratio=6：4：x, x=0.25, 0.5, 1, 2） were prepared by a simple one‐step inverse co‐precipitation method to investigate the influence of the incorporation of Al3＋ into CeO2‐MnOx mixed oxides. CeO2‐MnOx, CeO2‐Al2O3, and MnOx‐Al2O3 mixed oxides, and CeO2 were prepared by the same method for comparison. The samples were characterized by XRD, Raman, N2 physisorption, H2‐TPR, XPS, and in situ DRIFTS. The catalytic re‐duction of NO by CO was chosen as a model reaction to evaluate the catalytic performance. The incorporation of a small amount of Al3＋into CeO2‐MnOx mixed oxides resulted in a decrease of crys‐tallite size, with the increase of the BET specific surface area and pore volume, as well as the in‐crease of Ce3＋and Mn4＋. The former benefits good contact between catalyst and reactants, and the latter promotes the adsorption of CO and the desorption, conversion and dissociation of adsorbed NO. All these enhanced the catalytic performance for the NO＋CO model reaction. A reaction mecha‐nism was proposed to explain the excellent catalytic performance of CeO2‐MnOx‐Al2O3 catalysts for NO reduction by CO.

Modification of Activated Carbon Fiber by Loading Metals and Their Performance on SO2 Removal

Metal-loaded activated carbon fibers （ACFs） were prepared by impregnation and characterized by N2 adsorption at 77K, XRD, XPS and SEM. Their properties on SO2 removal were examined in a tubular fixed bed reactor with a model flue gas. Cobalt-loaded ACF showed the best activity among the prepared metal-loaded ACFs and a constant removal ratio of SO2 above 87% during continuous exposure to the flow of SO2/O2/H2O/N2 at 45℃ for more than 216h. The characteristic of the prepared loaded-ACFs showed that the exceptional activity of Co-ACF was attributed to the high amount of active sites due to modification by loading cobalt.

Preparation of activated carbons and their adsorption properties for greenhouse gases:CH_4 and CO_2

Three kinds of activated carbons were prepared using coconut-shells as carbon precursors and characterized by XRD, FT-IR and texture property test. The results indicate that the prepared activated carbons were mainly amorphous and only a few impurity groups were adsorbed on their surfaces. The texture property test reveals that the activated carbons displayed different texture properties, especially the micropore size distribution. The adsorption capacities of the activated carbons were investigated by adsorbing CH4, CO2, N2 and O2 at 25 ？C in the pressure range of 0-200 kPa. The results reveal that all the activated carbons had high CO2 adsorption capacity, one of which had the highest CO2 adsorption value of 2.55 mmol/g at 200 kPa. And the highest adsorption capacity for CH4 of the activated carbons can reach 1.93 mmol/g at 200 kPa. In the pressure range of 0-200 kPa, the adsorption capacities for N2 and O2 were increased linearly with the change of pressure and K-AC is an excellent adsorbent towards the adsorption separation of greenhouse gases.

SYNTHESIS AND PROPERTIES OF SULFHYDRYL CHITOSAN

A new adsorbent for heavy metal ions, sulfhydryl chitosan (S chitosan), was produced by treatment of chitosan with sulhydryl acetic acid in the presence of sulfuric acid as a catalyst. Its structure was confirmed by elemental analysis and FT IR spectra analysis. The adsorption properties of sulfhydryl chitosan for Cu(Ⅱ), Cd(Ⅱ), Pb(Ⅱ), Cr(Ⅲ) and Ni(Ⅱ) were investigated, and the effect of pH value on adsorption, adsorption kinetics, and selective adsorption was examined. It was shown that S chitosan has good adsorption for Pb(Ⅱ), Cu(Ⅱ) and Cd(Ⅱ) like chitosan, is also insoluble in acid solution; has good adsorption kinetic properties for heavy metal ions; and can be used in acid solution. The adsorption capacities of S chitosan can be affected by media acidity. The adsorbed Cu(Ⅱ) Cd(Ⅱ)and Pb(Ⅱ) could be eluted by diluted chlorhydric acid.

Theoretical study of small Mo clusters and molecular nitrogen adsorption on Mo clusters

This paper studies the small molybdenum clusters of Mon （n=2 8） and their adsorption of N2 molecule by using the density functional theory （DFT） with the generalized gradient approximation. The optimized structures of Mon clusters show the onset of a structural transition from a close-packed structure towards a body-centred cubic structure occurred at n = 7. An analysis of adsorption energies suggests that the Mo2 is of high inertness and Mo6 cluster is of high activity against the adsorption of N2. Calculated results indicate that the N2 molecule prefers end-on mode by forming a linear or quasi-linear structure Mo-N-N, and the adsorption of nitrogen on molybdenum clusters is molecular adsorption with slightly elongated N-N bond. The electron density of highest occupied molecular orbital and lowest unoccupied molecular orbital, and the partial density of states of representative cluster are also used to characterize the adsorption properties of N2 on the sized Mon clusters.

Microwave hydrothermal synthesis,characterization and excellent uranium adsorption properties of CoFe_(2)O_(4)@rGO nanocomposite

To improve the adsorption performance and simplify uranium separation from aqueous media in post-treatment processes,a magnetic CoFe_(2)O_(4)@rGO composite was synthesized by microwave-hydrothermal method.The results of XRD,Raman,TEM/HRTEM,FTIR,BET and VSM characterization show that spinel-type cobalt ferrite CoFe_(2)O_(4) nanoparticles ca.13.4 nm in size are dispersedly anchored on the graphene sheet,and the saturation magnetization of the nanocomposite is 46.7 mA/(m^(2)·g).The effects of different pH,initial concentration and other conditions on uranium adsorption capacity were investigated,and adsorption kinetics equations were fitted to determine the adsorption behaviour of uranium on CoFe_(2)O_(4)@rGO in simulated uranium-containing seawater.It was observed that the uranium adsorption capacity of CoFe_(2)O_(4)@rGO composite at pH=5 is 127.6 mg/g,which is 1.31 and 2.43 times that of rGO and pure CoFe_(2)O_(4).The adsorption process conforms to Langmuir and quasi-second-order kinetic model.The excellent adsorption performance of CoFe_(2)O_(4)@rGO makes it potentially useful in the treatment of uranium-polluted water.

Experimental and Theoretical Study of the Effect of Moisture on Methane Adsorption and Desorption by Activated Carbon at 273.5 K

Adsorption and desorption of methane by activated carbon （AC） at constant temperature and at various pressures were investigated. The effect of moisture was also studied. A volumetric method was used, up to 40 bar, at a temperature of 273.5 K. Results of a dry AC sample were compared with those obtained from a moist sample and two different ACs with different physical and surface properties were used. As expected, the results showed that the existence of moisture, trapped in the AC pores, could lead to a decrease in the amount of methane adsorbed and a decrease in the amount of methane delivered during desorption. To model the experimental results, a large variety of adsorption isotherms were used. The regressed parameters for the adsorption isotherms were obtained using the experimental data generated in the present study. The accuracy of the results obtained from the different adsorption isotherms was favorably compared.

Template synthesis and adsorption properties of chitosan salicylal Schiff bases

To improve the adsorption properties of chemically modified chitosan, the chelating resin of salicylal chitosan Schiff bases was prepared by the template cross-linking method using Cu（Ⅱ） as template ion and ethylene glycol bisglycidyl ether as cross-linking agent in microwave, and was characterized by IR. The adsorption capacity and selectivity coefficient of the chemically modified chitosan for Cu（Ⅱ）, Fe（Ⅲ） and Zn（Ⅱ） were investigated, respectively. The results show that the adsorption capacity of the resin 2.73 mmol/g for Cu（Ⅱ） is bigger than that for other two metal ions, 0.22 mmol/g for Fe（Ⅲ）, and 0.42 mmol/g for Zn（Ⅱ）, and the selectivity coefficients are as follows: KCu（Ⅱ）/Fe（Ⅲ）=12.4, KCu（Ⅱ）/Zn（Ⅱ）=6.5.

Comparison and Analysis of Toluene Adsorption Properties of ZSM-5 Molecular Sieve Treated by Different Modification Methods: Adsorption Kinetic and Mechanism Studies

MFI molecular sieve with high specific surface area,adjustable pore size and low production cost have been recognized as an effective adsorbent for VOCs removal.In this paper,NaOH solution was used to etch ZSM-5 to increase specific surface area and micro-mesoporous content.Graphene oxide(GO)was loaded on ZSM-5 by ultrasonic-assisted heating immersion method,and largeπ-bond structure and oxygen-containing functional groups were added to ZSM-5 for improving the composite adsorption performance.In addition,the properties of OH-ZSM-5 and ZSM-5@GO composites for toluene adsorption under different factors were also studied.It was positively correlated with initial concentration and adsorbent mass,but was negatively correlated with temperature.Meanwhile,the results showed that the saturated adsorption capacity of OH-ZSM-5(107.3 mg/g)was 1.34 times higher than that of ZG-15%(80.2 mg/g).The pseudo-first-order and pseudo-second-order kinetic model can well describe the adsorption behavior of toluene on the OH-ZSM-5 and ZG-15%,respectively.The adsorption mechanism of OH-ZSM-5 was mainly pore-filled adsorption.However,the adsorption mechanisms of ZSM-5@GO composite were pore-filled adsorption,π-πinteraction,and H-bond interaction.This study will help to design a new strategy for enhancing the performance of traditional adsorbent ZSM-5 in VOCs removal.

Modification of pore size in activated carbon by benzene deposition and its effects on CH4/N2 separation

Anthracite coal was used as raw material to prepare activated carbons as the carbon support in the carbonization-activation process. Modification of the pore size of the activated carbon by chemical vapor deposition of carbon from benzene was examined. These samples were characterized by adsorption of N2 at 77 K and CH4 and N2 at 303 K. The microporosity of these samples was evaluated by the Dubinin-Astakhov Equation. The pore size distribution was obtained by the DFT method applied to the N2 adsorption data at 77 K. The separation selectivity was obtained by the Langmuir Equation. The surface morphology was characterized by an environmental scanning electron microscope. It was observed that all samples of carbon molecular sieves studied were microporous carbonaceous materials. CMS-2 prepared in the present study has a better N2/CH4 separation performance; it can satisfy the requirements of the pressure swing adsorption for concentrating CH4 from the N2/CH4 mixture gas.

Study of Dibenzothiophene Adsorption Over Carbon Nanotube Supported CoMo HDS Catalysts

Adsorption properties of dibenzothiophene (DBT) on a CNT (carbon nanotube) support as well as on CoMoS/CNT and CoMoO/CNT catalysts have been studied. Consecutive desorption of adsorbates was measured by TGA. The commonly used carriers AC (activated carbon), γ-Al_2O_3, and their supported catalysts (CoMoO/AC, CoMoS/AC, CoMoO/γ-Al_2O_3, CoMoS/γ-Al_2O_3)were also subjected to analysis for comparison. The acidic properties of the samples were characterized using the NH_3-TPD technique. Correlation between the adsorption of DBT and the acidic properties of the catalysts has been established. It was found that the Co-Mo catalysts in the sulfide state adsorbed much more DBT molecules than the corresponding Co-Mo catalysts in the oxide state. The CoMoS/CNT catalyst exhibited very high HDS activity and selectivity, as compared with the CoMoS/γ-Al)_2O_3 catalysts. Based on the BET data and the high hydrogenolysis/hydrogenation selectivity of the CoMoS/CNT, it was deduced that more than 90% of the DBT molecules adsorbed on the CoMoS/CNT with an end-on mode, and the surface of the CoMoS/CNT catalyst was almost fully covered with DBT molecules. Although the AC support had very high surface area and high loading ability, the AC supported CoMoS catalyst showed lower HDS activity, as compared with the CoMoS/γ-Al_2O_3 catalyst.

Influence of Calcination on the Physical Characteristics and Nitrogen Removal Performance of Clinoptilolites

The influences of roasting activation on the particle morphology, microscopic structure, and adsorption properties of natural clinoptilolites were investigated. The experimental results show that the optimal modified conditions include a calcination temperature at 400 ℃, a roasting time of 0.5 h, and furnace cooling. The ammonia nitrogen removal rate from analog renewable water of the modified clinoptilolites reached 72% in the optimized conditions, which is 12% higher than that of natural ones. Scanning electron microscopy analysis showed that the surface morphology changed, the micro-hole size increased, and the surface became smoother and more uniform after calcination. The single-point total adsorption average pore width increased from 7.74 nm to 10.64 nm.