Zhirong Liu

Selective adsorption of uranium(VI) from aqueous solutions using the ion-imprinted magnetic chitosan resins

The ion-imprinted magnetic chitosan resins (IMCR) prepared using U(VI) as a template and glutaraldehyde as a cross-linker showed higher adsorption capacity and selectivity for the U(VI) ions compared with the non-imprinted magnetic chitosan resins (NIMCR) without a template. The results showed that the adsorption of U(VI) on the magnetic chitosan resins was affected by the initial pH value, the initial U(VI) concentration, as well as the temperature. Both kinetics and thermodynamic parameters of the adsorption process were estimated. These data indicated an exothermic spontaneous adsorption process that kinetically followed the second-order adsorption process. Equilibrium experiments were fitted in Langmuir, Freundlich, and Dubinin-Radushkevich adsorption isotherm models to show very good fits with the Langmuir isotherm equation for the monolayer adsorption process. The monolayer adsorption capacity values of 187.26 mg/g for IMCR and 160.77 mg/g for NIMCR were very close to the maximum capacity values obtained at pH 5.0, temperature 298 K, adsorbent dose 50 mg, and contact time 3 h. The selectivity coefficient of uranyl ions and other metal ions on IMCR indicated an overall preference for uranyl ions. Furthermore, the IMCR could be regenerated through the desorption of the U(VI) ions using 0.5 M HNO(3) solution and could be reused to adsorb again.

Competitive adsorption of heavy metal ions on peat

Abstract The uptake capacities, and the adsorption kinetics, of copper, Cu(II), nickel, Ni(II), and cadmium, Cd(II), on peat have been studied under static conditions. The results show that the adsorption rates are rapid: equilibrium is reached in twenty minutes. The adsorption of copper, nickel and cadmium is pH dependent over the pH range from 2 to 6. The adsorption kinetics can be excellently described by the Elovich kinetic equation. The adsorption isotherm fits a Langmuir model very well. The adsorption capacities follow the order Cu2+ > Ni2+ > Cd2+ in single-component systems and the competitive adsorption capacities fall in the decreasing order Cu2+ > Ni2+ > Cd2+ in multi-component systems. The adsorption capacities of these three heavy metal ions on peat are consistent with their observed competitive adsorption capacities.

Development of a first-order kinetics-based model for the adsorption of nickel onto peat

Abstract The use of peat for the removal of nickel from aqueous solutions has been investigated at various pH values by means of static conditions. The present research shows that the ability of Ni to bind to peat increases as the pH value increases. The solutions reach adsorption equilibrium rapidly. A reasonable kinetic model, first-order in nickel concentration, has been developed and fitted to the adsorption of nickel (II) onto peat. The first-order model provides a good correlation to the experimental data. The characteristic parameters of the Langmuir isotherm were determined at various temperatures. The relationship between kinetics and equilibrium isotherms was established through the forward- and backward-rate-constants, k1 and k2, and the equilibrium constant, K.

Fractal dimension of Gaomiaozi Na-bentonite by different methods

A knowledge of surface morphology is a useful element in microstructural characterization. Gaomiaozi Na-bentonite is the candidate buffer/backfill material for the Chinese repository. The results show that Gaomiaozi Na-bentonite is rough and mesoporous. The fractal dimension is 2.5870 by means of the F–H–H method compared with the Freundlich method. The correlation between the fractal dimensions and adsorption capacity has been observed.

Preparation of Fe-loaded activated carbon and its adsorption property of U(VI) in aqueous solution

AbstractThree kinds of method were employed to prepare Fe loaded activated carbon (Fe-AC), liquid reduction method, carbonthermal method, incipient wetness method, respectively. Before and after adsorption, the adsorption property of Fe-AC had been analysed. Results indicated that the removal mechanisms were mainly redox reaction, adsorption and precipitation. In addition, the adsorption models fitted with the kinetic model and adsorption isotherm model. Based on the analysis of six influencing factors, we obtain some actual information to deal with the humic acid and the “back to acid”.