Yansheng Li

Continuous electrochemical oxidation of methyl orange waste water using a three-dimensional electrode reactor

The removal of methyl orange wastewater was experimentally investigated using a three-dimensional electrode reactor with granular activated carbon and titanium filter electrodes arrays. The effects of the electric current, the residence time and the initial dye concentration on the methyl orange removal were evaluated. For the initial concentration of 1150 mg/L, the COD removal was obtained as 90% under the conditions of electric current 2 A, residence time 40 min. The effluent path of the electrochemical cell was optimized, using the anode effluent instead of the top effluent, where the COD removal was increased to 93% and the corresponding energy consumption was decreased from 15.5 to 14.6 kW-hr/kg COD.

CH4-CO2 reforming to syngas over Pt-CeO2-ZrO2/MgO catalysts： Modification of support using ion exchange resin method

Abstract Pt-CeO2-ZrO2/MgO (Pt-CZ/MgO) catalysts with 0.8 wt% Pt, 3.0 wt% CeO2 and 3.0 wt% ZrO2 were prepared by wet impregnation method. Support MgO was obtained using ion exchange resin method or using commercial MgO. XRD, BET, SEM, TEM, DTA-TG and CO2-TPD were used to characterize the catalysts. CH4-CO2 reforming to synthesis gas (syngas) was performed to test the catalytic behavior of the catalysts. The catalyst Pt-CZ/MgO-IE(D) prepared using ion exchange resin exhibits more regular structure, smaller and more unique particle sizes, and stronger basicity than the catalyst Pt-CZ/MgO prepared from commercial MgO. At 1073 K and atmospheric pressure, Pt-CZ/MgO-IE(D) catalyst has a higher activity and greater stability than Pt-CZ/MgO catalyst for CH4-CO2 reforming reaction at high gas hourly space velocity of 36000 mL/(g·h) with a stoichiometric feed of CH4 and CO2. Activity measurement and characterization results demonstrate that modification of the support using ion exchange resin method can promote the surface structural property and stability, therefore enhancing the activity and stability for CH4-CO2 reforming reaction.

A novel electrochemical ion exchange system and its application in water treatment.

A novel electrochemical ion exchange system with porous cylinder electrodes is proposed for treatment of wastewater. This system can be used for desalination without the costly ion-exchange membrane and extra chemical reagents. Since the electrodes are completely uniform and no ion-exchange membrane was used in this system, it can be operated by switching anodes and cathodes flexibly for eliminating the scaling on the surface of electrodes. The strong base ion-exchange resin grains placed among the anode and cathode have played as supporting electrolyte, which is capable for the treatment of wastewater with low conductivity. The concentrated and neutralized anolyte containing chlorine is effective for disinfection and contaminants removal. Under the experimental conditions, the removal percentage of total dissolved salts was 83% and the removal percentage of chemical oxygen demand was 92% without consumption of extra chemical reagents.

Effect of calcium on adsorption capacity of powdered activated carbon

We investigated the effect of calcium ion on the adsorption of humic acid (HA) (as a target pollutant) by powered activated carbon. The HA adsorption isotherms at different pH and kinetics of two different solutions including HA alone and HA doped Ca(2+), were performed. It was showed that the adsorption capacity of powdered activated carbon (PAC) for HA was markedly enhanced when Ca(2+) was doped into HA. Also, HA and Ca(2+) taken as nitrate were tested on the uptake of each other respectively and it was showed that the adsorbed amounts of both of them were significantly promoted when HA and calcium co-existed. Furthermore, the adsorbed amount of HA slightly decreased with the increasing of Ca(2+) concentration, whereas the amount of calcium increased with the increasing of HA concentration, but all above the amounts without addition. Finally, the change of pH before and after adsorption process is studied. In the two different solutions including HA alone and HA doped Ca(2+), pH had a small rise, but the extent of pH of later solution was bigger.

Electrochemical in situ regeneration of granular activated carbon using a three-dimensional reactor

Electrochemical in situ regeneration of granular activated carbon (GAC) saturated with phenol was experimentally investigated using a three-dimensional electrode reactor with titanium filter electrode arrays. The feasibility of the electrochemical regeneration has been assessed by monitoring the regeneration efficiency and chemical oxygen demand (COD). The influence of the applied current, the effluent flow rate, and the effluent path of the electrochemical cell have been systematically studied. Under the optimum conditions, the regeneration efficiency of GAC could reach 94% in 2 hr, and no significant declination was observed after five-time continuous adsorption-regeneration cycles. The adsorption of organic pollutants was almost completely mineralized due to electrochemical oxidation, indicating that this regeneration process is much more potentially cost-effective for application.

Regeneration of spent powdered activated carbon saturated with inorganic ions by cavitation united with ion exchange method

Using ion exchange resin as transfer media, regenerate powdered activated carbon (PAC) adsorbed inorganic ions by cavitation to enhance the transfer; we studied how the regeneration time and the mass ratio of resin and PAC influence the regeneration rate respectively through re-adsorption. The result showed that the effective regeneration of PAC saturated with inorganic ions was above 90% using ion exchange resin as media and transfer carrier, the quantity of PAC did not reduced but activated in the process.

Preparation of Nanometer MgO by Ion Exchange Resin Method

In this paper, nanometer MgO powder was prepared by using MgCl2•6H2O as the raw material, and environmental benign strong-base anion exchange resin as the induced-precipitation regent. The influence of the concentration of MgCl2 solution, drying method, calcination temperature and time on particle size and physico-chemical features of MgO was studied. The optimal technical conditions were obtained. The XRD and SEM results show that the nanometer MgO prepared under the optimal technical conditions has regular hexagonal lamellar structure, and is composed of nanocrystals with average size between 10 to 25 nm. The existence of dry N2 prevented the sintering of MgO during decomposition processing of Mg(OH)2. Compared with the other nanometer MgO preparation methods, ion exchange resin method has the advantages of low cost, low pollution, high yield and environmental benign; therefore, it appears to be a promising method for the industrial manufacturing of nanometer MgO.

A new regeneration approach to cation resins with aluminum salts: application of desalination by its mixed bed

A novel method for the regeneration of cation exchange resins by aluminum (Al) salts was investigated in order to improve the regeneration efficiency of resins and reduce the dosage of regenerant. The influences of Al3+ concentration and the pH of regeneration solution on resin transformation had been studied. The desalination experiments were carried out to evaluate the characteristics of the Al form resins. Experimental results showed that the regeneration rate of resins was strictly dependent on Al3+ concentration and the pH of the solution. Compared to the conventional regeneration method, the Al form mixed bed exhibited the same desalination capability as the H form mixed bed (MB), and the total organic carbon (TOC) removal was up to 90%, clearly higher than that of the H form. Al salt solution could be utilized repeatedly to regenerate Al form resins.

Study on methane conversion to syngas over nano Pt-CeO2-ZrO2/MgO catalysts: Structure and catalytic behavior of catalysts prepared by using ion exchange resin method.

Nano Pt-Ce02-Zr02/MgO catalysts with 0.8 wt.% Pt, 3.0 wt.% Ce02 and 3.0 wt.% Zr02 were prepared by wet impregnation mothod. Support MgO was obtained using ion exchange resin method or using commercial MgO. SBET, XRD, TEM and C02-TPD were used to characterize the supports and catalysts. CH4-C02 reforming to synthesis gas was performed to test the catalytic behavior of the catalysts. The catalysts prepared using ion exchange resin exhibited more regular structure, more basic sites and higher stability of Pt and MgO than prepared from commercial MgO. At 1073 K, atmospheric pressure, and at high gas hourly space velocity of 36,000 mL/(g-hr) with a stoichiometric feed of CH4 and C02, the catalyst supported on the MOH(GD)-IE showed a higher and more stable activity for CH4-C02 reforming reaction than the catalyst prepared using commercial MgO. The characterisation results demonstrated that the high activity and stability of the catalyst stem from the high dispersion of Pt, the stable structure and the high resistance to carbon deposition on the catalyst.

Mg/Al double-metal hydroxide regeneration of anion exchange resin by electric field intensification

Fouled anion exchange resins were regenerated by electric field intensification of Mg/Al double-metal hydroxides. Regenerative experiments were performed with varying voltages (10-30 V) and dosages of Mg/Al hydroxides (0.045-0.135 mol and 0.015-0.045 mol, respectively) for 1-5 h. Optimal results were obtained under the following regenerative conditions: 20 V, 4 h, and 0.09/0.03 mol of Mg/Al hydroxides. The maximum regenerative capacity of resins was increased to 41.07%. The regenerative mechanism was presented by Fourier-transform infrared spectrum of resins and Mg/Al hydroxides, and the regenerative degree was analyzed with respect to conductivity, pH value, and electric current. Mg/Al hydroxides were also recycled after the regeneration. This method was proven to be cost-effective and environmentally friendly.