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A laboratory-scale investigation was carried out to study the characteristics of electrokinetic (EK) movement for separation of salts from tideland. The salinity of tideland material, including the sodium and chloride contents, was investigated as a function of operation time under a constant voltage gradient of 1 V/cm. As the operation period increased, the salinity of tideland material decreased gradually. However, the rate of decrease gradually diminished with an increase in the operation period. The electrical current increased gradually with the operation time. Ten days of electrokinetic operation decreased the electrical conductivity of the tideland material to 65.5% of the initial value. Sodium was removed completely, but the removal efficiency of chloride was 58.5% after 10 days. The lower removal of chloride was due to the formation of complexes with magnesium and calcium. High concentrations of chloride formed chlorine gas in the anolyte, and aqueous chlorine oxidized the circulation tube. The pH distribution after electrokinetic treatment showed a typical shape, and the change in water content was negligible. The results demonstrate that the electrokinetic process is a suitable means to remove salinity from tidelands.

Salinization of greenhouse soils has become a serious problem in Korea because of the extensive use of chemical fertilizers to improve crop yield. This study investigated the feasibility of electrokinetic (EK) treatment for reclamation of saline soil. Experiments were conducted using voltage gradients of 1, 2, and 3 V/cm applied for 48 and 96 h. Anions such as chloride, sulfate, and nitrate were transported toward the anode and accumulated there, whereas cations were transferred toward the cathode by electromigration. Among the various ions, the highest removal efficiency was achieved for nitrate: [80% at 48 h and [99% at 96 h. Chloride removal after 96 h was substantially higher than that after 48 h because the longer period of time allowed more electrical transport via electromigration and electro-osmosis. However, the removal efficiency for sulfate and calcium did not change significantly between 48 and 96 h. Soil EC was lower than the initial value in all soil sections at 96 h. The lowest value, 1.8 dS/m, was seen in the experiment employing a gradient of 3 V/cm for 48 h. This study demonstrated that nitrate can be readily removed from soil by electromigration. Further, other ions can also be removed by EK treatment; therefore, it could be successfully used for reclamation of saline soils.

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Electrokinetic (EK) process was performed to restore sulfate-originated saline soil and to evaluate the effect of treatment duration. Sulfate and potassium were the major ionic salts in the saline soil used in this study. A constant voltage gradient of 1 V/cm was applied for 8, 12, and 16 days. After EK treatment, anions and cations were transported toward anode and cathode, respectively, by electromigration. Chloride was completely removed, and 85.6% of nitrate was removed after 8 days of treatment. The increase of treatment period from 8 to 12 days had a negligible effect on the enhancement in the rate of sulfate removal; however, over 70% was removed after16 days. At the end of experiment, the electrical conductivity (EC) of the soil, an indicator of soil salinity, decreased to 1.93 dS/m from an initial value of 5.3 dS/m, and the distribution of sulfate was similar to that of EC. The operation time of 16 days was sufficient to restore the sulfate-originated saline soil using the EK process.

An anatase TiO2 and three kinds of novel TiO2 nanoparticles were prepared by a hydrothermal method for dye-sensitized solar cells (DSSCs), which were obtained by mixing NaOH (10 M), KOH (14 M) and LiOH (10 M) solution with an anatase TiO2 powder, respectively. The TiO2 working electrodes of DSSCs were prepared and the photoelectric properties of the cells were characterized. The influence of different poly(ethylene glycol) contents in TiO2 films with and without HNO3 treatment on the electron transfer in DSSCs were investigated. It is found that the DSSC with HNO3 (0.002 mol/l)-treated film containing 16.7 wt% PEG shows the higher power conversion efficiency of 6.0%, which was mainly depended on the degrees of TiO2 pore size and uniformity of TiO2 films.

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