A novel solid-phase microextraction (SPME) setup, circulating cooling solid-phase microextraction (CC-SPME), is developed for determining organochlorine pesticides (OCPs) in water. The linearity area of this method is 0.5-120g/l, its RSD value is less than 10% and detection limit is in the low ng/l when it is used to detect-hexachlorocyclohexane, which is better than traditional headspace SPME (HS-SPME) and direct immersion SPME (DI-SPME) methods. The influence of factors such as pH, ionic intensity, adsorption time, and adsorption temperature were also investigated, respectively.

A Cu-TiO2/Ti dual rotating disk photocatalytic (PC) reactor has been developed based on our single rotating disk photoelectrocatalytic (PEC) reactor (Y. Xu, et. al, Environ. Sci. Technol. 2008, 42, 2612-2617), and successfully applied to the treatment of laboratory and industrial dye wastewater. Round TiO2/Ti and Cu disks of the same size are connected by a Cu wire and fixed parallel on an axis continually rotating at 90 rpm. High treatment efficiency is obtaineddueto direct photooxidation on the TiO2/Ti photoanode as well as additional degradation on the Cu cathode, which is speculated via indirect hydrogen peroxide (H2O2) oxidation and direct electro-reduction of dye on cathode. The mechanism of the Cu-TiO2/Ti dual rotating disk PC reactor was investigated. In a 20 mg L-1 Rhodamine B (RB) solution, approximately 100mV of potential and 10μA of current were measured between the Cu and TiO2/Ti electrode during PC treatment. Such phenomenon was explained by spontaneous electron transfer based on the same principle of establishing a Schottky barrier. On the Cu electrode surface, the photoelectrons either reduced dye molecules directly or reacted with dissolved oxygen (DO) to form H2O2. Rotation of electrodes out of the solution enhanced the mass transfer of target compound and kept the aqueous film fresh. The Cu-TiO2/Ti dual rotating disk PC reactor is a simple and effective device for the treatment of RB dye wastewater.

A TiO2/Ti rotating disk photoelectrocatalytic (PEC) reactor has been developed and successfully applied to degrade Rhodamine B (RB) and other dyes in textile effluents. The innovative concept behind the reactor design is to simultaneously perform two processes on one electrode. These two processes are (1) highly effective thin-film PEC, in which the upper half of the round disk photoanode was coated with a thin layer of wastewater and exposed to UV radiation in air; and (2) the conventional PEC, in which the other half of the disk was immersed in bulk wastewater and irradiated by the same light source. The average aqueous film thickness was about 75μm. The disk electrode was kept rotating at 90 rpm to continuously refresh the thin aqueous film for the upper side of the electrode and to promote the mass transfer of the target pollutants and the degradation products on the lower part of the disk. Using 20-150 mg L-1 RB solutions as a model system, thin-film PEC removed total color and total organic carbon (TOC) by 27-84% and 7-48%, respectively, within 1 h,muchhigher than 3-55% and 0-30% removal by conventional PEC under the same treatment conditions. Results also suggest that the thinfilm process was especially superior for treating high concentration solutions. Application of the rotating disk PEC reactor in industrial textile effluents showed a satisfactory result. The recycle experiments demonstrated excellent stability and reliability of the rotating disk PEC electrode. This study proposed a new concept for designing a PEC reactor applicable to industrial wastewater treatment.