Performance of tetramethoxyphenyl porphyrin cobalt(II) (CoTMPP) based stainless steel cathode in the electricigenic permeable reactive barrier for groundwater organic contamination remediation.

An electricigenic permeable reactive barrier (EPRB) technology was brought forward for remediation of organic-contaminated groundwater, with a benefit that it overcame the limitations of electron acceptor addition in other groundwater remediation methods. To investigate performances of constructions and materials used in EPRB system, several kinds of reactors were designed and prepared in laboratory. Stainless steel wires, a kind of nontoxic, inexpensive and conductive material, were used as basic material of electrode. In order to improve cathodic oxygen reduction capability, a cathode based on tetramethoxyphenyl porphyrin cobalt (II) (CoTMPP) was prepared and studied in this paper. Results showed that a high catalytic activity for oxygen reduction was exhibited by the CoTMPP based cathode, with an electricity generation 3 times as high as that of the naked stainless steel cathode. Some evidence indicated that by loading on the surface of stainless steel wires and heat-treated under anaerobic conditions, epoxy resin, with its curing agents, might have got a catalytic capability for oxygen reduction.

[Rapid determination of internal resistance in an electricigenic microorganism reaction system].

Internal resistance (R(int)) is an important parameter for kinetic studies on an electricigenic microorganism reaction system (EMRS). The traditional polarization curve measurement method is too laborious and tedious, usually leads to remarkable disturbance on system running. An improved method was put forward in this study, by decreasing the adjustment range of the external resistance value (R(ext)). In the situation of 10 omega of R(ext) step length and 1 min of voltage stabilization time, the whole test can be finished in 10 min, and the differences of the system current before and after R(int) determination were less than 20 microA. Different stabilization time has little influence on the results. Though to shorten the R(ext) step length can lessen the disturbance on the system running,it simultaneously leads to a larger measurement errors because of the multimeter precision limitation. The method advanced may be used to monitor the real-time R(int) change of EMRS.

[Detecting organophosphorus pesticide in water environment using an enzyme biosensor].

Based on a screen printed carbon electrode which contained a sensitive film prepared by crosslinking acetylcholine esterase (AChE) with glutaraldehyde on the surface of working electrode, an amperometric enzyme biosensor was taken on the determination of organophosphorus (OP) pesticide in water environment. Cyclic voltammetry was applied to assess the coherence of prepared screen printed electrodes. The results show that the variation is less than 10%. The sensor sensitivity was optimized with respect to content of enzyme, crosslinker and substrate. The best sensitivity is obtained using 0.2% of glutaraldehyde, 0.5 mg/mL of AChE and 10 mmol/L of acetylthiocholine chloride (ATChCl). Amperometric I-t curve was conducted to detect the decrease rate of the current after the addition of two kind of OPs (terbufos and parathion), respectively. The detection limit for two kind of OPs are found to be 1 ng/mL with the linear range 1 ng/mL - 10 000 ng/mL. Cyclic voltammetry was conducted to detect parathion on the sensors which immobilized AChE by physical adsorption. The results show that it can achieve a better sensitivity than amperometric I-t curve.