Gaixiu Yang

Factors affecting the performance of a single-chamber microbial fuel cell-type biological oxygen demand sensor.

Microbial fuel cells (MFCs) are devices that exploit microorganisms as biocatalysts to degrade organic matter or sludge present in wastewater (WW), and thereby generate electricity. We developed a simple, low-cost single-chamber microbial fuel cell (SCMFC)-type biochemical oxygen demand (BOD) sensor using carbon felt (anode) and activated sludge, and demonstrated its feasibility in the construction of a real-time BOD measurement system. Further, the effects of anodic pH and organic concentration on SCMFC performance were examined, and the correlation between BOD concentration and its response time was analyzed. Our results demonstrated that the SCMFC exhibited a stable voltage after 132 min following the addition of synthetic WW (BOD concentration: 200 mg/L). Notably, the response signal increased with an increase in BOD concentration (range: 5-200 mg/L) and was found to be directly proportional to the substrate concentration. However, at higher BOD concentrations (>120 mg/L) the response signal remained unaltered. Furthermore, we optimized the SCMFC using synthetic WW, and tested it with real WW. Upon feeding real WW, the BOD values exhibited a standard deviation from 2.08 to 8.3% when compared to the standard BOD5 method, thus demonstrating the practical applicability of the developed system to real treatment effluents.

Core-shell Au-Pd nanoparticles as cathode catalysts for microbial fuel cell applications

Bimetallic nanoparticles with core-shell structures usually display enhanced catalytic properties due to the lattice strain created between the core and shell regions. In this study, we demonstrate the application of bimetallic Au-Pd nanoparticles with an Au core and a thin Pd shell as cathode catalysts in microbial fuel cells, which represent a promising technology for wastewater treatment, while directly generating electrical energy. In specific, in comparison with the hollow structured Pt nanoparticles, a benchmark for the electrocatalysis, the bimetallic core-shell Au-Pd nanoparticles are found to have superior activity and stability for oxygen reduction reaction in a neutral condition due to the strong electronic interaction and lattice strain effect between the Au core and the Pd shell domains. The maximum power density generated in a membraneless single-chamber microbial fuel cell running on wastewater with core-shell Au-Pd as cathode catalysts is ca. 16.0 W m−3 and remains stable over 150 days, clearly illustrating the potential of core-shell nanostructures in the applications of microbial fuel cells.

Electrocatalytic performance of the carbon supported Pd-P catalyst for formic acid oxidation

Abstract The Pd-P/C catalyst with the high content of P 0 was successfully prepared with the organic impregnation-reduction method. Pd-P/C catalysts with different Pd/P atomic ratios were characterized by X-ray diffraction (XRD), Energy dispersive X-ray spectrometer (EDX). The effect of Pd-P/C catalysts with different Pd/P atomic ratios on the oxidation of formic acid was also demonstrated by several electrochemical measures. It was found that the potential of the anodic peak of formic acid at catalyst electrodes increased in the order of Pd 1 P 6 /C 1 P 8 /C 1 P 6 /C >Pd 1 P 8 /C>Pd/C. The Pd 1 P 6 catalyst showed the best performance for the oxidation of formic acid. The Pd-P/C catalysts with the suitable atomic ratio of Pd and P had higher activity and stability for the oxidation of formic acid.

Application of surface-modified carbon powder in microbial fuel cells

Abstract The catalytic activity of surface-modified carbon powder, Vulcan XC-72R (XC), for the oxygen reduction reaction (ORR) at an air cathode in a microbial fuel cell (MFC) has been investigated. The effects of treatment with different chemicals such as nitric acid and ammonia on the chemical characteristics of XC were studied. The catalysts were characterized by Fourier transform infrared spectroscopy (FTIR), Boehm titration, and X-ray photoelectron spectroscopy. FTIR analysis showed that the functional groups of the materials were changed by chemical treatment, with nitric acid causing the introduction of oxygen-containing groups, and ammonia leading to the introduction of nitrogen-containing groups. Electrochemical measurements of MFCs containing various modified carbon materials as ORR catalysts were performed, and the results showed that chemically modified carbon materials are promising catalysts in MFCs.

Third- and high-order nonlinear optical properties of an intramolecular charge-transfer compound

An oligo(phenylenevinylene) bridged intramolecular charge-transfer (ICT) compound, (TCNQ)2OPV3, has been synthesized and its third- and fifth-order nonlinear optical refraction indexes have been determined by measurement with the 4f system with a phase-object, under near-infrared excitation.

Hydrolysis dynamics for batch anaerobic digestion of elephant grass

Elephant grass might be a potential source of fine chemical precursors and bioenergy. In the present study, we investigated the dynamics of hydrolysis of elephant grass. Three models were used to fit the hydrolysis rate constants—flat, spherical, and cylindrical models. The hydrolysis rate constants obtained using the spherical model presented the best fit between the experimental and theoretical values. Furthermore, we determined the secondary reinforcement points and interventions that can be introduced to speed up the hydrolysis process. Our findings will provide information for studies on the hydrolysis of elephant grass and promote its application in the biogas industry as an alternative biofuel.