Improved performance of solid oxide fuel cell operating on biogas using tin anode-infiltration

This work presents a novel method of Sn-infiltration on SOFC anodes for SOFC operation in biogas dry reforming. Using commercially available NiYSZ-based anode supported half cells with hand-painted LSM/YSZ cathode layers, Sn-infiltrated NiYSZ SOFCs containing different amounts of Sn were manufactured. These SOFCs were tested for their electrochemical performance and quantity of deposited carbon during operation on simulated biogas of 1:2 volume ratio of CO2:CH4 without humidification but with 25% Helium added to the feed stream to enable measurements of the fuel cell outlet gas composition using a quadrupole mass spectrometer. Most of the SOFCs were tested in biogas for 1 day (22 hours), but several cells were tested for 6 days (150 hours) to evaluate performance degradation. The electrochemical performance tests at 750 oC showed that with H2 as fuel the non-infiltrated NiYSZ SOFCs were able to reliably generate a moderate level of current of 350 mA cm-2 at 0.7 V; however when simulated biogas was introduced, current dropped significantly to 90-200 mA cm-2. Contrary to non-infiltrated cells, a series of Sn-infiltrated cells under the same operating conditions performed equally well both on H2 and biogas producing 310 to 420 mA cm-2 at 0.7 V. Several cells showed stable electrochemical performance over 150 hours of operation both on H2 and biogas. Using Temperature Programmed Oxidation (TPO), both Sn-infiltrated and non-infiltrated SOFCs showed low quantities of carbon formed during 22 hours operation on biogas. Visual observation and SEM images of the anode surface after 150 hours operation on biogas showed no sign of deposited carbon. The conclusion is that Sn-infiltrated NiYSZ-based SOFC can be operated on simulated biogas with significantly higher electrochemical performance and low carbon deposition, given the anode is adequately modified

Application of Dry Biomass of Aphanothece sp. as A Biosorbent of Copper Heavy Metal

Various technologies have been developed to reduce heavy metal content in the wastewater. The biosorption method is a technique that is widely applied because it is cheap, environmentally friendly, and has high efficiency. This study aims to ascertain the potential of dry biomass of microalgae Aphanothece sp. as a biosorbent of Cu (II) ions in synthetic wastewater and determine the appropriate biosorption kinetics model. Analysis of Cu (II) ion concentrations was carried out using Atomic Absorption Spectrophotometer (AAS). The results showed that the optimum conditions for the biosorption process were at pH 4, and the contact time was 210 minutes with the removal efficiency of Cu (II) ions reaching 80.02%. The results of tests on the adsorption isotherm model showed that the biosorption process of Cu (II) ions using dry biomass biosorbent Aphanothece sp. follows the Freundlich isotherm model with an R2 value of 0.9962.</p

Improved Performance and Durability of Anode Supported SOFC Operating on Biogas

Performance curves for both Sn-doped Ni-YSZ and un-doped Ni-YSZ single cells are presented in Fig.1.  The cell tests were carried out at 750oC under dry hydrogen flowing at 7mL/min Helium and 21mL/min H2 followed by biogas flowing at 7mL/min CO2: 14mL/min CH4: 7 mL/min He with the cathode side open to ambient air.   The cells were allowed to reduce under H2 for a minimum of 3hrs in OCV mode before any initial   data was obtained. Operation on hydrogen was run for 26 hours to stabilize cell performance before the fuel was switched to biogas. After stabilization on hydrogen the Sn-doped Ni-YSZ gave 390mA/cm2 at 0.7V compared to the un-doped Ni-YSZ cell which gave 100mA/cm2 at 0.7V.</jats:p