Ceramics powder of BaCe0.54Zr0.36Y0.1O2.95 (BCZY) was synthesized using three different methods namely sol-gel (SG), supercritical fluid (SC) and supercritical fluid assisted sol-gel (SCSG). The respective prepared samples were denoted as S1, S2 and S3. TG thermogram of the dried powders for all samples showed three stages of weight loss. Each stage was corroborated by one or two exothermic peaks as shown in DTG signal. Complete thermal decomposition for all the samples was almost accomplished at 1000°C for about 2 h. At calcination temperature of 1100°C, S1 showed a single-phase of perovskite-type oxides as proven by XRD result. Morphology of the calcined powders by SEM micrograph showed that S1 is in spherical shape, S2 is in cubic structure and S3 has a mixture of spherical and rod-like structure. Therefore, as comparison, SG method gives better characteristics of cerate-zirconate ceramics powder compared to SC and SGSC.
A nitrate-based nickel salt was used to prepare NiO-BaCe0.54Zr0.36Y0.1O2.95 (NiO-BCZY) composite powders by an evaporation
and decomposition of solution and suspension (EDSS) method. The prepared powders with different weight ratios of NiO to
BCZY (NiO:BCZY) were denoted as S1 (50:50) and S2 (60:40). The powders were characterized using Thermogravimertic
analyzer (TGA), X-ray diffractometer (XRD) and scanning electron microscope (SEM) equipped with energy dispersive
X-ray (EDX) spectrometer. TGA results showed that the thermal decomposition of intermediate compounds in the dried
powder (T = 150°C) completed at ~700°C. XRD analysis confirmed that the calcined powder (T = 1100°C) of S1 and
S2 did not show any crystalline peaks related to BCZY compound as the peaks associated to impurity phases of BaCeO3
and BaZrO3
were appeared in their XRD patterns. The impurity phases along with NiO still remained in the S1 sample
after it was calcined at 1400°C. As the calcination temperature increased, the particles size of S1 also increased and Zr
elemental composition deviates from the nominal stoichiometric of the NiO-BCZY as proven by SEM/EDX analysis. The
results indicate that the formation of homogenize NiO-BCZY composite prepared using EDSS method was not favored even
after calcined at high temperature (T = 1400°C).
Many kinds of substrates have been used to investigate bioelectricity production with Microbial Fuel Cell (MFC). Dry algae biomass has the highest maximum power density compared to other substrates due to high carbon sources from its lipid. However, the bacterial digestion of algae biomass is not simple because of the complexity and strength of the algal cell wall structure. An algae biomass extraction is needed to break the cell wall structure and facilitate digestion. Spray drying method is commonly used in highvalue products but may degrade some algal components which are crucial for microbial degradation in MFC, while the freeze-drying method is able to preserve algal cell constituents. The MFC was fed with freeze dried and spray dried algae biomass to produce energy and determine the degradation efficiency. Results showed the average voltage generated was 739 mV and 740 mV from freeze dried and spray dried algae biomass, respectively. The maximum power density of freeze dried algae biomass is 159.9 mW/m2 and spray dried algae biomass is 152.3 mW/m2. Freeze dried algae biomass has 54.2% of COD removal and 28.4% of Coulombic Efficiency while spray dried algae biomass has 50.1% of COD removal and 24.9% of Coulombic Efficiency.
Zaidatul Salwa Mahmud, Siti Nor Hafiza Mohd Yusoff, Nur Hamizah Mohd Zaki, Mohamad Fariz Mohamad Taib, Mohamad Kamil Yaakob, Oskar Hasdinor Hassan, et al.
A free-standing film consisting of 49% PMMA grafted-natural rubber electrolytes was prepared. Potassium hydroxide (KOH) and propylene carbonate (PC) was added to the preparation and the properties of the electrolytes measured using complex impedance analysis at various temperatures. The addition of plasticiser in alkaline polymer electrolyte gives rise to the ionic conductivity up to 2.647 x 10-6 S cm-1 at composition consisting of 50wt.% of PC. The dielectric properties of the GPEs were studied and the relaxations at higher frequencies appear in both imaginary and real part of the permittivity. These relaxations are related with the interface ion polarisations at the polymer-electrode interface and segmental motion of the polymer electrolyte molecular chains. The influence of the impedance spectra on temperature was studied. Results showed rising temperature increased conductivity, top frequency (f*), relative dielectric constant (εr) and geometrical capacitance (Cg) due to the mobility of free ion carriers.
io-electricity generation by Microbial Fuel Cell (MFC) has gained considerable attention due to
its integration with wastewater treatment such as Palm Oil Mill Effluent (POME). Investigation
into pH effect and determination of optimal pH value ranges growth for acidogenic, acetogenic
and methanogenic by natural mixed culture
electroactive bacteria (exoelectrogens) growth
in original non-Deoxygenated Mixed POME
(nDMP) and Deoxygenated Mixed POME (DMP)
in MFC was carried out. Current generation,
power generation and maximum power were
also monitored. Experimental results show that
exoelectrogens in nDMP with pH 6.8 yielded the
highest current generation of 61.51 mAm-2 and
maximum power of 17.63 mWm-2. Overall, nDMP
substrates with 3 pH ranges (5.5, 6.8 and 8.0)
showed equal potential to generate power that is
higher than DMP substrates. Comparison carried
out for inter DMP substrates demonstrated that
DMP with pH 6.8 and DMP with pH 8.0 showed equal potential to generate power, but not for DMP with pH 5.5. Subsequently, nDMP with pH 6.8 and
nDMP with pH 8.0 showed equal potential for higher maximum power compared to nDMP with pH
5.5 and DMP substrates. This finding indicates that mixed microbial communities in DMP substrate
are dominant with obligate anaerobic exoelectrogens bacteria which have less capability to generate
electricity compared to nDMP substrate that was dominated by the aerotolerant and/or facultative
anaerobic exoelectrogens bacteria.