Synthesis and application of polypyrrole/carrageenan nano-bio composite as a cathode catalyst in microbial fuel cells

A novel nano-bio composite polypyrrole (PPy)/kappa-carrageenan(KC) was fabricated and characterized for application as a cathode catalyst in a microbial fuel cell (MFC). High resolution SEM and TEM verified the bud-like shape and uniform distribution of the PPy in the KC matrix. X-ray diffraction (XRD) has approved the amorphous structure of the PPy/KC as well. The PPy/KC nano-bio composites were then studied as an electrode material, due to their oxygen reduction reaction (ORR) ability as the cathode catalyst in the MFC and the results were compared with platinum (Pt) as the most common cathode catalyst. The produced power density of the PPy/KC was 72.1 mW/m2 while it was 46.8 mW/m2 and 28.8 mW/m2 for KC and PPy individually. The efficiency of the PPy/KC electrode system is slightly lower than a Pt electrode (79.9 mW/m2) but due to the high cost of Pt electrodes, the PPy/KC electrode system has potential to be an alternative electrode system for MFCs

Effects of montmorillonite (MMT) on morphological, tensile, physical barrier properties and biodegradability of polylactic acid/starch/MMT nanocomposites

Biodegradable polymer nanocomposites have received great attention due to their synergistic properties of good mechanical and barrier properties; yet, they are biodegradable. In this research, prior to compression into thin sheets, polylactic acid (PLA), tapioca starch, glycerol and maleic anhydride (MA) were compounded with different loadings of montmorillonite (MMT) through a twin screw extruder. MMT was added to improve the mechanical and barrier properties of PLA/starch blend. The effects of MMT loadings on tensile property, morphology and biodegradability were studied. X-Ray diffraction analysis showed that samples with MMT loadings below 6 phr exhibited exfoliated structure, while samples that contained MMT above 6 phr (5.66 wt%) exhibited intercalated structure. The exfoliated-type structure was observed using transmission electron microscopy. These effects were manifested in the tensile results, which showed an increase in modulus, tensile strength and elongation at break. However, for the modulus, the MMT content was limited to 4 phr (3.85 wt%). Beyond that, the modulus decreased. It was thought that above 4 phr, the MMT particles agglomerated, thus reducing the modulus of the samples. This argument was supported by field emission scanning electron microscopic images, which showed big lump when MMT loadings were at 6 and 8 phr (7.41 wt%). Meanwhile, the addition of MMT has improved the water barrier property and hastened the rate of biodegradation. The nanosized MMT particles disturb the continuity of PLA/starch chain, which formed pathways for microorganisms to enter and attack the chain, thus increasing the biodegradation rate. The particle is also able to block a tortuous pathway for water to enter the starch chain, thus reducing the water uptake and improving the physical barrier of nanocomposite

Electerochemical study of speek/cloisite 15a (r)/tap membrane at moderate temperature for DMFC application

This study was to investigate the properties of the sulfonated poly(ether ether ketone) (SPEEK) nanocomposite membranes filled with Cloisite 15A® clay, in the presence of 2,4,6 triaminopyrimidine (TAP) as a compatibilizer. The membranes were prepared via solution intercalation method, before they were subjected to performance tests in the temperature range of 27 to 80 oC for comparison with Nafion® 117. The SPEEK membranes were then utilized to measure the open circuit voltage (OCV) and power density for direct methanol fuel cell (DMFC) applications in the temperature range of 27 to 60 oC. The best data obtained, among all the tested membranes, were methanol permeability of 0.52 ×10-6 cm2s-1 and proton conductivity of 47 mScm-1 with the methanol selectivity of 9.1 × 104 S.s.cm-3, even at a high temperature of 60oC

Influence of mesoporous phosphotungstic acid on the physicochemical properties and performance of sulfonated poly ether ether ketone in proton exchange membrane fuel cell

This study demonstrates the successful development of hybrid mesoporous siliceous phosphotungstic acid (mPTA-Si) and sulfonated poly ether ether ketone (SPEEK) as a proton exchange membrane with a high performance in hydrogen proton exchange membrane fuel cells (PEMFC). SPEEK acts as a polymeric membrane matrix and mPTA-Si acts as the mechanical reinforcer and proton conducting enhancer. Interestingly, incorporating mPTA-Si did not affect the morphological aspect of SPEEK as dense membrane upon loading the amount of mPTA-Si up to 2.5 wt%. The water uptake reduced to 14% from 21.5% when mPTA-Si content increases from 0.5 to 2.5 wt% respectively. Meanwhile, the proton conductivity increased to 0.01 Scm−1 with 1.0 wt% mPTA-Si and maximum power density of 180.87 mWcm−2 which is 200% improvement as compared to pristine SPEEK membrane. The systematic study of hybrid SP-mPTA-Si membrane proved a substantial enhancement in the performance together with further improvement on physicochemical properties of parent SPEEK membrane desirable for the PEMFC application

Synthesis, modification and optimization of titanate nanotubes-polyamide thin film nanocomposite (TFN) membrane for forward osmosis (FO) application

In the present study, the self-synthesized thin film nanocomposite (TFN) membrane incorporated with hydrophilic functionalized titanate nanotubes (TNTs) has been fabricated and tested for forward osmosis (FO) desalination. The ATR-FTIR results showed that NH2-TNTS were successfully modified by AATPS and while TEM and XRD revealed the tubular morphology and crystal structure of NH2-TNTs nanotubes, respectively. The presence of the chemical bondings between NH2-TNTs and polyamide (PA) selective top layer of TFN is corroborated with the FTIR results. The existence of NH2-TNTs in PA top layer was further confirmed by XPS analysis on the control and TFN membranes. The effect of NH2-TNTs on the PA layer was investigated and discussed in terms of surface morphology and separation performance. The morphology of the PA layer was investigated through FESEM and AFM micrographs and the outgrowth of the "leaf-like" structure was observed following the increase in NH2-TNTs content. Compared to the thin film composite (TFC) control membrane, the TFN membrane embedded with 0.05wt% NH2-TNTs (designated as TFN0.05) exhibited two times improvement in water flux without sacrificing salt rejection

Transport properties of SPEEK nanocomposite proton conducting membranes: optimization of additives content by response surface methodology

The addition of Cloisite 15A Clay (CC) and 2,4,6-triaminopyrimidine (TAP) to enhance the transport properties of sulfonated poly ether ether ketone (SPEEK) nanocomposite membrane, which is a promising candidate for direct methanol fuel cell (DMFC) application, was investigated. The central composite design (CCD) of the response surface method (RSM) was utilized to optimize the content of incorporated additives in SPEEK nanocomposite membrane and predict its performance. Three models correlating the independent parameters (contents of added CC and TAP) and the responses (proton conductivity, methanol permeability and selectivity) were developed and verified with experimental data. The optimum parameters for achieving highest performance represented by methanol permeability of 2.56×10(cm/s), proton conductivity of 17.12(mS/cm) and membrane selectivity of 55773.7sS/cm were obtained at contents of CC and TAP of 2.92 and 5.68wt%, respectively. The deviation of the corresponding experimental data was found to be in an acceptable range, confirming the suitability of RSM for predicting the membrane performance and optimizing the additives contents. The membrane with optimum additives content showed an improved structure as revealed by the field emission scanning electron microscopy (FESEM)

Treatment of two different water resources in desalination and microbial fuel cell processes by poly sulfone/sulfonated poly ether ether ketone hybrid membrane

The PS (Polysulfone)/SPEEK (sulfonated poly ether ether ketone) hybrid membranes were fabricated and modified with low and high DS (degrees of sulfonation) for the desalination of brackish water and proton exchange membrane in microbial fuel cell. The results illustrated that SPEEK has changed the morphology of membranes and increase their hydrophilicity. PS/SPEEK with lower DS (29%) had the rejection percentage of 62% for NaCl and 68% for MgSO4; while it was 67% and 81% for PS/SPEEK (76%) at 4 bars. Furthermore, the water flux for PS at 10 bar was 12.41 L m-2 h-1. It was four times higher for PS/SPEEK (29%) which means 49.5 L m-2 h-1 and 13 times higher for PS/SPEEK (76%) with means 157.76 L m-2 h-1. However, in MFC (microbial fuel cell), the highest power production was 97.47 mW/m2 by PS/SPEEK (29%) followed by 41.42 mW/m2 for PS/SPEEK (76%), and 9.4 mW/m2 for PS. This revealed that the sulfonation of PEEK (poly ether ether ketone) made it a better additive for PS for desalination, because it created a membrane with higher hydrophilicity, better pore size and better for salt rejection. Although for the separator, the degree of sulfonation was limited; otherwise it made a membrane to transfer some of the unwanted ions

Development of dense void-free electrospun SPEEK-Cloisite15A membrane for direct methanol fuel cell application: optimization using response surface methodology

Response surface methodology (RSM) was utilized to design the experiments at the settings of solution concentration, voltage and the collector distance. It also imparted the evaluation of the significance of each parameter on the resultant physico chemicals (proton conductivity, methanol permeability and water uptake). The investigations were carried out in the two-variable process domains of several collector distances as applied voltage and the solution concentration were varied at a fixed polymer molecular weight. The result showed that all three factors were found statistically significant in the production of void free electrospun SPEEK/Cloisite membrane. All responses were correlated to these variables by using a second order polynomial function. The optimum condition for void free electrospun SPEEK/cloisite was at 0.17 wt% concentration with applied voltage of 22.15 kV and 18.83 cm distance from needle tip to screen collector