الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
In this work, attempts have been made to synthesize and characterize functionalized polymer to act as polyelectrolyte membranes to be use in different applications such as microbial fuel cell, direct glycerol fuel cell and microbial desalination fuel cell. A trial has been made on the optimization of the reaction parameters including effect of solvent, effect of comonomer concentration, effect of comonomer composition and irradiation dose for production of the proposed polymeric membranes. In this connection, commercially available inert polymer low density polyethylene was radiation grafted with glycidyl methacrylate and vinyl acetate to prepare cation exchange membrane and dimethylaminoethylmethacrylate to prepare anion exchange membrane by means of gamma radiations, as a source of initiation and copolymerization to obtain the copolymer of required properties.
Part (I): Radiation induced graft copolymerization of glycidyal metha crylate-co-vinyl acetate onto low density polyethylene sheets to prepared cation exchange membrane for microbial fuel cell application
The obtained results are summarized in the following:
- Optimization of radiation grafting conditions shows that; acetone is the best solvent among other solvents used and show that the grafting degree increases with the increase in comonomer concentration in feed solution as well as the glycidyl methacrylate content in feed solution and radiation dose.
- FT-IR spectroscopic analysis of LDPE-g-P (GMA-co-VAc) has confirmed the presence of the characteristic bands of VAc and GMA.
- Chemical modification of grafted sheets was characterized by FT-IR and the obtained result confirmed the achievement of the chemical conversion of the epoxide group in to sulfonate groups.
- The sulfonation kinetics of PGMA chains showed that the optimal sulfonation time was 16 h whereas the sulfonation density increases as the grafting degree increase.
- The scanning electron microscopy (SEM) showed the change in surface morphology of the LDPE-g-P (GMA-co-VAc) in response to the change in the degree of grafting as well as sulfonation treatment.
- The swelling behavior of prepared LDPE-g-P(GMA-co-VAc) sheets and its sulfonated ones increase as grafting degree increase in the study range from (82 - 401) % are (3.3-12.6) and (11.7-34.5) % respectively.
- Ion exchange capacity and Proton conductivity increase (0.89-2.08) meq.g-1 and (0.84-280) mS.cm-1 as grafting degree increase (20-231) %.
- Thermogravimetric analysis (TGA) studied of the sulfonated LDPE-g-P (GMA-co-VAc) membranes in comparison with trunk LDPE and its grafted form and the result shows that the membranes possess lower thermal stability after sulfonation.
- Internal resistance of the sulfonated LDPE-g-P (GMA-co-VAc) membrane was measured as a function of grafting degree to deduce the Nyquist and Bode plot and the result indicated the increase of proton conductivity as the grafting degree increase.
- Studying the mechanical properties shows that the stiffenes and rigidity of sulfonated LDPE-g-P (GMA-co-VAc) membrane increase as the grafting degree increase.
- Open circuit voltage (OCV) values of MFCs using sulfonated grafted membranes of different grafting degree were measured as a function of time. The maximum OCV value is 0.895 and 0.51 V for membrane with 80 and 20% grafting degree respectively.
- Polarization and power density of MFCs using sulfonated grafted membranes of different grafting degree shows that; the power density obtained were 2720 m W m−2 at a current density of 21.7 mA m−2 and 234 m W m−2 at a current density of 2.07 mA m−2 for membrane with 80 and 20% grafting degree respectively.
- Cathodic oxidants with high redox potentials are able to improve the MFC efficiency. The obtained results show that, the using of 10 mM KMnO4 as electron acceptors increase the generated (OCV) to reach its maximum at 1.545 V instead of 0.895 V in absence KMnO4. The data also show that, outputted power density increase to be 356.46 W/m2 at current density of 613.54 mA/m2 with use of 10 mM KMnO4 instead of 2.72 W/m2 at current density of 21.7 mA/m2 in the absence KMnO4.
- The electrochemical impedance spectroscopies (EIS) of the sulfonated membrane with grafting degree (20 and 80%) are 127 KΩ and 415 Ω respectively.
- The water quality before and after MFCs operation using sulfonated LDPE-g-P (GMA -co-VAc) membranes with different grafting degree were followed in terms of COD and the data shows that, the reduction achieved in COD reach about 87.5 and 90 % for LDPE-g-P (GMA-co-VAc) membranes of 20 and 80 % grafting degree. Moreover, there is a clear reduction in TDS values as well as the turbidity which indicates effective treatment of the domestic wastewater.
- The columbic efficiency (CE), Columbic removal measurements (CR) and energy harvest rates (E) of the sulfonated LDPE-g-P (GMA-co-VAc) membranes of 20 and 80 % grafting degree are 1.3 and 10.1 %, 1.18 and 8.7%, 0. 28 and 2.09 C h−1 respectively.
Part II (A): Radiation induced graft polymerization of dimethyle amino- ethylemethacrylate onto low density polyethylene sheets to prepared anion exchange membrane for direct glycerol fuel cell application
The obtained result are summarized in the following
- Optimization of radiation grafting conditions shows that; methanol is the best solvent among other solvents that were used, also the grafting degree increase; with increase in monomer concentration in feed solution and with increase in radiation dose.
- FT-IR spectroscopic analysis of LDPE-g-P(DMAEMA) as well as the subsequent quaterniztion of the tertiary amino groups of the grafted PDMAEMA chains were confirmed the presence of the characteristic bands of DMAEMA. On the other hand, the quaterniztion of DMAEMA-g-LDPE membrane indicated conversion of the quaternary ammonium groups into tertiary amino group.
- SEM images showed the changes in morphological structure of the pristine LDPE in response to grafting of DMAEMA and the subsequent quaterniztion of the grafted membrane.
- The thermal analysis of the quaternized LDPE-g-DMAEMA in comparison with trunk LDPE and its grafted form showed that the membranes possess lower thermal stability after quaterniztion.
- It was found that the swelling behavior of LDPE-g- P(DMAEMA) slightly increases with increasing the grafting degrees. Also, the obtained data shows that, the highest water sorption capacity of quaternized LDPE-g- p (DMAEMA) was achieved in the presence of OH¯ as counter-ions than those achieved in the presence of Cl¯ and I¯ as counter-ions.
- Ion exchange capacity was calculated theoretically and experimentally as a function of grafting degree and the results obtained are 1.62–2.57 are (0.82 –2.17) meqg-1 respectively at grafting degree of ≈50 – ≈200%.
- Anionic conductivity measurements, Nyquist plot, of the quaternized LDPE-g-P (DMAEMA) membranes with different grafting degree show that, anionic conductivity increase as the grafting degrees increase.
- The chemical stability of the AEM was determined by observing changes in conductivity values with time and by varying the concentration of NaOH solution. The results obtained show that, the alkaline stability of quaterniztion (LDPE-g-DMAEMA) membrane in different concentration of NaOH up to 8 M solution and it is stable over extended periods of time reaching 16 days at the same concentration (0.1 M) of NaOH.
Part II (b): Synthesis and characterization of nano reduced graphene oxide decorated CuO as a conductive ink for anodic catalytic oxidation of glycerol
- FTIR spectra of GO and CuO/rGO nanocomposite show the appearance of characteristic peak of GO and CuO appeared at 510cm-1. Whereas, X-ray diffraction (XRD) of CuO/rGO nanoparticles showed that the average crystalline size of Cu nanoparticles were about 9.6, 10.7, 12.7, 13.9 and 20.3 nm at different Cu content.
- The phase and microstructure of the GO and CuO/rGO were investigation using TEM.
- The thermal stability of the CuO/rGO nanocomposite of different Cu contents in comparison with GO showed that, the introduction of CuO enhanced the thermal stability of GO and the thermal stability increase by increase of Cu content.
- Cyclic voltammetry of the synthesized CuO/rGO with different Cu content shows almost the same anodic oxidation peak current and cathodic reduction peak.
- Electrochemical impedance spectroscopy (EIS) of CuO/rGO with different Cu content; Nyquist plot, Bode magnitude and phase angle shows that the samples with lowest Cu content show highest conductivity and the conductivity decrease as the Cu content increases.
- Linear sweep voltammetry (LSV) analysis of synthesized CuO/rGO nanocomposite shows that the CuO/rGO nanocomposites with the lowest Cu content possesses more positive onset potential of 0.193 V and highest current density at the same potential; -0.07 mA cm-2 at -0.4 V.
- Scan rate dependence studies show that, the redox peak currents varied linearly as a function of the square root scan rate with the diffusion coefficient of 7.1 × 10−5 cm2 s− 1 and surface coverage of 4.04 × 10−8 mol cm−2. However, at higher scan rates, the potential values of the redox peaks are proportional to the Napierian logarithm of the scan rate with the electron transfer coefficient of 0.75 and number of transferred electron of 1.99.
- Cyclic voltammetry analysis of the CuO/rGO nanocomposite of 65 wt. % Cu electrocatalysts were carried out using Glycerol/KOH solution of different compositions at a scan rate of 50mVs-1. The data shows that as the KOH content in the fuel increase, the anodic peak current of glycerol oxidation increases in the time, its potential value shifts negatively up to 2 M KOH, then the anodic peak current falls off.
- Electrochemical impedance spectroscopy (EIS) analysis was utilized to measure the activation loss in the half cell using Glycerol/KOH solution of different compositions. The obtained data reveal that half-cell used 2M KOH possesses the lowest activation loss among other fuel compositions.
- Linear sweeping voltammetry (LSV) of the Glycerol/KOH fuel of different compositions shows that glycerol oxidation exhibits a single well-defined peak with an upturned tail in high potentials. The data also shows that the onset potentials and peak current of glycerol oxidation using a fuel of 2M KOH exhibits highest peak current densities and more positive onset potentials.
- Applying different scan rate for electro-oxidation of glycerol with 2M KOH, at higher scan rates, the potential values of the redox peaks are proportional to the Napierian logarithm of the scan rate with the electron transfer number of 2.81.
- For non-Nobel metal ORR catalysts, long-term stability is of more concerned than the catalytic activity. The CuO/rGO conductive ink shows efficiency about 93% for oxidation of glycerol after 200 cycles.
Part II (c): Synthesis and characterization of nano reduced graphene oxide decorated NiCoS as a conductive ink for air cathodic catalytic reaction.
- FTIR spectra of GO and NiCoS/rGO show the appearance of characteristic peak of GO and peaks which can be assigned to metal sulfide.
- X-ray diffraction (XRD) showed that, the positions of diffraction peaks of NiCoS/rGO nanoparticles matched well with standard.
- The phase and microstructure of the GO and NiCoS/rGO were investigation using TEM.
- The thermal stability of the NiCoS/rGO nanocomposite in comparison with GO was investigated using thermogravimetric analysis (TGA). The data show that the introduction of NiCoS increases the thermal stability of the nanocomposite.
- Cyclic voltammetry of the prepared NiCoS/rGO with different Ni/Co composition show almost rectangular shape of CV curves and symmetric current-potential characteristics with no obvious redox peaks.
- The CV analysis of NiCoS/ rGO based inks at different scan rates shows that, as the scan rate increased, the CV area also increased retaining its rectangular shape.
- Electrochemical impedance spectroscopy (EIS), Nyquist plot and Bode magnitude plot of the NiCoS/rGO based electrodes with different Ni/Co content show that the electrode with the highest Ni content has highest conductivity among the sample investigated.
- The phase angle of the NiCoS/rGO ink with different Ni contents reveal that NiCoS/rGO ink with the highest Ni content has a much higher phase angle (θ) -79.5° in comparison to other investigated samples.
- Linear Sweep Voltammetry analysis (LSV) of NiCoS/rGO nanocomposite electrodes with different Ni contents shows that the NiCoS/rGO nanocomposite with the highest Ni content possesses more positive onset potential of 0.199 V and highest current density at the same potential; -0.043 mA cm-2 at -0.40 V.
Part II (D): Direct glycerol fuel cell construction using CuO/rGO as anode catalyst
- Open circuit voltage (OCV) for (DGFC) operated at different temperatures using the prepared AEM of different grafting degree. The data shows that the OCV increases with increasing of the operating temperature as well as the increase in the grafting degree.
- The polarization and power density curves of DGFC with different grafting degree operated at 80 °C. The data shows that the polarization and power density output increase as the grafting degree increase.
- The products of glycerol electro-oxidation were qualitatively determined by HPLC. The data shows that, different products of glycerol oxidation with the change of grafting degree.
Part II (E): Electrochemical characterization of nano reduced graphene oxide decorated NiCoS as a conductive ink for anodic catalytic oxidation of glycerol
- Cyclic voltammetry of the synthesized NiCoS/rGO with different Ni content shows two intense redox peaks potential at about 0.41 and 0.23 V.
- Electrochemical impedance spectroscopy (EIS) of the NiCoS/rGO with different Ni contents; Nyquist and Bode magnitude plot based electrodes shows that the sample with the highest Ni contents has highest conductivity among the samples investigated.
- The phase angle of the NiCoS/rGO ink with different Ni contents reveal that NiCoS/rGO ink with the highest Ni content has a much higher phase angle (θ) -83°in comparison to the other investigated samples.
- Linear Sweep Voltammetry (LSV) analysis of synthesized NiCoS/rGO nanocomposite with different Ni content shows that the NiCoS/rGO nanocomposite with the highest Ni content possesses more positive onset potential of 0.193 V and highest current density at the same potential; -0.082 mA cm-2 at -0.38 V.
- Scan rate dependence studies show that, the redox peak currents varied linearly as a function of the square root scan rate with the diffusion coefficient of 5.3 × 10−5 cm2 s−1 and surface coverage of 3.04 × 10−8 mol cm−2. However, at higher scan rates, the potential values of the redox peaks are proportional to the Napierian logarithm of the scan rate with the electron transfer coefficient of 0.503 and number of transferred electron of 2.6.
- Cyclic Voltammetry analysis of the NiCoS/rGO nanocomposite of 65 wt. % Ni electrocatalysts were carried out using Glycerol/KOH solution of different compositions at a scan rate of 50mVs-1. The data shows that as the KOH content in the fuel increase, the anodic peak current of glycerol oxidation increases in the time, its potential value shifts negatively up to 2M KOH, then the anodic peak current falls off.
- Electrochemical impedance spectroscopy (EIS) analysis was utilized to measure the activation loss in the half cell using Glycerol/KOH solution of different compositions. The obtained data reveals that half cell used 2M KOH possesses the lowest activation loss among other fuel compositions.
- Linear sweeping voltammetry (LSV) of the Glycerol/KOH fuel of different compositions shows that glycerol oxidation exhibits a single well-defined peak with an upturned tail in high potentials. The data also shows that the onset potentials and peak current of glycerol oxidation using a fuel of 2M KOH exhibits highest peak current densities and more positive onset potentials.
- For non-Nobel metal ORR catalysts, long-term stability is of more concerned than the catalytic activity. The NiCoS/rGO conductive ink shows efficiency about 86% for oxidation of glycerol after 200 cycles.
Part II (F): Direct glycerol fuel cell construction using different catalysts
- Open circuit voltage (OCV) for (DGFC) operated at different temperatures using the prepared AEM of grafting degree 200 % at different catalyst type. The data shows that the OCV increases with increasing of the operating temperature as well as the increase with using of CuO/rGO.
- The polarization and power density curves of DGFC with different catalysts type operated at 80 °C. The data shows that; the polarization and power density output increase with using CuO/rGO as anode catalyst.
- The products of glycerol electro-oxidation were qualitatively determined by HPLC. The data shows that, products of glycerol electro-oxidation change with using different catalysts.
Part (III): Application of prepared cation and anion exchange membranes in microbial desalination fuel cell
- The operation of MDFCs using bio-catholyte as electron acceptor achieved the lowest salt removal, (OCV), polarization and power density of 44.15%, 0.525 V and 33.5 Wm-2 at a current density of 186.1 mA m−2 respectively while using KMnO4 as acceptor achieved highest values of 60.17 %, 1.350 V and 151.5 W m-2 at a current density of 275.57 mA m−2 respectively.
- The internal resistance loss is a significant factor that affects power production in MDFCs. The obtained result shows that, the internal resistance decreased from 1.7Ω using bio-catholyte as electron acceptor to 0. 8 Ω using KMnO4.
- The COD removal, Columbic efficiency (CE), columbic removal measurement (CR) and average energy harvest rate in MDFCs using bio-catholyte as electron acceptor were 69.9 %, 13.5%, 9.4 % and 0.520 C h−1 respectively while KMnO4 were 85.8% ,20.6%, 17.4% and 0.961 C h−1 respectivly.