Mostafa Ghasemi

A review on the effect of proton exchange membranes in microbial fuel cells

Microorganisms in microbial fuel cells (MFC) liberate electrons while the electron donors are consumed. In the anaerobic anode compartment, substrates such as carbohydrates are utilized and as a result bioelectricity is produced in the MFC. MFCs may be utilized as electricity generators in small devices such as biosensors. MFCs still face practical barriers such as low generated power and current density. Recently, a great deal of attention has been given to MFCs due to their ability to operate at mild conditions and using different biodegradable substrates as fuel. The MFC consists of anode and cathode compartments. Active microorganisms are actively catabolized to carbon sources, therefore generating bioelectricity. The produced electron is transmitted to the anode surface but the generated protons must pass through the proton exchange membrane (PEM) in order to reach the cathode compartment. PEM as a key factor affecting electricity generation in MFCs has been investigated here and its importance fully discussed.

Separators used in microbial electrochemical technologies: Current status and future prospects

Microbial electrochemical technologies (METs) are emerging green processes producing useful products from renewable sources without causing environmental pollution and treating wastes. The separator, an important part of METs that greatly affects the latters performance, is commonly made of Nafion proton exchange membrane (PEM). However, many problems have been identified associated with the Nafion PEM such as high cost of membrane, significant oxygen and substrate crossovers, and transport of cations other than protons protons and biofouling. A variety of materials have been offered as alternative separators such as ion-exchange membranes, salt bridges, glass fibers, composite membranes and porous materials. It has been claimed that low cost porous materials perform better than PEM. These include J-cloth, nylon filter, glass fiber mat, non-woven cloth, earthen pot and ceramics that enable non-ion selective charge transfer. This paper provides an up-to-date review on porous separators and plots directions for future studies.

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/m(2) while it was 46.8 mW/m(2) and 28.8 mW/m(2) for KC and PPy individually. The efficiency of the PPy/KC electrode system is slightly lower than a Pt electrode (79.9 mW/m(2)) but due to the high cost of Pt electrodes, the PPy/KC electrode system has potential to be an alternative electrode system for MFCs.

A novel application of a neuro–fuzzy computational technique in modeling of thermal cracking of heavy feedstock to light olefin

In the present paper, the ability and accuracy of an Adaptive Neuro–Fuzzy Inference System (ANFIS) was investigated for the process evaluation of thermal cracking to light olefin. The main objective of this research is to predict product yields as a function of Coil Outlet Temperature (COT), steam ratio, and feed flow rate, at the reactor tube outlet. Temperature, flow rate and steam-to-hydrocarbon ratio were in the range of 1023–1173 K, 3–7 g g−1, and 0.5–1.4 g min−1, respectively. The Adaptive Network-Based Fuzzy Inference System (ANFIS) technique was trained using historical data to generate the membership functions and rules that best interpret the input/output relationships of the process. Four fuzzy inference systems were independently developed for four output parameters, each of which consisted of three inputs and 27 rules. In order to better understand the capability of the present technique, an extensive comparison test was applied to the ANFIS, kinetic modeling, and response surface methodology. The obtained results demonstrate that these three models are in good agreement with the experimental data. The NF model showed the best results of all.

Evaluation of solvent dearomatization effect in heavy feedstock thermal cracking to light olefin: An optimization study

Response surface method was used to study the effect of aromatic extraction of heavy feedstock in thermal cracking. N-methylpyrrolidone as the solvent performing dearomatization of feedstock was at different temperature and molar solvent to oil ratios. Temperature, flow rate and steam-to-hydrocarbon ratio were in the range of 1,053–1,143 K, 1–2 g/g, and 0.75–1.2 g/min, respectively. From the CCD studies, the effects of flow rate and coil outlet temperature were the key factors influencing the yield of light olefins. Ethylene and propylene yields increased more than 10% by dearomatization. C5+ decreased by 13% on average. Finally, we obtained the single maximum yield of ethylene, propylene, and simultaneous maximum yields for untreated and raffinate.

Catalytic performance of CeAPSO-34 molecular sieve with various cerium content for methanol conversion to olefin

A series of CeAPSO-34s with various cerium contents was synthesized and characterized by multiple techniques such as XRD, SEM, BET, 29Si MAS NMR, NH3-TPD and CO2-TPD. NH3-TPD spectra showed that a number of acid sites, especially those of strong acidity, is reduced with the increasing of Ce incorporation. Incorporation of metal ions gave rise to more silica-islands in the CeAPSO-34 framework. CO2-TPD showed that basic sites on the surface of modified samples are due to the presence of Ce-containing species incorporation into the framework of CeAPSO-34 molecular sieves. The performance of the catalysts was studied in methanol to olefin reactions at 425 °C under the atmospheric pressure. The results showed that the incorporation of cerium ions had great effects on the structure and acidity of the molecular sieves. All SAPO-34 and MeAPSO-34 molecular sieves were the very active and selective catalyst for light olefins production. Cerium incorporation improved the catalyst lifetime and favored the ethylene and propylene generation. However, an excess Ce content resulted in an inferior catalytic performance and stability. Therefore, there existed optimal cerium content for a specific SAPO-34.

Investigation of the Effect of Electrospun Polyethersulfone Nanofibers in Membrane

One dimensional (1D) nanostructure materials such as nanowires, nanofibers, and nanorods with porous structures have potential for use in various applications. Electrospinning is one of the versatile techniques with the ability of producing cost-effective, large production, highly porous nanofibers and membrane with large surface to volume ratios. Poly ether sulfone (PES) is a kind of special engineering plastic with good processing characteristics. In this paper, synthesis of PES membrane was investigated by two main methods, i.e. phase inversion and electrospiing. For electrospining, the main effective parameters such as concentration of polymer and solvent, for finding the optimized condition of electrospun PES membrane was studied. The produced membranes were characterized by SEM for morphology and BET observation of surface area, permeability, flux, and mechanical propertise for different applications.

SPEEK/PES composite membranes as an alternative for proton exchange membrane in microbial fuel cell (MFC)

A solid polymer electrolyte (SPE) membranes were synthesized by incorporation of sulfonated poly(ether ether ketone) (SPEEK) in poly(ether sulfone) (PES) for electricity generation in microbial fuel cells (MFC). The composite membranes were prepared at 5% percent weight of SPEEK mixed with PES by phase inversion method and characterized by measuring proton conductivity, oxygen diffusion, water crossover and level of biofouling. Membrane electrode assemblies (MEA) were made by hot pressing the composite membranes with a Pt-loaded cathode on one side of membranes. The MEA, with effective area of 9 cm2, were tested using single chamber MFC. The blended SPEEK/PES membrane had low resistivity to water crossover and oxygen diffusion while high in conductivity compared to Nafion and PES membranes. The MFC using the composite membranes generated an average power density of 140 mW m−2 which was double that produced by MFC using Nafion membranes in every fed-batch cycle which lasted for 24 hours. The experimental results suggested that SPEEK/PES composite membrane could be a promising alternative to costly perfluorosulfonate membranes as proton exchange membrane in MFC system.

Carbon-Based Polymer Nanocomposites as Electrodes for Microbial Fuel Cells

Abstract Being a green and sustainable technology, microbial fuel cells (MFCs) offer an integrated pathway to simultaneously produce bioelectricity and treat wastewater. However; their applications are limited due to their relatively low-output power density. The MFC’s low-output power density is related to low electron-transfer rate at the anode and/or the cathode. The transfer of electrons is greatly influenced by the electrode materials’ properties. Carbon-based materials are seen as promising candidates for electrodes in MFCs because of their favorable characteristics in terms of weight, microbial adhesion, stability, and cost. However, the use of plain carbon material led to weak biofilm formation and all the required properties for the oxygen reduction reaction in cathode could not be met. The MFC performance could be improved by modifying the carbon-based electrodes through nano- and/or polymeric materials. This chapter presents a review of the modified carbon-based polymer nanocomposites as they serve as electrodes for MFCs.

Synthesis and Characterization of PES/TiO2 Nanofibers Membrane

An important recent discovery in the membrane science is the polymeric nanofiber membrane. Membranes have many applications in protein purification, wastewater treatment and fuel cells. One of the versatile technique with the ability of producing cost-effective, highly porous non-woven membranes with large surface area is electrospining. In this study the effect of TiO2 nanoparticles in membrane performance has been investigated. A PES/TiO2 nanofibers membrane has higher flux and permeability than a pristine PES membrane. Also the measurments show that the surface area of the membrane will increase by addition of TiO2 nanoparticles. Moreover, the contact angle was investigated.