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Talk Show Budaya Bersama Sujiwo Tejo
Talk Show Budaya Bersama Sujiwo Tejo
Sebuah
kegiatan yang pastinya seorang budayawan berbicara tentang dunia
pendidikan. ayok ikuti acara di Universitas Islam Indonesia.
Untuk lebih lengkapnya kunjungi website penyelenggara.
Deadline Pendaftaran
18 May 2015 16:13
Timeline Acara
18 Mei 2015
Kategori Peserta
Pelajar SMP
Pelajar SMA
Mahasiswa
Masyarakat Umum
Hadiah/Fasilitas
mendapatkan ilmu yang banyak dan tentunya bermanfaat
Seminar
Nasional merupakan salah satu rangkaian acara kegiatan Chemistry Week
2015, dengan tema One Step To Make A Better Indonesian with Science and
Technology.
Kegiatan Seminar Nasional ini merupakan suatu bentuk acara yang bertujuan agar peserta
dapat memiliki pengetahuan dan wawasan tentang pengaruh dan pentingnya
riset serta teknologi bagi mahasiswa dengan contoh pengaplikasian Tenaga
Nuklir untuk Indonesia yang lebih baik.
Seminar Nasional ini terdiri dari 3 sesi, yaitu sesi 1 diisi oleh M.
Natsir selaku Menteri Riset dan Teknologi , Nurul Taufiqurrohman selaku
Peneliti Nanoteknologi dan Dr. Eng. Eniya selaku Peneliti Fuel Cell.
Diharapkan peserta seminar nasional ini dapat mengimplementasikan dalam
kehidupan sehari-hari, contohnya melalui riset, PKM, dsb karena ini
merupakan langkah untuk menjadikan Indonesia lebih baik.
Bentuk Kegiatan
Diskusi Panel merupakan sebuah diskusi yang dilakukan oleh sekelompok
orang yang membahas suatu topik yang menjadi perhatian khalayak umum.
Tujuan
Memberikan pengetahuan dan wawasan tentang penting dan pengaruhnya riset
dan teknologi oleh mahasiswa dengan contoh pengaplikasian Tenaga Nuklir
untuk Indonesia yang lebih baik.
Target
Terciptanya pengetahuan dan wawasan tentang pengaruh dan pentingnya
riset serta teknologi oleh mahasiswa dengan contoh pengaplikasian Tenaga
Nuklir untuk Indonesia yang lebih baik.
Sasaran
Mahasiswa umum
Target peserta : 200 orang
Pembicara
1. M Natsir (Menteri Riset dan Teknologi)
2. Nurul Taufiqurrahman (Peneliti Nanoteknologi)
3. Dr. Eng Eniya (Peneliti Fuel Cell)
Untuk info lebih lengkap, klik link berikut: Klik
A microbial fuel cell (MFC) or biological fuel cell is a bio-electrochemical system that drives a current by using bacteria and mimicking bacterial interactions found in nature.
MFCs can be grouped into two general categories, those that use a
mediator and those that are mediator-less. The first MFCs, demonstrated
in the early 20th century, used a mediator: a chemical that transfers
electrons from the bacteria in the cell to the anode. Mediator-less MFCs
are a more recent development dating to the 1970s; in this type of MFC
the bacteria typically have electrochemically active redoxproteins such as cytochromes on their outer membrane that can transfer electrons directly to the anode.[1][2] Since the turn of the 21st century MFCs have started to find a commercial use in the treatment of wastewater.[3]
The idea of using microbial cells in an attempt to produce electricity was first conceived in the early twentieth century. M. Potter was the first to perform work on the subject in 1911.[4] A professor of botany at the University of Durham, Potter managed to generate electricity from E. coli,
but the work was not to receive any major coverage. In 1931, however,
Barnet Cohen drew more attention to the area when he created a number of
microbial half fuel cells that, when connected in series, were capable
of producing over 35 volts, though only with a current of 2 milliamps.[5]
More work on the subject came with a study by DelDuca et al. who used hydrogen produced by the fermentation of glucose by Clostridium butyricum
as the reactant at the anode of a hydrogen and air fuel cell. Though
the cell functioned, it was found to be unreliable owing to the unstable
nature of hydrogen production by the micro-organisms.[6] Although this issue was later resolved in work by Suzuki et al. in 1976[7] the current design concept of an MFC came into existence a year later with work once again by Suzuki.[8]
By the time of Suzuki’s work in the late 1970s, little was understood
about how microbial fuel cells functioned; however, the idea was picked
up and studied later in more detail first by MJ Allen and then later by
H. Peter Bennetto both from King's College London.
People saw the fuel cell as a possible method for the generation of
electricity for developing countries. His work, starting in the early
1980s, helped build an understanding of how fuel cells operate, and
until his retirement, he was seen by many[who?] as the foremost authority on the subject.
It is now known that electricity can be produced directly from the
degradation of organic matter in a microbial fuel cell. Like a normal
fuel cell, an MFC has both an anode and a cathode chamber. The anoxic
anode chamber is connected internally to the cathode chamber via an ion
exchange membrane with the circuit completed by an external wire.
In May 2007, the University of Queensland, Australia completed its prototype MFC as a cooperative effort with Foster's Brewing. The prototype, a 10 L design, converts brewery wastewater into carbon dioxide, clean water, and electricity. With the prototype proven successful,[9]
plans are in effect to produce a 660 gallon version for the brewery,
which is estimated to produce 2 kilowatts of power. While this is a
small amount of power, the production of clean water is of utmost
importance to Australia, for which drought is a constant threat.
Types
Definition
A microbial fuel cell is a device that converts chemical energy to electrical energy by the catalytic reaction of microorganisms.[10]
A typical microbial fuel cell consists of anode and cathode compartments separated by a cation (positively charged ion) specific membrane. In the anode compartment, fuel is oxidized by microorganisms, generating CO2, electrons and protons.
Electrons are transferred to the cathode compartment through an
external electric circuit, while protons are transferred to the cathode
compartment through the membrane. Electrons and protons are consumed in
the cathode compartment, combining with oxygen to form water.[citation needed]
More broadly, there are two types of microbial fuel cell: mediator and mediator-less microbial fuel cells.
Mediator microbial fuel cell
Most of the microbial cells are electrochemically inactive. The electron transfer from microbial cells to the electrode is facilitated by mediators such as thionine, methyl viologen, methyl blue, humic acid, and neutral red.[11][12] Most of the mediators available are expensive and toxic.
Mediator-free microbial fuel cell
A plant microbial fuel cell (PMFC)
Mediator-free microbial fuel cells do not require a mediator but use
electrochemically active bacteria to transfer electrons to the electrode
(electrons are carried directly from the bacterial respiratory enzyme
to the electrode). Among the electrochemically active bacteria are, Shewanella putrefaciens,[13]Aeromonas hydrophila,[14] and others. Some bacteria, which have pili
on their external membrane, are able to transfer their electron
production via these pili. Mediator-less MFCs are a more recent area of
research and, due to this, factors that affect optimum efficiency, such
as the strain of bacteria used in the system, type of ion-exchange membrane, and system conditions (temperature, pH, etc.) are not particularly well understood.
Mediator-less microbial fuel cells can, besides running on
wastewater, also derive energy directly from certain plants. This
configuration is known as a plant microbial fuel cell. Possible plants include reed sweetgrass, cordgrass, rice, tomatoes, lupines, and algae.[15][16][17]
Given that the power is thus derived from living plants (in situ-energy
production), this variant can provide additional ecological advantages.
A variation of the mediator-less MFC is the microbial electrolysis
cells (MEC). Whilst MFC's produce electric current by the bacterial
decomposition of organic compounds in water, MECs partially reverse the
process to generate hydrogen or methane by applying a voltage to
bacteria to supplement the voltage generated by the microbial
decomposition of organics sufficiently lead to the electrolysis of water or the production of methane.[18][19] A complete reversal of the MFC principle is found in microbial electrosynthesis, in which carbon dioxide is reduced by bacteria using an external electric current to form multi-carbon organic compounds.[20]
Soil-based microbial fuel cell
A soil-based MFC
Soil-based microbial fuel cells adhere to the same basic MFC
principles as described above, whereby soil acts as the nutrient-rich
anodic media, the inoculum, and the proton exchange membrane (PEM). The anode is placed at a certain depth within the soil, while the cathode rests on top the soil and is exposed to the oxygen in the air above it.
Soils are naturally teeming with a diverse consortium of microbes,
including the electrogenic microbes needed for MFCs, and are full of
complex sugars and other nutrients that have accumulated over millions
of years of plant and animal material decay. Moreover, the aerobic
(oxygen consuming) microbes present in the soil act as an oxygen
filter, much like the expensive PEM materials used in laboratory MFC
systems, which cause the redox
potential of the soil to decrease with greater depth. Soil-based MFCs
are becoming popular educational tools for science classrooms.[21]
Sediment microbial fuel cells (SMFCs) application for wastewater treatment is a relatively new field. SMFCs with simple structures can generate electrical energy while decontaminating wastewater.
Most SMFCs used for wastewater treatment contain plants to mimic
constructed wetlands. Both synthetic and real wastewaters have been used
as substrates in SMFCs that achieved satisfactory performance in
organic removal. SMFC tests have reached more than 150 L.[22]
In 2015 researchers announced an SMFC application that extracts energy and charges a battery.
Salts found in the waste dissociates into positively and negatively
charged ions in water, and move and adhere to the respective negative
and positive electrodes, charging the battery and making it possible to
remove the salt effecting microbial capacitive desalination. The microbes produce more energy than is required for the desalination process.[23]
Phototrophic biofilm microbial fuel cell
Phototrophic biofilm MFCs (PBMFCs) are the ones that make use of anode with a phototrophic biofilm
containing photosynthetic microorganism like chlorophyta, cyanophyta
etc., since they could carry out photosynthesis and thus they act as
both producers of organic metabolites and also as electron donors.[24]
A study conducted by Strik et al. reveals that PBMFCs yield one of the highest power densities
and, therefore, show promise in practical applications. Researchers
face difficulties in increasing their power density and long-term
performance so as to obtain a cost-effective MFC.[25]
The sub-category of phototrophic microbial fuel cells that use purely
oxygenic photosynthetic material at the anode are sometimes called biological photovoltaic systems.[26]
Nanoporous membrane microbial fuel cells
The United States Naval Research Laboratory
(NRL) developed the nanoporous membrane microbial fuel cells which
operate the same as most MFCs, but use a non-PEM to generate passive
diffusion within the cell.[27]
The membrane used instead is a nonporous polymer filter (nylon,
cellulose, or polycarbonate) which generates comparable power densities
as Nafion
(a well known PEM) while remaining more durable than Nafion. Porous
membranes allow passive diffusion thereby reducing the necessary power
supplied to the MFC in order to keep the PEM active and increasing the
total output of energy from the cell.[28]
MFCs that do not use a membrane can deploy anaerobic bacteria in
aerobic environments however, membrane-less MFCs will experience cathode
contamination by the indigenous bacteria and the power-supplying
microbe. The novel passive diffusion of nanoporous membranes can achieve
the benefits of a membrane-less MFC without worry of cathode
contamination.
Nanoporous membranes are also ten times cheaper than Nafion (Nafion-117, $0.22/cm2 vs. polycarbonate, <$0.02/cm2).
Electrical generation process
When micro-organisms consume a substance such as sugar in aerobic conditions, they produce carbon dioxide and water. However, when oxygen is not present, they produce carbon dioxide, protons, and electrons, as described below:[29]
C12H22O11 + 13H2O → 12CO2 + 48H+ + 48e− (Eqt. 1)
Microbial fuel cells use inorganic mediators to tap into the electron transport chain of cells and channel electrons produced. The mediator crosses the outer cell lipid membranes and bacterial outer membrane;
then, it begins to liberate electrons from the electron transport chain
that normally would be taken up by oxygen or other intermediates.
The now-reduced mediator exits the cell laden with electrons that it
transfers to an electrode where it deposits them; this electrode becomes
the electro-generic anode (negatively charged electrode). The release
of the electrons means that the mediator returns to its original
oxidised state ready to repeat the process. It is important to note that
this can happen only under anaerobic conditions; if oxygen is present, it will collect all the electrons, as it has a greater electronegativity than mediators.
In a microbial fuel cell operation, the anode is the terminal
electron acceptor recognized by bacteria in the anodic chamber.
Therefore, the microbial activity is strongly dependent on the redox
potential of the anode. In fact, it was recently published that a Michaelis-Menten
curve was obtained between the anodic potential and the power output of
an acetate driven microbial fuel cell. A critical anodic potential
seems to exist at which a maximum power output of a microbial fuel cell
is achieved.[30]
A number of mediators have been suggested for use in microbial fuel
cells. These include natural red, methylene blue, thionine, or
resorufin.[31]
This is the principle behind generating a flow of electrons from most
micro-organisms (the organisms capable of producing an electric current
are termed exoelectrogens).
In order to turn this into a usable supply of electricity, this process
has to be accommodated in a fuel cell. In order to generate a useful
current it is necessary to create a complete circuit, and not just
transfer electrons to a single point.
The mediator and micro-organism, in this case yeast, are mixed
together in a solution to which is added a suitable substrate such as
glucose. This mixture is placed in a sealed chamber to stop oxygen
entering, thus forcing the micro-organism to use anaerobic respiration. An electrode is placed in the solution that will act as the anode as described previously.
In the second chamber of the MFC is another solution and electrode.
This electrode, called the cathode is positively charged and is the
equivalent of the oxygen sink at the end of the electron transport
chain, only now it is external to the biological cell. The solution is
an oxidizing agent
that picks up the electrons at the cathode. As with the electron chain
in the yeast cell, this could be a number of molecules such as oxygen.
However, this is not particularly practical as it would require large
volumes of circulating gas. A more convenient option is to use a
solution of a solid oxidizing agent.
Connecting the two electrodes is a wire (or other electrically
conductive path, which may include some electrically powered device such
as a light bulb) and completing the circuit and connecting the two
chambers is a salt bridge or ion-exchange membrane. This last feature
allows the protons produced, as described in Eqt. 1 to pass from the anode chamber to the cathode chamber.
The reduced mediator carries electrons from the cell to the
electrode. Here the mediator is oxidized as it deposits the electrons.
These then flow across the wire to the second electrode, which acts as
an electron sink. From here they pass to an oxidising material.
Soil-based microbial fuel cells are popular educational tools, as
they employ a range of scientific disciplines (microbiology,
geochemistry, electrical engineering, etc.), and can be made using
commonly available materials, such as soils and items from the
refrigerator. There are also kits available for classrooms and
hobbyists,[43] and research-grade kits for scientific laboratories and corporations.[44]
Biosensor
Since the current generated from a microbial fuel cell is directly
proportional to the energy content of wastewater used as the fuel, an
MFC can be used to measure the solute concentration of wastewater (i.e.,
as a biosensor system).[45]
The strength of wastewater is commonly evaluated as biochemical oxygen demand (BOD) values.[clarification needed]
BOD values are determined incubating samples for 5 days with proper
source of microbes, usually activate sludge collected from sewage works.
When BOD values are used as a real-time control parameter, 5 days'
incubation is too long.
An MFC-type BOD sensor can be used to measure real-time BOD values.
Oxygen and nitrate are preferred electron acceptors over the electrode
reducing current generation from an MFC. MFC-type BOD sensors
underestimate BOD values in the presence of these electron acceptors.
This can be avoided by inhibiting aerobic and nitrate respirations in
the MFC using terminal oxidase inhibitors such as cyanide and azide.[46] This type of BOD sensor is commercially available.
The United States Navy
is looking into microbial fuel cells particularly for environmental
sensors. The use of microbial fuel cells to power environmental sensors
would be beneficial because they would be able to sustain power for a
longer amount of time and enable the collection and retrieval of
undersea data without using a wire infrastructure. The energy created by
these fuel cells was enough to sustain sensors after an initial startup
time in research to demonstrate the effectiveness of the fuel cell as a
power source for such sensors. [47]
Due to undersea conditions (high salt concentrations, fluctuating
temperatures, and limited nutrient supply), the U.S. Navy is looking to
deploy their MFCs with a mixture of salt-tolerant microorganisms. A
mixture would also allow for a more complete utilization of available
nutrients to be converted into electricity. Currently, Shewanella oneidensis is their primary microorganism for electrical generation, but their mixture might also include Shewanella spp. as it is very heat- and cold-tolerant. [48]
If the Navy is able to have data from undersea with no reliance on an
input of energy, the various missions of the United States Navy’s
submarine force can be that more effective. This alternative energy form
will be more helpful as it continues to be improved.
Biorecovery
In 2010, A. ter Heijne et al.[49] constructed a device capable of producing electricity and reduce the ion Cu (II) to copper metal.
Microbial electrolysis cells have been demonstrated to produce hydrogen.[50]
Water treatment
Microbial Fuel Cells are being used in the water treatment process to
harvest energy utilizing anaerobic digestion (a method used in the
microbial fuel cell to collect bioenergy from wastewater). The process
is well developed and can handle a high volume of wastewater and reduce
pathogens. However, the process requires high temperatures (upwards of
30 degrees Celsius) and requires an extra step in order to convert
biogas to electricity. Spiral spacers may also be used to increase
electricity generation by creating a helical flow in the microbial fuel
cells. The challenge is that it is difficult to scale up the MFCs for
practical wastewater treatment because of the power output challenges of
a larger surface area MFC.[51]
Current research practices
Some researchers[52] point out some undesirable practices, such as recording the maximum current obtained by the cell when connecting it to a resistance
as an indication of its performance, instead of the steady-state
current that is often a degree of magnitude lower. Often the data about
the values of the used resistance is minimal, or even non-existent,
making much of the data non-comparable across all studies. This makes
extrapolation from standardized procedures difficult if not impossible.
Commercial applications
A number of companies have emerged to commercialize microbial fuel
cells. These companies have attempted to tap into both the remediation
and electricity generating aspects of the technologies. Some of these
are companies are mentioned here.[53]
Pant,
D.; Singh, A.; Van Bogaert, G.; Gallego, Y. A.; Diels, L.;
Vanbroekhoven, K. (2011). "An introduction to the life cycle assessment
(LCA) of bioelectrochemical systems (BES) for sustainable energy and
product generation: Relevance and key aspects". Renewable and Sustainable Energy Reviews15 (2): 1305–1313. doi:10.1016/j.rser.2010.10.005.
Liu H, Cheng S and Logan BE (2005).
"Production of electricity from acetate or butyrate using a
single-chamber microbial fuel cell". Environ Sci Technol32 (2): 658–62. doi:10.1021/es048927c.
Rabaey, K. & W. Verstraete (2005). "Microbial fuel cells: novel biotechnology for energy generations". Trends Biotechnol23 (6): 291–298. doi:10.1016/j.tibtech.2005.04.008. PMID15922081.
Yue P.L. and Lowther K. (1986). Enzymatic Oxidation of C1 compounds
in a Biochemical Fuel Cell. The Chemical Engineering Journal, 33B, p
69-77
Further reading
Rabaey, K. et al. (May 2007). "Microbial ecology meets electrochemistry: electricity-driven and driving communities". Isme J.1 (1): 9–18. doi:10.1038/ismej.2007.4. PMID18043609.
Min,
B., Cheng, S. and Logan B. E. (2005). Electricity generation using
membrane and salt bridge microbial fuel cells, Water Research, 39 (9),
pp1675–86
Potter,
M.C. Potter (1911). Electrical effects accompanying the decomposition
of organic compounds. Royal Society (Formerly Proceedings of the Royal
Society) B, 84, p260-276
Cohen, B. (1931). The Bacterial Culture as an Electrical Half-Cell, Journal of Bacteriology, 21, pp18–19
DelDuca,
M. G., Friscoe, J. M. and Zurilla, R. W. (1963). Developments in
Industrial Microbiology. American Institute of Biological Sciences, 4,
pp81–84.
Karube, I., T. Matasunga, S. Suzuki & S. Tsuru. (1976). Continuous hydrogen production by immobilized whole cells of Clostridium butyricum Biocheimica et Biophysica Acta 24:2 338–343
Allen, R.M.; Bennetto, H.P. (1993). "Microbial fuel cells: Electricity production from carbohydrates". Applied Biochemistry and Biotechnology. 39-40: 27–40. doi:10.1007/bf02918975.
Delaney,
G. M.; Bennetto, H. P.; Mason, J. R.; Roller, S. D.; Stirling, J. L.;
Thurston, C. F. (2008). "Electron-transfer coupling in microbial fuel
cells. 2. Performance of fuel cells containing selected
microorganism-mediator-substrate combinations". Journal of Chemical Technology and Biotechnology. Biotechnology34: 13. doi:10.1002/jctb.280340104.
Lithgow,
A.M., Romero, L., Sanchez, I.C., Souto, F.A., and Vega, C.A. (1986).
Interception of electron-transport chain in bacteria with hydrophilic
redox mediators. J. Chem. Research, (S):178–179.
Pham,
C. A.; Jung, S. J.; Phung, N. T.; Lee, J.; Chang, I. S.; Kim, B. H.;
Yi, H.; Chun, J. (2003). "A novel electrochemically active and
Fe(III)-reducing bacterium phylogenetically related to Aeromonas
hydrophila, isolated from a microbial fuel cell". FEMS Microbiology Letters223 (1): 129–134. doi:10.1016/S0378-1097(03)00354-9. PMID12799011.
Bombelli,
Paolo; Bradley, Robert W.; Scott, Amanda M.; Philips, Alexander J.;
McCormick, Alistair J.; Cruz, Sonia M.; Anderson, Alexander; Yunus,
Kamran; Bendall, Derek S.; Cameron, Petra J.; Davies, Julia M.; Smith,
Alison G.; Howe, Christopher J.; Fisher, Adrian C. (2011). "Quantitative
analysis of the factors limiting solar power transduction by
Synechocystis sp. PCC 6803 in biological photovoltaic devices". Energy & Environmental Science4 (11): 4690–4698. doi:10.1039/c1ee02531g.
Gong,
Y., Radachowsky, S. E., Wolf, M., Nielsen, M. E., Girguis, P. R., &
Reimers, C. E. (2011). "Benthic Microbial Fuel Cell as Direct Power
Source for an Acoustic Modem and Seawater Oxygen/Temperature Sensor
System". Environmental Science and Technology45 (11): 5047–53. doi:10.1021/es104383q.
Zhang,
Fei, He, Zhen, Ge, Zheng (2013). "Using Microbial Fuel Cells to Treat
Raw Sludge and Primary Effluent for Bioelectricity Generation". Department of Civil Engineering and Mechanics; University of Wisconsin - Milwaukee.
Menicucci,
Joseph Anthony Jr., Haluk Beyenal, Enrico Marsili, Raaja Raajan
Angathevar Veluchamy, Goksel Demir, and Zbigniew Lewandowski,
Sustainable Power Measurement for a Microbial Fuel Cell, AIChE Annual Meeting 2005, Cincinnati, USA
