mini project 2014

8/12/2019 Mini Project 2014

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INTRODUCTION

Methyl tert -butyl ether, also known as methyl tertiary butyl ether and MTBE, is an

organic compound with molecular formula (CH 3)3COCH 3. MTBE is a volatile, flammable, and

colorless liquid that is immiscible with water. It has a minty odor vaguely reminiscent of diethyl

ether, leading to unpleasant taste and odor in water. MTBE is a gasoline additive, used as an

oxygenate to raise the octane number. Its use is controversial in the US and declining in that

country in part because of its occurrence in groundwater and legislation favoring ethanol.

Worldwide production of MTBE has been constant at about 18 million tons/y (2005) owing to

growth in Asian markets which are less subject to ethanol subsidies.

MTBE is manufactured via the chemical reaction of methanol and isobutylene. Methanol

is derived from natural gas, and isobutylene is derived from butane obtained from crude oil or

natural gas, thus MTBE is derived from fossil fuels. In the United States, it was produced in very

large quantities (more than 200,000 barrels per day in 1999) during its use as a fuel additive.

MTBE is almost exclusively used as a fuel component in fuel for gasoline engines. It is

one of a group of chemicals commonly known as oxygenates because they raise the oxygen

content of gasoline. The uses of MTBE are as anti-knocking agent, alternatives to MTBE as an

anti-knock agent and as a solvent.

Firstly, in the US it has been used in gasoline at low levels since 1979 to replace

tetraethyl lead and to increase its octane rating helping prevent engine knocking. Oxygenates

help gasoline burn more completely, reducing tailpipe emissions from pre-1984 motor vehicles;

dilutes or displaces gasoline components such as aromatics (e.g., benzene) and sulfur; and
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optimizes the oxidation during combustion. Most refiners chose MTBE over other oxygenates

primarily for its blending characteristics and low cost.

Secondly, other compounds are available as additives for gasoline including ethanol and

some ethers such as tert-amyl methyl ether (TAME).Ethanol has been advertised as a safe

alternative by the agricultural interest groups in the USA and Europe. Its lack of toxicity is not

different from MTBE, but as a polar solvent, it drives off nonpolar hydrocarbons from the

gasoline, a problem that MTBE does not cause. Some volatile hydrocarbons in gasoline vapors

are carcinogens, and gasoline vapors produce photochemical smog. Ethanol's higher cost

requires government intervention in the form of subsidies or mandated usage to be competitive.

In 2003, California was the first U.S. state to start replacing MTBE with ethanol. Several

other states started switching soon thereafter.Advocates of both sides of the debate in the

United States sometimes claim that gasoline manufacturers have been forced to add MTBE to

gasoline by law. It might be more correct to say they have been induced to do so, although any

oxygenate would fulfill the law.An alternative to straight ethanol is the related ether ETBE, which

is manufactured from ethanol and isobutene. Its performance as an additive is similar to MTBE,

but due to the higher price of ethanol compared to methanol, it is more expensive.Higher quality

gasoline is also an alternative, i.e., so that additives such as MTBE are unnecessary. Iso-octane

itself is used. MTBE plants can be retrofitted to produce iso-octane from isobutylene.

Then,as a solvent, MTBE possesses one distinct advantage over most ethers - it has a

reduced tendency to form explosive organic peroxides. Opened bottles of diethyl ether or THF

can build up dangerous levels of these peroxides in months, whereas samples of MTBE are

usually safe for years (but they should still be tested periodically). For this reason (as well as its

higher boiling point), MTBE is used as a solvent extensively in industry, where safety concerns

and regulations make working with diethyl ether, THF, or other ethers much more difficult and
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PROCESS OVERVIEW

MTBE (Methyl-tert-Butyl Ether) is a volatile, low viscosity clear liquid at roomtemperature with an ether odour; boiling point 55.2 C; melting point -109 C. MTBE is flammable

and can form explosive mixtures with air. It is slightly soluble in water and very soluble ethers

and alcohol and in most organic solvents including hydro carbons. MTBE is an ether which

contains an oxygen atom bonded to two carbon atoms. In Methyl-tert-Butyl Ether, one carbon

atom is that of a methyl group and the other is the central atom in a tertiary butyl group.

MTBE is prepared by reacting isobutylene contained in a mixed C4 stream with

methanol in the presence of an acidic ion-exchange resin catalyst such as sulfonated styrene

linked with divinyl benzene at 100 C. Isobutylene can also be prepared from TBA by

dehydration and from n-butane by isomerization without dehydration. The most quantity

produced worldwide is used as an oxygenate to gasoline. It is added both to increase octane

enhancement to replace banned tetraethyl lead and to raise the oxygen content in gasoline. It is

known that MTBE in fuel reduces exhaust emissions of VOC (volatile organic compounds:

acetaldehyde, benzene, 1,3-butadiene, ethylbenzene, formaldehyde, toluene, xylenes, and

particulate organic matter) except formaldehyde. Ozone is formed by the reaction of sunlight

with NOx and VOCs.

Some quantity of MTBE is used in the preparation of isobutene. With strong solvating

capabilities for a wide variety of compounds including unsaturated hydrocarbons and steroids,

MTBE is used as a reaction medium and extraction solvent to replace methylene chloride,

aromatics, and other ethers. MTBE is a non-chlorinated process solvent. It is used as a solvent

for chromotographic techniques. The sterically hindered tertiary butyl group imparts stability. It

possesses a much lower tendency to form explosive organic peroxides than most ethers. It has


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also an acid stability compare to other diether acetals. It forms azeotrope with water (52 - 53 C)

and methanol (51 - 52 C). It is used as a solvent in Grignard synthesis and other organometallic

reactions. It is used as an anionic and cationic polymerization solvent.


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EXAMPLE PROCESS FLOW DIAGRAM 1


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EXAMPLE PROCESS FLOW DIAGRAM 2


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ESTIMATION COST FOR DESIGN BASIS FOR MTBE

Based on a review of data on the typical MTBE concentrations and flow rates required totreat, available from USGS studies (Squillace et al., 1996; Delzer, 1996), and CAL-DHS (1998)

information, two general cases have been identified: (1) low concentration (30-100 ug/L) levels

and high flow rates, in the range of 500-1000 gpm (gallons per minute), which are typical of

contaminated drinking water supplies, whether from surface waters or from groundwater

pumping wells; and (2) high concentration (100-5000 ug/L) and low flow rates, in the range of

10-500 gpm, typical of groundwater wells near the source of contamination, usually a leakingunderground storage tank. Ten combinations of flow rate and concentration were selected as

the influent characteristics, as indicated in Table 1 :

Table 1. Combinations of MTBE Concentration and Flow rate Used for Design

CASE 1 2 3 4 5 6 7 8 9 10

Concentration (ug/L) 100 100 100 500 1000 5000 100 500 1000 5000

Flow rate (gpm) 1000 500 100 100 100 100 10 10 10 10

Although USEPA has in effect a 35 ug/L advisory level, we consider the CAL-DHS

secondary MCL level (5 ug/L) as the treatment goal in our design calculations. For some

selected cases we evaluate the cost differential between treatment to a 5 ug/L level and a 35

ug/L level.


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Capital costs are amortized over a 20 year horizon, at a 4% discount rate. Operation and

Maintenance (O&M) costs include operator(s) for the units, materials and electrical power, as

well as fuel for the thermal treatment when considered. The costs estimated here are at the

feasibility level (accuracy of at best -30% to +50%). For all the technologies considered,

additional costs may be required for pretreatment, depending on influent conditions, and post

treatment polishing or storage.

Equipment costs are calculated using the CapCost software (Turton et al., 1998). To

estimate the total capital costs, the following factors are applied:

(1) piping, electrical and valves (30% of equipment)

(2) site work (10% of equipment)

(3) contractor fees (15% of equipment plus items 1 and 2)

(4) engineering costs (15% on top of equipment plus items 1, 2, and 3)

(5) contingency (20% on top of all previous costs)

O&M costs are calculated based on electrical power requirements (at $0.08/kW-h), fuel

(at $1.6/million BTU and 3 BTU/scfm), labor (at $30/hr), materials considering 3% of equipment

per year, and contingency plus administrative of 15% on top of all other O&M costs.

The following sections present design considerations and cost estimates for air stripping,

granular activated carbon, ozone/hydrogen peroxide oxidation, and hollow fiber membranes.

The advantages and disadvantages of each technology are also discussed. Section 6

summarizes the cost estimates for the various technologies and provides recommendations for

the various cases studied. Experimental studies were conducted to verify parameter values

required for the calculations. The results are presented in the relevant sections.


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PROCESS AND MEASUREMENT

1) DISCLAIMER

Methyl tert-butyl ether (MTBE) is a flammable liquid with a distinctive, disagreeable odor.

It is made from blending chemicals such as isobutylene and methanol, and has been used since

the 1980s as an additive for unleaded gasolines to achieve more efficient burning.MTBE is also

used to dissolve gallstones. Patients treated in this way have MTBE delivered directly to their

gallbladders through special tubes that are surgically inserted.

MTBE quickly evaporates from open containers and surface water, so it is commonly

found as a vapor in the air. Small amounts of MTBE may dissolve in water and get into

underground water. It remains in underground water for a long time. MTBE may stick to

particles in water, which will cause it to eventually settle to the bottom sediment. MTBE may be

broken down quickly in the air by sunlight. MTBE does not build up significantly in plants and

animals.

Breathing small amounts of MTBE for short periods may cause nose and throat irritation.

Some people exposed to MTBE while pumping gasoline, driving their cars, or working in gas

stations have reported having headaches, nausea, dizziness, and mental confusion. However,

the actual levels of exposure in these cases are unknown. In addition, these symptoms may

have been caused by exposure to other chemicals. There is no data on the effects in people of

drinking MTBE. Studies with rats and mice suggest that drinking MTBE may cause

gastrointestinal irritation, liver and kidney damage, and nervous system effects.
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There is no evidence that MTBE causes cancer in humans. One study with rats found that

breathing high levels of MTBE for long periods may cause kidney cancer. Another study with

mice found that breathing high levels of MTBE for long periods may cause liver cancer. The

Department of Health and Human Services (DHHS), the International Agency for Research on

Cancer (IARC), and the EPA have not classified MTBE as to its carcinogenicity.

MTBE and its breakdown product, butyl alcohol, can be detected in your breath, blood,

or urine for up to 1 or 2 days after exposure. These tests aren't available at most doctors'

offices, but can be done at special laboratories that have the right equipment. There is no other

test specific to determining MTBE exposure.

The EPA has issued guidelines recommending that, to protect children, drinking water

levels of MTBE not exceed 4 milligrams per liter of water (4 mg/L) for an exposure of 1-10 days,

and 3 mg/L for longer-term exposures.

EXPOSURE PATHWAYS

Touching the skin or breathing contaminated air while pumping gasoline

Breathing exhaust fumes while driving a car

Breathing air near highways or in cities

Drinking, swimming, or showering in water that has been contaminated with MTBE

Receiving MTBE treatment for gallstones


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2) ABSTRACT

We developed an isotope-dilution method for measuring methyl tert-butyl ether (MTBE)

and tert-butyl alcohol (TBA) in whole human blood using a purge-and-trap gas chromatographic-

mass spectrometric method. The labeled analogues for MTBE and TBA were [2H12]methyl tert-

butyl ether and [2H9]-tert-butyl alcohol, respectively. Volatiles were removed from the blood by

direct helium purging of the liquid; were trapped on a Tenax trap; and were desorbed,

cryofocused, and chromatographed on a DB-624 capillary column that was connected directly to

the ion source of a mass spectrometer. Detection was by mass analysis using a double-

focusing magnetic-sector mass spectrometer operating in the full-scan mode at the medium

mass resolution of 3000.

For the isotope-dilution method, the minimum detection limits in blood (5-10 mL) are

0.01 microgram/L for MTBE and 0.06 microgram/L for TBA. The isotope-dilution method proved

to be a big improvement in recovery, reproducibility, and sensitivity over our previous analytical

method, which used the labeled ketone, [4-2H3]-2-butanone, as the internal standard for both

MTBE and TBA. The isotope-dilution method has sufficient sensitivity for monitoring blood levelsof MTBE and TBA in populations exposed to oxygenated fuels containing MTBE.


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REFERENCE

1. http://en.wikipedia.org/wiki/methyl_tert-butyl_ether ...

excess on 01/05/2014 at 2.45pm

2. http://www.epn.gov/mtbe/faq.htm#concerns ...


3. http://monographs.iarc.fr


4. INSTEP Notebook

5. MMSB/PPMSB SDN BHD manual/procedure of a MTBE plant ISO 9001 : 2000

6. http://pww.datakimia.petronas.com.my/datakimia/msds.exe ?....


7. Chemwatch Material Safety Data Sheet (REVIEW)
http://en.wikipedia.org/wiki/methyl_tert-butyl_etherhttp://en.wikipedia.org/wiki/methyl_tert-butyl_etherhttp://www.epn.gov/mtbe/faq.htm#concernshttp://www.epn.gov/mtbe/faq.htm#concernshttp://monographs.iarc.fr/http://monographs.iarc.fr/http://pww.datakimia.petronas.com.my/datakimia/msds.exehttp://pww.datakimia.petronas.com.my/datakimia/msds.exehttp://monographs.iarc.fr/http://www.epn.gov/mtbe/faq.htm#concernshttp://en.wikipedia.org/wiki/methyl_tert-butyl_ether

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