A process for the preparation of cysteine from cystine
- El Cerrito, CA
- Oakland, CA
- Morristown, NJ
The present invention in one aspect relates to a process for the simultaneous removal of NO.sub.x and SO.sub.2 from a fluid stream comprising mixtures thereof and in another aspect relates to the separation, use and/or regeneration of various chemicals contaminated or spent in the process and which includes the steps of: (A) contacting the fluid stream at a temperature of between about 105.degree. and 180.degree. C. with a liquid aqueous slurry or solution comprising an effective amount of an iron chelate of an amino acid moiety having at least one --SH group; (B) separating the fluid stream from the particulates formed in step (A) comprising the chelate of the amino acid moiety and fly ash; (C) washing and separating the particulates of step (B) with an aqeous solution having a pH value of between about 5 to 8; (D) subsequently washing and separating the particulates of step (C) with a strongly acidic aqueous solution having a pH value of between about 1 to 3; (E) washing and separating the particulates of step (D) with an basic aqueous solution having a pH value of between about 9 to 12; (F) optionally adding additional amino acid moiety, iron (II) and alkali to the aqueous liquid from step (D) to produce an aqueous solution or slurry similar to that in step (A) having a pH value of between about 4 to 12; and (G) recycling the aqueous slurry of step (F) to the contacting zone of step (A). Steps (D) and (E) can be carried out in the reverse sequence, however the preferred order is (D) and then (E). In a preferred embodiment the present invention provides an improved process for the preparation (regeneration) of cysteine from cystine, which includes reacting an aqueous solution of cystine at a pH of between about 9 to 13 with a reducing agent selected from hydrogen sulfide or alkali metal sulfides, sulfur dioxide, an alkali metal sulfite or mixtures thereof for a time and at a temperature effective to cleave and reduce the cystine to cysteine with subsequent recovery of the cysteine. In another preferred embodiment the present invention provides a process for the removal of NO.sub.x, SO.sub.2 and particulates from a fluid stream which includes the steps of (A) injecting into a reaction zone an aqueous solution itself comprising (i) an amino acid moiety selected from those described above; (ii) iron (II) ion; and (iii) an alkali, wherein the aqueous solution has a pH of between about 4 and 11; followed by solids separation and washing as is described in steps (B), (C), (D) and (E) above. The overall process is useful to reduce acid rain components from combustion gas sources.
- Research Organization:
- Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
- DOE Contract Number:
- AC03-76SF00098
- Assignee:
- United States of America as represented by United States (Washington, DC)
- Patent Number(s):
- US 4837361
- OSTI ID:
- 866988
- Country of Publication:
- United States
- Language:
- English
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Process for the combined removal of SO/sub 2/ and NO/sub x/ from flue gas
A process for the preparation of cysteine from cystine
Related Subjects
preparation
cysteine
cystine
aspect
relates
simultaneous
removal
fluid
stream
comprising
mixtures
separation
regeneration
various
chemicals
contaminated
spent
steps
contacting
temperature
105
degree
180
liquid
aqueous
slurry
solution
effective
amount
iron
chelate
amino
acid
moiety
-sh
separating
particulates
formed
step
fly
ash
washing
aqeous
ph
value
subsequently
strongly
acidic
basic
12
optionally
adding
additional
ii
alkali
produce
similar
recycling
zone
carried
reverse
sequence
preferred
embodiment
provides
improved
reacting
13
reducing
agent
selected
hydrogen
sulfide
metal
sulfides
sulfur
dioxide
sulfite
time
cleave
reduce
subsequent
recovery
injecting
reaction
described
iii
11
followed
solids
overall
useful
rain
components
combustion
gas
sources
optionally adding
metal sulfides
simultaneous removal
liquid aqueous
temperature effective
improved process
effective amount
metal sulfide
aspect relates
fluid stream
fly ash
amino acid
alkali metal
preferred embodiment
aqueous solution
reaction zone
sulfur dioxide
hydrogen sulfide
reducing agent
solution comprising
combustion gas
aqueous slurry
gas source
stream comprising
aqueous liquid
ph value
acidic aqueous
overall process
acid moiety
agent selected
moiety selected
strongly acidic
contacting zone
solids separation
comprising mixtures
iron chelate
various chemical
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