CET I Flashcards
Salt mining
Chlor-alkali industry. Salt solution (brine) electrolysed to make Cl2 and NaOH. Cl2=base component to be used in solvents (chlorinated alkanes) and polymers (e.g. PVC). Historically Cl2 used for CFCs (before banned by Montreal protocol 1989).
Saturated salt solutions problematic in long pipelines bc brine is corrosive.
naphtha cracker
Primary product=C2 and C3 alkenes i.e. ethene and propene. Ethene=>polymer production (e.g. polythene, PVA), organic feedstock to refrigerants (HFCs and prior CFCs), solvents like ethyl acetate, acids such as ethanoic acid, ethanol, MEG etc. Propene=>polypropene, acrylic acid, propanol.
Side product is pyrolysis gasoline. Goes to BTX (benzene, toluene, xylene) so can get polymers. Benzene to nylon, paraxylene to PET,
Ammonia
Synthesised following syngas generation by methane reforming. Fertilisers (ammonium nitrate, ammonia, urea), mineral acids (nitric acid), amines, nitriles, nylon.
plant next to a river
excellent import/export conduit, heat sink if necessary
permit to work
controls work and maintenance activities NOT routine activities which should come under standard operating instructions
Single ideal stage of gas absorption into a liquid solvent assumptions
steady state, dilute systems (i.e. gas flow mainly a species insoluble in the solvent, together with a small proportion of a species soluble in the solvent), involatile solvent, isobaric and isothermal contacting stage, constant molar overflow (rate of transfer between streams much less than flowrate of either stream)
Codon bias example and two ways to overcome it
The tRNA which recognises the codon AGA (for Arg) used more frequently in human cells than in E. coli, i.e. it has a higher concentration
change by mutation or DNA synthesis the codon frequencies to fit with the E. coli frequencies
modify the strain of E. coli so that it expresses all tRNAs at higher concentrations
E coli undesired products
toxic lipopolysaccharide
start codon and example of a stop codon
AUG for start (methionine), then e.g. UAG for stop
when might two cstr’s be used in serie for growing yeast (biomass) using a substrate (glucose)?
A two-stage cstr permits continuous production of products that are synthesised only DURING THE STATIONARY PHASE, i.e. the first cstr can act as a cell production tank and the second as a product formation tank. Additional nutrients and/or precursor molecules (e.g. for antibiotics) can be added to the second tank to facilitate product formation.
