Chemical processes Chemical engineering products, processes, and challenges CommoditiesMoleculesNanostructures Key costspeed to market function Basisunit operationsdiscovery properties

Chemical processes A commodity: TiO 2 (titanium oxide) Extremely white, opaque, edible, dirt resistant. Used in paper, food, cosmetics, paint, textiles, plastics. World consumption: 4 million tons/yr. Cost: $2,000/ton. Total world value = $8 billion/yr. A 1% increase in production efficiency = 0.01*2*10 3 *4*10 6 $/yr = $80 million/yr.

Chemical processes Molecules Small and simple: ammonia (NH 3 ) sulfuric acid (H 2 SO 4 ) ethylene (C 2 H 4 ) sugar (C 12 H 22 O 11 ) Large and complex: insulin C 257 H 383 N 65 O 77 S 6 Large and simple (polymers): polyethylene[-CH 2 -CH 2 ] n See for a very good introduction to polymers.

Chemical processes Polymers, e.g. polyethylene is made up of many monomers:

Chemical processes Copolymers are made up of two kinds of monomers, say A and B

Chemical processes SBS rubber (tires, shoe soles) The polystyrene is tough; the polybutadiene is rubbery

Chemical processes Nano applications of polymers Organized block copolymer of PMMA (polymethylmethacrylate) and PS (polystyrene). Spin casting in electric field produces cylinders of PS embedded in the PMMA which are oriented in the direction of the electric field PMMA cylinders are 14nm diameter, 24nm apart. PS can be dissolved with acetic acid to leave holes. Use as a microscopic filter?

Chemical processes Cylindrical holes are electrochemically filled with magnetic cobalt. Each cylindrical hole can then store 1 “bit” of information. bit/cm = 1 / (2.4*10 -7 ) bit/cm 2 = 1.7*10 11 Computer application:

Chemical processes Genetic engineering: production of synthetic insulin 1) Extract a plasmid (a circular molecule of DNA) from the bacterium E-coli 2) Break the circle 3) Insert a section of human DNA containing the insulin-producing gene 4) Insert this engineered gene back into the E-coli bacterium 5) The E-coli and its offspring now produce insulin

Chemical processes Chemical Engineering Two strategies for obtaining chemical compounds and materials: 1) Create the desired compound from raw materials via one or more chemical reactions in a “reactor” 2) Isolate the compound where it exists in combination with other substances through a “separation process”

Chemical processes Reactors raw materials energy product + contaminants byproducts catalyst Reactor fermenters in a brewery pharmaceuticals reactor

Chemical processes Separations Based on differences between individual substances: Boiling point Freezing point Density Volatility Surface Tension Viscosity Molecular Complexity Size Geometry Polarization

Chemical processes Separations Based on differences in the presence of other materials Solubility Chemical reactivity

Chemical processes Separations: Garbage

Chemical processes Garbage separation (cont.)

Chemical processes Garbage separation (cont.)

Chemical processes

Chemical processes

Chemical processes

Chemical processes

Chemical processes

Chemical processes stage 1 V 1 = oil + less dyeV 2 = oil + dye L 0 = waterL 1 = water + some dye Oil flow = V(1-y A ) = V′ = constant (conservation of oil) Water flow = L(1-x A ) = L′ = constant (conservation of water) Then, for mass balance of the A component (dye) Mass of dye contained in oil and coming from stage 2. Mass of dye contained in water and leaving stage 1.

Chemical processes Assume that the dye concentrations in the mixing stage come into equilibrium according to Henry’s Law that defines the relative concentration of dye in the oil and the water: y A1 = H x A2, where H depends on the substances A, B, C

Chemical processes

Chemical processes Single stage countercurrent centrifugal extractor (Rousselet-Robatel)

Chemical processes Counter-current heat exchangers in nature

Chemical processes Counter-current heat exchangers How do they work? limited heat exchange good heat exchange appendage body T b-out T b-in heat loss exchanger body appendage T b-out T b-in exchanger