Spring, 2012 Session 4 – General Chemistry Pt 2

 Inorganic chemistry applications to process technology  Analytical methods

 Pulp and paper mills  Refineries  Energy Generation  Food processing  Water and wastewater treatment

 Cooking (digestion)  Oxygen delignification  Chlorine bleaching  Chemical recovery

Cooking or digestion – depolymerization by means of sodium sulfide and sodium hydroxide NaOH + Na 2 S + H 2 CO 3 = NaHS + Na 2 CO 3 + H 2 O

1.Na 2 SO C → Na 2 S + 2 CO 2 2.Na 2 S + Na 2 CO 3 + Ca(OH) 2 ←→ Na 2 S + 2NaOH + CaCO 3 3.CaCO 3 → CaO + CO 2 4.CaO + H 2 O → Ca(OH) 2

A

 Hydrodesulfurization  Hydrogen sulfide reaction with amines  Sulfur plant

 C 2 H 5 SH + H 2 → C 2 H 6 + H 2 S  MoS catalytic hydrodesulfurization

 H 2 S + RNH 2 (amine) = RNH 3 HS  Methyldiethanolamine (MDEA)

Sulfur plant

 2H 2 S + 3 O 2 → 2 SO H 2 O (step 1)  2H 2 S + SO 2 → 3S + 2H 2 O (step 2)  2H 2 S + SO 2 → 3S + 2H 2 O (overall reaction)  Other reactions on surface of catalyst ◦ COS + H 2 0 → H 2 S + CO 2 ◦ CS 2 + 2H 2 0 → 2H 2 S + CO 2 ◦ COS and CS 2 are formed in the furnace

 Combustion  Hydrogen generation  Fuel cells

 C n H 2n+2 + (3n/2 + ½)O 2 = nCO 2 + (n+1)H 2 O (complete combustion)  C n H 2n+2 + (n + ½)O 2 = n CO + (n+1)H 2 O (incomplete combustion)

 Steam reforming: CH 4 + H 2 O = CO + 3H 2 or CH 4 + 2H 2 O = CO 2 + 4H 2  Water gas shift reaction: CO (g) + H 2 O (v) → CO 2(g) + H 2(g)

H 2 + ½ O 2 = H 2 O

 Based upon combination of oxygen and hydrogen to make water and produce electricity  Different types of fuel cells (phosphoric acid, alkali, proton exchange membrane, etc.) 

2H 2 O = 2H 2 + O 2

Battery electrolysis of water

Hydrogen gas reservoir

 Hydrogen loses electrons, is oxidized, at the anode  Oxygen gains electrons, is reduced, at the cathode  To electrolyze gram mole of water to produce gram mole of oxygen gas (O 2 ) and gram moles of hydrogen gas (H 2 ) requires the transfer of one faraday of electricity ( coulombs)  gram mole of hydrogen is equivalent to 22.4 ml of gas at standard conditions  For a cell resistance of 20 ohms and a 3 volt battery, the current flow through the cell would be 3 V / 20 ohms = 0.15 A (0.15 coulombs/second). At this current flow, assuming 100% efficiency, it would take about 11 minutes to generate 22.4 ml of gas

 Sugar refining  Beer brewing  Sterilization

 Primary treatment (physical separation)  Secondary treatment (biological oxidation)  Disinfection  Tertiary treatment (chemical treatment)

 KAl(SO 4 ) 2 ·12H 2 O + 2Ca(OH) 2 = Al(OH) 3 + 2CaSO 4 + KOH  Cl 2 + H 2 O = HClO + HCl

 Lab glassware  Water analysis ◦ Physical ◦ Chemical  Oil analysis ◦ Physical ◦ Chemical

 Beakers – used to contain liquids for mixing together and can be used for rough volume measurements  Pipette – used to deliver measured amounts of liquids into beakers and flasks  Burette – used to deliver measured amounts of liquids for titration  Crucible – used to dry or ash solids

 Color (comparison to color standards)  Turbidity (obscuration of light) ◦ Measured in turbidity units (JTU, NTU)  Settleable solids (Imhoff cone) in ml solids/l liquid  Suspended solids (filter, dry solids at 103 deg C) measured as mg of solids per liter of liquid, mg/l  Dissolved solids (filter, dry filtrate at 103 deg C) mg/l  Volatile suspended solids (fire dry solids at 600 deg C) mg/l

Turbidity and turbidimeters

Settleable solids by Imhoff cone

Suspended, volatile and dissolved solids

 Standard solutions used for analysis  pH measurement by electrodes  Alkalinity (carbonate and hydroxide content)  Hardness (calcium and magnesium concentrations) ◦ < 50 mg/l is soft water ◦ > 150 mg/l is hard water  Iron and manganese (cause color and stains)  Trace metals (zinc, arsenic, etc.)

pH meter

Hardness (total and calcium)

Organic material ◦ Chemical Oxygen Demand (COD) for amount of oxygen necessary to oxidize organic material mg oxygen required/l – determined by a chemical oxidation ◦ Total Organic Carbon (TOC) for amount of carbon (oxidation of organics to carbon dioxide and measurement of carbon dioxide) mg carbon/l – determined by an instrument ◦ Organic acids (absorption and chemical neutralization ) mg/l

Total Organic Carbon (TOC)

 Water pH testing 9xY 9xY  Water hardness d3a8 d3a8

Jar tests are used to determine the effectiveness of chemicals added to coagulate and flocculate wastewaters, and to precipitate species. In these tests, different chemicals are added in different doses to see what dose causes the best coagulation and settling.

Jar test apparatus and results

 Physical testing ◦ Density ◦ Distillation fractions ◦ Gas chromatograph  Chemical testing ◦ Elemental testing by ignition ◦ Boiler feed water analysis

 Ca(HCO 3 ) 2 + NaOH = CaCO 3 + NaHCO 3 + H 2 O (hardness)  NaHCO 3 + HCl = NaCl + CO 2 + H 2 O (bicarbonate alkalinity)  Others (silica, iron, etc.)