What types of analytes can be analyzed using gas chromatography? What types of analytes are unsuitable for analysis with this technique? Which would be expected to elute first on a polydimethyl sioxane column, butane, or butanol? Why? What factors determine relative retention time with gas chromatography?

What is the basis for separation in gas chromatography? (I.e. adsorption, partition, size exclusion, ion exchange, or affinity?)

1. A gas mixture containing a solute with a concentration of Y₁=0.02 to be absorbed in a packed tower. The gas-liquid equilibrium is described by: Y^*=1.0X.

(a) (10%) To achieve a 99% solute recovery, calculate the required gas phase overall mass transfer unit N_tOG and the composition X₁ at the liquid exit. X₂=0.0001 at the liquid inlet with L/G=1.2.

(b) (10%) For pure liquid inlet with L/G=0.8, what is the maximum percentage solute recovery?

2. For a packed tower for gas absorption operation, under a given operating condition, it is found that kya=kxa=0.026 kmol/m2.s. The equilibrium equation is given by: y=5x. Given that ky?G0.8, calculate the percentage reduction in overall mass transfer coefficient if the gas flow rate is doubled while the liquid flow rate remains unchanged.

Describe three techniques for “perpetual storage” of hazardous wastes. If you had to make a decision among the three techniques for disposing of dioxin-contaminated waste, would you be able to recommend one?

500 kmol/h of an air stream at a pressure of 2 atm is to be heated from 15 celsius to 90 celsius in a heat exchanger with 600 kPa steam condensing in the shell side of the heat exchanger. Steam enters the exchanger as a saturated vapor and leaves as a saturated liquid.

A) How much steam would be required if a conventional heat exchanger were used? what is the total entropy change during this process?
B) How much steam would be required if the process of heating the air was carried out by using the heat transferred from the steam to drive a reversible carnot engine and by using the air stream as the heat sink? what would be the total work output of this engine?

An air stream at 87.8°C having a humidity H = 0.030 kg H2O/kg dry air is contacted in an adiabatic saturator with water. It is cooled and humidified to 90% saturation. (a) What are the final values of H and T? (b) For 100% saturation, what would be H and T?

Air entering a dryer has a temperature (dry bulb) of 60°C and a dew point of 26.7°C. Using the humidity chart, determine the actual humidity H, percentage humidity HP, humid heat cS and humid volume vH.

An evaporator is used to concentrate 4536 kg/h of a 20% NaOH solution entering at 60?C to a product of 50% solids. The pressure of the saturated steam used is 170 kPa and the vapour space pressure of the evaporator is at 12 kPa. The overall coefficient U is 1560 W/m2K. Calculate the steam used, the steam economy (kg vaporized / kg steam used) and the heating surface area.

A box has two compartments of equal size. One side there are 6 moles of hydrogen gas and the other has 2 moles of nitrogen gas. The box is kept at 20C and the barrier between the two compartments is removed. Assume ideal gas behavior and calculate Gibbs energy when allowing the gases to mix.

Consider a mid-size city of 3,000,000 people in the Cairo city . Suppose that its residents produce, on average, 6.0 kg a day of MSW. At present this waste is being hauled 180 miles away (in a southeasterly direction) where it is being used to fill in an abandoned open pit nickel mine. The mine and deposited wastes abut a shallow marine embayment. Seaweed, shellfish, crustaceans, and fish are harvested from this embayment and eaten by both the local fishermen and their families as well as by the residents of the city.

Facts about the waste:

55 % of the waste is composed of agricultural waste and household non-sewer organics

35 % of the waste is household waste, including paper, glass and plastics

10 % of the waste is a combination of metal, wood, chemical, petroleum, and other miscellaneous materials.

Calculate how much methane could be generated from the anaerobic decay of the landfill waste over a 10 year time period. What, if anything, could be done with this methane? Would more, less, or the same amount of methane be produced if the waste was simply incinerated? Which waste disposal method provides the biggest threat to environmental sustainability and human health? Explain your answer.

Pure water at 26.1 degres celcius flows at the rate of 5.514x10^-7 m^3/s through a packed bed of benzoic acid spheres having a diameter of 6.375 mm. The total surface area of the spheres in the bed s 0.01198m^2 and the void fraction is 0.436. The tower diameter is 0.0667m. The solubility of benzoic acid is 2.9488x10^-2 kg mol/m^3.

a. What is the mass tranfer coefficient?

b. What is the outlet concentration of benzoic acid in the water?

Your engineering consulting firm has been retained to develop an absorption process that removes 98% of the SO2 from an air stream. The column operates at 30 oC and 5 atm. The design assumes 250 mol/min of an air stream contaminated with 10 mol% SO2 fed to the bottom of the column. Regenerated absorbent is fed to the top of the column. The absorbent is an aqueous solution, where the absorbent species is non-volatile. Some water will vaporize based on its vapor pressure at 30 oC (approximately 35 mmHg), so the treated gas will contain air, residual SO2, and water vapor. The absorbent stream leaving the column contains SO2 in a molar ratio of 15:1 (solvent:SO2). The absorbent is recovered in a stripping column operating at 120 oC and 2 atm. The stripping gas is 250 mol/min steam which is fed to the bottom of the stripping column and removes 98% of the SO2. Some of the steam condenses in the absorbent phase at a ratio of 2:1 (aqueous solvent:condensate). The absorbent is non-volatile, so the exiting steam only contains water and SO2. Your task is to analyze this process. Follow the problem solving procedure outlined in your notes and the textbook. You must: prepare a fully labeled process flow diagram, conduct a degree of freedom analysis on each system (overall, absorber, and stripper), clearly identify unknown variables and units, write all appropriate equations (materials balances, etc.) needed to solve for the unknowns, solve the problem.

In a hypothetical experiment, electrical current of 15 AMPs driven by an applied potential of 100 volts passes through a cylindrical rod (3 mm in diameter and 7 cm long). Recall, the power is calculated by power(Watts) = potential(VOLTS) x current(AMPS). The electrical power heats the cylindrical rod to a high temperature. The rod is inside of a ceramic tube (ID = 12 mm). The wall temperature of the ceramic tube is 600 C (maintained at this stead temperature by air cooling on the outside). Assuming that convection and conduction between the resistor and the ceramic tube are negligible compared to thermal radiation, estimate the surface temperature of the rod. The emissivity of the ceramic tube is 0.9 and the emissivity of the resistor is 0.8.

A mixture containing 20 mole % butane, 35 mole % pentane and 45 mole % hexane is to be separated by fractional distillation into a distillate product with a composition 95 mole % butane, 4 mole % pentane and 1 mole % hexane, and a bottoms product. The recovery of butane in the distillate must be 90%. Determine the composition of the bottoms product.