Heavy Liquids Separation

Heavy Liquids

Overview• Methylene iodide (MI; ρ = 3.32 g/cm3) is used to

concentrate material according to density. • When added to MI, materials with greater

density will sink while others will float• The density of MI can be adjusted through

dilution to target specific material*MI is poisonous. Contact with skin and inhalation

of vapors must be avoided.*

Heavy liquids

Safety and chemical handling• Under no circumstance should MI be heated as it will

produce poisonous gas• Proper PPE including gloves and a lab coat must be worn

during MI use• MI should be stored and used in the fume hood at all times.• Samples must be rinsed completely of MI using acetone prior

to drying• Do not add water to MI • All gloves and wipes used during the MI separation must be

evaporated in the hood overnight before being discarded

Heavy Liquids

Set up– Before starting, ensure all

glassware is clean. Wipe out all beakers to be used with acetone.

– Clean stopper and fitting with acetone

– Three 500 ml beakers are used during the separation:

1. The working MI solution2. MI + Acetone rinsed from filters and

cleaning between samples3. Acetone + small amount of MI from

cleaning samples before drying

Heavy Liquids

Set up– The density of MI is adjusted by

diluting with acetone then measured using the hygrometer

– The ratio of MI to acetone required can be calculated as followed: fMI = (ρn + ρA)/(ρMI – ρA)

ρn: Needed density

ρA: Acetone density, 0.79 g/cm3

ρMI: MI density, 3.32 g/cm3

Heavy Liquids

Sample separation, adding sample:• Add sample to the top of the column, do not

overload. • Gently stir to break surface tension and rinse

material stuck to sides down with acetone. • Let stand for at least 5 min, fine material may

require up to 30 min.

Heavy Liquids

Sample separation, removing sample:• After sample has settled, set a filter under

the column, P8 for >125 um, P4 for <125 um

• Rotate the stopper to drain the bottom of the column, close once the settled material has been removed from the column

*Open slowly to avoid splashing*• After MI has drained, rinse filter and

sample thoroughly in acetone and transfer sample to a 250 ml beaker.

• Repeat for the floating material.

Heavy liquids

Sample cleaning• Rinse and decant acetone from the sample 2-3 times.• Ultrasonically clean the sample in acetone for 5 min. • Fill the sonicator bath with water to the third set of holes to

avoid damaging the motor. • Ensure sample beakers are not floating in the bath as they

will tip and the contents will be lost. • Rinse and decant with acetone 2-3 additional times. • Repeat the process a total of 2-3 times, or more for finer

material• Once all MI is removed, dry the sample under the heat lamp

Heavy Liquids

Clean up• MI must be recovered for reuse as much as possible• Leave beakers with working MI and acetone rinses

in the hood. Over time, acetone will separate to the top and evaporate leaving pure MI behind.

• Before returning it to the bottle, ensure the MI has a density >3 g/cm3 and pass it through a P2 filter