Heavy Liquids Separation

Heavy Liquids Overview Methylene iodide (MI; ρ = 3.32 g/cm 3 ) 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 solution 2.MI + Acetone rinsed from filters and cleaning between samples 3.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: f MI = (ρ n + ρ A )/(ρ MI – ρ A ) ρ n : Needed density ρ A : Acetone density, 0.79 g/cm 3 ρ MI : MI density, 3.32 g/cm 3

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/cm 3 and pass it through a P2 filter