Filtering Out Barium: The Plan

In our assignment, we were given a sample of water with two possible contaminants; Silver (Ag+) or Barium (Ba2+). To tackle the situation, we made a plan!

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We first decided to extract any silver ions in the sample using acetate (C2H3O2). If there had been any silver in the water, the resulting precipitate would have been AgC2H3O2, or silver acetate. In our specific case, there were no silver ions in the water, thus no silver acetate was produced.

http://www.hydrochloricacidlr.com/prd/sulphuric-acid-commercial.jpg

(“Sulfuric Acid”, n.d.)

Afterwards, we still had to face the possibility of barium contaminating our water sample. We chose sulfuric acid to precipitate out any barium ions. Eureka! Our solution instantly produced a precipitate, which we knew to be barium sulfate (BaSO4).

After determining which ions were present in our sample, we could continue on with the rest of the experiment: testing our homemade filter.

Our DIY filter had a total of 9 layers, with 6 different materials; cotton, cheese-cloth like fabric,

Our DIY filter (it's a bit irritated because we poured contaminated water down it..)

Our DIY filter (it’s a bit irritated because we poured contaminated water down it..)

activated charcoal, coffee filters, an old pantyhose and  sand. Other materials include a 2L plastic bottle, rubber bands, duct tape, clear tape and a beaker. In this filter, most of the layers focused on cleansing the water of any ‘large’ particles that may  interfere with the reactions while the activated charcoal and sand focused on removing the ions and small particles.

Activated charcoal is treated with oxygen to help open up millions of tiny pores between the carbon atoms. This tiny pores adsorb/ attaches itself to other impurities (usually ‘organic’ chemicals) and filter them out (“What is activated charcoal and why is it used in filters?”, 2000). Sand is also frequently used to remove suspended solids from water (“Sand filtration”, n.d.).

Procedure: After preparing a control by measuring out 20ml of our water solution and adding 25 drops of sulfuric acid, we poured 25ml of just water solution through our filter (to accommodate for loss of solution during the filtering process) and

The test-tube on top is the control.

The test-tube on top is the control.

added 25 drops of acid post-filtration. After both precipitates had settled to the bottom, it was evident that our first trial  had less precipitate than our control. To make sure it wasn’t a fluke, we repeated the process once more.

For our second trial, we first replaced the coffee filters at the very bottom and just above the charcoal to the filter to ensure optimal filtration. We repeated the steps, with 25 ml of solution and 25 drops. It yielded the same observation and we could now be certain of our filter’s ability to filter out barium ions!

From left to right: trial #2, trial #1 and control

From left to right: trial #2, trial #1 and control

 

 

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