Tuesday, July 14, 2009

Busy With The Columns

Author: Hong Ting (Sam) Chiu

It has been more than 3 weeks since my last post!! Recall that the AAS wasn't working properly and I needed the result in order to move on with the batch. At the end, I decided not to be idle and switched gear to the rapid small scale column test (RSSCT). Since then, I have been pretty busy and working on the RSSCT.

How RSSCT occupied my time? Here it goes...

For the first week of RSSCT, I had to gather and setup all the equipments and chemicals. I have chosen a 100 liter tank for the source water to prevent the lack and the non-uniformity of the source. I have to move the tank up to the bench before filling it up (filling up the tank is often fun to watch; only if the filling tube doesn't fall out the tank and makes a spill...) - because it is too heavy to move after filling. I also put a stirrer and a pH meter inside; but to secure the equipments, I used numerous stands and metal rods, which looks like a sculpture. As the tank is on the bench, I have to climate up the bench to add acid/base to adjust the pH.

RSSCT Setup.

The two columns.

Glass wool.
Some bad stuff.
The glass is still be able to cut my fingers when I have the gloves on.

After the first week, I have to actually run and analyze the samples collected. For the first set, I would like to have a close-to-complete break through, therefore, it was ran for 56 hours duration. The other trials with different parameters are then decided to keep at maximum of 10 hours. Many samples were collected.

I was collecting the effluent samples.

I attempted to run the AAS again and the signals were way less than usual. Therefore, the lab staff decided to change the graphite tube. After that, everything works fine (and it is still okay as of today). So, there is no more un-solvable AAS problem.

But, one problem gone and another faded in. When preparing the source, I used 388 mL of stock As(V) solution. That 100 L tank supposes to last for one more set of column; I need to run at least two more sets. And unfortunately, the lab runs out of As(V) stock solution and the salt went missing. They have to order a new salt and I have no idea when it would be delivered. I guess I will consult the lab staff when I really need that stock solution and hope it would arrive soon.

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