10.7.1 Apparatus and Equipment:
Radiometer Copenhagen TTT 80 Titrator
Radiometer Copenhagen PHM 82 standard pH meter Spatula
Stirrer
Plastic containers Overhead Stirrer 10.7.2 Reagents:
TP 207 Iminodiacetic acid CuS04.5H20
Distilled water NaOH
10.7.3 Procedure:
Two solutions were prepared 6 and 0.6 g/L for testing. From equilibrium data the amount of resin that was used for kinetic tests were calculated using 0.0322 g/L as the finial concentration for loading. The following amounts 609.89 and 58.03 mL was obtained respectively as the amount of resin to use for the concentrations mentioned above. Two particle size distributions were used for testing, 850JlIlland 600 Jlm.
The two solutions were placed in plastic containers and were attached to a mechanical stirrer.
The water was removed from the resin using a pipette and placed with the respective solutions.
A Comparative Study of Contacting Equipment for the Recovery of Copper from a Cupric Sulphate
Solution 48
Chapter Ten: Experimental Procedures
The Radiometer Copenhagen TTT 80 Titrator was set at a pH of 3 and a Radiometer Copenha- gen PHM 82 standard pH meter was placed within the plastic container to monitor the pH at all times. The speed of the mechanical stirrer was set at 310 rpm and the stopwatch was started.
A sample of 5mL of solution was taken at set-intervals for 24 hours. The resin was tapped to determine the swelling of the resin saturated with copper. Copper solution remaining was meas- ured with a measuring cylinder to compare values with the volume balance. Samples of the so- lution were analyzed with an AA spectrometer.
10.8 Effect of Swelling of TP 207 resins
For the mini column tests resins in three different forms were required. The hydrogen, di so- dium and the mono sodium forms.
10.8.1 Conversion into the Hydrogen form 10.8.1.1 Procedure:
Three litres of resin in the H+ form was required. The conversion of the resin into the hydrogen form was followed from Section 10.1. Two litres of this resin was used for the conversion to the other forms and one litre was to be kept in the hydrogen form.
The following were the results obtained from the hydrogen form:
Volume of resin required [H+ form] = 1000mL.
pH of resin at the end of conversion [H+ form] = 2.5
10.8.2 Conversion into the Di Sodium form 10.8.2.1 Procedure:
One litre of resin in the H+ form was required. The resin was loaded into a column. A solution of 2M NaOH was prepared using 239.94g of NaOH in 3L distilled water. A Watson Marlow peristaltic pump (refer to Figure 10.3) was used to set the flow rate at 1 Uhr. 2 M NaOH solu- tion was passed up flow through the inlet of the column at the required flow rate. The resin was water washed down flow with four litres of distilled water for two hours. The resin was tapped (using the tapped wet volume method) and the pH was measured.
The final resin was in the Di Na+form with the following result:
Volume of resin [Di Na+ form] = 1349 mL pH of resin [Di Na+ form] =11.50
A Comparative Study of Contacting Equipment for the Recovery of Copper from a Cupric Sulphate
~~oo ~
Chapter Ten: Experimental Procedures
10.8.3 Conversion into the Mono Sodium form 10.8.3.1 Procedure:
One litre of resin in the
W
form was required. The resin was loaded into a column and water washed for two hours with four litres of water until the pH of the resin was greater than 2.5. The excess water was sucked out with a pipette. A solution of 0.475 M NaOH was prepared using 37.99g of NaOH in 2L distilled water. The 0.475 M NaOH solution and the one litre of resin in the H+ form were placed in a bucket with an over head stirrer. The speed of the mechanical stir- rer was set at 310 rpm. The resin was tapped and the pH was measured.The resin was in the Mono Na+ form with the following result:
Volume of resin [Mono Na+form] = 1250 mL pH of resin [Mono Na+ form] =6.71
Note:
• Di Sodium form
The resin that was converted to the Di sodium form must be converted using upward flow movement for the following reason:
The resin is in the H+ form and is exchanging 2H+ for 2Na+. As the resin is converted to the Di sodium form the resin swells. This implies that the resin increases in size. If the process was operated down flow the resin which would expand might crack the bottom of the column.
Therefore the flow needs to be upwards to allow the resin to expand.
• Mono Sodium form
The resin that was converted to the mono sodium form needs to be converted using the batch method because if it were done using up flow, only the bottom half of the column would be converted to the Na+ form and the top part of the column would still be in the H+ form. The converse is also true (down flow).
Using the batch system allows the Na+ to be evenly distributed into the resin. The batch system allows for well mixing of the resin and the solution.
A Comparative Study of Contacting Equipment for the Recovery of Copper from a Cupric Sulphate
Solution 50
Chapter Ten: Experimental Procedures