Automatic Ammonium Ion Concentration of Cultivation Processes

Author : Alcanzare, Edilberto Angeles
Major Adviser : Chay, Pham Binh
Committee Members :
Year : 1989
Month : March
Type : Thesis
Degree: BS
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The effects of temperature, pH and other ionic species (Na+, K+, Mg2+ and Ca2+) on the output potential of an Ammonium Ion Measurement System (AIMS) were studied. The output potentials of the test samples were determined and compared with a calibration curve done at 30°C.

Different concentrations of standard solutions (50 mM, 200 mM, 350 mM and 500 mM) showed increasing step responses to temperature changes. With 30°C as the base temperature, the increase in output potential for every degree rise in temperature is 3.38%, 4.73%, 5.92% and 6.44% for 50 mM, 200 mM, 350 mM and 500 mM, respectively.

The pH of the system significantly changed the readings of the AIMS at pH values > 6. There was generally a decrease in output at increasing pH above 7 and below 7 the output is relatively constant.

Potassium ion, K+, showed the greatest interference in the output potential of the AIMS at 0.133/M. The ions, Na+ and Ca2+, have significant interferences at 0.075/M and 0.054/M, respectively. The interference of Mg2+, 0.033/M, can be neglected.

To develop a control system for ammonium ion concentration in a cultivation process, the effects of temperature and ionic species should be taken into account and their compensation be included in the design.

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