Abstract:
The streaming potential method is commonly used for charge analysis in water
treatment and the paper industry. The colloidal charge of water determines its
quality. This research focused on the construction of a system for determining the
electric potential in a water sample through measurement of the output voltage at
different pH values. Using AutoCAD®, the mechanical part of the system was first
drawn in 3-dimension. Design and implementation of these parts involved
construction of the system cell, its housing and the cam system. The motor control
circuit developed is based on pulse width modulation (PWM). The various circuits
were drawn using Circuitmaker ®. Measurements of electric potential were carried
out on water sample as a function of pH in the range 2-13. The pH of the sample was
adjusted with small quantities of calcium hydroxide solution, 2 Ca(OH) in the range
7-13, and with hydrochloric acid, HCl in the range 2-7. The results obtained showed
that the output of the system varied with water pH level. In the pH range 2-6, the
system output depicted a drop in potential from 33 mV to 24 mV while in the range
6-13, an increase in the output potential from 24 mV to 42 mV was noticed. From
the results , the negative and positive gradient of the graph implies presence of acidic
and basic media respectively. From these results, the relationship between the system
output and the ionic concentration of particles in the water can be used in
determining the stability of these particles hence the amount of alum needed during
water treatment process. Various recommendations are given for future research
especially in the automation of the system and calibration to allow measurement of
other parameters such as temperature and turbidity that affect water quality.