Disinfection of Water and Industrial Effluents by Electrochemical Activation Mariam Ismail

1
Disinfection of Water and Industrial Effluents
by Electrochemical Activation


Mariam Ismail
Chen-Lu
YangDepartment of Chemistry and Biochemistry
Advanced Technology Manufacturing
CenterUniversity of Massachusetts - Dartmouth
University of Massachusetts - Dartmouth
University of Massachusetts Dartmouth Chapter







Sigma Xi
Scientific Research Society







12th Umass Dartmouth Research
Exhibition







April 25-26,
2006
Introduction
Conditions and Results
Electrochemical activation of water involves the
exposure of water and the salts added to it, to
an electrical potential difference. Using an NaCl
solution with an applied potential, we will be
able to produce hypochlorite, which is a chlorine
based that is commonly used in treatment of water
to kill micro-organisms, such as E.coli.
An electrochemical reactor was designed using two
ruthenium oxide coated titanium electrodes with
surface area of 138 cm2, and a patented porous
zirconium oxide membrane. This specially
designed membrane separates the two chambers, and
allows the ions to pass unimpeded, but is still
largely impermeable to unionized water as well as
organic molecules. The net result is an
enrichment of chlorine ions in the anode chamber,
and sodium ions in the cathode chamber. Water is
also ionized extensively and migrates towards the
opposite poles. As high concentrations of Cl- and
OH- build up on either sides of the membrane ,
with out the compensation of Na and H building
up on either side of the membrane, this unstable
chemical state results in complex reactions,
which produces a meta-stable solution that
contains a wide variety of very reactive ions and
free radicals. Some of the important reactive
constituents are hypochlorite, hydrogen peroxide,
ozone, and chlorine.
Figure 3 Wavelength Scan Anolyte Solution
Figure 4 Time vs. Absorbance _at_ 20V
Figure 5 Wavelength Scan Catholyte Solution
Coliscan MF Membrane FilterSteps 1 through 4
Figure 6 Time vs. Absorbance _at_ 20V
Steps 5 through 9
Figure 7 Time vs. Current
Figure 8 Shelf-life of Anolyte Solution
Before and After- Incubation at 35C2C for
18-24 hours
Figure 1 Experimental Setup
Figure 1 Time vs. pH Anolyte chamber
Conclusions
Figure 2 Time vs. pH Catholyte chamber
Important Reactive Constituents Formed

• Maximum absorbance for the anolyte solution was
  found to be at 305 nm, and for the catholyte
  solution at 292 nm
• Absorbance increased with application time
• Anolyte chamber became more acidic with applied
  time
• Catholyte chamber became more basic with applied
  time
• Current decreased with time under all conditions
• Anolyte solution was 100 effective up to 48
  hours
• Absorbance decreased as time (day) increased

• Hypochlorite
• Chlorine
• Hydrogen Peroxide
• Ozone
• Hydroxide ions
• Hydrochloric acid

Electrolytic Formation of hypochlorite
2 Cl- ? Cl2 2e-
Cl2 (aq) H2O ? HClO Cl- H
HClO ? ClO- H