Presentation nainesh
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Electrochemical treatment is a wastewater treatment technique that uses electric current to introduce charged species through electrodes placed in a reactor. This removes metals, solids, and inorganic pollutants. Types of electrochemical methods include electrooxidation, electrocoagulation, electroflotation, electrodeposition, and electrodisinfection. Electrocoagulation works by generating coagulant ions electrically from the anode like aluminum or iron ions. Electroflotation generates gas bubbles electrically to attach and float flocs to the water surface. Graphite and lead dioxide electrodes are commonly used but are unstable, so improved dioxide-ruthenium electrodes have been developed.
Presentation nainesh
- 1. By : Nainesh Patel
- 2. What is Electrochemical treatment? • Electrochemical treatment is a technique in which the wastewater is treated by applying electric current through electrodes in a reactor. • This technology is used for removal of metals, colloidal solids and particles, and soluble inorganic pollutants from aqueous media by introducing highly charged polymeric metal hydroxide species.
- 3. Types of electro chemical methods: 1.Electro oxidation 2.Electro coagulation 3.Electro flotation 4.Electro deposition 5.Electro disinfection 6.Electro reduction
- 4. 1.Electrooxidation • Indirect electro oxidation Cl2 formation H2 O2 generation O3 generation mediator, Ag2+ • Direct oxidation OH radicals for complete mineralization
- 5. Analysis of Available Electrodes • Graphite: unstable, ineffective, cheap • Pt, IrO2 : too expensive, ineffective • PbO2 , SnO2 : unstable, easy to make • B-diamond (BDD), effective, expensive
- 6. Formation Potential of Typical Chemical Reactants Oxidants Formation potential H2 O/ •OH (hydroxyl radical) O2 /O3 (ozone) SO42-/S2 O82- (peroxodisulfate) MnO2 /MnO42- (permanganate ion) H2 O/H2 O2 (hydrogen peroxide) Cl-/ClO2- (chlorine dioxide) Ag+/Ag2+ (silver (II) ion) Cl-/Cl2 (chlorine) Cr3+/Cr2 O72- (dichromate) H2 O/O2 (oxygen) 2.80 2.07 2.01 1.77 1.77 1.57 1.50 1.36 1.23 1.23
- 7. Basic Requirements of Electrodes • Good activity • High stability • Low cost
- 8. Electro-coagulation and electro-flocculation • Generating coagulant electrically • Al – 3e Al 3+ • Fe – 2e Fe 2+ • Sludge floated by hydrogen gas • 2H2 O + 2e H2 + 2OH-
- 10. Applications of Electrocoagulation • Suspended solids • Oil & grease Facilities Required • Al or Fe plates as electrodes • DC power supply • Pumping facility
- 11. Electro-flotation • Electro-flotation is a continuous process • Generating gas bubbles electrically • 2H2 O - 4e O2 + 4H+ • 2H2 O + 2e H2 + 2OH- • Gas bubbles attaching to flocs • Floating to top of water surface
- 12. This process mainly consists of four steps: (1) gas bubblegeneration (2) contact between gas bubble and oil drop (3) gas bubble adsorption onthe surface of the particle (4) gas bubble and oil drops rising on to the surface.
- 13. Challenges in O2 Evolution Anodes • Pt (wire, mesh, plates) • PbO2 • Graphite • DSA (TiO2 -RuO2 ; IrO2 with Ta2 O5 , ZrO2 or CeO2 ) • O2 Evolution Anodes • DSA (Ti/IrO2 -Sb2 O5 -SnO2 ) • Economical • Stable • Active
- 14. Electro disinfection • Generating chlorine electrically • 2Cl- -2e Cl2 (anode) • 2H2 O + 2e H2 + 2OH- (cathode) • Generating OH radicals electrically • (similar to electro oxidation)
- 15. Electroreduction • Direct reduction on the surface of cathode Mn+ + ne M (cathode) Mediated reduction by H2 generated 2H2O + 2e H2 + 2OH- (cathode) Mediated reduction by Fe2+generated Fe - 2e Fe2+ (anode)