Presented by Kathiresan NadarMchem. Engg.

Under the guidance of Dr. Parag. R. GogateAssistant prof.ICT Mumbai.

Introduction Waste water generation.

Impurities in waste water.

Causes of impurities.

Traditional method of water treatment.

Importance of hydroxyl radical.

Fenton Processes

Advantage No energy input is necessary to activate hydrogen

peroxide

Fenton's reagent is relatively inexpensive and the process is easy to operate and maintain

Short reaction time among all advanced oxidation processes

There is no mass transfer limitation due to its homogeneous catalytic nature

There is no form of energy involved as catalyst

Disadvantage Ferrous ions are consumed more rapidly than they are

regenerated

Treatment of the sludge-containing Fe ions at the end of the wastewater treatment is expensive and needs large amount of chemicals and manpower

It is limited by a narrow pH range (pH 2–3)

Iron ions may be deactivated due to complexion with some iron complexing reagents such as phosphate anions and intermediate oxidation products

Additional water pollution caused by the homogeneous catalyst that added as an iron salt, cannot be retained in the process

Fenton Chemistry H2O2 + Fe2+ Fe3+ + OH- + OH•

Fe3+ + H2O2 Fe2+ + HO2• + H+

Fe3+ + HO2• Fe2+ + O2 + H+

H2O2 + OH• H2O + HO2•

Fe2+ + •OH Fe3+ + OH-

HO2• + HO2

• H2O2 + O2

Fe2+ + H2O2 [Fe(OH)2]2+ Fe3+ + OH• + OH-

Electrolytic processes for waste water treatment

Electro coagulation

This technique involve the addition of coagulant in the form of sacrificial anode

Electroflotation

electrically generated tiny bubbles of hydrogen and oxygen gas interact with pollutant

particles making them to coagulate and float on the surface of water

Electrocoagulation flotation

This method as the name indicate includes both Coagulation and Flotation techniques

Electro Fenton

Electro Fenton EF technology is based on the continuous electro generation of H2O2 at a suitable cathode

fed with O2 or air, along with the addition of an iron catalyst to the treated solution to produce oxidant •OH at the bulk via Fenton’s reaction

Advantage

1. The on-site production of H2O2

2. controlling degradation kinetics to allow mechanistic studies

3. The higher degradation rate of organic pollutants because of the continuous regeneration of Fe2+ at the cathode, which also minimizes sludge production

4. The feasibility of overall mineralization at relatively low cost

Classification of electro FentonEAOPs

H2O2 onsite produced at cathode

Combined Electro Fenton Processes

Per oxide coagulationPhoto assisted electro

Fenton processes

Photo electron Fenton

Solar photo electron Fenton

Photo peroxycoagulation

Photo electrochemical electro Fenton

Sonoelectro FentonCathodic generation of

Fe2+

H2O2 is added to the solution from the outside

Electrochemical Fenton Processes

Electro chemical peroxide processes

Fered Fenton Processes

Anodic Fenton treatment

Combined Fenton Processes

Photo assisted fered fenton

Photo assisted ECP processes

Plasma assisted fenton Processes

Anodic H2O2

electrogeneration

Electrolytic Fenton chemistry O2(g) + 2H+ + 2e- H2O2

O2(g) + 4H+ + 4e- 2H2O

H2O2 HO2• + H+ + e-

HO2• O2(g) + H+ + e-

H2O2 + 2H+ + 2e- 2H2O

2H2O2 O2(g) + 2H2O

Destruction of hydrogen

peroxide at anode

Production of hydrogen peroxide

Destruction of hydrogen

peroxide at cathode

Production of Hydrogen peroxide

O2(g) + H2O +2e- HO2- + OH-

O2(g)+ + 2 H2O + 4e- 4OH-

Divided cell and undivided cell Configuration for H2O2 Production

Divided cell

Undivided cell

Advance Electro Fenton processes

H2O2 generation using water (Novel Electro Fenton processes)

Songhu Yuan et al (2011)

2H2O O2(g) + 4H+ + 4e-

2H2O + 2e- H2(g) + 2OH-

H2(g) + O2(g) H2O2

Factor affecting the production of H2O2pH of the solution

accumulated H2O2 maximum concentration was 21.6 mg/L for a pH of 2 but as the pH increased to 3 its concentration falls to 5 mg/L

Current in compartment 1

•Increasing the current decreasing the current efficiency though we are increasing the production H2O2. He attributed that solubility of formed hydrogen and oxygen is much less

•novel process possesses a moderate ability to accumulate H2O2

Microbial fuel cell as a power source for electro Fenton reaction•Electro Fenton processes for waste water treatment Bruce E Logan et al. used a Microbial fuel cell design (MFCs) for the degradation of phenol

•Microbial fuel cells are bio electrochemical systems that use bacteria to oxidize organic wastes and generate electricity

•The power output of MFCs has increased from only a few mill watts per square meter of electrode to 4.3 W/m2. These higher power densities could therefore make it practical to use MFCs as power sources for electro-Fenton systems

Combined electro Fenton processes technologies.

Peroxi-Coagulation (PC) Process

involve the sacrificial anode as the ferrous anode and gas diffusing cathode production of H2O2

Photoelectro-Fenton (PEF) and Solar Photoelectro-Fenton (SPEF) Processes

The photo electron processes make use of the ultra violate rays for the acceleration in removal of organic pollutants from the solution the attributions

Fe(OH)]2+ + hV Fe2+ + •OH

Fe(OOCR)2+ + hV Fe2+ + CO2+ + R•

Sonoelectro-Fenton (SEF) Process This technique make use of application of ultrasound in waste water solution

H2O + ))) •OH + H•

Fered-Fenton ProcessFered Fenton processes involve the addition of H2O­2 from the outside initially iron catalyst in the form of ferrous or ferric is added to the acidic solution followed by the addition of hydrogen peroxide

Reactors for Electro Fenton processes

Trickle bed reactor•Zhemin Shen et al (2013)

•cathode frame which involve the housing of Cathodic particle which helps in the production of hydrogen peroxide

•H2O2 was generated at a current of 0.3 A with a CE of 60%. After 2 h of electrolysis, the H2O2 concentration and production rate were 9.43 mmolL−1 and 125 µmolh−1cm−2

•The more effective oxygen transfer from the gas phase to the electrolyte–cathode interface

•Dye wastewater with a concentration of 123 mgL−1 was 97% decolorized within 20 min and 87% mineralized within 3h

Bubble ReactorM.A. Sanroman et al. (2009)

Lissamine Green B as a model pollutant for graphite cathode

This Bubble column reactor follows an ideal CSTR behaviour and it is confirmed by the Residence time distribution (RTD) studies

Fluidised Bed Lu et al. (2010) had used a fluidized bed Fenton and electro

Fenton processes for the degradation of Aniline as a model pollutant

The removal ratio of TOC in the electro-Fenton and fluidized-bed Fenton processes after reacting for 60 min was about 20–30% and 18–35%, respectively

The results show that mineralization efficiency in the fluidized bed Fenton process was higher than that of the electro-Fenton process

Electro Fenton is slightly superior to the Fenton processes since in Electro Fenton complete mineralisation of aniline occur

Parameters for operation

Parameters are evaluated for the study of degradation of phenol by Mao et al. and removal of reactive 69 by Nader et al.

pH of the solution

Electric current effect

Type of electrode material

Amount of ferrous ion

Concentration of hydrogen peroxide

Impurities removal enhances with the increase in hydrogen peroxide concentration but it efficiency reduces since destruction of hydrogen peroxide

will be enhanced.

Initial concentration of the pollutant

Operating temperature

increasing temperature the rate constant increases this is optimum to temperature up to 40◦C with further increase in temperature hydrogen peroxide degrades to hydrogen and oxygen

Conclusion Though various pollutant degradation methods are

available electro Fenton processes has the indeed advantage of using at ambient temperature and pressure. The strict Ph control and initial concentration of ferrous, H2O2 and pollutant concentration needs to be maintained for the optimum operation of processes.

References Enric Brillas, Ignasi Sire’s, and Mehmet A.Oturan Electro-Fenton Process and Related Electrochemical Technologies Based

on Fenton’s Reaction; Chemistry Chem. Rev 109: France, 2009,; PP 6570–6631.

Xiuping Zhu, Bruce E. Logan, Using single-chamber microbial fuel cells as renewable power sources of electro-Fenton reactors for organic pollutant treatment; Journal of Hazardous Materials 252– 253: United States, 2013; PP 198– 203.

Parag R.Gogate, Aniruddha B.Pandit, A review of imperative technologies for wastewater treatment I: oxidation technologies at ambient conditions; Advances in Environmental Research 8: Mumbai, India, 2004; PP 501-551.

E. Rosales, M. Pazos, M.A. Longo, M.A. Sanromán, Electro-Fenton decoloration of dyes in a continuous reactor: A promising technology in colored wastewater treatment; Chemical Engineering Journal 155: Spain, 2009; PP62-67.

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Songhu Yuan, Ye Fan, Yucheng Zhang, Man Tong, and Peng Liao; Pd-Catalytic In Situ Generation of H2O2 from H2 and O2Produced by Water Electrolysis for the Efficient Electro-Fenton Degradation of Rhodamine B; ACS Publication, Environment science and technology 45: China, 2011; PP 8514–8520.

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Md. Ahsan Habib, Iqbal Mohmmad Ibrahim Ismail, Abu Jafar Mahmood1 and Md. Rafique Ullah, Decolorizationand mineralization of brilliant golden yellow (BGY) by Fenton and photo-Fenton processes; African Journal of Pure and Applied Chemistry Vol. 6: Bangladesh, 2012; PP 153-158.

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