Electrochemical regeneration

Electrochemical Regeneration

The electrochemical regeneration of activated carbon based adsorbents involves the removal of molecules adsorbed onto the surface of the adsorbent with the use of an electric current in an electrochemical cell restoring the carbon’s adsorptive capacity. Electrochemical regeneration represents an...

 of activated carbon

Activated carbon

Activated carbon, also called activated charcoal, activated coal or carbo activatus, is a form of carbon that has been processed to make it extremely porous and thus to have a very large surface area available for adsorption or chemical reactions.The word activated in the name is sometimes replaced...

 adsorbents such as granular activated carbon present an alternative to thermal regeneration or land filling at the end of useful adsorbent life. Continuous adsorption-electrochemical regeneration encompasses the adsorption and regeneration steps, typically separated in the bulk of industrial processes due to long adsorption equilibrium times (ranging from hours to months), into one continuous system. This is possible using a non-porous, electrically conducting carbon derivative called Nyex. The non-porosity of Nyex allows it to achieve its full adsorptive capacity within a few minutes and its electrical conductivity allows it to form part of the electrode in an electrochemical cell

Electrochemical cell

An electrochemical cell is a device capable of either deriving electrical energy from chemical reactions, or facilitating chemical reactions through the introduction of electrical energy. A common example of an electrochemical cell is a standard 1.5-volt "battery"...

 . As a result of its properties Nyex can undergo quick adsorption and fast electrochemical regeneration in a combined adsorption-electrochemical regeneration cell achieving 100% regeneration efficiency .

A Continuous Adsorption-Regeneration Cell

The adsorption regeneration process is divided into three key elements which occur in different parts of the cell. All three occur continuously and simultaneously, with parameters such as charge

Electric charge

Electric charge is a physical property of matter that causes it to experience a force when near other electrically charged matter. Electric charge comes in two types, called positive and negative. Two positively charged substances, or objects, experience a mutual repulsive force, as do two...

 passed, rate of effluent

Effluent

Effluent is an outflowing of water or gas from a natural body of water, or from a human-made structure.Effluent is defined by the United States Environmental Protection Agency as “wastewater - treated or untreated - that flows out of a treatment plant, sewer, or industrial outfall. Generally refers...

 in/outflow and air inlet rate varied according to pollutant type and concentration.

Pollutant Contacting and Adsorption

Polluted effluent is added into the bottom of the cell and mixed with the adsorbent in the adsorption zone 1.1 where adsorption of the pollutants onto the surface of the adsorbent occurs. Mixing between the adsorbent and the polluted effluent is promoted by air spargers

Sparging (chemistry)

In chemistry, sparging, also known as gas flushing in metallurgy, is a technique which involves bubbling a chemically inert gas, such as nitrogen, argon, or helium, through a liquid. This can be used to remove dissolved gases In chemistry, sparging, also known as gas flushing in metallurgy, is a...

 at the base of the cell which also facilitate the migration of the adsorbent upwards and into the cell’s sedimentation

Sedimentation

Sedimentation is the tendency for particles in suspension to settle out of the fluid in which they are entrained, and come to rest against a barrier. This is due to their motion through the fluid in response to the forces acting on them: these forces can be due to gravity, centrifugal acceleration...

 zone.

Adsorbent-Treated Effluent Separation

The adsorbent is separated from the now treated effluent in the sedimentation zone where the density of the adsorbent allows separation by gravitational sedimentation. The treated effluent is allowed to overflow out of the cell.

Adsorbent Electrochemical Regeneration

The adsorbent, loaded with adsorbed pollutant on its surface sediments and forms a bed in the regeneration zone in the cell. The mass of the Nyex causes the bed to travel down the regeneration column slowly and eventually pass back into the cell. During the journey down the regeneration column, a DC current

Electric current

Electric current is a flow of electric charge through a medium.This charge is typically carried by moving electrons in a conductor such as wire...

 is passed across the electrochemical cell of which the adsorbent forms the anode

Anode

An anode is an electrode through which electric current flows into a polarized electrical device. Mnemonic: ACID ....

. The applied current causes the pollutants adsorbed on the surface of the Nyex to be electrochemically oxidised regenerating the adsorbent surface restoring its full adsorptive capacity completing the adsorption-regeneration cycle .

Applications

This technology is currently being incorporated into a variety of industries for applications in effluent treatment areas such as:

• Groundwater remediation
  Groundwater remediation
  Groundwater remediation is the process that is used to remove pollution from groundwater. Groundwater is water present below the ground surface that saturates the pore space in the subsurface. At least one half of the population of the United States depends upon groundwater as a source of...
  
  
• Volatile Organic Compound
  Volatile organic compound
  Volatile organic compounds are organic chemicals that have a high vapor pressure at ordinary, room-temperature conditions. Their high vapor pressure results from a low boiling point, which causes large numbers of molecules to evaporate or sublimate from the liquid or solid form of the compound and...
  
  Removal
• Dye-house Effluent De-Colourisation
• Electrochemical Disinfection