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Environmental applications for hydrogen peroxide

Albone®, developed by Arkema as a concentrated hydrogen peroxide solution with environmental  compatibility, helps customers adhere to the strict compliance regulations and is able to treat pollutants in the gaseous phase, the liquid phase and the solid  phase.

 

 

Wastewater

Gaseous

effluent

Soils and

groundwater

Organic

compound

COD / BOD / TOC

 

Phenols

 

Formaldehyde

 

 

Hydrocarbons

 

Halogens

 

Mineral

compound

Hydrogen sulfide

 

Mercaptans

 

Sulphur dioxide

 

 

Active chlorine

 

 

Nitrogen oxide

 

 

Nitrite

 

Miscellanous

Sludge

 

 

Odor

 

Color

 

 

When compared to other oxidizing agents used for environmental applications or existing technologies, the application of hydrogen peroxide offers definite advantages:

  • Hydrogen peroxide's decomposition products are water and oxygen. Therefore, there is no additional pollutant.

The decomposition reaction is presented below:

2 H2O2 -> 2 H2O + O2

  • Hydrogen peroxide is easy to use with minimum installation of equipment and thus requires less capital investment, making it competitive with existing technologies.

The storage and handling requirements of Albone® are no more stringent than those already followed in chemical manufacturing plants or wastewater treatment plants that use caustic soda, sodium hypochlorite, etc.

Oxidation of sulfur and mercaptans

Hydrogen sulfide is a toxic and corrosive gas that is easy to detect at very low concentration (1 ppb), with a characteristic odor of "rotten eggs". However, this odor disappears at higher concentrations. The effects of hydrogen sulfide on human health vary with the concentration: hydrogen sulfide can irritate the eyes and respiratory tract at a concentration of 100 ppm. At higher concentrations, it can affect the nervous system and cause digestive problems, and even a loss of consciousness.

 

The exposure recommendations from the guide of the World Health Organization are 150 µg/m3 as daily average, and 7 µg/m3 for an exposure of ½ hour. Treatment of gas stream containing sulfur by physical-chemical washing

 

Hydrogen peroxide can be used as an oxidizing agent for the chemical washing of a gaseous stream containing sulfur compounds. A first washing tower with sulphuric acid can generally neutralize ammonia. A second washing tower using hydrogen peroxide under alkaline conditions will neutralize sulphur compounds.

 

Sulfur compounds and mercaptans are oxidized under alkaline conditions according to the following reaction :

S2- + 4 H2O2  -> SO42- + 4 H2O

 

As much as 99% of sulphur compounds and 85% of mercaptans are eliminated through this reaction. The resulting sulfate compounds are soluble and inert in the effluent.

 

Among the many applications of chemical washing with hydrogen peroxide are meat rendering factories and lubricants manufacturing.

 

Water treatment

 

The injection of hydrogen peroxide into the effluent stream causes the destruction of sulfur compounds and mercaptans. The reaction forms colloidal sulphur or sulfate according to the pH value.

 

  • Acidic pH : S2- + 4 H2O2  -> SO42- + 4 H2O
  • Alkaline pH : H2S + H2O2  -> 1/8 S8 + 2 H2O

 

In wastewater treatment plants, hydrogen sulfide is formed by the anaerobic fermentation of organic substances. The elimination of hydrogen sulfide in the sewer network or in the treatment plant is a well known application for hydrogen peroxide. Hydrogen peroxide also is an excellent source of dissolved oxygen to supplement oxygen deficient biological treatment.

 

Many industrial manufacturing processes can generate hydrogen sulfide from the chemical reactions of various sulfur compounds (oil refining and cracking of high sulfur petroleum, vulcanization of rubber, fabrication of viscose, processing of leather, the acidic treatment in wastewater treatment plants). The application of hydrogen peroxide requires very little installation (a storage tank, a metering pump and piping), resulting in reduced capital investment.

Elimination of sulfur dioxide

Sulfur dioxide (SO2) emissions into the atmosphere can raise the acidity of the atmosphere, contributing to the phenomenon of acid rain. In the atmosphere, sulfur dioxide is transformed mainly into sulphuric acid, which precipitates at the ground level. This acid contributes, in association with other pollutants, to the acidification and the depletion of the natural environment. Sulfur dioxide is a corrosive chemical that can affect human health, such as irritating the respiratory tract.

 

The chemical washing of sulfur dioxide gas with hydrogen peroxide is carried out according to the following reaction:

 

SO2 + H2O2 -> H2SO4

 

The application of the stoechiometric amount of hydrogen peroxide eliminates sulfur dioxide from the gas stream. The chemical reaction is fast and exothermic.

Reduction of active chlorine

Active chlorine is toxic to many aquatic organisms. Therefore, the treatment and destruction of it in effluents is extremely important.

 

Under alkaline pH conditions, Hydrogen Peroxide acts as a reducing agent according to the reaction:

 

ClO- + H2O2 -> Cl- + O2 + H2O.

 

This reaction is very fast and a simple injection of hydrogen peroxide into the effluent can eliminate active chlorine. The dosage of hydrogen peroxide is made by the redox potential.

 

Sodium bisulfite is widely used for chlorine reduction, however, it is not always the ideal solution. The preparation of this solution is cumbersome and the risk of residual in the effluent is often a problem. The advantages of using hydrogen peroxide include the lower treatment cost and formation of salts in the effluent. The presence of residual hydrogen peroxide in the effluent should not be a problem, since the decomposition of H2O2 will produce oxygen and water.

 

On the other hand, hydrogen peroxide offers the possibility to reduce organic pollution (the reaction with chlorine generates oxidizing species that are highly reactive). Chlorinated compounds and their derivatives can be treated in the gaseous phase. These products are removed with caustic soda in a washing column before being treated with hydrogen peroxide.

Removal of cyanide

The cyanide ion (CN-) is highly soluble in water and can be toxic to aquatic organisms.

 

The addition of hydrogen peroxide allows the transformation of cyanide ions into cyanates, which will hydrolyze in water to ammonium and carbonate compounds according to the following reactions:

 

CN- + H2O2 → OCN- + H2O

OCN- + 2 H2O → NH4+ + CO32-

 

Many processes have developed in this domain that produce a high yield of elimination with excellent economics. The addition of sodium hypochlorite to hydrogen peroxide will form an oxygen singlet, which has a higher oxidizing power than hydrogen peroxide. The reaction can also be catalyzed by copper ions. Cyanide removal with hydrogen peroxide is a technique practiced by the metals surface treatment industry as well as by the chemical industry and the gold mining industry.

Soils and groundwater treatment

Soils are the object of several threats, which were under estimated for long time due to their physical and chemical degradation related to conjugated effects from various factors such as: atmosphere, agriculture, urban and industrial.

 

In the treatment of soils, hydrogen peroxide can be used in two ways:

  • As an oxidizing reagent with the Fenton process: H2O2 is catalyzed by Fe 2+
  • As a source of oxygen for in-situ bioremediation of the soil, in particular for the elimination of hydrocarbons.

Oxidizing treatments with systems using O3/H2O2 ou H2O2/UV alone or coupled with an activated carbon treatment are well adapted to the elimination of organic pollutants present in groundwater (aromatic compounds, chlorinated organics).

 

Please do not hesitate to contact us to receive further information on environmental applications of hydrogen peroxide.