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Zeolites-applications

Natural zeolite is a new and very good natural filter medium available for the filtration of water. It offers superior performance to sand and carbon filters, giving purer water and higher throughput rates with less maintenance required. It has many advantages over sand and can be used to directly replace sand in a normal sand filter.

There are three main uses of zeolites in industry: catalysis, gas separation and ion exchange.

  • Catalysis: Zeolites are extremely useful as catalysts for several important reactions involving organic molecules. The most important are cracking, isomerisation and hydrocarbon synthesis. Zeolites can promote a diverse range of catalytic reactions including acid-base and metal induced reactions. Zeolites can also be acid catalysts and can be used as supports for active metals or reagents.
    Zeolites can be shape-selective catalysts either by transition state selectivity or by exclusion of competing reactants on the basis of molecular diameter. They have also been used as oxidation catalysts. The reactions can take place within the pores of the zeolite, which allows a greater degree of product control.
    The main industrial application areas are: petroleum refining, synfuels production, and petrochemical production. Synthetic zeolites are the most important catalysts in petrochemical refineries.
  • Adsorption: Zeolites are used to adsorb a variety of materials. This includes applications in drying, purification, and separation. They can remove water to very low partial pressures and are very effective desiccants, with a capacity of up to more than 25% of their weight in water. They can remove volatile organic chemicals from air streams, separate isomers and mixtures of gases. A widely used property of zeolites is that of gas separation. The porous structure of zeolites can be used to "sieve" molecules having certain dimensions and allow them to enter the pores. This property can be fine tuned by variating the structure by changing the size and number of cations around the pores. Other applications that can take place within the pore include polymerisation of semi conducting materials and conducting polymers to produce materials having unusual physical and electrical attributes.
  • Ion exchange: Hydrated cations within the zeolite pores are bound loosely to the zeolite framework, and can readily exchange with other cations when in aqueous media. Applications of this can be seen in water softening devices, and the use of zeolites in detergents and soaps. The largest volume use for zeolites is in detergent formulations where they have replaced phosphates as water-softening agents. They do this by exchanging the sodium in the zeolite for the calcium and magnesium present in the water. It is even possible to remove radioactive ions from contaminated water.

For more information about the removal of substances by zeolites click here.

From a practical point of view, zeolite can be adapted for a variety of uses:

Agriculture:

  • Odour control
  • Confined animal environmental control
  • Livestock feed additives

In Eastern Europe, Japan and Cuba zeolites have been traditionally used in agriculture. About a 5% addition to livestock rations reduces ammonia and odour emissions, improves feed utilisation, assists with mycotoxin absorption and may contribute trace elements. Several years ago NASA used nutrient loaded zeolites as slow release fertilisers.

Horticulture:

  • Nurseries, Greenhouses
  • Floriculture
  • Vegetables/herbs
  • Foliage
  • Tree and shrub transplanting
  • Turf grass soil amendment
  • Reclamation, revegetation, landscaping
  • Silviculture (forestry, tree plantations)
  • Medium for hydroponics growing

Aquaculture:
  • Ammonia filtration in fish hatcheries
  • Biofilter media

In a fish farm the load of the water with fish can be very high. This results in quick pollution of the water and as a result the concentrations of toxic substances can increase rapidly. Therefore extensive water purification is necessary. The zeolites can be used in various steps of the purification process: as a secondary filtration unit after biological purification and/or aeration; as a support material for bacteria; as a filter medium for the removal of solid and suspended particles and removal of unwanted ions at the same time.

Household products:

  • Household odour control
  • Pet odour control

Domestic uses relate primarily to the odour and liquid adsorbing characteristics of zeolite. A range of gases including formaldehyde, hydrogen sulphide has been shown to be adsorbed by zeolite.
In the USA, zeolite is routinely added to small air filters to adsorb such gases and reduce allergy problems. It can be used to dry sports shoes, reduce moisture in wardrobes and is commonly used to adsorb cigarette odours. A very useful carpet cleaner had zeolite as its base material.
The most common use for zeolite around the home is as kitty litter and as a fat absorber for barbecues. It is also used in fish tanks to adsorb ammonia. When fully utilised the spent product makes an ideal addition to composts where it will assist in conditioning and eventually contribute to soil moisture and nutrient holding capacity.

Industrial products:
  • Absorbents for oil and spills
  • Gas separations

Industrial uses focus on the liquid and vapour absorbing characteristics of zeolite. It can be an ideal granular oil/chemical spill cleanup; it is inert and safe to use.

Radioactive Waste:

  • Site remediation/decontamination

Water treatment:

Wastewater treatment:

  • Ammonia/ammonium removal in municipal sludge/wastewater
  • Heavy metal removal
  • Septic leach fields

Click here for an introduction to zeolites or find more information about zeolite structure and types.

Contact us for further details concerning zeolites.

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