APPLICATION: ZEOLITE FOR WATER PURIFICATION
Zeolite in industrial water treatment
Zeolite (clinoptilolite) is an aqueous framework of aluminosilicate. Inside the negatively charged framework there are positively charged ions of alkali and alkaline earth metals, which compensate for the charge of the lattice and are able to participate in ion exchange reactions. The crystallochemical formula of clinoptilolite: (K2Na2Ca) 3 [Al6Si30O72] 20H2O zeolite possesses sorption, ion exchange and catalytic properties.
The composition of the zeolite-containing rock used in water treatment
Zeolite sorbents for water purification are fractionated rock that has undergone special processing. For water purification, as a rule, a natural volcanogenic-sedimentary zeolite is used with a content of the main mineral clinoptilolite of more than 70%. Modified zeolites of sedimentary origin with a lower clinoptilolite content are less commonly used.
In addition to zeolite (clinoptilolite), the rock may contain montmorillonite, opal-cristobalite, smectite — all these minerals are natural sorbents. Also, as impurities, the rock may contain calcite – chalk and a small amount – quartz.
Where and in what processes is zeolite used?
For removing ammonium ions (ion exchanger);
For holding heavy metals (ion exchanger);
For protection against radionuclides (ion exchanger);
In the process of deferrization, as a support for a catalytic film and filter media;
In the process of mechanical filtration as a load with increased sorption properties to protect subsequent loads.
Where and in what processes is zeolite used?
Recommended speed – 10 m / h
Backwash at a fraction of 0.5-1 – 35 m / h
Expansion – 30%
Height 1.2 m
Regeneration with 6-10% NaCl solution. Exposure time – 40 minutes
Zeolite as a mechanical filter
Zeolite is less dense than sand.
When replacing quartz sand with zeolite, the following effects are observed:
1. Increasing the duration of filtration cycles;
2. Reduction of the volume of wash water by 30%;
3. Reduction of energy consumption for pumping during flushing;
4. Positive influence on the operation of subsequent units (zeolite is not just a mechanical filter, but a sorbent and ion exchanger).
Zeolite as a mechanical filter
Due to the fact that the framework of the zeolite is negatively charged, positively charged metal ions or hydrogen ions are retained in its pores. Zeolite is characterized by an effective pore diameter of 4 A, i.e. its pores can accommodate particles no more than 4 A. Due to this, the zeolite exhibits selectivity – selective absorption. This phenomenon is called the molecular sieve effect.
The selectivity of absorption, in addition to the size of the ion, also depends on the activity of the ions.
Zeolite is less dense than sand.
When replacing quartz sand with zeolite, the following effects are observed:
1. Increasing the duration of filtration cycles;
2. Reduction of the volume of wash water by 30%;
3. Reduction of energy consumption for pumping during flushing;
4. Positive influence on the operation of subsequent units (zeolite is not just a mechanical filter, but a sorbent and ion exchanger).
Zeolite is less dense than sand.
When replacing quartz sand with zeolite, the following effects are observed:
1. Increasing the duration of filtration cycles;
2. Reduction of the volume of wash water by 30%;
3. Reduction of energy consumption for pumping during flushing;
4. Positive influence on the operation of subsequent units (zeolite is not just a mechanical filter, but a sorbent and ion exchanger).
Benefits of using zeolite:
01
Cleaning from a wide range of impurities
02
High degree of purification
03
Large ion exchange capacity
04
Flexibility in modifications
05
Chemical resistance and recoverability
06
100% environmentally friendly mineral
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