Chemical Carriers - Growing Commercial Applications of Zeolites
Growing Commercial Applications of Zeolites
Containing alkali and alkaline materials, Zeolites are a unique group of minerals characterised in construction by their crystalline and hydrated aluminosilicates properties. Their structure is based on a three dimensional framework structure of silica-oxygen tetrahedra. Arranged in a honeycomb network, the crystal framework is characterised with numerous pores holding negative charges which are balanced with cations such as calcium, magnesium, potassium and sodium.
There are approximately 40 different Zeolite types and their occurrence depends on conditions during formation. Mines located in the North Island of New Zealand are renowned for the production of clinoptilolite, a notable variation in the zeolite group which are young in age and contain unsurpassed absorption qualities. Zeolites have been utilised for their unique properties for ionic absorption in many commercial applications. Their large internal surface area allows them to absorb liquids efficiently, with the ability to absorb up to 70% in their own weight as a liquid. These qualities make the zeolites a perfect solution for absorbing odours, cations from wastewater and as a base for slow release fertilisers. Additionally, Zeolite granules, which can be modified to suit specific applications, are an ideal chemical carrier for insecticides, fungicides, pesticides and industrial chemicals. The open crystal structure of the Zeolite combined with high moisture holding capacity and high cation exchange capacity, allows the Zeolite to be used as an active carrier.
Due to these properties, zeolites have a lot of important applications in chemical technology, with the range of use ever increasing. One of the most important fields of application of zeolites is their use in the process of heavy metal cations immobilisation. Natural zeolites are important aluminosilicates in absorption processes because of their low cost and selectivity. In environmental applications, zeolites have been studied extensively to remove harmful substances from wastewater by absorption and ion exchange processes. Many toxic heavy metals and organic pollutants have been discharged into the environment as industrial wastes, causing serious soil and water pollution. Advanced treatment units are essential in the removal of such pollutants, with absorption and ion exchange processes being the most common technologies used in advanced wastewater treatment. In recent developments, zeolites have been considered for radioactive waste treatment due to their high cation exchange capacities.
Advancements in the carrier effect of zeolites has created new commercial opportunities for the mineral, including the development and manufacture of new construction products as well as building materials, which have been successfully applied to overcome construction difficulties. In modern society, China has evolved to be the largest user of zeolites, with the highest consumption being utilised in cement production. The unique properties of Zeolite as a carrier agent means that it can be used as a blended material in most of the cement plants to solve production and use issues, such as volume stability concerns of hardened cement. Recent research has shown that the use of Zeolite can prevent bleeding, segregation and delamination of fresh concrete so as to make the pumping process easier, decrease permeability of hardened concrete, enhance durability, increase concrete strength and minimise cracking caused by shrinkage. In response to its successful application the cement industry, the development of a range of new building products are currently under investigation utilising the unique characteristics of Zeolite, as a carrier agent promoting the ion exchange and an absorption functions, in an effort to solve current problems in building design and construction.
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