Zeolite Potential for Processing Industrial and Radioactive Waste

industrial waste processing with zeolite

Zeolite natural minerals are usually still mixed with other minerals such as calcite, gypsum, feldspar, and quartz and are found in areas around the volcano or settling in hot spring areas. Zeolites are also found as sedimentary rocks in basalt type soils and their chemical composition depends on the hydrothermal conditions of the local environment, such as temperature, local vapor pressure, and groundwater composition of the location. That makes zeolites with the same color and texture may differ in their chemical composition when taken from different locations, due to the combination of minerals in the form of fine particles with other impurities.

Sizable zeolite natural mineral deposits are found in several countries such as the United States, the Soviet Union, Japan, Australia, Cuba, and some eastern European countries such as the Czech Republic and Hungary.

In Indonesia, zeolites were discovered in 1985 by PPTM Bandung in large numbers, including scattered in several regions of Sumatra and Java. However, of the 46 zeolite locations, only a few locations were intensively mined, including in Bayah, Banten, Cikalong, Tasikmalaya, Cikembar, Sukabumi, Nanggung, Bogor and Lampung.

The use of zeolites is still not widely known, which at present zeolites in Indonesia are marketed in the form of nature, especially in the fertilization of agriculture. The following will discuss the potential of zeolites in waste treatment.

In 1984 Professor Joseph V. Smith the United States crystallographer defined zeolite as:

“Zeolite is an aluminosilicate with a framework structure enclosing cavities occupied by large ions and water molecules, both of which have considerable freedom of movement, permitting ion-exchange and reversible dehydration”.

As such, zeolites are minerals consisting of hydrated aluminosilicate crystals containing alkaline or alkaline earth cations in a three-dimensional framework. The metal ions can be replaced by other cations without damaging the zeolite structure and can absorb water reversibly.

At present, there are about 40 species of natural zeolites, although there are about 12 types of commercial value, including clinoptilolite, mordenite, filipsite, kabasite, and erionite. Synthetic zeolites are produced from several companies such as Union Carbide, ICI and Mobil Oil, and more than 100 species have been recognized, including zeolite A, X, Y, ZSM / AlPO4 group (Zeolite Sieving Materials / Aluminum Phosphate) and even recently known Zeotip groups, namely materials such as zeolites but not alumino-silicate compounds.

Read : Natural Zeolite Exploration in Indonesia

In the zeolite structure, all Al atoms are in tetrahedral form so that Al atoms will be negatively charged because they coordinate with 4 oxygen atoms and are always neutralized by alkaline or alkaline earth cations to reach stable compounds. Another case with clay rocks (clay materials) with a structural layer, where the ion exchange properties are caused by 1) broken bonds, namely the smaller the absorption particles the larger, 2) hydroxide groups where hydrogen atoms can be replaced with other cations or 3) substitution isomorph Al in tetrahedral Si causes Al-Si bonds to be quite strong and reduce swelling.

The ability of ion exchange (sometimes with the term absorption ability of ions or sorption) zeolites is the main parameter in determining the quality of zeolites to be used, usually known as CEC (cation exchangeability). CEC is the number of metal ions that can be absorbed maximum by 1 g of zeolite under equilibrium conditions.

Zeolite granular
Zeolite granular

For the separation of ammonia/ammonium ions from industrial wastewater, for the separation of fission products from radioactive waste and use in the field of agricultural waste. Clinoptilolite can separate 99% of ammonia/ammonium from industrial waste. Tsitsisvii (1980) and Blanchard (1984) found clinoptilolite can also separate heavy metals (Pb, Cu, Cd, Zn, Co, Ni, and Hg) both in industrial waste or in agricultural soils for “soil conditioning”. In treating nuclear waste, Ames from 1959-1962 was a researcher using clinoptilolite for the separation of radioactive substances. Finally, clinoptilolite has also been used to decontaminate reactor cooling water in the Three Mile Island reactor accident in America in 1979 (10). Zeolite was also used to decontaminate the cooling water of the Three Mile Island Unit II reactor and in 1987 to absorb radioactive gas in the Chernobyl reactor which caught fire.

Zeolite from the California deposit is used for the separation of fission radionuclides in nuclear fuel storage pool water at the British Nuclear Fuel Limited’s SIXEP (Site Ion-Exchange Plant), Sellafield, UK. In addition to sand substitutes, a mixture of zeolites, fly ash, and slugs are used in the cement cementation process. In the United Kingdom and Korea, cementation waste does not use sand because the sand will increase the volume of waste contrary to the principle of “minimized waste” or volume reduction.

Natural Zeolite Exploration in Indonesia

Zeolites are a group of minerals which in the sense/naming of minerals are one type of non-metal minerals or industrial mineral minerals from 50 existing types. Until now more than 50 natural zeolite forming minerals have been known, but only nine of them are often found, namely clinoptilolite, mordenite, analsim, khabasit, erionite, ferrierite, heulandite, laumonite, and filipsite. From the results of investigations that have been done, the types of zeolite minerals found in Indonesia are modernite and clinoptilolite.

This natural zeolite is formed from a reaction between fine-grained acidic acid and rhyolitic tuffs with pore water or meteoric water (rainwater). This mineral is a group of hydrated aluminosilicates with the main elements consisting of cations, alkalis, and alkaline soils, having pores that can be filled by water molecules. The water content trapped in the zeolite cavity is usually around 10-50%. When hydrated cations in the cavity will be covered with water molecules, these water molecules are unstable or easily detached. The general nature of zeolites, among others, have a rather soft crystal structure, a specific gravity of 2-2.4, turquoise, white and brown.

Geologically, zeolites begin to be found in tuff rocks formed from the results of sedimentation, volcanic dust that has undergone an alteration process. There are four processes as a picture of starting to become zeolite, namely the process of volcanic dust sedimentation in an alkaline lake environment, alteration process, diagenesis process and hydrothermal process.

It has been mentioned that water molecules found in zeolites are unstable so that by heating above 100 degrees celsius, the pore water can be expelled so that zeolite pores are formed which can allow zeolites to absorb molecules that have smaller diameters than zeolite pores the.

In addition to natural zeolites, there are also types of artificial zeolites, each of which has advantages and disadvantages compared to each other. Artificial zeolite consists of aluminosilicate gel by imitating the hydrothermal process in one of the processes starting to become natural zeolite. This type of gel is made from a solution of sodium aluminate, sodium silicate, and sodium hydroxide. There are three types of chemicals on the market that are of the same use as natural zeolites, namely activated carbon, silica gel, and artificial zeolites.

Based on research, the ability of activated carbon and silica gel as an absorber did not exceed natural zeolites. Artificial zeolites can indeed be purer and have broader capabilities compared to natural zeolites, especially as catalysts. The use of zeolite has been developed in such a way that it can be used for several purposes in industry and agriculture, also for the environment, especially to eliminate odors, because zeolites can absorb gas molecules such as CO, CO2, H2S, and others. Zeolites are non-metallic minerals or multi-use industrial minerals because they have unique physical and chemical properties, namely as an absorber, ion exchange, molecular filter, and as a catalyst.

Exploration of the field done by surveying and mapping the spot at first. When compared with the other areas in the world, Indonesian zeolites are young in geological terms. From the Rotorua’Taupo, it can be recognized that intense volcanic activity have been occurred about 250.000 years ago. The deposits might be located in layers of sediment approximately 30 metres depth or even more.

For sampling, an excavator will dig pits in the survey area to get samples. The samples are then tested using x-ray diffraction. Zeolites use unique crystal structure with many unique surfaces. Zeolite minerals in Indonesia have properties which are slightly different than other countries Zeolite. By way of example. Zeolite powder like in the Taupo Volcanic Zone have soft and porous properties.

There are approximately 40 minerals known as zeolites. One minerals found in the Taupo Volcanic Zone is really a silica-rich mineral called Clinoptilolite. Mineral that is used in agriculture and also in the oil market.

Once big deposit confirmed commercial viability, a quarry is produced to extract the mineral. In Indonesia, there are many quarries where mineral ore is mined. Open-pit mining may be the type used in Zeolite Indonesia. Usually, overburden is first stripped to allow access to the ore. The ore is then drilled or stripped. and hydraulic excavators are then employed for loading. The raw material might be crushed and screened on mining site and positioned in stockpiles for drying from the outside. or it just transported towards the processing mill where it will likely be crushed and screened.

Improving the Quality of Biogas Fuels with Natural Zeolites


Human dependence on fossil fuels causes reserves of energy sources is increasingly diminishing, besides it also impacts on the environment, such as air pollution. Fossil fuels or mineral fuels are natural resources that contain hydrocarbons such as coal, petroleum, and natural gas. 

Fossil fuels are formed because of the natural process of decay from organisms that died hundreds of millions of years ago. Dinosaurs, trees, and almost all living things that died were deposited on the ground and now have become petroleum, natural gas, or coal. Natural gas has the form of gas, liquid petroleum, and solid coal. due to differences in the pressure and heat, they receive in the bowels of the earth over millions of years ago.

Fossil fuels are a kind of non-renewable natural resource. Because this fossil fuel is formed from the process of sedimentation and decomposition of living things and takes millions of years. 

This makes many people aware that dependence on fossil fuels must be reduced immediately. To overcome this problem, alternative fuels that are cheap and easy to obtain are needed. One of the alternative fuels is biogas. 

Biogas is a gas produced by anaerobic activity or fermentation of organic materials including human and animal feces, domestic (household) waste, biodegradable waste, or any biodegradable organic waste in anaerobic conditions. The main material in making biogas are Methane and Carbon Dioxide. Biogas also can be used as vehicle fuel or to turn on electric things.

Biogas is reprocessed into more specific fuel oil. The process of purification (purification) of natural gas or often also called the process of gas purification is carried out with the aim of removing/separating impurities (impurities) that are not desired in the natural gas. Before the purification process is carried out, natural gas obtained from the well must first go through a testing phase in the laboratory to find out the chemical compounds that are dissolved in it. This is needed to determine the purification process, the number of processing units, the type of chemical, and the chemical dose to be used. The addition of activated carbon in raw materials in the form of cow dung serves to increase the C / N ratio, which can improve the anaerobic digestion process and obtain optimum conditions in producing methane gas. The study also used a CO2 scrubber with a solution of Ca (OH) 2 (lime water) and KOH solution.

Biogas is produced through the process of fermentation of organic waste such as garbage, food scraps, animal waste and food industry waste. The elements contained in biogas are methane gas (CH4), carbon dioxide gas (CO2), oxygen gas (O2), hydrogen sulfide gas (H2S), hydrogen gas (H2), and carbon monoxide gas (CO).

Of all these elements that play a role in determining the quality of biogas, namely methane (CH4) and carbon dioxide (CO2) gas. If the CH4 level is high, the biogas will have a high heating value. Conversely, if CO2 levels are high, the biogas calorific value will be low. Therefore to increase the heating value of biogas the CO2 gas content must be low. The content of methane gas (CH4) from biogas can be increased by separating corrosive carbon dioxide (CO2) and hydrogen sulfide (H2S) gas from biogas.

To overcome this problem, many attempts were made to refine biogas. Researchers studied the biogas purification process using zeolite which was activated with a solution of NaOH and the zeolite was modified by mixing several materials such as bentonite, kaolin, limestone, tapioca/starch, and liquid chitosan. In addition, other efforts have also been made to improve the quality and quantity of biogas, namely the addition of activated carbon and the use of CO2 scrubbers.

Read: Zeolite Uses In Agriculture

An interesting method of biogas purification to be studied is by using adsorbents. The adsorbent is a substance that can absorb fluid, both liquid, and gas so that later it will form a thin layer on the surface of the substance. One type of adsorbent that can be used is zeolite.

Zeolite was chosen because besides being easily obtained, the price was also quite cheap. So that the zeolite adsorption process takes place faster than before the activation process should be done first. The activation process can be done in two ways, namely physically with the heat treatment process and chemically using an acid or base solution. One type of chemical that can be used for the chemical activation process is potassium hydroxide (KOH) or its Latin name, Potassium Hydroxide. KOH is a strong base compound that is stable and dissolves easily.

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