Which one of the following materials is suitable for water purification?

Zeolites are highly suitable for water purification due to their unique crystalline aluminosilicate structure, which provides a high cation-exchange capacity and large surface area for adsorption [t1, t10]. They are widely used in water softening processes to remove hardness-causing ions like calcium (Ca2+) and magnesium (Mg2+), replacing them with sodium ions through reversible ion exchange [t3, t6]. Additionally, zeolites act as molecular sieves and adsorbents for eliminating heavy metals, ammonia, and organic contaminants from drinking water and wastewater [t1, t5, t9]. While quartz sand is used in filtration beds to remove suspended solids, it primarily acts as a physical barrier rather than a chemical purifier [t4, t8]. In contrast, asbestos is a hazardous water pollutant linked to lung cancer (asbestosis) and is not a purification material [c2]. Silicones are synthetic polymers generally used for sealing or lubrication rather than active water treatment.

Sources

1. [1] https://www.nature.com/articles/s41598-022-07679-2