New Sorption Properties of Diatomaceous Earth for Water Desalination and Reducing Salt Stress of Plants

Abstract

A new practical application of the unique sorption abilities of Diatomaceous Earth (DE) or diatomite, a widely accessible and promising natural mineral, has been studied. By analyzing aqueous extracts of natural diatomite, it was shown that DE probably contains various inorganic salts, which are released into the solution in the form of ions, such as Cl-, SO42-, Na+, Ca2+, Mg2+, K+ and, apparently, others. Diatomite was able to exchange these ions with the environment, exhibiting the properties of a natural ion exchanger. Studying the kinetics of ion release from diatomite showed that the ion desorption process continues for 4‒5 h until the surrounding solution is saturated with ions, after which it is dynamically balanced by the sorption process. In order to significantly reduce the ionic content of diatomite, DE samples were processed in a technologically simple and environmentally friendly way. Thus, as a result of deionization, the content of ions released from diatomite significantly decreases. Deionized diatomite was applied to study the adsorption of sodium and chloride ions from aqueous solutions. The maximum adsorption was 50.2 mg/g, and the maximum degree of extraction, corresponding to the concentration range of 5‒100 mg/l, was 53.9%. The observed effect was also applicable for increasing the resistance of plants to salt stress, improving the germination and growth of wheat samples. The developed method can be used in the manufacturing of filters for water desalination, both drinking and technological; in ecology; in agriculture to reduce salt stress of plants, as well as for the restoration of lands contaminated by salt.

Modified Natural Diatomite with Various Additives and Its Environmental Potential

“…The spectrum of generative and environmental processes causes diatomite rocks to be characterized by diversity in terms of some chemical indices. Diatomite is a highly variable material, containing many impurities, like terrigenous particles and inorganic oxides; it is also highly heterogeneous, as type, shape, size and fragmentation of the frustules result in unpredictable behaviour [ 28 , 29 , 30 , 31 ].…”

“…The results show that, irrespective of grain diameter, pure diatomites had lower pH and EC values compared with mixtures. According to Alsar et al [ 28 ], DT contains various inorganic salts that can be released into solution as ions. It can therefore be assumed that the pH and EC values of diatomite suspensions and distilled water will depend on the quantity and quality of the desorbed ions.…”

Review of phenotypic response of diatoms to salinization with biotechnological relevance

“…Although most of their biotechnological use is not specifically linked to their salt tolerance (B-Béres et al, 2022), there are some examples for those linked to salinity (Marella et al, 2020a(Marella et al, , 2020b. One of them is to find a way using diatoms to obtain drinking water from unconventional water supplies as brackish groundwater or reclaimed water (Ikehata et al, 2018), although this ability of diatoms has only recently been used in water reuse and desalination (Ikehata et al, 2017(Ikehata et al, , 2018Alsar et al, 2020). It is well known that silica is essential for building the cell wall of diatoms, thus these algae efficiently extract dissolved silica from water.…”

“…In addition, Nitzschia and Pseudostaurosira species were effectively applied in reverse osmosis methods, in which 95% of concentrate aqueous silica (78 mgl −1 ) was removed under suboptimal conditions within 72 h (Ikehata et al, 2018). Not only diatom cells but also deionized diatomite (Diatomaceous Earth) can be used in desalinization processes as the pretreated diatomite was able to remove even more than 50% of NaCl content of waters (Alsar et al, 2020).…”

Acid Modification of Diatomite-Based Sorbents

“…In [9] have been studied the adsorption of sodium and chloride ions from aqueous solutions using deionized diatomite. As a result, it was established that the maximum adsorption was 50.2 mg/g, and the maximum degree of extraction, corresponding to the concentration range of 5-100 mg/l, was 53.9%.…”