Modification of natural zeolites and their applications for heavy metal removal from polluted environments: Challenges, recent advances, and perspectives

Validation of microwave acid digestion, diffusive gradients in thin-film preconcentration and inductively coupled plasma optical emission spectrometry methodology for the determination of REEs in natural zeolites

“…The concentrations of SiO 2 and Al 2 O 3 , the two oxides with the most signicant contribution to the total mass of zeolite, were in a similar range in the three deposits and in the range of concentrations frequently reported for volcanic tuff deposits worldwide. 13 However, some signicant differences were noted for the other oxides, i.e., in Macicasu, there are higher amounts of Fe 2 O 3 , Na 2 O and CaO and a less important amount of K 2 O than in the other two deposits are present. In the case of the zeolite from the Racos deposit, the concentration of MgO was higher than in the other two deposits.…”

“…12 Natural zeolites are well-known as being crystalline porous aluminosilicates with a structure composed of SiO 4 and AlO 4 tetrahedrons interconnected by oxygen atoms. 13 Due to their adsorptive properties and negative charge, 14 natural zeolites have an excellent affinity for REEs. Generally, the published literature on REEs and zeolites is dedicated to the application of zeolites as adsorbents for the recovery of REEs from aqueous solutions.…”

“…Generally, the published literature on REEs and zeolites is dedicated to the application of zeolites as adsorbents for the recovery of REEs from aqueous solutions. 1,13,[15][16][17] In these studies, the adsorption capacity of zeolites toward REEs is usually calculated using the concentration of REEs in the initial solution and the concentration remaining in the solution aer adsorption, rather than the elements accumulated in the zeolite. 18,19 However, to our knowledge, no literature data have been published on the content of REEs naturally occurring in natural zeolite deposits.…”

Temperature‐Induced Modifications in Natural Zeolite Clinoptilolite: Effects on Acidity and Catalytic Acetalization

“…However, they often need to be changed to increase their activity. [16][17][18][19] Clinoptilolite, a prevalent natural zeolite, boasts a unique two-dimensional pore structure housing elliptical oxygen-10membered rings (4.1×7.5 Å) in channel A, along with oxygen-8membered rings (3.6×4.6 and 2.81×4.7 Å) in channels B and C, arranged alternately. [1,13,20,21] Channel connectivity is facilitated by perpendicular running C channels.…”

Optimizing methylene blue adsorption conditions on hydrothermally synthesized NaX zeolite through a full two-level factorial design

“…[15][16][17][18][19] Among adsorbents, synthetic and natural zeolites, due to their ability to adsorb drugs, pesticides, pharmaceuticals, metal ions, and dyes have been widely explored. [20][21][22] Andrunik et al 20 tested the potential of y ashbased zeolites and zeolite-carbon composites to remove pesticides from water. Amokrane et al 21 revealed that zeolites X and Y have better nitrogen adsorption capacity, unlike zeolite A. Senila et al 22 reviewed and summarized previous research into the modication of zeolites to improve their adsorption capacity, showing that natural zeolites can reduce costs and pollution compared with synthetic adsorbents.…”