Zeolite for Potential Toxic Metal Uptake from Contaminated Soil: A Brief Review

Abstract

Soil pollution is an increasingly urgent problem for the global environment. Soil can be contaminated with potential toxic metals from many anthropogenic activities, besides fossil fuel combustion and crude oil production, ranging from industry to mining and agriculture. Many technologies have been analysed to solve this type of environmental pollution and methods involving the use of minerals (e.g., clay minerals, zeolites, and natural silica adsorbents) are widely described in the literature. This article provides a summary of studies concerning the use of zeolites in soil remediation. A considerable number of these experiments were conducted using natural zeolites, while fewer concerned the utilization of synthetic zeolites. The mechanism controlling the successful application of these minerals was analysed through referring to global data published on this topic over the last few decades. This review also briefly discusses the limitations on zeolite applications and the drawbacks of the approaches analysed.

Immobilization of Potentially Toxic Elements in Contaminated Soils Using Thermally Treated Natural Zeolite

“…Among in situ methods, the application of soil amendments to immobilize PTEs has been broadly used, due to its fast and easy application and commercial viability. Immobilization is a process which puts the PTE into a chemical form which will behave as inert to biological systems and highly insoluble under normally Materials 2021, 14, 3777 2 of 15 existing conditions [2,9]. The use of suitable immobilizing agents can lead to cost-effective and efficient soil remediation [8,10].…”

“…Soil pollution is a type of land degradation that takes place when a range of natural or anthropogenic constituents exceed the concentrations normally found in natural soils, affecting its quality and ecological services [ 1 ]. Generally, the main anthropogenic sources of soil pollution are represented by industry, agriculture, and household activities [ 2 ].…”

“…In this regard, the remediation using amendment with reactive minerals (carbonates, phosphate rocks, clay minerals, and zeolites) reduces the bioavailability of PTE, often without significantly altering the natural functions of soil [ 11 ]. Some of these amendments modify the soil pH, leading to precipitation of insoluble phases containing PTE, while others immobilize the PTE by sorption or encapsulation in their crystalline structure [ 2 ].…”

“…Due to the wide variety of natural zeolites, it is difficult to specify a universal zeolite application rate that ensures an efficient PTEs immobilization. The climatic and environmental conditions together with the soil and zeolite type plays an important role in the PTE immobilization efficiency [ 2 , 15 ]. The long-term effects of natural zeolites on soil pH and essential metals’ availability, the mechanism of Na release from zeolites, or the PTE binding to zeolite are not fully understood.…”

Efficiency in Ofloxacin Antibiotic Water Remediation by Magnetic Zeolites Formed Combining Pure Sources and Wastes

“…[2][3][4][5][6]. However, synthetic zeolites are characterized by other properties such as well-defined micropore dimension, high porosity, and surface area, making them good candidates for soil [7][8][9][10][11][12][13][14] and polluted water remediation [15][16][17][18][19][20].…”