A Review of Modified Clay Minerals for Thallium Absorption from Aqueous Environment: Preparation, Application, and Mechanism

Thallium is a highly toxic heavy metal element that can penetrate the human skin and still cause harm to the humans and the environment at low concentrations. Adsorption method is an effective environment-mature and mature method for treating wastewater containing thallium (Tl). The use of cheap adsorbents with large adsorption capacity will make the competitive advantage of adsorption more obvious. As an easy-to-obtain adsorbent, clay minerals are widely used in practical production due to their cheap and reliable advantages. Meanwhile, clay minerals are usually modified to improve their adsorption capacity for Tl. This paper summarizes different modification methods of clay minerals, including physical modification, inorganic chemical, organic modification, and pillared modification. Furthermore, the ion purification and metal inorganic doping are effective treatment methods of clay minerals for Tl removal. The main factors influencing Tl removal in water by clay minerals, such as initial metal concentration, solution pH, coexisting ions, and adsorbent type, are discussed in this paper. Moreover, the adsorption kinetics and adsorption isotherms of Tl by clay minerals are mainly reviewed, and the adsorption mechanism, mainly ion exchange and oxidative adsorption, is described in detail. The main purpose of this paper is to introduce the potential of natural as well as modified clay minerals for the adsorption of metals in wastewater to provide a more comprehensive perspective on Tl pollution treatment.

Automated summary

This paper summarizes the modification methods and adsorption mechanisms of clay minerals for treating thallium pollution in wastewater, discusses the main factors influencing the adsorption efficiency, and introduces the potential of clay minerals as adsorbents.