Mechanistic Understanding of the Adsorption Behavior of Metal Lead Ions by Attapulgite-Induced Porous Nanocomposite Hydrogels

Abstract

Hydrogels have many advantages as a kind of heavy-metal adsorbent, such as simple separation, high efficiency, and recyclability, but their applications are limited by their poor mechanical strengths. To this end, versatile natural phyllosilicate minerals are introduced into hydrogels to enhance the mechanical strengths of hydrogels. However, mechanistically understanding the clay-induced effect is still limited. In this work, attapulgite-induced porous network structures were observed, which are interpreted in terms of the nonsacrificial starch-like pore formation mechanism. Furthermore, the influence of the porous structure of the attapulgite nanocomposite hydrogels on the adsorption of Pb 2+ from an aqueous solution was comprehensively studied. The adsorption kinetics fits a pseudo-second kinetic model well, and the syllogistic Weber−Morris model study reveals that the porous structures of nanocomposite hydrogels improves their ability to internally diffuse. The adsorption isotherm displays over 98.2% of goodness of fit for the Langmuir isothermal model, with a maximum adsorption capacity of 864.5 mg/g for the adsorption of Pb 2+ . Moreover, the adsorption thermodynamics study indicates that the enthalpy changes of chemical adsorption decrease from 62.31 to 51.01 kJ/mol for hydrogels after the addition of 10% attapulgite. On the basis of the above findings, a reasonable adsorption mechanism including surface adsorption and internal diffusion is proposed.

Recent Developments of Nanomaterials in Hydrogels: Characteristics, Influences, and Applications

“…In addition, some nanoclay minerals similar to MMT will reconstruct the three‐dimensional network structure of the hydrogel, and structural changes will also have a certain impact on the adsorption. Taking attapulgite as an example, due to the different swelling properties of attapulgite and attapulgite‐based nanocomposite hydrogel, the space is reconstructed to form pores during the swelling [193] . As shown in Figure 14, these pores enhance the internal diffusion capacity of the hydrogel, and have a stronger adsorption capacity compared with the hydrogel without addition of attapulgite.…”

A facile approach to synthesize CdS–attapulgite as a photocatalyst for reduction reactions in water

“…The adsorption, carrier and catalytic properties of ATP make it a promising catalyst in sewage disposal. [42][43][44] In the CdS-ATP composites, ATP may not only play a role in xing and avoiding agglomeration, but also can reduce light corrosion and improve light tolerance. In addition, as an ideal photocatalytic carrier material, ATP can also provide many microreaction sites for photocatalytic reaction.…”

Reinforced Supramolecular Hydrogels from Attapulgite and Cyclodextrin Pseudopolyrotaxane for Sustained Intra‐Articular Drug Delivery

“…Attapulgite (ATP) is a kind of versatile 1D natural magnesium aluminum silicate clay mineral material, whose theoretical formula is Si 8 (Mg,Al,Fe) 5 O 20 (OH) 2 (OH 2 ) 4 •4H 2 O, which exhibits a rigid, rod-like morphology with a length ranging from 100 nm to several micrometers and a width of ≈30 nm. [30][31][32][33][34] Compared with other synthetic 1D nanomaterials, the excellent mechanical property and abundant hydroxyl groups of the natural ATP nanorods make it more favorable to interact with α-CD PPR and further improve the mechanical properties of PPR hydrogel. More importantly, the pioneering studies have demonstrated that enhanced stem and progenitor cell proliferation and differentiation could be observed in response to clay-mineral-incorporated scaffolds.…”