Thiol–Yne Click Synthesis of Polyamide–Amine Dendritic Magnetic Halloysite Nanotubes for the Efficient Removal of Pb(II)

Abstract

Heavy metals such as Pb­(II) pollutions in wastewater have been a serious environmental problem. In this study, we loaded polyamide–amine (PAMAM) on the surface of magnetic halloysite nanotubes (MHNTs) via one-step thiol–yne click chemistry to obtain dendritic magnetic halloysite nanotubes (MHNTs-PAMAM) with high-density amine groups for the highly efficient adsorption of Pb­(II). The synthesized MHNTs-PAMAM were characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) spectroscopy, and thermogravimetric analysis (TGA), which confirmed the formed nanostructures and chemical features of MHNTs-PAMAM. And batch adsorption experiments were carried out to investigate the effect of pH and other variables on the adsorption amount. Here, TGA shows that PAMAM grafting on halloysite nanotubes (HNTs) achieves a sufficiently high graft ratio of 6.1 wt %, which ensures sufficient active adsorption sites on the surface of the composite. With the increase of the grafted PAMAM generation, the functional group density and adsorption capacity of the material also gradually increased, and the maximum adsorption capacity of the material for Pb­(II) was up to 194.4 mg g–1. The adsorption kinetics agrees well with the pseudo-second-order equations, and the equilibrium data can be described by the Langmuir isotherm (R 2 = 0.940).

Efficient and selective removal of Pb(ii) from aqueous solution by a thioether-functionalized lignin-based magnetic adsorbent

“…The magnetization curves showed that the saturation magnetization of both SMNP (54.46 emu g À1 ) and L@MNP (51.00 emu g À1 ) sharply decreased compared to that of the Fe 3 O 4 MNPs (84.13 emu g À1 ) due to the modication of non-magnetic silicon and lignin layers. It is worth mentioning that the saturation magnetization of L@MNP is superior to that of many reported magnetic adsorbents, 33,41 which enables its quick recovery (within 15 s, Fig. S3 †) from the aqueous system using an external magnet.…”

A Super‐Amphiphilic 3D Silicone Sponge with High Porosity for the Efficient Adsorption of Various Pollutants

“…Waste liquids from industry and daily life caused serious environmental problems, and they are extremely toxic and generally carcinogenic along the biological chain and thus cause unavoidable damage to humans when including heavy metals and dyes. [ 1–3 ] Adsorption holds considerable promise among all the strategies to reduce these contaminations. However, reducing the pollutants to drinkable levels is still challenging, and there are several excellent materials in recent years (they were listed and compared in Table S1).…”

Past, Present and Future Perspectives on Halloysite Clay Minerals

“…More recently, thiol modified magnetic halloysite was subjected to a thiolene click reaction with terminal alkyne PAMAM units to form a dendrimer modified HNT with high amino group density for water remediation ( Figure 17 ) [ 147 ]. The nanomaterial was used as sorbent for Pb 2+ ions demonstrating a high adsorption capacity of 194.4 mg g −1 .…”

“… Schematic diagram showing the synthetic route of PAMAM grafted magnetic halloysite and removal of Pb(II) from water. Reproduced with permission from [ 147 ]. …”