Preparation of Heavy Metal Trapping Flocculant Polyacrylamide–Glutathione and Its Application for Cadmium Removal from Water

Abstract

In this study, a heavy metal trapping gel with multiple ligand groups was prepared for the first time using response surface methodology. The gel was produced by condensing and grafting glutathione as a grafting monomer onto the main polyacrylamide chain, based on the Mannich reaction mechanism with formaldehyde. FTIR, SEM, TG-DSC, and zeta potentials were used to characterize the gel. The results demonstrated that the gel was morphologically folded and porous, with a net-like structure, which enhanced its net trapping and sweeping abilities, and that glutathione was used to provide sulfhydryl groups to boost the metal trapping ability of polyacrylamide. Coagulation experiments showed that the highest efficiency of the removal of Cd ions from water samples was achieved when the concentration of polyacrylamide–glutathione was 84.48 mgL−1, the concentration of Cd was 10.0 mgL−1, the initial turbidity was 10.40 NTU, and the initial pH was 9.0. Furthermore, the presence of two cations, Cu and Zn, had an inhibitory effect on the removal of Cd ions. In addition, analysis of the zeta potential revealed the flocculation of polyacrylamide–glutathione. The flocculation mechanism of glutathione is mainly chelation, adsorption bridging, and netting sweeping.

Glutathione as a novel engineered biomaterial for heavy metal ion quantification and remediation

“…The immediate effects of heavy metal ions can lead to harmful ailments in the living bodies if found above permissible limits as set by the Environmental Protection agency as well as the World Health Organization. Figure 2 demonstrates the sources as well as bioaccumulation of these heavy metals into our flora and fauna [11,12] . As far as the sources of heavy metal ions are concerned, they are mostly anthropogenic, barring a few natural sources such as volcanic eruption or acid rain, etc.…”

“…In the same note, glutathione's specificity in binding with heavy metal ions allows for the development of sensors that can distinguish between different types of heavy metal ions. This selectivity is crucial for accurately identifying the presence of specific heavy metals in a complex sample [7][8][9][10][11][12][13] . Mn-doped ZnSQDs Pb (II), Cr (II), Hg (II) 0.93 µM for mixed HMIs [25] AgNPs Ni (II) 75 µM [26] Gold Nanostars Pb (II) 0.5 µM [27] Square Wave Anodic Stripping Voltammetry, SWASV Magnetic NPs Cd (II), Pb (II) 1.6 nM (0.182 µg/L); 0.8 nM (0.172 µg/L) [28] Glassy-Carbon Electrode Cd (II) 0.05 nM [29] Carbon Paste Electrode Cd (II) 8.5 nM [30] As evident in Table 1, there are reports of lead ion detection via colorimetry where glutathione stabilized gold as well as silver nanoparticles had been effectively used [15][16][17] .…”

Circulating Flow–Electric-Field-Configuration-Enhanced Cadmium Cementation from Sulfate Systems and Its Optimization Mechanism

“…4 Zinc loses electrons to turn into zinc ions. 5 Hydrated zinc ions leave the anode surface. 6 Hydrated zinc ions leave the boundary layer.…”

“…Nevertheless, this trend has been limited in recent years by increasingly stringent policies in some countries [2,3]. This is mainly due to the fact that cadmium is a biotoxic heavy metal, and the treatment of cadmium pollution in nature involves huge costs and significant side effects [4][5][6]. Therefore, the production and use of cadmium in various countries is increasingly restricted [7].…”