Metal ion remediation by polyamidoamine dendrimers: a comparison of metal ion, oxidation state, and titania immobilization

Abstract

The exceptional ability of dendrimers to coordinate metal ions yields the potential for many applications including wastewater remediation, which is the focus of this study. Here, the comparison of metal ion removal rate from simulated wastewater by generation 4 dendrimers with external hydroxyl functional groups (G4-OH) is evaluated for Ni 2? , Fe 2? , and Fe 3? ions. Ni 2? to amine complexation occurred more rapidly than Fe 3? , which was more rapid than Fe 2? complexation. These results indicate that both charge density and d-electron configuration are important toward the chelation rate. The impact of both factors is discussed in light of existing models in which precursor aquation rates have been proposed as a key intermediate step. Additionally, the application of the dendrimers as chelation agents is further advanced by immobilizing the dendrimer to titania and re-evaluating its chelation ability for Ni 2? removal. The dendrimer immobilization decreased the pseudo-first-order rate coefficient for Ni 2? -amine complexation at a pH of 7 by a factor of 7.5. This result is significant as it suggests that mass transfer becomes important following immobilization of the dendrimer to titania.

Removal of Heavy Metals Using Adsorption Processes Subject to an External Magnetic Field

“…In this context, there are few reports that have studied the effect of oxidation number of heavy metals in the adsorption process and particularly, the works related with the adsorption by complexation mechanism have considered this property. For example, in the removal of Ni 2+ , Fe 2+ and Fe 3+ (with external hydroxyl functional groups) was demonstrated that high-valence species complex more quickly than the lowvalence due to the ability to accept more of the ligand's electron donation, where the adsorption followed the trend Ni 2+ > Fe 3+ > Fe 2+ [70].…”

A Comprehensive Review of Polymeric Wastewater Purification Membranes

“…Figure 2 suggests the removal mechanism of positive metal ions through dendrimers-Ti composite. Castillo et al [14] studied the removal capacity of Ni and Fe oxidation states utilizin 4th generation PAMAM with the G4-OH group. They also investigated the influence o G4-OH immobilization on Ti enhanced materials and their chelating potential on Ni(I removal.…”

Impact of various amendments on immobilization and phytoavailability of nickel and zinc in a contaminated floodplain soil

“…Metals can become mobilized, leading to soil and groundwater contamination that increase the possibility of entering into the food chain and finally into the human body (Taghipour et al 2013;Shaheen et al 2014a, b, c). Thus, remediation of PTMs in contaminated soils has received increasing attention and is an important issue for adequate environmental management (Ok et al 2011a;Castillo et al 2014;Shaheen et al 2015).…”