Related Experiment Video
Updated: Jun 10, 2026
10:42
Combining Solid-state and Solution-based Techniques: Synthesis and Reactivity of Chalcogenidoplumbates(II or IV)
Published on: December 29, 2016
Interactions of chelating agents with Pb-goethite at the solid-liquid interface: Pb extraction and re-adsorption
Theo C M Yip1, Daniel C W Tsang, Irene M C Lo
1Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Hong Kong, China. cmtheo@ust.hk
Chemosphere
|July 21, 2010
Summary
Ethylenediamine disuccinate (EDDS) is a biodegradable alternative to EDTA for lead extraction from soil. Differences in their zwitterionic structures influence pH-dependent lead extraction and re-adsorption efficiencies.
Area of Science:
- Environmental Chemistry
- Soil Science
- Green Chemistry
Background:
- Ethylenediaminetetraacetic acid (EDTA) is effective for soil remediation but poses environmental risks due to its persistence and toxicity.
- Biodegradable alternatives like [S,S]-ethylenediamine disuccinate ([S,S]-EDDS) are being explored for safer soil remediation.
- Understanding the mechanisms of lead (Pb) extraction by these chelating agents is crucial for optimizing soil cleanup strategies.
Purpose of the Study:
- To compare the efficiency of [S,S]-EDDS and EDTA in extracting lead (Pb) from goethite.
- To investigate the pH-dependent mechanisms governing Pb extraction by EDDS and EDTA at the solid-liquid interface.
- To elucidate the role of zwitterionic structures in the performance of these chelating agents.
Main Methods:
- Batch experiments were conducted to quantify Pb extraction by EDDS and EDTA from goethite.
- Attenuated total reflectance-Fourier transform infrared (ATR/FT-IR) spectroscopy was employed to analyze surface interactions.
- Experiments were performed across a range of pH values and reaction times to assess environmental factors.
Main Results:
- Pb extraction was pH-dependent for both EDDS and EDTA, with optimal conditions differing between the two.
- EDTA showed higher Pb extraction efficiency under mildly acidic conditions, while EDDS performed better under mildly alkaline conditions.
- EDTA exhibited greater Pb re-adsorption compared to EDDS, linked to altered goethite properties and iron dissolution.
Conclusions:
- The distinct zwitterionic properties of EDDS and EDTA significantly influence their Pb extraction and re-adsorption behavior.
- EDDS offers a potentially more environmentally benign option for lead remediation due to lower re-adsorption.
- Further research into the structural-functional relationships of chelating agents is warranted for sustainable soil remediation.
More Related Videos
Related Concept Videos
00:56Extraction: Advanced Methods
Metal ions can be separated from one another by complexation with organic ligands–the chelating agent– to form uncharged chelates. Here, the chelating agent must contain hydrophobic groups and behave as a weak acid, losing a proton to bind with the metal. Since most organic ligands used in this process are insoluble or undergo oxidation in the aqueous phase, the chelating agent is initially added to the organic phase and extracted into the aqueous phase. The metal-ligand complex is formed in...
01:19Complexation Equilibria: The Chelate Effect
In complexation reactions, metal atoms or cations interact with ligands to form donor-acceptor adducts called metal complexes. Ligands that bind through one donor site are monodentate, ligands with two donor sites are bidentate, and those with more than two donor sites are polydentate ligands. For example, ethylene diamine is a bidentate ligand that binds through two nitrogen donor atoms, forming a five-membered ring. EDTA is a polydentate ligand that binds through four oxygen and two nitrogen...
01:09Colloidal precipitates
The high insolubility of some precipitates can result in an unfavorable relative supersaturation. This can lead to colloidal particles with a large surface-to-mass ratio, where adsorption is promoted. For instance, in the precipitation of silver chloride, silver ions are adsorbed on the surface of the colloidal particles, forming a primary layer. This layer attracts ions of opposite charge (such as nitrate ions), forming a diffuse secondary layer of adsorbed ions. This electric double layer...
01:25Microbial Bioremediation of Uranium
Microorganisms play a critical role in the transformation and immobilization of uranium in contaminated environments through four main pathways: bioreduction, biosorption, bioaccumulation, and biomineralization. These mechanisms reduce uranium’s toxicity and prevent its migration through groundwater systems, offering sustainable approaches for in situ bioremediation.Bioreduction of UraniumBioreduction is driven by anaerobic bacteria such as certain strains of Geobacter and Shewanella, which use...
01:17Precipitation and Co-precipitation
Precipitation and coprecipitation methods can be used to separate a mixture of ions in a solution. In qualitative inorganic analysis, ions that form sparingly soluble precipitates with the same reagent are separated based on the differences in solubility products. For example, consider the separation of Cu(II) and Fe(II) ions by precipitation as insoluble sulfides. First, copper(II) sulfide is precipitated by the addition of acidic H2S, where the dissociation of H2S is suppressed. Adding H2S...
01:27Microbial Leaching
Microbial leaching, also known as bioleaching, is an environmentally favorable method for extracting metals from low-grade ores using specific microorganisms. This biotechnological approach is particularly valuable for mining operations targeting copper, gold, and uranium, where traditional extraction methods may be economically or environmentally impractical.Copper Leaching and Microbial CatalysisIn copper bioleaching, crushed ore is arranged into heaps and irrigated with a dilute sulfuric...