Removal Efficiency and Binding Mechanisms of Copper and Copper−EDTA Complexes Using Polyethyleneimine

Abstract

Copper is used extensively in semiconductor circuits as the multilayer metal. In addition to copper, waste streams often contain chelating agents like EDTA, which is widely used in the process to enhance solubility of copper, and it tends to form copper-chelated complexes. PEI--agarose adsorbents in a packed-bed column are capable of removing these anionic complexes, but the competitive binding between this chelating agent and PEI for copper is not well understood and needs to be explored. The current work focuses on investigating copper sorption by PEI-agarose adsorbent in the presence of EDTA. The pH of the column is fixed at 5.5 using 0.1 M acetate buffer. The ratio of chelator to copper ions is varied. Copper binding capacity and copper breakthrough curves are compared and contrasted to results without additional chelator present. An excess of EDTA leads to an increase in the fraction of free dissociated (anionic) ligand that competes for electrostatic attraction on protonated amine groups and therefore leads to a decrease in sorption capacity in the column. However, this waste treatment technique is still feasible for the semiconductor industry as large volumes of copper-contaminated solutions from actual waste can be concentrated 12-fold. When equimolar (copper to EDTA) or higher concentrations of EDTA are present, acetate can be utilized to recover the metal; for low ratios of copper to EDTA, metal recovery is achieved using hydrochloric acid.

Response surface methodology as a powerful tool to optimize the synthesis of polymer-based graphene oxide nanocomposites for simultaneous removal of cationic and anionic heavy metal contaminants

“…[22][23][24] Because of the large number of amine groups in its structure, PEI has been shown to be a good chelating polymer for metal cations specically Cu 2+ . 25,26 Modication of CS beads with PEI signicantly increased the amine groups present in the new material, giving it better adsorption capacity towards Cu 2+ ions compared to unmodied beads. 27 In addition, PEI can easily be protonated at low pH conditions, making it favorable for anionic metal ions, such as Cr(VI), via electrostatic attraction.…”

Polyethyleneimine as a novel desorbent for anionic organic dyes on layered double hydroxide surface

“…Notably, the hydrophobic vinyl of PEI can interact with hydrophobic chains of some compounds through hydrophobic interaction [19]. Therefore, PEI with the three predominant features exhibits strong adsorption capacity for a series of substances [20][21][22][23]. For example, PEI was grafted onto the surface of nanoparticles to improve the adsorption capacity of nanoparticles toward anionic contaminants through electrostatic attraction [24].…”

“…The PEI/SiO 2 composite material was successfully fabricated to adsorb 2,4,6-trinitrotoluene through hydrogen bonding between PEI and 2,4,6-trinitrotoluene [25]. Although there are many cases about the efficient adsorption capacity of PEI [20][21][22][23], to the best of our knowledge, no studies have investigated the use of PEI as a desired desorbent for the removal of adsorbed compounds from materials. There is apparently no good reason to disregard this promising desorbent.…”

Adsorption of Cu(II)–EDTA chelates on tri-ammonium-functionalized mesoporous silica from aqueous solution

“…In this regard, previous work of Juang et al have investigated the adsorption behavior of Cu(II)-EDTA chelates onto polyaminated chitosan beads [8]. In addition, Maketon et al have described the removal efficiency of copper and Cu(II)-EDTA complexes on polyethyleneimine and explored the adsorption mechanisms with variable copper/EDTA ratios [9]. Besides, Wu et al have reported that polymeric Fe/Zr pillared montmorillonite could be utilized as an effective sorbent for the removal of Cu(II)-EDTA chelates from wastewater [10].…”