Measurement of Binding Constants of Poly(ethylenimine) with Metal Ions and Metal Chelates in Aqueous Media by Ultrafiltration

Abstract

Equilibrium constants for the binding of poly(ethylenimine) (PEI) with metal ions and metal chelates of ethylenediaminetetraacetic acid and nitrilotriacetic acid in the aqueous sulfate solutions were determined by batch ultrafiltration (UF) in the pH range of 3.0−3.8. The average coordination number of PEI groups interacting with one metal ion and metal chelate was also obtained by varying the initial concentration ratio of PEI to metal ion. A simple chemical equilibrium model proposed in this work enabled us to satisfactorily predict the rejection coefficient of UF of metal ions and metal chelates in the presence of PEI. Also, the effect of the formation of soluble hydroxy complexes of metal chelates on their retention was emphasized.

Removal of chromium ions from aqueous solutions by polymer-enhanced ultrafiltration

“…At pH values higher than 10, the anionic species Cr(OH) 4 − starts to appear to become the only species at pH 13 and above. Fig.…”

“…Since pore size of ultrafiltration membranes are not suitable to separate heavy metal ions, water-soluble polymers are used to bind the metals to form macromolecular complexes [2][3][4][5]. These large molecules, having a larger molecular weight than the molecular weight cut off of the membrane, will be retained, while the non-complexed ions pass through the membrane.…”

Removal of chromium from aqueous solution using cellulose acetate and sulfonated poly(ether ether ketone) blend ultrafiltration membranes

“…The effect of pH was studied by adjusting the pH of the chromium solutions to 3-6, using 0.1 M NaOH for various concentrations of chromium with 2 wt.% PVA. The solution containing PVA and chromium ions were thoroughly mixed and kept for complete binding [20,21]. Pure CA (100%) membrane was chosen for this study.…”

Hybrid materials: Magnetite–Polyethylenimine–Montmorillonite, as magnetic adsorbents for Cr(VI) water treatment

“…CrO 2À 4 anion is the predominant species at pH values above 6.5; HCrO À 4 and Cr 2 O 2À 7 anions account for about 80% and 20%, respectively, in the pH range of 2-5; and H 2 CrO 4 and HCrO À 4 are the major species at pH values below 2 [77]. Regarding PEI, it is well known that PEI is being highly effective for the neutralization of excess anionic colloidal charge, especially under acidic and neutral pH [78,79]. The amine groups (-NH, -N<, -NH 2 ) in PEI would be protonated at pH below 10 anions would be reduced, decreasing the removal efficiency considerably.…”