Promising Biocompatible, Biodegradable, and Inert Polymers for Purification of Wastewater by Simultaneous Removal of Carcinogenic Cr(VI) and Present Toxic Heavy Metal Cations: Reduction of Chromium(VI) by Poly(ethylene glycol) in Aqueous Perchlorate Solutions

Refat M Hassan; Samia M Ibrahim; Suzan A Sayed; Ishaq A Zaafarany

doi:10.1021/acsomega.9b03485

Promising Biocompatible, Biodegradable, and Inert Polymers for Purification of Wastewater by Simultaneous Removal of Carcinogenic Cr(VI) and Present Toxic Heavy Metal Cations: Reduction of Chromium(VI) by Poly(ethylene glycol) in Aqueous Perchlorate Solutions

ACS Omega. 2020 Feb 26;5(9):4424-4432. doi: 10.1021/acsomega.9b03485. eCollection 2020 Mar 10.

Authors

Refat M Hassan¹, Samia M Ibrahim², Suzan A Sayed¹, Ishaq A Zaafarany³

Affiliations

¹ Chemistry Department, Faculty of Science, Assiut University, Assiut 71516, Egypt.
² Chemistry Department, Faculty of Science, New Valley University, El-Kharga 72511, New Valley, Egypt.
³ Chemistry Department, Faculty of Applied Sciences, Umm Al-Qura University, Makkah Al-Mukarramah 13401, Saudi Arabia.

Abstract

A spectrophotometric technique has been applied for studying the reduction of chromium(VI) by poly(ethylene glycol) (PEG) as water-soluble and nontoxic synthetic polymer at a constant ionic strength of 4.0 mol dm^-3 in the absence and presence of the ruthenium(III) catalyst. In the absence of the catalyst, the reaction orders in [Cr(VI)] and [PEG] were found to be unity and fractional first orders, respectively. The oxidation process was found to be acid-catalyzed with fractional second order in [H⁺]. The addition of Ru(III) was found to catalyze the oxidation rates with observation of zero-order reaction in [CrO₄ ^2-] and fractional orders in both [PEG] and [Ru(III)], respectively. The PEG reduces the soluble toxic hexavalent Cr(VI) as a model pollutant to the insoluble nontoxic Cr(III) complex, which is known to be eco-friendly and more safer from the environmental points of view. The acid derivative of PEG was found to possess high affinity for the removal of poisonous heavy metal ions from contaminant matters by chelation. Formation of the 1:1 intermediate complex has been kinetically revealed. A consistent reaction mechanism of oxidation was postulated and discussed.