Hassan Refat M, Ibrahim Samia M, Sayed Suzan A, Zaafarany Ishaq A
Chemistry Department, Faculty of Science, Assiut University, Assiut 71516, Egypt.
Chemistry Department, Faculty of Science, New Valley University, El-Kharga 72511, New Valley, Egypt.
ACS Omega. 2020 Feb 26;5(9):4424-4432. doi: 10.1021/acsomega.9b03485. eCollection 2020 Mar 10.
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 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 [CrO ] 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.
已应用分光光度技术研究在4.0 mol dm的恒定离子强度下，在不存在和存在钌(III)催化剂的情况下，聚乙二醇(PEG)作为水溶性无毒合成聚合物对铬(VI)的还原作用。在不存在催化剂的情况下，发现[Cr(VI)]和[PEG]的反应级数分别为一级和分数一级。发现氧化过程是酸催化的，[H]的反应级数为分数二级。发现添加Ru(III)可催化氧化速率，观察到[CrO ]的反应级数为零级，[PEG]和[Ru(III)]的反应级数均为分数级。PEG将作为模型污染物的可溶性有毒六价Cr(VI)还原为不溶性无毒Cr(III)络合物，从环境角度来看，该络合物已知是生态友好且更安全的。发现PEG的酸衍生物通过螯合对从污染物中去除有毒重金属离子具有高亲和力。动力学揭示了1:1中间络合物的形成。提出并讨论了一致的氧化反应机理。
