Abstract

Galvanizing industries generate large amounts of effluents rich in toxic and carcinogenic chromium(VI) species. Effective and sustainable treatments are required to comply with environmental regulations. This work focused on the development of innovative treatments for Cr(VI) by its removal from a galvanizing industry wastewater (pH_initial = 5.9) containing Cr (78 mg.L⁻¹) and Zn (2178 mg.L⁻¹) using the liquid surfactant membranes technique. The membrane phase carrier was Alamine® 336 in Escaid™ 110. For a synthetic solution (Cr(VI) = 353mg.L⁻¹, pH_{internal phase} = 1.5), 99.9% of Cr(VI) was extracted in three stages ([KOH]_{internal phase} = 0.27 mol.L⁻¹). For the galvanizing wastewater, two selective extractions treatments were proposed: (1) 87% of Cr(VI) and 2% of Zn(II) were extracted in a single stage ([HCl]_{feed phase} = 0.03 mol.L⁻¹, [KOH]_{internal phase} = 0.6 mol.L⁻¹); (2) 95.6% of Cr(VI) and practically no zinc were extracted in a single stage ([HCl] _{feed phase} = 10⁻⁶mol.L⁻¹, [HCl] _{internal phase} = 5mol.L⁻¹). In another treatment condition ([HCl] _{feed phase} = 2mol.L⁻¹ and [KOH] _{internal phase} = 1.2 mol.L⁻¹), the simultaneous Cr(VI) and Zn(II) extractions (95% and 70%, respectively) were obtained in a single stage and more than 99% of both metals in three stages. This resulted in a depleted feed phase with 0.01 mg.L⁻¹ of Cr(VI), that allows its discharge, according to the Brazilian legislation (≤0.1 mg/L).

抽象的

镀锌工业产生大量的废水，这些废水富含有毒和致癌的铬（VI）物种。需要有效且可持续的处理方法以符合环境法规。这项工作的重点是通过从含铬（78 mg.L ^-1）和锌（2178 mg.L ^-1）的镀锌工业废水（pH_初始值= 5.9）中去除Cr（VI）的创新方法的开发。液体表面活性剂膜技术。膜相载体是Escaid™110中的336。对于合成溶液（Cr（VI）= 353mg.L ^-1，pH_内相= 1.5），分三步提取了99.9％的Cr（VI）（[ KOH]_内相＝ 0.27mol.L ^-1）。对于镀锌废水，提出了两种选择性萃取处理方法：（1）在一个阶段中萃取了87％的Cr（VI）和2％的Zn（II）（[HCl]_进料相= 0.03 mol.L ^-1， [KOH]_内相＝ 0.6mol.L ^-1）；（2）在一个阶段（[HCl]_进料相＝ 10 ^-6 mol.L ^-1，[HCl]_内相＝ 5mol.L ^-1）中萃取了95.6％的Cr（VI）并且几乎没有锌。在另一种处理条件下（[HCl]_进料相= 2摩尔L ^-1和[KOH]_内相= 1.2摩尔L ^-1），在一个步骤中同时提取了Cr（VI）和Zn（II）（分别为95％和70％），在三个步骤中同时获得了99％以上的两种金属。根据巴西法律（≤0.1mg / L），这导致进料阶段含0.01 mg.L ^-1的Cr（VI）耗尽，可将其排出。