Acid recovery from copper metallurgical process streams polluted with arsenic by diffusion dialysis. Issue 1 (February 2021)

• Record Type: Journal Article
• Authors: López, J.; de Oliveira, R.R.; Reig, M.; Vecino, X.; Gibert, O.; de Juan, A.; Cortina, J.L.
• Is Part Of: Journal of environmental chemical engineering. Volume 9:Issue 1(2021)
• Publication Date: 2021-02
• Subjects: Neosepta-AFX -- H2SO4 -- Diffusion dialysis -- As(III)/As(V) speciation -- Waste minimisation -- UV-spectra; Chemical engineering -- Environmental aspects -- Periodicals; Environmental engineering -- Periodicals; Chemical engineering -- Environmental aspects; Environmental engineering; Periodicals; 660.0286
• DOI: 10.1016/j.jece.2020.104692
• Languages: English
• ISSNs: 2213-2929

Abstract

Graphical abstract: Highlights: Generation of a H2 SO4 stream containing As in the off-gases treatment from copper smelters. Treatment with diffusion dialysis (Neosepta-AFX) for acid recovery. Development of a UV–vis spectroscopy method to quantify As(III) concentration. Arsenic transport is favoured due to its presence as un-charged species. Abstract: A copper smelter generates solutions containing H2 SO4 (220 ± 10 g/L), non-metals (3.4 ± 0.2 g/L As ) and metals (0.5 ± 0.1 g/L Zn, 0.13 ± 0.01 g/L Fe and 0.11 ± 0.01 g/L Cd) that are treated with lime as disposal option. In order to promote circularity, the recovery of H2 SO4 by diffusion dialysis (DD) was evaluated with a lab-stack unit containing Anion Exchange Membranes (Neosepta-AFX) that allow the transport of HSO4 − and H +, while rejecting metallic species in cationic form. Initially, dialysis coefficients were determined with cycling type experiments, which showed the possibility to purify H2 SO4, but As was also transported. Then, dynamic experiments were carried out to study the effect of different variables, such as operational ones (acid and water flow rates) and As speciation (As(V) or As(III)). At the optimum operating conditions (water and acid flow rates of 0.86 L/m 2 h), Neosepta-AFX proved to allow the transport of H2 SO4 (67 ± 2 % of acid was recovered, 146 ± 12 g/L) and rejected the metallic impurities (>85 %) effectively. Nevertheless, As permeated across the membrane (1.26 g/L in the recovered acid) due to its presence as neutral species (H3 AsO4 / H3 AsO3 ). In order to overcome it, the use of a solvent extraction step devoted to remove As before the treatment with DD was proposed.