Abstract
Acid mine drainage (AMD) is globally recognized as one of the environmental pollutants of the priority concern due to high concentrations of toxic metals and sulfates. More rigorous environmental legislation requires exploitation of effective technologies to remove toxic metals from contaminated streams. In view of high selectivity, effectiveness, durability, and low energy demands, the separation of toxic metal ions using immobilized membranes with admixed extractants could ameliorate water quality. Cellulose triacetate based polymer inclusion membranes (PIMs), with extractant and plasticizer, were studied for their ability to transport of As(V) ions from synthetic aqueous leachates. The effects of the type and concentration of extractant, plasticizer content, and sulfuric acid concentration in source phase on the arsenic removal efficiency have been assessed. Under the best of applied conditions, PIM with Cyanex 921 as extractant and o-nitrophenyl octyl ether (o-NPOE) as plasticizer showed high repeatability and excellent transport activity for selective removal of As(V) from AMD.
Highlights
Mining of minerals is associated with acid drainage problems that can give rise to long-term impairment to aquatic environment and biodiversity
The changes of concentration of As(V) ions in the source, receiving and the membrane phases were analyzed to determine their transport through polymer inclusion membranes (PIMs) containing Cyanex 921 by creating a concentration profile of the metal as a function of time (Figure 2)
The obtained exponential curves of c/c0 to time corroborates the kinetic model of metal ions transport suggested by Danesi et al (1984)
Summary
Mining of minerals is associated with acid drainage problems that can give rise to long-term impairment to aquatic environment and biodiversity. Long-term, effective passive AMD treatment systems based on geogenic (geochemical and biological) processes allow for acidity neutralization, oxidation, or metals and arsenic reduction and precipitation, and are suitable for small and medium AMD discharges. PIM made of 52% CTA, 48% Aliquat 336 (w/w), and 2 M NaCl as a receiving phase obtained As(V) removal efficiency within the range of 53–81% in different water samples They noted that transport was not dependent on the kind of polymer and the membrane thickness [39]. The effects of various parameters on the removal efficiency of arsenic were studied, including the plasticizer content, type, and concentration of a carrier in the membrane, and the sulfuric acid concentration in the source phase. In order to extend the applicability of the separation technique, we have evaluated reusability of PIM, and tested the PIM-system for selective removal of arsenic from a real AMD sample
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