Abstract
Acid mine drainage (AMD) is a severe form of environmental pollution that has the potential to contaminate surface and ground waters by introducing heavy metals and lowering the pH. The feasibility of using nanofiltration (NF) as a potentially attractive and cost-effective remediation method to treat acid mine drainage was investigated in this study. The performance of an acid-stable NF membrane focusing on the effects of the water pH and membrane charge on ion rejection was systematically studied. A single salt solution experiment showed that Mg, Cu, and Mn containing species were highly rejected at above 97%. Below the membrane iso-electric point (IEP), Mn showed an increased rejection of 99%, while Mg and Mn rejections were relatively constant within the investigated pH range of pH 2 to 7. Rejection of monovalent Cl− decreased with increasing concentration of an accompanying divalent SO42−, showing that Donnan related effects are more prominent at higher ionic concentrations. The sulfate rejection decreased drastically below pH 3 due to the formation of HSO4−, which permeated through the membrane, which can be utilized as a way of separation of the metals from the accompanying sulfur-containing compounds. For mixed salt solutions, rejection of silicate dropped from 52% to 38% when magnesium sulfate was added, owing to shielding of the membrane surface charge by Mg2+ ions. The NF process performance with a simulated AMD solution was found to be similar to that with model salt solution experiments, both in terms of ion rejection values and general pH-dependent rejection trends. The results obtained can be used as a fast preliminary tool for evaluating the feasibility of using NF for treating AMD with a given ionic composition and pH.
Highlights
Acid mine drainage (AMD) is an acidic, sulfur-rich, metallic wastewater, originating from mine discharge of both operational and abandoned mines [1]
This study found that the electrostatic repulsion between the (–COO–) groups on the membrane surface and the OH– groups in the feed solution at high pH results in pore shrinkage which decreases the permeate flux
An in-house made NF membrane was used in this study. It is a thin film composite, which consists of a PAN substrate support layer and a surface skin layer, which chemical composition is under know-how protection
Summary
Acid mine drainage (AMD) is an acidic, sulfur-rich, metallic wastewater, originating from mine discharge of both operational and abandoned mines [1]. Sulfide minerals such as pyrite (FeS2 ), mackinawite (FeNiS), and chalcocite (Cu2 S) are being exposed. These exposed minerals are oxidized by the combined effect of water and oxygen resulting in the release of metal and sulfates. AMD can be formed from pyrite through a series of oxidative reactions (Equations (1)–(4)) where ferric iron acts as the primary oxidant [2,3]: (aq). Sci. 2020, 10, 400; doi:10.3390/app10010400 (1) (2) (3).
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
