Industrial waste acids not only pose environmental risks but also represent underutilized resources. Conventional neutralization and precipitation methods remove metal ions but result in substantial acid loss and secondary pollution. Acid-resistant NF membranes can operate stably under low pH conditions, achieving efficient separation of acids and metals, offering new avenues for acid recovery and industrial RO membrane wastewater reuse.
Acid-resistant NF membranes, prepared via modified polyamide, perfluorinated polymers, or composite inorganic layers, can operate stably in pH 1–3 environments. They exhibit high rejection for multivalent metal ions (Cu²⁺, Ni²⁺, Zn²⁺) while allowing monovalent anions (SO₄²⁻) to pass, enabling high acid recovery. With high flux under low pressure and anti-fouling surface designs, these membranes are well-suited for large-scale industrial applications.
Acid-resistant NF membranes can directly treat waste acids from electroplating and metal surface treatment, enabling acid concentration and recovery. Coupling NF with RO membranes in an acid-resistant nanofiltration and RO hybrid system allows production of high-purity acids at low pressure while recovering metal ions for reuse.
In waste acids, selective NF membranes can retain multivalent metal ions while passing acids. Integration with acid-resistant RO elements in chemical industries enables further concentration and recovery of precious and rare metals, enhancing economic and environmental benefits.
By employing NF-RO composite systems, waste acid effluents can be purified and reused, realizing RO membrane for waste acid concentration and purification, thereby reducing water consumption and environmental impact.
With increasing environmental regulations and industrial acid consumption, the market for acid-resistant NF membranes and NF-RO hybrid systems is expanding. Over the next 5–10 years, industries like electroplating, chemical, and metallurgy are expected to widely adopt industrial RO membrane for acid recovery solutions. Integration of NF-RO hybrid systems with optimized flux, enhanced acid resistance, and intelligent control will enable full-process waste acid resource management. Membrane material innovations-including high-temperature, high-acid polymer, inorganic composite, and self-cleaning membranes-will ensure long-term industrial applicability, supporting green manufacturing and circular economy.
Acid-resistant NF membranes demonstrate significant advantages in waste acid and metal ion separation. Integration with RO membranes enhances acid and metal recovery while enabling industrial wastewater reuse. With advances in material science, membrane fabrication, and intelligent control, acid-resistant nanofiltration and RO hybrid systems are expected to gain wide adoption in chemical, metallurgical, and electroplating industries, driving sustainable acid resource recovery, environmental protection, and economic benefits.
