A study of the ammonium ion extraction properties of polymer inclusion membranes containing commercial dinonylnaphthalene sulfonic acid

• Dinonylnaphthalene sulfonic acid (DNNS) has the ability to extract ammonia.
• Polymer inclusion membranes (PIMs) containing DNNS as the carrier are characterized.
• DNNS-based PIMs with CTA (base polymer) have better performance without plasticizer.
• PIMs with PVC (base polymer) perform better when 1-tetradecanol is added as modifier.
• DNNS is supplied in 50% solvent, and different solvents affect the PIMs properties.

Polymer inclusion membranes (PIMs) containing commercial dinonylnaphthalene sulfonic acid (DNNS) as the carrier were studied to ascertain their potential for use as the semi-permeable barrier in a passive sampler for the accumulation of ammonia. Extensive screening of membrane compositions using cellulose triacetate (CTA) and poly(vinyl chloride) (PVC) as the base polymers and different plasticizers/modifiers (i.e. 2-nitrophenyloctylether (NPOE), dioctyl phthalate (DOP) and 1-tetradecanol) was conducted and successful membranes were studied for their ability to extract and back-extract ammonia using a 3.00 mg L−1 NH4+ aqueous feed solution and 1.0 mol L−1 HCl aqueous receiving solution. The CTA and PVC-based PIM providing the highest extraction rates and best stability contained 70 wt% CTA and 30 wt% commercial DNNS; and 80 wt% PVC, 10 wt% commercial DNNS and 10 wt% 1-tetradecanol as a modifier. The PVC-based PIM was found to be more stable than the CTA-based PIM, having a mass loss of its liquid phase of only 3.2 wt% after 24 h of immersion in the NH4+ feed solution compared to 11 wt% for the CTA-based PIM. Commercial DNNS from three different suppliers was characterized titrimetrically and by gas chromatography–mass spectrometry. The extraction properties of PIMs containing commercial DNNS from different suppliers were compared. These properties differed in the case of the CTA-based membranes while no differences were observed when PVC was used as the base polymer.