Evaluation of Different Capture Solutions for Ammonia Recovery in Suspended Gas Permeable Membrane Systems

Abstract

Gas permeable membranes (GPM) are a promising technology for the capture and recovery of ammonia (NH3). The work presented herein assessed the impact of the capture solution and temperature on NH3 recovery for suspended GPM systems, evaluating at a laboratory scale the performance of eight different trapping solutions (water and sulfuric, phosphoric, nitric, carbonic, carbonic, acetic, citric, and maleic acids) at 25 and 2 °C. At 25 °C, the highest NH3 capture efficiency was achieved using strong acids (87% and 77% for sulfuric and nitric acid, respectively), followed by citric and phosphoric acid (65%) and water (62%). However, a remarkable improvement was observed for phosphoric acid (+15%), citric acid (+16%), maleic acid (+22%), and water (+12%) when the capture solution was at 2 °C. The economic analysis showed that water would be the cheapest option at any working temperature, with costs of 2.13 and 2.52 €/g N (vs. 3.33 and 3.43 €/g N for sulfuric acid) in the winter and summer scenarios, respectively. As for phosphoric and citric acid, they could be promising NH3 trapping solutions in the winter months, with associated costs of 3.20 and 3.96 €/g N, respectively. Based on capture performance and economic and environmental considerations, the reported findings support that water, phosphoric acid, and citric acid can be viable alternatives to the strong acids commonly used as NH3 adsorbents in these systems.

Portable, wearable and implantable artificial kidney systems: needs, opportunities and challenges

“…To prevent a rise in dialysate sodium concentration, a sodium-free dialysate reservoir could be used to dilute the released sodium, but this approach would be at the expense of miniaturization 32 . Alternative methods for ammonium capture that minimize Ca 2+ and Mg 2+ removal and Na + and H + release should be explored, such as use of a gas-permeable hydrophobic coating for zirconium phosphate to enable binding of ammonia (NH 3 ) 32 , 36 .…”

Transmembrane Chemical Absorption Process for Recovering Ammonia as an Organic Fertilizer Using Citric Acid as the Trapping Solution

“…On the one hand, this approach has the advantage of using a cheap acid and obtaining a well-established fertilizer [17]. On the other hand, the use of such a strong acid presents safety risks for the plant operators, and the inorganic product has a low market value (0.43 €•kg −1 ) and is mainly suitable for agricultural fields with sulfur deficiency [28,29]. Moreover, the fertilizers obtained with the use of inorganic acids are, by definition, not useable for organic farming, hindering the expansion of ammonia recovery technologies.…”

“…However, one of the related studies was performed during a conventional ammonia stripping-scrubbing process [37] and the other one in a TMCA set up to treat a synthetic solution where the membranes were suspended in air, resulting in a gas-liquid membrane contactor configuration [28]. This means that there is information lacking on the use of citric acid as a trapping solution for recovering nitrogen with membrane contactors in liquid-liquid configurations.…”

“…There are also few studies on the economic performance of the TMCA process [12,38]. The number of studies that included an economic analysis is even lower for the systems that considered a trapping solution different to sulfuric acid [28].…”

State of the Art Membrane Science and Technology in the Iberian Peninsula 2021–2022

“…Using various e-PTFE membrane systems, NH 3 in an acidic solution from a pig farm is extracted for its use as a fertiliser. In a second work, Soto et al [ 3 ] continued this study by analysing the optimal conditions for NH 3 capture in suspended gas membrane systems, analysing the usefulness of different capture solutions in terms of NH 3 captured and economic cost.…”