Session: Rising Stars of Mechanical Engineering Celebration & Showcase

Paper Number: 150227

150227 - Membranes as a Tool to Decarbonize Fertilizer Production 

The current production methods of fertilizer raw materials - nitrogen(N, in the form of ammonia, NH₃), phosphorus(P) and potassium (K) are highly energy intensive ; yet their demands are expected to rise in proportion to the population growth. The demand for Ammonia, for example, is expected to be >$200 Billion over the next few years and the production of ammonia by itself is associated with ~1.8% of global CO₂ emissions.  New methods of producing these critical raw materials are clearly important to develop and herein membranes could play a very important role. Our group is currently working on two alternate methods of ammonia production - (a) development of polyelectrolyte based membranes for recovering the fertilizer nutrients from concentrated nutrich-rich liquid sources (e.g. anaerobic digestate) and (b) design of metal embedded carbon molecular sieve membrane reactors for ammonia production. 

Concentrated wastewater sources (e.g. anerobic digestate/poultry litter) are nutrient-rich, and in fact, estimates have shown that ~13% of the global nutrient demand can be met via their recovery from wastewater. Results from our group have shown that surface modified nanofiltration (NF) membranes, when coupled with vivianite precipitation, enable high nutrient (N,P,K) recoveries while simultaneoulsy rejecting majority of the unwanted organic constituents under circumneutral pH conditions. A range of surface modification parameters are available to tune the properties of these membranes and under optimum synthesis conditions, these membranes show ~ 2.5X higher nutrient/organic selectivities vs. commercial NF membranes.  Beyond organic/nutrient selectivities, these membranes also demonstrate higher intra-nutrient selectivities, i.e. NH₄⁺/K⁺ selectivities vs. commercial NF membranes which is surprinsing since these nutrient ions are exactly same-sized.  We believe that under optimum conditions, these novel surface modified membranes facilitate a unique desolvation based separation mechnanism which is distinct from conventional size based exclusion and charge based separation.  This is a unique feature of these membranes and we are currently exploring a strategy of controlling the site density of crosslinked domains within these modified NF membranes to maximize this intra-nutrient selectivity. Results obtained from characterization techniques beyond simple transport based techniques such as ATR -FTIR will also be included in this poster. 

The 2nd part of this poster will focus on metal (Fe) incorporated carbon molecular sieve (CMS) membranes which are currently being explored as membrane reactor materials for ammonia synthesis from N₂ and H₂.  The precise molecular sieving abilities of CMS membranes are envisioned to provide high NH₃/N₂ and NH₃/H₂ selectivities which are expected to aid in shifting the equilibrium towards NH₃ production and in the process lower the energy intensity of traditional ammonia production methods. Our proof of concept data have demonstrated comparable NH₃ production (normalized per gm. of metal) in these Fe-CMS membranes as traditional Fe-coated carbon supported catalysts. In addition, we will present a fundamental approach of characterizing the CMS membrane structure using the dual mode sorption and diffusion transport theory which enables distinguishing the contributions of the two distinct sorption and diffusion domains within these membranes. Furthermore, this analysis helps to clearly demonstrate the effects of high temperature H₂ exposure on these CMS membranes and these analyses help to predict the performance of these membranes under reaction conditions. 

Presenting Author: Oishi Sanyal West Virginia University

Presenting Author Biography: Dr. Oishi Sanyal is the Wayne and Kathy Richards Faculty Fellow and Assistant Professor in Chemical Engineering at West Virginia University. Her group works on new membrane material development, membrane manufacturing strategies and novel separation applications. Dr. Sanyal is a recipient of the NSF CAREER Award (2024). She was also selected as a 2022 AIChE Journal Futures Issue Investigator and was one of the participants for the NAE Frontiers of Engineering Symposium (2021). Prior to joining WVU, she was a postdoctoral researcher at Georgia Tech and got her BS and PhD degrees from Manipal University (India) and Michigan State University respectively.

Authors:

Oishi Sanyal West Virginia University
Km Prottoy Shariar Piash West Virginia University
Nhan Khuu West Virginia University