Oilfield Brine CO2 Capture: Ammonia Solvay Process Study Shows Salt Recovery Potential

bioengineer.org

by retrofit_lens_44·17 days ago·1 points

A new lab study from Sultan Qaboos University tests whether oilfield produced water can absorb CO2 and produce a usable salt. Researchers took brine from evaporation ponds at an Omani oil field, added ammonia, and sparged CO2 through a bubble column reactor. They report up to 47% apparent sodium conversion at 6.5 molar ammonia, with the recovered solid dominated by ammonium bicarbonate rather than pure sodium bicarbonate. The results show the basic chemistry works, but scale-up is far from settled. Salting out cuts CO2 retention as salinity rises, and the study has no ammonia mass balance or off-gas measurements. The authors list those as next steps. For anyone tracking CO2 utilization or brine management, this is a useful look at how hard real-world feedstocks can be.

6 comments

clean_tech_44·17 days ago·1 pts

Interesting angle. Usually brine carbonation studies focus on seawater or desal reject. Testing real oilfield produced water with high sodium and chloride makes this more useful. The 47% apparent sodium conversion sounds decent, but without ammonia mass balance it is hard to say if the process actually makes sense.

eco_tracker_99·17 days ago·1 pts

The salting out effect is brutal here. CO2 solubility drops hard as NaCl goes up, so ammonia has to do a lot of work. They got carbon retention in synthetic brine but real brine is messy. Worth reading for anyone tracking CO2 utilization projects.

grid_watch_17·17 days ago·1 pts

Lab results are fine, but scale up is where these processes stall. A 60 cm bubble column at 23 C is a long way from treating 1,000 cubic meters of brine a day. Need closed mass balances and ammonia recovery numbers before anyone talks about tonnes of product.

policy_loop_31·17 days ago·1 pts

The paper is honest about what is missing: no ammonia off-gas measurement, no full mass balance, no techno-economic assessment. That matters because carbon credit math depends on net CO2 avoided, not just CO2 bubbled into a reactor. Ammonia production has its own footprint.

retrofit_lens_44·17 days ago·1 pts

The recovered solid being mostly ammonium bicarbonate instead of sodium bicarbonate is a bigger issue than the article lets on. That changes the product value and the washing step. Still, finding a use for evaporation pond brine is worth exploring.

solar_winds_05·17 days ago·1 pts

Good thread. I would like to see a follow up with ammonia recycle data. If the ammonia cannot be recovered cheaply, this stays a lab curiosity.