Industrial Symbiosis: CO2 Utilization by Producing Disodium Octaborate Tetrahydrate and Baking Soda from Borax

This paper proposesa novel method for CO2 capture,utilization, and sequestration (CCUS) with borax producing disodiumoctaborate tetrahydrate (Na2O & BULL;4(B2O3)& BULL;4H(2)O & EQUIV; Na2B8O13 & BULL;4H(2)O, DSOBTH) equivalent boron compoundsand sodium bicarbonate (NaHCO3). We tested the performanceof this method experimentally using aqueous ammonium (NH4 (+)) solutions in a pressurized reactor (1 L) continuouslypurged with pure (99.9%) CO2. Experimental parameters werechanged as temperature (T), 45-65 & DEG;C; solid-to-liquidratio (SLR), 0.69-0.92 g/mL; reaction time (t), 30-60 min; pressure (P), 5-30 bar;NH3 concentration (AC) 2.82-5.65 M; and steeringspeed (SS), 500 rpm. The results showed that P and T were highly influential on the performance. The best conditionsfor CO2 utilization were found as P =20 bar; T = 60 & DEG;C; SLR = 0.77 g/ml; t = 50 min; and AC = 4.76 M. Per ton of tincal, under theseconditions, produced were 0.274 ton of DSOBTH (& SIM;67% B2O3), 0.216 ton of NaHCO3 (& SIM;95% purity),0.386 ton of avoided boric acid, and 0.417 ton of avoided CO2. The total potential added value can be about $1100/ton of tincal.