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[Display omitted] • A cost-efficient removal of organics from Bayer liquor by TCA was provided. • The existence state of organics in Bayer liquor was particularly investigated. • Micelle, solvated Ca2+, and active concave generated the multilayer adsorption. • A maximum organic carbon adsorption capacity of 32.46 mg·g−1 was achieved. The existence state and effective removal of organics from Bayer liquor have troubled the alumina industry for six decades. This study delved into the aggregation behavior and micellization of organics in Bayer liquor. Tricalcium aluminate hexahydrate (3CaO·Al 2 O 3 ·6H 2 O, TCA) was then employed as a cost-effective adsorbent to remove organics by regulating the aggregation behavior of organics. Sodium dodecylsulfate (SDS), acting as a research object of organics, aggregated into inhomogeneous and large micelles (>3080.00 nm) with an extremely low critical micelle concentration (CMC) of 0.14 mmol·L−1 in the sodium aluminate solution (C Na2O = 2.42 mol·L−1, α K = 3.0, I ≥ 4.84 mol·L−1) at 298 K. Decreasing temperature facilitated the formation of these large micelles and the micellar size reached 2.20 μm in length. The solvated Ca2+ (Ca(OH)+) of TCA, acting as counterions with a content exceeding 11.97 wt%, initially induced the formation of micelles and then enlarged their size. Furthermore, these large micelles exhibited a preferential aggregation at the active concave of TCA. As a result, the interaction among inhomogeneous micelles, solvated Ca2+ (Ca(OH)+), and special active concave collectively contributed to the maximum organic carbon adsorption capacity of 32.46 mg·g−1 (equivalent to 64.92 mg·g−1 of SDS) at 298 K. These results open up new perspectives for understanding the existence state of the anionic organics in sodium aluminate solutions, as well as a cost-effective and eco-friendly approach to removing organics from Bayer liquor. [ABSTRACT FROM AUTHOR]

• Organics generated a minimum viscosity of the sodium aluminate solution. • Minimum viscosity of the solution nearly occurred at CMC of anionic organics. • Micelles and variation in solution structures changed viscosity of the sodium aluminate solution. • Organics increased the viscous flow activation energy of sodium aluminate solutions. Complicated organic behavior in the sodium aluminate solution limits the economical alumina production and improvement in alumina quality by Bayer process. Sodium gluconate (SG) or sodium stearate (SS) in sodium aluminate solution containing sodium oxalate (SO) changed the interfacial occurrence of anionic organics. The single anionic organic compounds or mixed organics initially decreased and then raised the viscosity of the sodium aluminate solution, and further increasing total organic carbon (TOC) remarkably increased the viscosity of the industrial sodium aluminate solution. Correspondingly, increasing concentration of anionic organic compound raised initially and then reduced diffusion coefficient. The minimum viscosity of the solution nearly occurred at the critical micelle concentration (CMC) of the anionic organic compound. Anionic organics also increased the viscous flow activation energy of sodium aluminate solutions. The disordered structure of sodium aluminate solution reduced the viscosity and increased the diffusion coefficient at low concentrations of organics less than CMC. Further increasing the concentration of organic compound more than CMC, micelles then contributed to the ordered structure of the sodium aluminate solution, increasing viscosity and reducing the diffusion coefficient of the sodium aluminate solution. Therefore, a large amount of micelles and the different solution structures synergistically changed the viscosity and diffusion coefficient of the sodium aluminate solution. [ABSTRACT FROM AUTHOR]