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Hydrogel beads are emerging as alternate adsorbent material for the batch or continuous column treatment of dye wastewater. Polysaccharide-based gel beads are preferred for their uniform shape and size, large specific surface area, and easy separation by filtration and subsequent reuse. In this work, we prepare and rheologically characterize UV-active κ-carrageenan/TiO 2 beads for the adsorption and degradation of dyes. The 3-4 mm sized nanocomposite beads are formed by the extrusion of κ-carrageenan/TiO 2 gel solution in salt solutions. The maximum increase in modulus was observed with the addition of 1% w/v TiO 2 to κ-carrageenan and subsequent crosslinking with mixed salt of KCl and CaCl 2 . κ-carrageenan/TiO 2 beads crosslinked by mixed salt of KCl and CaCl 2 have higher adsorption capacity, as compared to beads crosslinked with single salt of KCl. The kinetic study indicated the chemisorption of Methylene Blue on the bead surface. κ-carrageenan/TiO 2 beads showed higher degradation for Methylene Blue and Nile Blue A than Rhodamine B in 5 and 50 ppm each multicomponent dye systems under UV irradiation. The κ-carrageenan/TiO 2 beads could form a porous column for the selective adsorption of positively charged dyes from a multicomponent dye system.

Surfactants in water and both alcohol‐water mixed solutions are used extensively in a host of industrial applications. This work presents the solution behavior and micellar transition of a cationic gemini surfactant (GS): N,N′‐dihexadecyl‐N,N,N′,N′‐tetramethyl‐N,N′‐ethanediyl‐diammonium dibromide (16‐2‐16) in water and mixed water‐ethanol media. Phase behavior for 16‐2‐16 in the ethanol–water system was investigated at ambient temperature. The rheological data obtained for these systems at varying alcohol concentrations showed that the system viscosity (η) decreased with as the ethanol concentration increased. Small‐angle neutron scattering (SANS) was used to probe the structural details of the cationic micelles as a function of ethanol concentration and temperature. The scattering data inferred a structural transition from unilamellar vesicles (ULV) through rod‐like micelles to ellipsoidal micelles occurs that is dependent on the solvent composition and temperature indicating the behavior of ethanol molecules as a cosolvent in the process of micelle breaking. The plausible physicochemical interactions in the 16‐2‐16‐ethanol mixed system were further investigated using a computational simulation study employing density functional theory (DFT)/B3LYP (Gauss View 5.0.9) utilizing a 3‐21G basis set.