Porosity Engineered 3D Printed Biopolymer Cryogels for Oil Sorption and Chemical Free Recovery

ABSTRACT We report the development of protein–polysaccharide hydrogel precursors enabling the additive manufacturing of biopolymer aerogels with tunable porosity and sorption performance. Sodium alginate–bovine serum albumin (BSA) complexes were formulated as shear‐thinning, extrusion‐printable bioinks that yield mechanically stable architectures with high shape fidelity, including multilayered and hollow structures. Subsequent freeze‐drying transformed the printed hydrogels into aerogels while preserving the designed geometries, and the freezing conditions were identified as key structural determinants. Rapid freezing in liquid nitrogen produced highly interconnected porous networks with sustained uptake of hydrophobic oils. In contrast, slow freezing at −20°C generated macroporous architectures characterized by accelerated but lower‐capacity sorption; notably, these structures enabled efficient oil release (>80 %) upon simple centrifugation, eliminating the need for chemical recovery. Incorporation of BSA into alginate matrices further loosens the polymer network, enhances pore connectivity, and markedly improves sorption performance, especially under fast‐freezing conditions. These findings establish a versatile processing platform that integrates extrusion‐based 3D printing with controlled freeze‐drying to tailor the hierarchical porosity of renewable biopolymer aerogels. This approach highlights the broader potential of protein–polysaccharide bioinks for engineering tunable aerogel architectures aimed at environmental remediation.