In recent years, multifunctional inorganic−organic hybrid materials have been widely investigated in order to determine their potential synergetic, antagonist, or independent effects in terms of reactivity. The aim of this study was to design and characterize a new hybrid material by coupling well-known photocatalytic TiO₂ nanoparticles with sodium surfactin (SS), a biosurfactant showing high binding affinity for metal cations as well as the ability to interact with and disrupt microorganisms’ cell membranes. We used both chemical and colloidal synthesis methodologies and investigated how different TiO₂:SS weight ratios affected colloidal, physicochemical, and functional properties. We discovered a clear breaking point between TiO₂ and SS single-component trends and identified different ranges of applicability by considering different functional properties such as photocatalytic, heavy metal sorption capacity, and antibacterial properties. At low SS contents, the photocatalytic properties of TiO₂ are preserved (conversion of organic dye = 99% after 40 min), and the hybrid system can be used in advanced oxidation processes, taking advantage of the additional antimicrobial SS properties. At high SS contents, the TiO₂ photoactivity is inhibited, and the hybrid can be usefully exploited as a UV blocker in cosmetics, avoiding undesired oxidative effects (UV adsorption in the range between 300–400 nm). Around the breaking point (TiO₂:SS 1:1), the hybrid material preserves the high surface area of TiO₂ (specific surface area around 180 m²/g) and demonstrates NOx depletion of up to 100% in 80 min, together with improved adhesion of hybrid antibacterial coating. The last design demonstrated the best results for the concurrent removal of inorganic, organic, and biological pollutants in water/soil remediation applications.

The development of multifunctional ferrites for diverse contaminant removal requires precise control over phase composition and surface chemistry. This study presents a systematic screening of calcium ferrites synthesized via a scalable sol–gel route, with calcination temperatures (300–1200 °C) and Ca:Fe ratios tuned to map phase evolution. Five distinct clusters were identified, including brownmillerite and orthorhombic spinel-like (O-CaFe₂O₄) phases. Among these, the CaFe 1:2 system calcined at 500 °C emerged as the optimal candidate, exhibiting high surface area (>100 m² g⁻¹) and significant magnetic response (Ms up to 28 Am2 KgFe⁻¹). This material achieved near-complete dye degradation and high phosphate adsorption (~100 mg g⁻¹) via PO₄³⁻/OH⁻ ion-exchange. Beyond process optimization, the analysis of performance distributions across the synthesis domain revealed robust phase-dependent selectivity trends. This screening-driven framework enables the rational design of ferrite-based sorbents, decoupling intrinsic structure-property relationships from specific operating conditions for enhanced environmental remediation.

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