Degradation of microcystin algal toxin by 3D printable polymer immobilized photocatalytic TiO2

Novel and sustainable solutions are needed for surface water treatment. Photocatalytic TiO2 is studied but is not directly deployable into natural water bodies due to settling and poor recoverability. This research capitalizes on a convergence of the emerging technologies of 3D printing biocompatible polymer (polylactic acid, PLA) com-posites, nanotechnology, and advanced oxidative processes to immobilize TiO2 into customizable, high surface area, deployable, and retrievable structures with localized kinetic specificity for harmful algal blooms (HAB). PLA-TiO2 composites at varying loadings (3-34 %) were extruded as feedstock for fused filament fabrication (FFF) enabling low cost printing design freedom of photocatalyst structures (disks, lattices). Large surface area, 3D lattices were printed as PLA composites with highly loaded (34 % w/w) TiO2. Prior to HAB cyanotoxin ex-periments, the photocatalytic performance of the 3D printed PLA-TiO2 lattice composites (t1/2 = 0.8 h) under UV light were confirmed comparable to free TiO2 (t1/2 = 0.9 h). Under environmentally relevant solar simulation, photocatalysis by printed lattices successfully reduced microcystin (MC) cyanotoxin (t1/2 = 3 h) faster than photolysis alone (t1/2 = 36 h). Lattice mediated photocatalysis of MC in presence of cyanobacteria cells (t1/2 = 11 h) was faster than photolysis (t1/2 = 58 h) but slower than water-only treatment due to cell activity and light attenuation. PLA-TiO2 reduces local pH, promoting MC adsorption and degradation. This research is founda-tional to novel photocatalytic composite optimization for reactive surface area prototyping enabled by 3D printing and scale-up for sustainable water treatment structures, with applicability to traditional and emerging contaminants.

Automated summary

Novel and sustainable solutions for surface water treatment are needed. This research utilizes 3D printing and nanotechnology to create a customizable and deployable structure for immobilizing TiO2, enabling efficient photocatalysis for harmful algal blooms (HAB). The PLA-TiO2 composite exhibits high catalytic performance and can effectively degrade harmful substances in water bodies.