Novel photosynthetic CO2 bioconvertor based on green algae entrapped in low-sodium silica gels

A photosynthetic bioreactor for CO 2 assimilation has been designed using silica sol-gel immobilisation technologies with the chlorophyta Botryococcus braunii (Kützing) and Chlorella vulgaris (Beijerinck). The living hybrid gels formed revealed a mesoporosity that enabled diffusion of nutrients and gases, promoting the light and dark photosynthetic reactions from within the bulk of the material. To determine the efficiency of the photosynthetic bioreactor in terms of CO 2 remediation, the activity and viability of the encapsulated cells have been monitored through oximetry, 14 C assimilation, pulse amplitude modulation fluorimetry and confocal microscopy, revealing a long term productivity of living hybrid materials capable of photosynthetic processes for at least 80 days. Structural and textural properties of the gels were established through 29 Si MASNMR and N 2 physisorption respectively. Microalgae, key organisms in photosynthetic CO 2 assimilation, are often found in siliceous environments. Inspired by nature, this work outlines successful encapsulations of active, living chlorophyta in abiotic silica for use in pollution remediation systems.