Waste Algal Biomass as a Binder for Shaping Technical Adsorbents

Spray-dried biomass from genetically engineered Chlamydomonas reinhardtii can be used as a binder to extrude alumina adsorbents. The proposed process involves heating at a moderate temperature (180 °C), replacing inorganic binders that require high sintering temperatures. The transformed genes present in the algal biomass were no longer detectable after the thermal treatment. Binder contents above 15% led to successful extrusion. Extrudability was found to correlate with the viscoelasticity coefficient, tan(δ), obtained from independent rheometric measurements. The extrudates have crush strengths of >27 N, complying with industrial requirements. The water vapor adsorption capacity in shaped alumina adsorbents was 7.5 mol/kg, indicating a 30% reduction compared with alumina powder. The mechanical and adsorption properties of the formed adsorbents remain unaltered after a 1 week immersion in water, ethanol, or n-heptane and after 10 gas-phase adsorption/desorption cycles. The results demonstrate that waste biomass from algal processes can be effectively used to produce functional industrial adsorbents.