Soybean peroxidase immobilised on cellulose-alginate hydrogels for removal of recalcitrant organic pollutants in water

In recent years, bioremediation has become very attractive for environmental applications, especially enzyme-based treatments, since they offer high catalytic capacity with milder reaction conditions, production of nontoxic compounds, and environmental friendliness. These aspects, together with the increasing attention toward the circular economy approach, encourage many researchers to investigate how to obtain materials with high added value from biomass waste. In this work, we focused our attention on Soybean hulls, which are agro-industrial waste rich in cellulose and soybean peroxidase (SBP), two interesting and versatile components exploitable for environmental treatments. Cellulose containing SBP and alginate were used to prepare fully bio-based hybrid hydrogels tested for removal of bisphenol A, 2,4,6-trichlorophenol and triclosan from both ultrapure and real water spiked solutions. Through both adsorption and enzymatic catalysis, in 5 hours, all contaminants are completely removed from the solution, with a corresponding significant reduction in toxicity. The efficiency of these materials is maintained for eight cycles of reuse and it is also confirmed in a real water matrix. Finally, the burial test in compost soil shows the biodegradability of the hydrogels proving the high eco-compatibility of the whole process.