Mushroom-derived chitosan-glucan nanopaper filters for the treatment of water

Contaminated water represents a significant threat to public health, with heavy metals present in industrial effluents constituting a particular hazard. Conventional heavy metal removal processes are often expensive and rely on synthetic materials. Renewable adsorbents or filters, such as chitosan, provide a low-cost, simple alternative for treatment of water. Fungal chitin and hence fungal chitosan is a cheap, renewable, easily isolated, and abundant alternative to crustacean chitin. This study investigated the water treatment potential of chitosan-glucan nanopapers derived from common white-button mushroom (A. bisporus) extract as adsorptive filter. These nanopapers completely rejected 10 nm gold nanoparticles, indicating potential for virus filtration. They had copper ion (2 mM) adsorption capacities (up to 120 mg g⁻¹) increasing with degree of deacetylation of fungal chitin on par with or even outperforming current chitosan membranes with the advantage of simpler production, not requiring further crosslinking. In order to improve the performance of fungal chitosan-glucan filters, hybrid filters with cellulose microfibres from fibre sludge were prepared. Hybrid nanopapers exhibited significantly increased copper ion adsorption (162 mg g⁻¹) in conjunction with high water permeances (63,000 to 121,000 L h⁻¹ m⁻² MPa⁻¹). The simple manufacturing process and impressive filtration/adsorbent properties of these renewable filters make them a viable option for water treatment helping to reduce the ecological impact of traditional water treatment processes.