Sustainable, decentralized water treatment system fabricated from domestic waste materials and ultrafast-reduced graphene oxide

The demand for fresh water will increase in the coming decades as the world population grows. While large-scale water purification plants will serve highly populated areas, the demand of fresh water will continue to grow even in remote and potentially under-developed locations. In this work, it has been shown that fresh water can be produced from seawater or polluted water using waste paper and direct solar exposure, without the need of electricity during water purification. The highly efficient solar evaporation system proposed here, which is based on graphene/cellulose aerogels, can be fabricated quickly without highly technical skills, requiring only a microwave oven, graphene oxide samples, and cellulose fibers obtained from packaging (i.e., waste paper and polyethylene foams). The produced aerogels show high photo-thermal conversion, excellent hydrophilicity and low thermal conductivity, properties that are conducive to evaporation rates as high as 1.83 kg m−2 h−1, photo-thermal efficiency of 92%, and stability for more than 40 operation cycles. Despite using waste materials, these performance metrics are superior to those reported for most materials to date, and are a consequence of the manufacturing process described here. Field tests confirmed that 1 m2 of the as-prepared aerogels can produce between 6.44 and 11.27 kg of fresh water from seawater or polluted water in a 12-hour period, which is the daily amount of drinking water required for three adults based on World Health Organization projections.