The amount of sugarcane bagasse being discarded in landfills every year is 123 million tons. Landfills take up a lot of land, which is already scarce in Hong Kong, and they create many harmful environmental problems such as the production of greenhouse gases that intensify global warming. Our project aims to upcycle bagasse waste to synthesize nanocellulose, which can be used to treat wastewater and to make a non-toxic, flexible and strong biofilm which can act as a replacement for cling films or plastic folders.

We synthesized nanocellulose from sugarcane bagasse by heating ground bagasse powder with nitric acid, sodium hydroxide and sodium hypochlorite separately, washing and filtering in between, and letting the mixture dry. This dried nanocellulose powder can be mixed with polluted water for an hour to adsorb the heavy metal ions, including mercury(II), lead(II) and copper(II) ions. Additionally, the nanocellulose powder can be heated with PVA and glycerol in the ratio of 10:6:1 to make a durable, flexible biofilm after drying.

Using sugarcane bagasse to make biofilm is more advantageous as it is a non-toxic and renewable material. Moreover, by upcycling bagasse waste into nanocellulose biofilm that has several applications, not only are we using up waste material that would have otherwise been wasted and taken up space in landfills, the folders or cling films the biofilm is used to produce can even replace current plastic ones. Since our biofilm is made of natural materials, it is biodegradable and far more environmentally friendly. Additionally, the nanocellulose we synthesized can more effectively adsorb heavy metal ions than untreated bagasse to treat wastewater. After using, the nanocellulose can even be regenerated and reused by removing the adsorbed heavy metal ions. This not only reduces the cost as nanocellulose would not have to be constantly resynthesized, it also reduces waste caused by throwing used nanocellulose away, further alleviating our waste problem.

Current industrial heavy metal ions removal uses the method of precipitation, which is only effective when the heavy metal ions are concentrated, while our nanocellulose can adsorb metal ions even at low concentrations. Some current biofilms are synthesized from cornstarch. Unlike those that use food, our product is made from food waste, which helps in alleviating the food waste problem by upcycling it instead of using what could have been consumed. Our product is also better than starch-based biofilms as starch may cause mold growth while ours can be reused for longer. These features of our product mean that it is highly sustainable and eco-friendly, even with multiple applications in different fields, promoting “green skills” in society. If popularized, our product can help boost sustainable development, protecting the environment and its resources and solving current issues of the abundance of food and plastic waste. Not only can our current society benefit from it, but our future generations will also be able to live on planet Earth protected from having to solve our problems for us when the consequences become even more dire in the future.