A template-free method of preparing zeolites from biomass can include using rice husk ash waste material as a precursor material. The zeolites can include ZSM-5 zeolites, such as, hierarchical pure zeolites and metal-loaded (Cu, Ni) ZSM-5 zeolites. This method allows for production of zeolites in a low cost and environmentally friendly manner. These ZSM-5 zeolites may be used for numerous applications, including killing cancer cells. The cancer cells may be human lung cancer cells.
