Factory Tea Waste Biosorbent for Cu(II) and Zn(II) Removal from Wastewater Patrick Tan Peng Jun, Wan Nur Aisyah Wan Osman, Shafirah Samsuri, Juniza Md Saad, Muhamad Fadli Samsudin and Eduard Hernández Yáñez E3S Web Conf., 287 (2021) 04006 Published online: 06 July 2021 DOI: 10.1051/e3sconf/202128704006