Silica Adsorption from Boiler Effluent Using Activated Charcoal Derived from Palm Oil Fibre Waste with H3PO4 Activator - Ricky Fernando; Shintawati Shintawati; Livia Rhea Alvita; Yeni Ria Wulandari; Adityas Agung Ramandani; Febrina Arief (CHEESA)