AIP Conference Proceedings [AIP Publishing PROCEEDINGS OF THE 3RD INTERNATIONAL SEMINAR ON METALLURGY AND MATERIALS (ISMM2019): Exploring New Innovation in Metallurgy and Materials - Tangerang Selatan, Indonesia (23–24 October 2019)] PROCEEDINGS OF THE 3RD INTERNATIONAL SEMINAR ON METALLURGY AND MATERIALS (ISMM2019): Exploring New Innovation in Metallurgy and Materials - Removal of methylene blue using biochar from cassava peel (Manihot utilissima) modified by sodium dodecyl sulphate (SDS) surfactant