<![CDATA[Developing an adsorbent from activated sludge waste of crumb rubber industry which was activated by H3PO4 for Adsorption of Cr(VI) had been done. The research was carried out by characterization of activated carbon in accordance with Indonesia National Standard (SNI) 06-3730-1995, involved determination of iodine absorption, water content, and bounded carbon content. The research was conducted in batch system for activated carbon and adsorbent without activation, by observed pH sollution, contact time, and initial concentration of the treatment solution. Determination of maximum absorption capacity of activated carbon on Cr(VI) used the Langmuir isotherm equation. From the characterization study of activated carbon was obtained that adsorption of iodine 482.6 mg/g, water content 0.14%, and bonded carbon content 24.925%. The results revealed that H3PO4 activator affected the adsorption of Cr(VI). Research with batch systems were obtained the optimum pH 2, contact time 120 minutes, and the optimum concentration 50 mg/L for adsorbent without activation and optimum pH 3, contact time 60 minutes, and the optimum concentration 50 mg/L for activated carbon. The maximum adsorption capacity was obtained 1.16 mg/g for adsorbent without activation and 1.99 mg/g for activated carbon.ABSTRAK Pengembangan adsorben dari limbah lumpur aktif Industri Crumb Rubber yang diaktivasi dengan H3PO4 untuk menyerap ion Cr(VI) telah dilakukan. Pada penelitian dilakukan karakterisasi karbon aktif sesuai dengan Standar Nasional Indonesia (SNI) 06-3730-1995, meliputi penentuan daya serap terhadap iodin, kadar air, dan kadar karbon terikat. Penelitian dilakukan dengan sistem batch terhadap karbon aktif dan adsorben tanpa aktivasi, dengan mengamati pH larutan, waktu kontak, dan konsentrasi awal larutan. Penentuan kapasitas serapan maksimum karbon aktif terhadap Cr(VI) menggunakan persamaan Isoterm Langmuir. Hasil penelitian karakterisasi karbon aktif didapatkan daya serap terhadap iodin 482,6 mg/g, kadar air 0,14%, dan kadar karbon terikat 24,925%. Dari hasil penelitian menunjukkan aktivator H3PO4 mempengaruhi daya serap terhadap Cr(VI). Penelitian dengan sistem batch didapatkan pH optimum 2, waktu kontak 120 menit, dan konsentrasi optimum 50 mg/L untuk adsorben tanpa aktivasi dan pH optimum 3, waktu kontak 60 menit, dan konsentrasi optimum 50 mg/L untuk karbon aktif. Kapasitas serapan maksimum didapatkan 1,16 mg/g untuk adsorben tanpa aktivasi dan 1,99 mg/g untuk  karbon aktif. ]]>
