Abstract Development of radio-purification for the large-volume liquid scintillator detector is a key to enhance search sensitivities in neutrino physics. In this paper, we describe laboratory studies on the radio-purification of the liquid scintillator detector by using the metal scavenger, aiming at the improved search for the neutrinoless double beta decay in KamLAND-Zen. In the purification tests, the 210 Pb reduction efficiency was evaluated. Based on the purification performance in small-scale system, we designed a large adsorption column for the metal scavenging applicable to the KamLAND purification system. We produced the column and constructed a purification test bench, and confirmed the 212 Pb reduction efficiency, the process speed, the LS contamination and quality changes, and the stability of chemical components in the Xe-LS. We found that the metal scavenging is a practical method for the large-volume LS purification, and will be effective to reduce metallic radioactive elements.