▎ 摘　　要

NOVELTY - An adsorbent (51) contains oxidized graphene or oxidized graphite which has a carboxyl group and phenolic hydroxyl group. The adsorbent desorbs 1 or more portion of calcium ion adsorbed by the liquid containing calcium ion and having pH of 7, and 1 or more portion of calcium ion adsorbed in the acidic liquid of pH of 2-6. USE - Adsorbent used for water softener and electrolyzed water manufacturing apparatus (all claimed). ADVANTAGE - The adsorbent improves the water-softening efficiency of electrolyzed water manufacturing apparatus and enables simple regeneration. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) water softener, which contains the adsorbent; and (2) electrolyzed water manufacturing apparatus (10a), which has electrolytic cell (11) which has an anode chamber (16) and cathode chamber (17), a pair of electrode (21,22) arranged in the anode chamber and cathode chamber respectively, power supply (30) for applying voltage to the electrode gap, water supply unit which supplies water to the anode chamber and cathode chamber, salt water supply unit which supplies salt water to the electrolytic cell, metal-ion removal unit (12) which removes the metal ion in the water supplied to the electrolytic cell and regeneration unit to flow acidic electrolyzed water to the metal-ion removal unit and to regenerate the metal-ion removal unit. DESCRIPTION OF DRAWING(S) - The drawing shows the conceptual view of electrolyzed water manufacturing apparatus. Electrolyzed water manufacturing apparatus (10a) Electrolytic cell (11) Metal-ion removal unit (12) Salt water tank (13) Acidic electrolyzed water tank (14) Cathode chamber (15) Anode chamber (16) Intermediate chamber (17) Cathode (21) Anode (22) Power supply (30) Adsorbent (51)