Prepartion of Polythiourea-immobilized Active Charcoal and Its Utilization for Selective Adsorption of Mercury (II) lon

Abstract

Several polyamines were reacted with carbon disulfide in water in the presence of palm-shell active charcoal. The reaction proceeded readily after the adsorption of the reactants on the charcoal to form polythiourea. The resultant polythiourea was firmly immobilized on the surface of the charcoal.
The polythiourea-immobilized charcoals showed superior adsorption ability for mer cury (II) ion. The highest adsorption was obtained for the polythiourea formed from polyethylenimine with molecular weight of 1800 and for which the immobilization ratio relative to charcoal was 11.8 wt%. The increased immobilization higher than this value caused decreases in surface area and adsorption ability. It was supposed that a thin layer of the polythiourea was formed on the charcoal in the former case. The polythiouraimmobilized charcoal was packed in a glass-tube, and for which an aqueous solution of 10 ppm of mercury (II) ion was eluted at a velocity of L V= 5. The mercury (II) ion concentration in the eluted solution rose above the upper limit value permitted by law (5 ppb) after 10 h. The total adsorption of mercury (II) ion was 0.6 mol per 1 liter of the polythiourea-immobilized charcoal.
The polythiourea-immobilized charcoal prepared by this method should p ractically be used as adsorbent of mercury (II) ion.