An Efficient Way to Synthesize Hiroshima University Silicate-1 (HUS-1) and the Selective Adsorption Property of Ni2+ from Seawater

Abstract An alternative and efficient way to synthesize HUS-1 (Hiroshima University Silicate-1, Si10O24H8·2[(CH3)4N]), and a new notable function of HUS-1 are reported. HUS-1, which is an ast-type layered silicate, was originally synthesized through a complicated process from two kinds of dealuminated zeolites, FAU and *BEA, with tetramethylammonium (TMA) and benzyltrimethylammonium hydroxides, respectively. In this article, the synthesis of HUS-1 by using only amorphous silica and TMA as a silica source and a structure directing reagent, respectively, with varied temperature, time, and composition of a starting mixture containing water, TMA hydroxide, sodium hydroxide, and amorphous silica, in the presence or the absence of a seed crystal was examined to find that HUS-1 successfully formed for a wide range of NaOH/SiO2 (0.2–0.6) and TMA/SiO2 (0.2–0.8) ratios and reaction time (3–21 days) at a H2O/SiO2 ratio of 5.5 and reaction temperature of 140 °C in the presence and the absence of a seed crystal. The particle size and crystallinity of HUS-1 varied depending on the synthetic conditions. The obtained HUS-1 selectively adsorbed Ni2+ from a mixed electrolytes solution mimicking seawater. The maximum amount of the adsorbed Ni2+ on HUS-1 was dependent on the synthetic conditions.