Evaluation of Surface Properties and Antimony (Sb) Adsorption Performance of Mesoporous Silica Synthesized by Extracting Silica from Clay Defective Molding Sand Waste

In this study, an environmentally friendly solution was devised by replacing the tetraethyl orthosilicate (TEOS) used in the manufacture of mesoporous silica (SBA-15) with SiO₂ from clay defective molding sand waste to produce a novel adsorbent (W-SBA-15). The prepared W-SBA-15 was used to remove antimony (Sb) from groundwater. The content of SiO₂ in W-SBA-15 and its recyclability were evaluated. The surface properties of W-SBA-15 and SBA-15 were compared. The performance of the novel adsorbent (W-SBA-15) was compared with that of traditional SBA-15 made with TEOS and an adsorbent made of pure Jumunjin sand (J-SBA-15). The content of SiO₂ in W-SBA-15 was 89%, and the concentration of harmful substances did not exceed the legal standard. Thus, the molding sand waste was considered to be suitable for synthesizing mesoporous silica. The surface properties of the W-SBA-15 prepared here were similar to those of the traditional mesoporous material according to SEM, TEM, BET, and FT-IR measurements. To evaluate the adsorption performance, a batch test evaluating Sb adsorption was performed under various concentration, time, pH, temperature, and isothermal adsorption equilibrium conditions. As a result, the Sb removal efficiency was in the order of SBA-15 >W-SBA-15 > J-SBA-15. The Sb removal efficiency of SBA-15 and W-SBA-15 was over 90%. Therefore, the W-SBA-15 prepared in this study can be used as an adsorbent.