Preparation of humidity-controlling porous ceramics from volcanic ash and waste glass

This work investigated the preparation of a humidity-controlling porous ceramic via sintering of a mixture of volcanic ash soil and waste glass at 800–815 °C for 5–10 min. The final products were analyzed to identify the porous and mechanical properties, the moisture adsorption–desorption performance characteristics, and the adsorbed moisture amount. The most superior ceramic product, manufactured by mixing 30% weathered volcanic ash and 70% waste glass, was sintered at 800 °C for 5 min. The porous properties included a BET surface area of 163.73 ± 12 m2/g, porosity of 52.08 ± 2.1%, and a pore size of approximately 9 nm in diameter. The total amount of water adsorbed by the superior ceramic product was 0.047 cm3/g. In addition, the mechanical characteristics, including a bulk density of 1.34 ± 0.2 g/cm3, 2.61 ± 0.1% shrinkage, 4.64 ± 0.3% ignition loss, and 6.58 ± 0.4 MPa bending strength, are consistent with those of commercial porous ceramics. The leaching concentration of heavy metals in the final products were all well below the TCLP regulation limits. Thus, the most superior products meet the standards for commercial porous ceramics.