A large quantity of waste plywood panel for concrete form has been generated with the progress of construction industry and its effective utilization becomes an urgent social problem. In this study, the production of charcoal from waste plywood panel (charcoal W) and its adsorption characteristics of anionic dyes were investigated. The plywood panel was first pulverized as a chip and carbonized under nitrogen atmosphere. The content of metal ions was found to be considerably larger in the charcoal W than in that from virgin panel (charcoal V). The partial graphitization of the charcoal W was proceeded by the catalytic action of the contained metal ions, causing the specific surface area of the charcoal W to became larger than that of the charcoal V. The adsorption isotherms of three anionic dyes were obtained and well treated by the Freundlich adsorption equation. The adsorption ability of acid blue 92 and acid blue 90 with the charcoal W of large molecular size became larger than those of the charcoal V and activated carbon (AC). The charcoal W was also found to have four times more mesopores capacity compared to AC. The charcoal W can be useful in environmental purification as an excellent absorbent.
15BaO-10PbO-5SrO-70P2O5 phosphate glass has been prepared by 2.45 GHz microwave heating. The glass prepared by microwave heating (MW glass) had higher stability against temperature and humidity than the glass prepared by conventional electric furnace heating (EF glass). In order to know the structural difference between MW and EF glasses, we measured 31P MAS NMR. Q0 band for single PO4 group at 0.0 ppm, Q1 band for end PO4 group at -12.0 ppm and Q2 band for middle PO4 group at -28.0 ppm were observed in the spectrum of EF glass. It is noteworthy that in the spectra of MW glasses, the strong Q3 band for branching PO4 group newly appeared around -45 ppm in addition to Q0, Q1 and Q2. Furthermore, MW glass has higher value of the degree of polymerization than EF glass. The presence of branching points means that MW glass has three-dimensional structure by normal condensation polymerization as thermal effect and radical polymerization as non-thermal microwave effect. Three-dimensional glass network and higher polymerization lead to higher stability of MW glass.
Lead-free glasses with a low melting point and good chemical durability are desirable for the sealing process in the ceramic and electronic fields. In this study, Li2B4O7, ZnO, and BaO were used to prepare lead-free sealing glasses with a low melting temperature. Glass transition temperature, softening temperature, and thermal expansion coefficients were measured in detail in the ternary systems (Li2B4O7-ZnO-BaO). The glass forming region, thermal stability, and surface morphology were evaluated. The dependencies of these properties on composition were quantitatively characterized. The ternary system glass (57.1 mol%Li2B4O7-33.9 mol%ZnO-8.97 mol%BaO) exhibited a low melting property, expedient thermal expansion coefficient, an amorphous structure, and good sealing properties. Especially, the ternary lead-free glass (25.6 mol%Li2B4O7-17.8 mol%ZnO-56.6 mol%BaO) showed the lowest glass transition temperature. To date, as borate glasses with the lower melting property are not developed, lead-free glasses proposed in this study will be epoch-making sealing materials for electronic products.