The adsorption of methyl red (MR) isomers (ortho, meta, and para) on metal-organic frameworks (MOFs) was investigated by using a fluorescence quenching technique. All three MR isomers were found to quench the fluorescence of MOFs effectively. Nonlinear fluorescence quenching trends were observed in Stern-Volmer plots. A modified nonlinear Stern-Volmer equation with the concepts of multiple adsorption sites, adsorption strength, and quencher accessibility was successfully adopted to fit the fluorescence quenching data. The fitted parameters were correlated with the structural properties of MRs and MOFs. The order of quenching efficiency was found to be m-MR > p-MR > o-MR for all MOFs. This indicates that MR molecules not only adsorb via carboxylate-metal bonding but also adsorb through π-π interactions between the aromatic rings of MR and linker molecules in MOFs. The position of the carboxylate group in MRs and the structure of the linkers in MOFs are the key factors affecting the fluorescence quenching efficiency.
Foamed concrete is prepared by the use of volcanic rock powder and ordinary portland cement and by means of chemical foaming method. The chemical composition and morphology of volcanic rock powder are analyzed,and the effect of volcanic rock powder addition into the portland cement slurry on the properties of foamed concrete is discussed.The results that the properties of the foam concrete could be prepared by controlling the addition of the volcanic rock powder content is 20%, The Compressive strength is as high as 1.36Mpa. The thermal conductivity is 0.048W/(m·K) and the dry density is 254kg/m3 for 28 days curing age. The main compositions of volcanic rock powder is SiO2 and the volcanic rock has a large number of closed and open pores.
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