UV-Visible Characterization of Zinc and Potassium Zinc Pyrophosphate

New Zn2P2O7, K2ZnP2O7 and KZn1.5P2O7 compounds were synthesized with conventional solid solid reaction method. The optical properties have been studied by using UV-Visible spectrophotometer. The optical band gaps (Eg) were found to be 3.76 eV, 3.39 eV and 3.59eV respectively. Optical parameters such as refractive index, Cauchy’s parameters and conductivity were deduced. The refractive index fitting in the visible range and the dispersion parameters (E0 and Ed) of these compounds were estimated using the Wemple–DiDomenico model.

Enzymatic depolymerization of highly crystalline polyethylene terephthalate enabled in moist-solid reaction mixtures

Less than 9% of the plastic produced is recycled after use, contributing to the global plastic pollution problem. While polyethylene terephthalate (PET) is one of the most common plastics, its thermomechanical recycling generates a material of lesser quality. Enzymes are highly selective, renewable catalysts active at mild temperatures; however, they lack activity toward the more crystalline forms of PET commonly found in consumer plastics, requiring the energy-expensive melt-amorphization step of PET before enzymatic depolymerization. We report here that, when used in moist-solid reaction mixtures instead of the typical dilute aqueous solutions or slurries, the cutinase from Humicola insolens can directly depolymerize amorphous and crystalline regions of PET equally, without any pretreatment, with a 13-fold higher space-time yield and a 15-fold higher enzyme efficiency than reported in prior studies with high-crystallinity material. Further, this process shows a 26-fold selectivity for terephthalic acid over other hydrolysis products.

Secondary Sintering Cement Clinker in SO2 Atmosphere: Composition and Structure Effects

A gas-solid reaction method was adopted in this work to explore the influence of SO2 gas on the composition and structure of secondary sintering cement clinker. In this process, the Portland cement clinker was secondarily sintered at different temperatures and a mixed gas mixed with SO2 was introduced simultaneously in a tube furnace. X-ray powder diffraction (XRD) combined with rietveld refinement was used to determine the phase composition of the cement clinker and the corresponding phase content. The experimental results showed that the increase in temperature conduced to increasing the content of SO3 solid solution, C2S and CaO, but decreasing the C3S content. Moreover, as the ratio of SO3/MgO (by mass) increases, the content of M1-type alite also increased. And the result of hydration heat release was positively correlated with the content of alite in the clinker. If the content of alite was low, the heat flow was low, as well as the cumulative heat, and vice versa.