Physicochemical properties of aqueous solutions of sodium glycinate in the non-precipitation regime from 298.15 to 343.15 K

The physicochemical properties,including the density,viscosity,and refractive index of aqueous solutions of sodium glycinate as a solvent for CO_2 absorption in the non-precipitation regime were measured under the wide temperature range of 298.15 to 343.15 K.The concentration of the sodium glycinate in an aqueous form in the non-precipitation regime was identified up to 2.0 mol ? L^(-1).The coefficients of thermal expansion values were estimated from measured density data.It was found that,the densities,viscosities and refractive indices of the aqueous sodium glycinate decrease with an increase in temperature,whereas with increasing sodium glycinate concentration in the solution,all three properties increase.Thermal expansion coefficients slightly increase with rising temperature and concentration.The measured values of density,viscosity and refractive index were correlated as a function of temperature by using the least squares method.The predicted data obtained from correlation equations for all measured properties were in fairly good agreement with the experimental data.

Effect of Different Ways of STPP Retarder Addition on Properties of Recycled Gypsum

We analyzed the influence of sodium polyphosphate（STPP） on the performances of recycled gypsum（RG）. This analysis was performed with two different ways of STPP addition： One was that the STPP was added into Plaster of Paris（POP）, then recycled plaster（R-SP） was obtained after a series of processes and the other was that the STPP was directly put into recycled plaster（R-PS）. The conclusions confirmed that STPP increased the water demand and delayed the hydration of R-PS. With regard to its hardened performance, STPP provided hardened recycled gypsum with a loose structure which led to the lower strength and higher water absorption than recycled plaster（R-P） without STPP. On the contrary, the water requirement and the setting time were decreased and shortened by STPP in R-SP, respectively. A dense structure was also possessed by R-SP which contributed to the high strength and low water absorption. The analysis shows that STPP is selectively chemisorbed on the（111） face of R-PS crystals, it inhibits the growth in c axis direction, resulting in the extending of setting time and the transformation of morphology, making the hardened R-PS crystals coarsened, which results in high W/P and low strength. Whereas the low W/P is made by both the rod-like crystals of low length-radius possessed by R-SP and the relatively high ζ-potential absolute value caused by –（PO_3Ca） on the surface of R-SP, leading to the complete development of crystals and their close overlapping, thus bringing about the increase of strength.

Effect of Konjac Glucomannan on Sodium Alginate Membrane

This paper introduces a blended membrane which is prepared by coagulation of sodium alginate and konjac glucomannan（KGM） in an aqueous solution, and studies the effect of different concentrations of KGM on sodium alginate films. The structural characterization of prepared blend film was implemented by scanning electron microscopy（SEM） and Fourier transform infrared spectroscopy（FT-IR）, and the optimum ratio was determined by comparing fracture elongation, moisture absorption and moisture retention. The results indicate that the two polysaccharide molecules, sodium alginate and KGM, in the blend membrane have a good compatibility. The surface of blend film is smooth and uniform. The addition of KGM can significantly improve the moisture absorption and moisture retention performance of sodium alginate film, and its mechanical performance is also improved to some extent. The ratio of sodium alginate and KGM is 3.2∶1.5.