Ternary Equilibrium Systems Research Articles

Solid–Liquid Phase Equilibrium of Ammonium Dihydrogen Phosphate and Agricultural Grade Ammonium Polyphosphate (Degree of Polymerization Ranging from 1 to 8) for Mixed Irrigation Strategy

Water-soluble ammonium polyphosphate (APP) has the advantages of good solubility and slow-release characteristics and has the potential to be used in combination with monoammonium phosphate (MAP) as a high phosphorus content slow-release fertilizer to improve the utilization rate of phosphorus during irrigation. Herein, the effects of the APP1 concentration and temperature (278.2–313.2 K) on the solubility of MAP, solution density, and pH value in the ternary equilibrium system (APP1–MAP–water) were measured. The simplified Apelblat model, two empirical polynomials, and rational two-dimensional functions can describe the experimental solubility data, solution density, and pH value well, respectively, with reliable modeling parameters (R2 > 0.99). In the OptiMax1001 reactor, the focused beam reflectance measurement (FBRM), the particle-view measurement (PVM), and the ReactIR 15 probes were used to observe and reverse verify that they can be synergistically codissolved to achieve economic efficiency. Basic thermodynamic data and models can guide their collaborative application in irrigation to improve the phosphorus utilization rate.

An Application of the Extended Principal Component Analysis to Circular Dichroism and Optical Rotatory Dispersion. A Case of Poly(α-l-glutamic acid) in the Helix-Coil Transition Region

Abstract The extended principal-component-analysis (PCA) method has been applied to circular dichroism (CD) and optical rotatory dispersion (ORD). The validity of this method has been examined with ideal binary and ternary equilibrium systems, for which the data CD spectra and ORD curves were computer-generated. Satisfactory results were obtained for these multicomponent optically active systems. As an example, the ultraviolet CD spectra of poly(α-l-glutamic acid) in the pH-induced helix-coil transition region were analyzed with the PCA procedure. By the extended PCA method, the pure CD spectra for both helix and random-coil conformations and the helix fractions in the transition region were determined from eight experimentally obtained CD spectra. By introducing an empirical parameter α into the Henderson-Hasselbalch equation, the helix-coil transition curve was reproduced reasonably well.