Solubility of Ethyl <i>p</i>‑Aminobenzoate in Six Alcohols within (283.15 to 327.15) K

The solubility of ethyl <i>p</i>-aminobenzoate (EPAB) was measured in six different alcohols (methanol, ethanol, <i>n</i>-propanol, <i>n</i>-butanol, isobutyl alcohol, isoamyl alcohol) within (283.15 to 327.15) K by the last solid disappearance method. The solubility increases with increasing temperature. The decreasing order satisfies the following sequence: methanol > ethanol > <i>n</i>-propanol > <i>n</i>-butanol > isoamyl alcohol > isobutyl alcohol. Four models, including modified Apelblat equation, <i>λh</i> model, NRTL model, and Wilson model, were used to correlate the experimental data of EPAB. It is found that the modified Apelblat equation, NRTL model, and Wilson model were suitable to correlate the solubility of EPAB in the selected solvents with an overall RAD less than 2%. In addition, the changes of thermodynamic properties of solution [standard molar enthalpy (Δ_dis<i>H</i>^o), standard molar entropy (Δ_dis<i>S</i>^o), and standard molar Gibbs energy (Δ_dis<i>G</i>^o)] were obtained. The results indicate that the dissolution process of EPAB in these alcohols is endothermic and an entropy-driven process

An Optical Algorithm for Relative Thickness of Each Monochrome Component in Multilayer Transparent Mixed Films

A modification of the two-flux Kubelka-Munk (K-M) model was proposed to describe the energy conservation of scattered light in colored mixed material with a defined scattered photometric, which is applied for the relative quantity distribution of each colored monochrome component in mixed material. A series of systematical experiments demonstrated a higher consistency with the reference quantity distribution than the common Lambert-Beer (L-B) law. Its application in the fibrogram of each component for measuring the cotton fiber&rsquo;s length was demonstrated to be good, extending its applicability to white and dark colored blended fibers, the length of which is harder to measure using L-B law

Synthesis of Methyl Sorbate Catalyzed by Deep Eutectic Solvent Based on Choline Chloride: Kinetics and Optimization

The synthesis process and kinetics of the esterification of methanol with sorbic acid catalyzed by deep eutectic solvents (DESs) were explored in this study. A series of green DESs composed of choline chloride (ChCl) and p-toluene sulfonic acid monohydrate (PTSA) were successfully prepared. Design and optimization of the process were conducted using the response surface methodology with Box-Behnen design. The influences of the value of z (z is the molar ratio of PTSA to ChCl), catalyst loading, methanol/sorbic acid molar ratio, and temperature on the conversion of sorbic acid were evaluated. Using ChCl-1.38PTSA as a catalyst, the kinetic data and chemical equilibrium compositions of the esterification were measured at a temperature range of 340.15–355.15 K. The UNIFAC model was utilized to estimate the equilibrium constants, and the thermodynamic data (ΔrH0, ΔrS0, ΔrG0) of the esterification reaction were calculated as well. The pseudohomogeneous model based on activity was then adopted to describe the reaction kinetics and the model fitted well with the experimental data. The activation energy of the forward and reverse reaction were calculated. In addition, the activity of ChCl-1.38PTSA declined not obviously after five cycles, suggesting that ChCl-1.38PTSA has good stability and recyclability