Hydration of natural gas hydrogen mixture test equipment

The use of hydrogen as an energy source is advantageous because its combustion processes only produce water vapor, but not carbon dioxide. This excess energy can be stored in underground gas storage facilities, where it is delivered mixed with natural gas. In gas- and oil industry the formation of hydrate crystals can cause significant damages. A huge amount of hydrate crystal is formed, it can cause hydrate plugs in the pipeline. Like natural gas, hydrate formation occurs in the case of a natural gas-hydrogen mixture. The paper presents a method which can be used to study hydrate formation in natural gas-hydrogen mixture.

Effects of Glycine, L-Arginine and their Complexation with Polyvinylpyrrolidone on Tetrahydrofuran Hydrate Formation

Hydrophilic amino acids as a new type hydrate inhibitor is a hot topic for scholars. In this paper, the influence of glycine and L-arginine, and their complexation with polyvinylpyrrolidone (PVP) on hydrate formation were clarified by tetrahydrofuran (THF) hydrate formation simulation experiments, and the intrinsic influence mechanism was revealed by many experimental methods. The results show that glycine has a strong inhibitory effect on water molecules because of its strong disturbance to water molecules, and the inhibitory effect is the best when the addition of glycine is 1.0 wt%. Due to the disturbance and binding of hydrophilic amino acids to water molecules, the effect of PVP on the semi-cage structure of water molecules as well as the adsorption and encapsulation of hydrate crystal particles, the combination of glycine and L-arginine and PVP has synergistic inhibitory effect on the formation of THF hydrate. When the total amount of hydrate inhibitor is 1.0 wt%, the synergistic inhibition ability of glycine and PVP is stronger. The results obtained in this paper provide an experimental and theoretical basis for the research and development of new hydrate inhibitors.

A Comprehensive Study of a New 1.75 Hydrate of Ciprofloxacin Salicylate: SCXRD Structure Determination, Solid Characterization, Water Stability, Solubility, and Dissolution Study

One problem that often arises during the formulation of a dosage form is the solubility and dissolution of the active ingredients. This problem arises in ciprofloxacin, which is a BCS class IV fluoroquinolone antibiotic. A pseudopolymorph is a kind of polymorph in which the number of hydrates is different. In this study, a new pseudopolymorph comprised of ciprofloxacin and salicylic acid was found, namely the salt ciprofloxacin salicylate 1.75 hydrate form. This new solid phase was analyzed by Fourier-transform infrared spectroscope (FTIR), Raman spectroscopy, and thermal analysis and proven by Powder X-ray Diffractometry (PXRD) analysis. The crystal structure was successfully determined by Single Crystal X-ray Diffractometry (SCXRD) analysis. It was found that the piperazinyl group of ciprofloxacin is protonated by H+ from the carboxylic group of salicylic acid. In the unit cell, two ciprofloxacin and two salicylic acid molecules were independent with four water molecules, in which one water molecule had 0.5 occupancy due to inversion symmetry. Interestingly, this hydrate crystal dehydrated by grinding for 105 minutes forms an anhydrous crystalline phase, which was analyzed with FTIR, Raman spectroscopy, thermal analysis, and PXRD. The solubility and dissolution tests were carried out using UV-Visible spectrophotometry and a multiple linear regression method. This new hydrate solid phase has a better profile than the original ciprofloxacin crystal, according to the solubility and dissolution tests.