Kinetic Analysis of Methane-Propane Hydrate Formation by the Use of Different Impellers

Explicating the amino acid effects for methane storage in hydrate form

Methane emissions increase day by day into the atmosphere and influence global temperatures. The necessity to capture these emissions at the source point is a primary concern. Several methods/techniques are being adopted to capture these emissions. The methane hydrates could be a viable method among them. The present study exposes various amino acids' effects in methane hydrate formation. The formation temperatures are around ∼268 to 273 K except for l-cys, which is about ∼277 K. The required subcooling for hydrates to trigger is high and is increasing in the order l-thr > l-met > l-phe > l-val > l-cys. The methane hydrate conversion is high in the presence of nearly all the amino acids with methane uptake capacity of ∼80-85%, except l-thr, for which it is only 30% of the total uptake capacity. The side chain of l-thr comprises the hydroxyl group, making it a polar and uncharged amino acid. It is ascertained that hydroxyl groups alone can form hydrogen bonds with water, increasing the hydrophilicity and solubility of molecules, causing lesser conversion in the l-thr system. The gas uptake kinetics is faster in l-met and l-phe systems (t 90 ∼ 40 min), and sluggish kinetics is observed in l-cys, l-val, and l-thr systems. The investigations positively indicate using amino acids, l-met, l-phe, l-cys, and l-val as efficient materials for methane gas capture and storage in hydrate form, although not l-thr. Amino acids are readily dissolvable in water and could be easily pelletized for methane gas storage and transportation.

Synthesis and Heavy-Metal Sorption Studies of N,N-Dimethylacrylamide-Based Hydrogels

In this work, a hydrogel system was produced via radical polymerization of N,N-dimethylacrylamide and 2-acrylamido-2-methylpropanesulfonic acid in the presence of N,N-methylene-bis-acrylamide as a crosslinker and ammonium persulfate as an initiator. Parameters that impact the conversion of copolymerization (such as initial concentration of monomers, temperature, initiator dose, and time) were studied. The swelling degree of the hydrogel was investigated with the addition of a crosslinker and initiator at different pH levels. A hydrogel with high conversion and high swelling degree was selected to investigate their ability for adsorption of Pb(II) ions from solutions. Adsorption behavior of Pb(II) ions in a hydrogel was examined as a function of reaction time and concentration of lead ions from a solution of Pb(II) ions.

Kinetic analysis of dual impellers on methane hydrate formation

This study investigates the effects of types of impellers and baffles on methane hydrate formation. Induction time, water conversion to hydrates (hydrate yield), hydrate formation rate and hydrate productivity are components that were estimated. The initial hydrate formation rate is generally higher with the use of Ruston turbine (RT) with higher values 28.93 × 10−8 mol/s in RT/RT with full baffle (FB) experiment, but the decline rate of hydrate formation was also high compared to up-pumping pitched blade turbine (PBTU). Power consumption is higher also in RT/RT and PBT/RT with higher value 392,000 W in PBT/RT with no baffle (NB) experiment compared to PBT/PBT and RT/PBT experiments respectively. Induction time values are higher in RT/RT experiments compared to PBT/PBT ones. Hydrate yield is always smaller when there is no baffle in all four groups of experiments while the higher values exist in experiments with full baffle. It should be noticed that PBT is the same with PBTU, since all experiments with mixed flow have upward trending.